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@article{faucris.106832484,
abstract = {Complete density-matrix equations and a one-photon counting probability are used to examine the photon statistics of fluorescence light of a single three-level atom, weakly coupled to an external cavity of low Q value. The internal structure of the atom is supposed to be characterized by a weak and a strong transition. The strong transition is coherently driven by an external laser field, whereas no external field is acting on the weak transition. In free space the system exhibits quantum jumps. By placing the atom within the mirrors of an external cavity, tuned close to the transition frequency of the two upper levels, modifications in the quantum jump behavior of the atom are shown due to a modified spontaneous decay rate between the two states. In particular, it is demonstrated that the effect of the cavity is to modify the repetition rate of quantum jumps into the metastable dark state and the average duration of bright periods of fluorescence, whereas the average duration of dark periods is not changed in first order of the spontaneous decay rates involved. In view of current experiments in our laboratory a quantitative analysis is presented for the special case of a single indium ion located between the mirrors of a high-order symmetric confocal cavity.},
author = {von Zanthier, Joachim and Agarwal, Girish S. and Walther, Herbert},
doi = {10.1103/PhysRevA.56.2242},
faupublication = {no},
journal = {Physical Review A},
pages = {2242-2248},
peerreviewed = {Yes},
title = {{Cavity}-induced modifications of quantum jumps},
volume = {56},
year = {1997}
}
@article{faucris.116522384,
abstract = {We discuss the possibility of quantum interferences and entanglement of photons that exist at different intervals of time, i.e., one photon being recorded before the other has been created. The corresponding two-photon correlation function is shown to violate Bell's inequalities. (c) 2011 Optical Society of America},
author = {Wiegner, Ralph and Thiel, Christoph and von Zanthier, Joachim and Agarwal, G. S.},
doi = {10.1364/OL.36.001512},
faupublication = {yes},
journal = {Optics Letters},
pages = {1512-1514},
peerreviewed = {Yes},
title = {{Quantum} interference and entanglement of photons that do not overlap in time},
volume = {36},
year = {2011}
}
@article{faucris.106828524,
abstract = {Superradiance, i.e., spontaneous emission of coherent radiation by an ensemble of two-level atoms in collective states introduced by Dicke in 1954, is one of the enigmatic problems of quantum optics. The startling gist is that even though the atoms have no dipole moment they radiate with increased intensity in particular directions. Following the advances in our understanding of superradiant emission by atoms in entangled W-states we examine the quantum statistical properties of superradiance. Such investigations require the system to have at least two excitations in order to explore the photon-photon correlations of the radiation emitted by such states. We present specifically results for the spatially resolved photon-photon correlations of systems prepared in doubly excited W-states and give conditions when the atomic system emits nonclassial light. Equally, we derive the conditions for the occurrence of bunching and even of superbunching, a rare phenomenon otherwise known only from nonclassical states of light like the squeezed vacuum. We finally investigate the photon-photon cross correlations of the spontaneously scattered light and highlight the nonclassicalty of such correlations. The theoretical findings can be implemented with current technology, e.g., using ions in a linear rf-trap, atoms in an optical lattice or quantum dots in a cavit},
author = {Bhatti, Daniel and von Zanthier, Joachim and Agarwal, Girish S.},
doi = {10.1038/srep17335},
faupublication = {yes},
journal = {Scientific Reports},
peerreviewed = {Yes},
title = {{Superbunching} and {Nonclassicality} as new {Hallmarks} of {Superradiance}},
volume = {5},
year = {2015}
}
@article{faucris.119199564,
abstract = {We present a mathematical proof of the algorithm allowing one to generate all-symmetric and nonsymmetric-total angular momentum eigenstates in remote matter qubits by projective measurements, proposed in Maser et al. [Phys. Rev. A 79, 033833 (2009)]. By deriving a recursion formula for the algorithm we show that the generated states are equal to the total angular momentum eigenstates obtained via the usual quantum-mechanical coupling of angular momenta. In this way we demonstrate that the algorithm is able to simulate the coupling of N spin-1/2 systems, and to implement the required Clebsch-Gordan coefficients, even though the particles never directly interact with each othe},
author = {Ammon, C. and Maser, Andreas and Schilling, Uwe and Bastin, T. and von Zanthier, Joachim},
doi = {10.1103/PhysRevA.86.052308},
faupublication = {yes},
journal = {Physical Review A},
peerreviewed = {Yes},
title = {{Simulating} the coupling of angular momenta in distant matter qubits},
volume = {86},
year = {2012}
}
@article{faucris.119207484,
abstract = {We report on recent experiments to observe the reflection of atoms off an enhanced evanescent wave. Optical measurements yield an enhancement factor of three orders of magnitude for the intensity of the evanescent wave. We have thus reflected atoms with detunings up to 140 GHz. We present results showing that the atoms at normal incidence are not reflected specularly but with an additional spreading of four recoil velocities in the direction orthogonal to the incidence direction. This effect is attributed to the surface roughness of the prism. Copyright © 1996 by MAHK Hayka/Interperiodica Publishing.},
author = {Kaiser, Robin and Labeyrie, Guillaume and Landragin, Arnaud and Vansteenkiste, N and Westbrook, Christoph and von Zanthier, Joachim and Aspect, Alain},
faupublication = {no},
journal = {Laser Physics},
pages = {409-413},
peerreviewed = {Yes},
title = {{Detecting} bouncing atoms},
url = {https://www.scopus.com/inward/record.url?partnerID=HzOxMe3b&scp=0030545814&origin=inward},
volume = {6},
year = {1996}
}
@article{faucris.121776644,
abstract = {The different behavior of first-order interferences and second-order correlations are investigated for the case of two coherently excited atoms. For intensity measurements this problem is in many respects equivalent to Young's double-slit experiment and was investigated in an experiment by Eichmann [Phys. Rev. Lett. 70, 2359 (1993)] and later analyzed in detail by Itano [Phys. Rev. A 57, 4176 (1998)]. Our results show that in cases where the intensity interferences disappear the intensity-intensity correlations can display an interference pattern with a visibility of up to 100%. The contrast depends on the polarization selected for the detection and is independent of the strength of the driving field. The nonclassical nature of the calculated intensity-intensity correlations is also discussed.},
author = {Agarwal, Girish S. and von Zanthier, Joachim and Skornia, Christoph and Walther, Herbert},
doi = {10.1103/PhysRevA.65.053826},
faupublication = {no},
journal = {Physical Review A},
peerreviewed = {Yes},
title = {{Intensity}-intensity correlations as a probe of interferences under conditions of noninterference in the intensity},
volume = {65},
year = {2002}
}
@article{faucris.108134884,
abstract = {In this paper we investigate the close relationship between Dicke superradiance, originally predicted for an ensemble of two-level atoms in entangled states, and the Hanbury Brown and Twiss effect, initially established in astronomy to determine the dimensions of classical light sources such as stars. By studying the state evolution of the fields produced by classical sources-defined by a positive Glauber-Sudarshan P function-when recording intensity correlations of higher order in a generalized Hanbury Brown and Twiss setup we find that the angular distribution of the last detected photon, apart from an offset, is identical to the superradiant emission pattern generated by an ensemble of two-level atoms in entangled symmetric Dicke states. We show that the phenomenon derives from projective measurements induced by the measurement of photons in the far field of the sources and the permutative superposition of quantum paths identical to those leading to superradiance in the case of single photon emitters. We thus point out an important similarity between classical sources and quantum emitters upon detection of photons if the particular photon source remains unknown. We finally present a compact result for the characteristic functional which generates intensity correlations of arbitrary order for any kind of light sourc},
author = {Bhatti, Daniel and Oppel, Steffen and Wiegner, Ralph and Agarwal, Girish and von Zanthier, Joachim},
doi = {10.1103/PhysRevA.94.013810},
faupublication = {yes},
journal = {Physical Review A},
peerreviewed = {Yes},
title = {{Simulating} {Dicke}-like superradiance with classical light sources},
volume = {94},
year = {2016}
}
@article{faucris.116525244,
abstract = {We propose a method for the generation of a large variety of entangled states, encoded in the polarization degrees of freedom of N photons, within the same experimental setup. Starting with uncorrelated photons, emitted from N arbitrary single-photon sources, and using linear optical tools only, we demonstrate the creation of all symmetric states (e. g., GHZ and W states), as well as all symmetric and nonsymmetric total angular momentum eigenstates of the N-qubit compoun},
author = {Maser, Andreas and Wiegner, Ralph and Schilling, Uwe and Thiel, Christoph and von Zanthier, Joachim},
doi = {10.1103/PhysRevA.81.053842},
faupublication = {yes},
journal = {Physical Review A},
peerreviewed = {Yes},
title = {{Versatile} source of polarization-entangled photons},
volume = {81},
year = {2010}
}
@article{faucris.116520404,
abstract = {We introduce an observable for reading out a which-way detector in a Young-type interferometer whose eigenstates either contain full which-way information or none at all. We calculate the which-way knowledge kappa that can be retrieved from this observable and find that kappa depends on the phase difference delta that the interfering quantum object accumulates on its passage through the interferometer. It turns out that for certain phase shifts kappa(delta) equals one, independent of the visibility of the interference pattern. In addition, within a certain range of phase shifts kappa(delta) can be larger than the which-way information obtained from the observable recognized to provide optimal which-way information on average. (C) 2012 Elsevier BM. All rights reserved.},
author = {Schilling, Uwe and von Zanthier, Joachim},
doi = {10.1016/j.physleta.2012.10.019},
faupublication = {yes},
journal = {Physics Letters A},
keywords = {Wave-particle duality;Which-way information;Quantum eraser;Micromaser},
pages = {3479-3484},
peerreviewed = {Yes},
title = {{Phase}-dependent which-way information},
volume = {376},
year = {2012}
}
@article{faucris.116521944,
abstract = {A scheme is discussed for measuring Nth-order coherences of two orthogonally polarized light fields in a single spatial mode at very limited experimental cost. To implement the scheme, the only measurements needed are the Nth-order intensity moments after the light beam has passed through two quarter-wave plates, one half-wave plate, and a polarizing beam splitter for specific settings of the wave plates. It is shown that this method can be applied for arbitrarily large N. A set of explicit values is given for the settings of the wave plates, constituting an optimal measurement of the Nth-order coherences for any N. For Fock states the method introduced here corresponds to a full state tomography. Applications of the scheme to systems other than polarization optics are discusse},
author = {Schilling, Uwe and von Zanthier, Joachim and Agarwal, G. S.},
doi = {10.1103/PhysRevA.81.013826},
faupublication = {yes},
journal = {Physical Review A},
month = {Jan},
peerreviewed = {Yes},
title = {{Measuring} arbitrary-order coherences: {Tomography} of single-mode multiphoton polarization-entangled states},
volume = {81},
year = {2010}
}
@article{faucris.123909544,
abstract = {We propose to use multiphoton interferences of photons emitted fromstatistically independent thermal light sources in combination with linear optical detection techniques to reconstruct, i.e., image, arbitrary source geometries in one dimension with subclassical resolution. The scheme is an extension of earlier work [S. Oppel et al., Phys. Rev. Lett. 109, 233603 (2012)], where N regularly spaced sources in one dimension were imaged by use of the Nth-order intensity correlation function. Here, we generalize the scheme to reconstruct any number of independent thermal light sources at arbitrary separations in one dimension, exploiting intensity correlation functions of order m >= 3. We present experimental results confirming the imaging protocol and provide a rigorous mathematical proof for the obtained subclassical resolutio},
author = {Classen, Anton and Waldmann, Felix and Giebel, Sebastian and Schneider, Raimund and Bhatti, Daniel and Mehringer, Thomas and von Zanthier, Joachim},
doi = {10.1103/PhysRevLett.117.253601},
faupublication = {yes},
journal = {Physical Review Letters},
peerreviewed = {Yes},
title = {{Superresolving} {Imaging} of {Arbitrary} {One}-{Dimensional} {Arrays} of {Thermal} {Light} {Sources} {Using} {Multiphoton} {Interference}},
volume = {117},
year = {2016}
}
@article{faucris.119203304,
abstract = {The emission characteristics in the fluorescence of two laser-driven dipole-dipole-interacting three-level atoms is investigated. When the light from both atoms is detected separately a correlation of the emission processes is observed in dependence of the dipole-dipole interaction. This opens the possibility to investigate the dipole-dipole interaction through the emission behavior. We present quantum Monte Carlo simulations which are in good agreement with the analytic solutions.},
author = {Skornia, Christoph and von Zanthier, Joachim and Agarwal, Girish S. and Werner, E and Walther, Herbert},
doi = {10.1103/PhysRevA.64.053803},
faupublication = {no},
journal = {Physical Review A},
peerreviewed = {Yes},
title = {{Monitoring} the dipole-dipole interaction via quantum jumps of individual atoms},
volume = {64},
year = {2001}
}
@article{faucris.116520624,
abstract = {An important topic of interest in imaging is the construction of protocols that are not diffraction limited. This can be achieved in a variety of ways, including classical superresolution techniques or quantum entanglement-based protocols. Here, we consider superresolving imaging in the far field using higher-order intensity correlations. We show that third-and fourth-order correlations can improve upon the first-and second-order correlations that are traditionally used in classical optics and Hanbury Brown-Twiss-type experiments. The improvement is achieved entirely by post-processing of the data. As a demonstrator, we simulate the far field intensity distribution of a circular aperture that emits thermal light and use maximum likelihood estimation to determine the radius of the aperture. We compare the achieved precision to the Cramer-Rao lower bound and find that the variance of measurements for the third-and fourth-order correlation functions are indeed closer to the Cramer-Rao bound than that of the second-order correlation function. The method presented here is general, and can be used for all kinds of incoherent emitters, geometries, and types of nois},
author = {Pearce, M. E. and Mehringer, Thomas and von Zanthier, Joachim and Kok, P.},
doi = {10.1103/PhysRevA.92.043831},
faupublication = {yes},
journal = {Physical Review A},
peerreviewed = {Yes},
title = {{Precision} estimation of source dimensions from higher-order intensity correlations},
volume = {92},
year = {2015}
}
@article{faucris.109061304,
abstract = {Superradiance typically requires preparation of atoms in highly entangled multiparticle states, the so-called Dicke states. In this paper we discuss an alternative route where we prepare such states from initially uncorrelated atoms by a measurement process. By measuring higher-order intensity-intensity correlations we demonstrate that we can simulate the emission characteristics of Dicke superradiance by starting with atoms in the fully excited state. We describe the essence of the scheme by first investigating two excited atoms. Here we demonstrate how via Hanbury Brown and Twiss type of measurements we can produce Dicke superradiance and subradiance displayed commonly with two atoms in the single excited symmetric and antisymmetric Dicke states, respectively. We thereafter generalize the scheme to arbitrary numbers of atoms and detectors, and explain in detail the mechanism which leads to this result. The approach shows that the Hanbury Brown and Twiss type of intensity interference and the phenomenon of Dicke superradiance can be regarded as two sides of the same coin. We also present a compact result for the characteristic functional which generates all order intensity-intensity correlation},
author = {Wiegner, Ralph and Oppel, Steffen and Bhatti, Daniel and von Zanthier, Joachim and Agarwal, G. S.},
doi = {10.1103/PhysRevA.92.033832},
faupublication = {yes},
journal = {Physical Review A},
peerreviewed = {Yes},
title = {{Simulating} superradiance from higher-order-intensity-correlation measurements: {Single} atoms},
volume = {92},
year = {2015}
}
@article{faucris.121748924,
abstract = {We demonstrate that intensity correlations of second order in the fluorescence light of N > 2 single-photon emitters may violate locality while the visibility of the signal remains below 1/root 2 approximate to 71%. For this, we derive a homogeneous Bell-Wigner-type inequality, which can be applied to a broad class of experimental setups. We trace the violation of this inequality back to path entanglement created by the process of detectio},
author = {Thiel, Christoph and Wiegner, Ralph and von Zanthier, Joachim and Agarwal, G. S.},
doi = {10.1103/PhysRevA.82.032116},
faupublication = {yes},
journal = {Physical Review A},
peerreviewed = {Yes},
title = {{Nonlocality} from {N} > 2 independent single-photon emitters},
volume = {82},
year = {2010}
}
@article{faucris.116536244,
abstract = {We have realized a resonant waveguide structure which enhances the intensity of an evanescent wave at a dielectric-vacuum interface by more than three orders of magnitude. We present a simple theoretical model including the effect of the losses in the waveguide, which gives a good description of the observed behaviour of the structure. We experimentally determine the enhancement factor by analysing the resonance of the reflected light intensity. This characterization technique allows for an easy in situ monitoring of the enhancement, which is a key feature for the understanding of atomic mirror experiments.},
author = {Labeyrie, Guillaume and Landragin, Arnaud and von Zanthier, Joachim and Kaiser, Robin and Vansteenkiste, N and Westbrook, Christoph and Aspect, Alain},
doi = {10.1088/1355-5111/8/3/022},
faupublication = {no},
journal = {Journal of Optics B Quantum and Semiclassical Optics},
pages = {603-627},
peerreviewed = {Yes},
title = {{Detailed} study of a high-finesse planar waveguide for evanescent wave atomic mirrors},
volume = {8},
year = {1996}
}
@article{faucris.121734844,
abstract = {Superradiance has been an outstanding problem in quantum optics since Dicke introduced the concept of enhanced directional spontaneous emission by an ensemble of identical two-level atoms. The effect is based on the correlated collective Dicke states which turn out to be highly entangled. Here we show that enhanced directional emission of spontaneous radiation can be produced also with statistically independent incoherent sources, via the measurement of higher-order correlation functions of the emitted radiation. Our analysis is applicable to a wide variety of quantum emitters, like trapped atoms, ions, quantum dots, or nitrogen-vacancy centers, and is also valid for incoherent classical emitters. This is experimentally confirmed with up to eight statistically independent thermal light sources. The arrangement to measure the higher-order correlation functions corresponds to a generalized Hanbury Brown-Twiss setup, demonstrating that the two phenomena, superradiance and the Hanbury Brown-Twiss effect, stem from the same interference phenomeno},
author = {Oppel, Steffen and Wiegner, Ralph and Agarwal, Girish Saran and von Zanthier, Joachim},
doi = {10.1103/PhysRevLett.113.263606},
faupublication = {yes},
journal = {Physical Review Letters},
peerreviewed = {Yes},
title = {{Directional} {Superradiant} {Emission} from {Statistically} {Independent} {Incoherent} {Nonclassical} and {Classical} {Sources}},
volume = {113},
year = {2014}
}
@article{faucris.116536024,
abstract = {A narrow transition of a single laser-cooled ion, stored in a radio-frequency trap, can serve as a reference for a frequency standard of very high accuracy and stability. For the implementation of such a system, we study the 5sS-5s5p P transition in In, at a wavelength of 237 nm. This resonance has a linewidth of 0.8 Hz, with systematic frequency shifts expected to be at the mHz level. A fractional resolution of 1.3 x 10 has been so far achieved, limited by the frequency instability of the clock laser used to excite the line. The absolute frequency of the S-P transition was measured using the frequency comb of a mode-locked fs laser, and as a reference a methane-stabilized He-Ne laser at 3.4 μm, which was calibrated against an atomic caesium fountain clock. The transition frequency was determined as 1267 402 452 899.92 (0.23) kHz, the uncertainty being limited by the uncertainty of the He-Ne standard. The short-term frequency stability of the clock laser was recently greatly improved. With a new laser set-up a linewidth < 4 Hz (FWHM) for integration times up to 26 s was achieved, using laser platforms which actively isolate from external mechanical vibrations.},
author = {Eichenseer, M and Nevsky, Alexander and Schwedes, Christian and von Zanthier, Joachim and Walther, Herbert},
doi = {10.1088/0953-4075/36/3/313},
faupublication = {no},
journal = {Journal of Physics B-Atomic Molecular and Optical Physics},
month = {Jan},
pages = {553-559},
peerreviewed = {Yes},
title = {{Towards} an indium single-ion optical frequency standard},
volume = {36},
year = {2003}
}
@article{faucris.121764544,
abstract = {We propose a technique to obtain subwavelength resolution in quantum imaging with potentially 100% contrast using incoherent light. Our method requires neither path-entangled number states nor multiphoton absorption. The scheme makes use of N photons spontaneously emitted by N atoms and registered by N detectors. It is shown that for coincident detection at particular detector positions a resolution of lambda/N can be achieve},
author = {Thiel, Christoph and Bastin, Thierry and Martin, J and Solano, Enrique and von Zanthier, Joachim and Agarwal, Girish S.},
doi = {10.1103/PhysRevLett.99.133603},
faupublication = {yes},
journal = {Physical Review Letters},
peerreviewed = {Yes},
title = {{Quantum} imaging with incoherent photons},
volume = {99},
year = {2007}
}
@article{faucris.123555344,
abstract = {We present a new possibility for the active frequency stabilization of a laser using transitions in neutral praseodymium. Because of its five outer electrons, this element shows a high density of energy levels leading to an extremely line-rich excitation spectrum with more than 25 000 known spectral lines ranging from the UV to the infrared. We demonstrate the active frequency stabilization of a diode laser on several praseodymium lines between 1105 and 1123 nm. The excitation signals were recorded in a hollow cathode lamp and observed via laser-induced fluorescence. These signals are strong enough to lock the diode laser onto most of the lines by using standard laser locking techniques. In this way, the frequency drifts of the unlocked laser of more than 30 MHz/h were eliminated and the laser frequency stabilized to within 1.4(1) MHz for averaging times > 0.2 s. Frequency quadrupling the stabilized diode laser can produce frequency-stable UV-light in the range from 276 to 281 nm. In particular, using a strong hyperfine component of the praseodymium excitation line E=16 502.616(7/2) cm(-1) -> E = 25442.742(9/2)(0) cm(-1) at lambda=1118.5397(4) nm makes it possible-after frequency quadruplication-to produce laser radiation at lambda/4=279.6349(1) nm, which can be used to excite the D(2) line in Mg(+).},
author = {Oppel, Steffen and Guthörlein, G. H. and Kaenders, W. and von Zanthier, Joachim},
doi = {10.1007/s00340-010-4007-9},
faupublication = {yes},
journal = {Applied Physics B-Lasers and Optics},
pages = {33-44},
peerreviewed = {Yes},
title = {{Active} laser frequency stabilization using neutral praseodymium ({Pr})},
volume = {101},
year = {2010}
}
@article{faucris.121735064,
abstract = {We calculate the radiative characteristics of emission from a system of entangled atoms which can have a relative distance larger than the emission wavelength. We develop a quantum multipath interference approach which explains both super-and subradiance though the entangled states have zero dipole moment. We derive a formula for the radiated intensity in terms of different interfering pathways. We further show how the interferences lead to directional emission from atoms prepared in symmetric W states. As a byproduct of our work we show how Dicke's classic result can be understood in terms of interfering pathways. In contrast to the previous works on ensembles of atoms, we focus on finite numbers of atoms prepared in well characterized state},
author = {Wiegner, Ralph and von Zanthier, Joachim and Agarwal, G. S.},
doi = {10.1103/PhysRevA.84.023805},
faupublication = {yes},
journal = {Physical Review A},
peerreviewed = {Yes},
title = {{Quantum}-interference-initiated superradiant and subradiant emission from entangled atoms},
volume = {84},
year = {2011}
}
@article{faucris.123556884,
abstract = {We demonstrate a novel approach of violating position-dependent Bell inequalities by photons emitted via independent single photon sources in free space. We trace this violation back to path entanglement created a posteriori by the selection of modes clue to the process of detection. (C) 2010 Elsevier B.V. All rights reserved.},
author = {Wiegner, Ralph and Thiel, Christoph and von Zanthier, Joachim and Agarwal, G. S.},
doi = {10.1016/j.physleta.2010.06.047},
faupublication = {yes},
journal = {Physics Letters A},
pages = {3405-3409},
peerreviewed = {Yes},
title = {{Creating} path entanglement and violating {Bell} inequalities by independent photon sources},
volume = {374},
year = {2010}
}
@article{faucris.121776204,
abstract = {We report on a frequency comparison of frequency-stabilized lasers located in remote laboratories resting on different foundations. By locating the lasers in this way correlated frequency excursions of the lasers are suppressed to a high degree. The beat signal between them shows a linewidth at the hertz level for averaging times of 1 s. The optical link is established by a 100 m single-mode optical fiber where the frequency noise induced by the fiber is reduced to the level of a few tens of millihertz. One laser is stabilized onto a Fabry-Perot resonator with a long-term precision of 25 mHz (fractional frequency instability, sigma(y) = 1.2 x 10(-16)), the highest lock fidelity obtained so far to our knowledge. (c) 2005 Optical Society of America.},
author = {Eichenseer, M and von Zanthier, Joachim and Walther, Herbert},
doi = {10.1364/OL.30.001662},
faupublication = {no},
journal = {Optics Letters},
pages = {1662-1664},
peerreviewed = {Yes},
title = {{Common}-mode-free frequency comparison of lasers with relative frequency stability at the millihertz level},
volume = {30},
year = {2005}
}
@article{faucris.116530964,
abstract = {We consider pump-probe spectroscopy of a single ion with a highly metastable (probe) clock transition that is monitored by using the quantum jump technique. For a weak clock laser, we obtain the well-known Autler-Townes splitting. For stronger powers of the clock laser, we demonstrate the transition to a new regime. The two regimes are distinguished by the transition of two complex eigenvalues to purely imaginary ones, which can be very different in magnitude. The transition is controlled by the power of the clock laser. For pump an resonance, we present simple analytical expressions for various linewidths and line positions.},
author = {von Zanthier, Joachim and Skornia, Christoph and Agarwal, Girish S. and Walther, Herbert},
doi = {10.1103/PhysRevA.63.013816},
faupublication = {no},
journal = {Physical Review A},
month = {Jan},
peerreviewed = {Yes},
title = {{Quantum} coherence in a single ion due to strong excitation of a metastable transition},
volume = {63},
year = {2001}
}
@article{faucris.112810984,
abstract = {Established x-ray diffraction methods allow for high-resolution structure determination of crystals, crystallized protein structures, or even single molecules. While these techniques rely on coherent scattering, incoherent processes like fluorescence emission-often the predominant scattering mechanism-are generally considered detrimental for imaging applications. Here, we show that intensity correlations of incoherently scattered x-ray radiation can be used to image the full 3D arrangement of the scattering atoms with significantly higher resolution compared to conventional coherent diffraction imaging and crystallography, including additional three-dimensional information in Fourier space for a single sample orientation. We present a number of properties of incoherent diffractive imaging that are conceptually superior to those of coherent method},
author = {Classen, Anton and Ayyer, Kartik and Chapman, Henry N. and Roehlsberger, Ralf and von Zanthier, Joachim},
doi = {10.1103/PhysRevLett.119.053401},
faupublication = {yes},
journal = {Physical Review Letters},
peerreviewed = {Yes},
title = {{Incoherent} {Diffractive} {Imaging} via {Intensity} {Correlations} of {Hard} {X} {Rays}},
volume = {119},
year = {2017}
}
@article{faucris.121785004,
abstract = {The absolute frequency of the In+ 5s(2) S-1(0)-5s5p P-3(0) clock transition at 237 nm was measured with an accuracy of 1.8 parts in 10(13). Using a phase-coherent frequency chain, we compared the S-1(0)-P-3(0) transition with a methane-stabilized He-Ne laser at 3.39 mum, which was calibrated against an atomic cesium fountain clock. A frequency gap of 37 THz at the fourth harmonic of the He-Ne standard was bridged by a frequency comb generated by a mode-locked femtosecond laser. The frequency of the In+ clock transition was found to be 1267 402 452 899.92(0.23) kHz, the accuracy being limited by the uncertainty of the He-Ne laser reference. This result represents an improvement in accuracy of more than 2 orders of magnitude over previous measurements of the line and now stands as what is to our knowledge the most accurate measurement of an optical transition in a single ion.s (C) 2000 Optical Society of America.},
author = {von Zanthier, Joachim and Becker, Thomas and Eichenseer, M and Nevsky, Alexander and Schwedes, Christian and Peik, E and Walther, Herbert and Holzwarth, R and Reichert, J and Udem, Thomas and Hänsch, Theodor and Pokasov, Pavel and Skvortsov, M N and Bagayev, S N},
doi = {10.1364/OL.25.001729},
faupublication = {no},
journal = {Optics Letters},
pages = {1729-1731},
peerreviewed = {Yes},
title = {{Absolute} frequency measurement of the {In}+ clock transition with a mode-locked laser},
volume = {25},
year = {2000}
}
@article{faucris.123957944,
abstract = {A Quantum Monte Carlo wave function approach is used to rule out the possibility of cooperative effects in the quantum jump statistics of adjacent three-level ions of the type discussed in a series of experiments and theoretical investigations. By deriving analytical results and examining quantum jumps in various subspaces, we track this outcome to the fact that a fast spontaneous decay inhibits dipole-dipole induced entanglement between the ions developing on a much slower time scale. This inhibition is demonstrated even for weak pumping of the fast transition. The Quantum Monte Carlo calculation thus sheds new light on the controversy arising from the findings of two recent conflicting experiments by Block et al. ( Eur. Phys. J. D, 7 (1999) 461) and Donald et al. (Europhys. Lett., 51 (2000) 388).},
author = {Skornia, Christoph and von Zanthier, Joachim and Agarwal, Girish S. and Werner, E and Walther, Herbert},
doi = {10.1209/epl/i2001-00572-5},
faupublication = {no},
journal = {EPL - Europhysics Letters},
pages = {665-671},
peerreviewed = {Yes},
title = {{Inhibition} of cooperative quantum jumps due to fast spontaneous decay},
volume = {56},
year = {2001}
}
@article{faucris.110576664,
abstract = {We propose to use intensity correlation microscopy in combination with structured illumination to image quantum emitters that exhibit antibunching with a spatial resolution reaching far beyond the Rayleigh limit. Combining intensity measurements and intensity autocorrelations up to order m creates an effective PSF with an FWHM shrunk by the factor root m. Structured illumination microscopy, on the other hand, introduces a resolution improvement of factor 2 by use of the principle of moire fringes. Here, we show that for linear low-intensity excitation and linear optical detection, the simultaneous use of both techniques leads to a theoretically unlimited resolution power, with the improvement scaling favorably as m + root m, dependent on the correlation order m. Hence, this technique should be of interest in microscopy for imaging a variety of samples, including biological ones. We present the underlying theory and simulations, demonstrating the highly increased spatial superresolution, and point out the requirements for an experimental implementation. (C) 2017 Optical Society of America},
author = {Classen, Anton and von Zanthier, Joachim and Scully, Marlan O. and Agarwal, Girish S.},
doi = {10.1364/OPTICA.4.000580},
faupublication = {yes},
journal = {Optica},
pages = {580-587},
peerreviewed = {Yes},
title = {{Superresolution} via structured illumination quantum correlation microscopy},
volume = {4},
year = {2017}
}
@article{faucris.108763424,
abstract = {We propose a new interferometric setup which displays a completely destructive generalized N-photon Hong–Ou–Mandel interference. The key property of this scheme is that it does not require any optical elements like beam splitters or integrated waveguide structures. The interference is intrinsically produced by the evolution of N photons in free space when emitted by N identical single photon sources and measured by N detectors in the far field. In this sense, the setup is a most simple and natural implementation of the Hong–Ou–Mandel interference effect, i.e. of a completely destructive multi-photon interference produced by independent incoherent sources.},
author = {Mährlein, Simon and Oppel, Steffen and Wiegner, Ralph and von Zanthier, Joachim},
doi = {10.1080/09500340.2016.1242790},
faupublication = {yes},
journal = {Journal of Modern Optics},
keywords = {Higher-order intensity correlations; Hong–Ou–Mandel effect; Multi-photon interference},
pages = {921-929},
peerreviewed = {unknown},
title = {{Hong}–{Ou}–{Mandel} interference without beam splitters},
volume = {64},
year = {2017}
}
@article{faucris.106831604,
abstract = {We propose a scheme enabling the universal coupling of angular momentum of N remote noninteracting qubits using linear optical tools only. Our system consists of N single-photon emitters in a Lambda configuration that are entangled among their long-lived ground-state qubits through suitably designed measurements of the emitted photons. In this manner, we present an experimentally feasible algorithm that is able to generate any of the 2(N) symmetric and nonsymmetric total angular momentum eigenstates spanning the Hilbert space of the N-qubit compoun},
author = {Maser, Andreas and Schilling, Uwe and Bastin, T. and Solano, E. and Thiel, Christoph and von Zanthier, Joachim},
doi = {10.1103/PhysRevA.79.033833},
faupublication = {yes},
journal = {Physical Review A},
keywords = {eigenvalues and eigenfunctions;ground states;Hilbert spaces;quantum computing;quantum entanglement;quantum optics},
peerreviewed = {Yes},
title = {{Generation} of total angular momentum eigenstates in remote qubits},
volume = {79},
year = {2009}
}
@article{faucris.106823464,
abstract = {The advent of accelerator-driven free-electron lasers (FEL) has opened new avenues for high-resolution structure determination via diffraction methods that go far beyond conventional X-ray crystallography methods(1-10). These techniques rely on coherent scattering processes that require the maintenance of first-order coherence of the radiation field throughout the imaging procedure. Here we show that higher-order degrees of coherence, displayed in the intensity correlations of incoherently scattered X-rays from an FEL, can be used to image two-dimensional objects with a spatial resolution close to or even below the Abbe limit. This constitutes a new approach towards structure determination based on incoherent processes(11,12), including fluorescence emission or wavefront distortions, generally considered detrimental for imaging applications. Our method is an extension of the landmark intensity correlation measurements of Hanbury Brown and Twiss(13) to higher than second order, paving the way towards determination of structure and dynamics of matter in regimes where coherent imaging methods have intrinsic limitations(14).},
author = {Schneider, Raimund and Mehringer, Thomas and Mercurio, Giuseppe and Wenthaus, Lukas and Classen, Anton and Brenner, Gunter and Gorobtsov, Oleg and Benz, Adrian and Bhatti, Daniel and Bocklage, Lars and Fischer, Birgit and Lazarev, Sergey and Obukhov, Yuri and Schlage, Kai and Skopintsev, Petr and Wagner, Jochen and Waldmann, Felix and Willing, Svenja and Zaluzhnyy, Ivan and Wurth, Wilfried and Vartanyants, Ivan A. and Rohlsberger, Ralf and von Zanthier, Joachim},
doi = {10.1038/NPHYS4301},
faupublication = {yes},
journal = {Nature Physics},
pages = {126-129},
peerreviewed = {Yes},
title = {{Quantum} imaging with incoherently scattered light from a free-electron laser},
volume = {14},
year = {2018}
}
@article{faucris.116515784,
abstract = {We report the possibility of completely destructive interference of three indistinguishable photons on a three port device providing a generalisation of the well known Hong-Ou-Mandel interference of two indistinguishable photons on a two port device. Our analysis is based on the underlying mathematical framework of SU(3) transformations rather than SU(2) transformations. We show the completely destructive three photon interference for a large range of parameters of the three port device and point out the physical origin of such interference in terms of the contributions from different quantum paths. As each output port can deliver zero to three photons the device generates higher dimensional entanglement. In particular, different forms of entangled states of qudits can be generated depending on the device parameters. Our system is different from a symmetric three port beam splitter which does not exhibit a three photon Hong-Ou-Mandel interference. (C) 2015 Optical Society of America},
author = {Mährlein, Simon and von Zanthier, Joachim and Agarwal, Girish S.},
doi = {10.1364/OE.23.015833},
faupublication = {yes},
journal = {Optics Express},
pages = {15833-15847},
peerreviewed = {Yes},
title = {{Complete} three photon {Hong}-{Ou}-{Mandel} interference at a three port device},
volume = {23},
year = {2015}
}
@article{faucris.121794904,
abstract = {A compact, tunable and narrow-bandwidth laser source for blue and ultraviolet radiation is presented. A grating-stabilized diode laser at 922 nm is frequency-stabilized to below 100 Hz relative to a reference resonator. Injection of the diode-laser light into a tapered amplifier yields a power of 0.5 W. In a first frequency-doubling stage, more than 200 mW of blue light at 461 nm is generated by use of a periodically poled KTP crystal. Subsequent second-harmonic generation employing a BBO crystal leads to about 1 mW of ultraviolet light at 231nm.},
author = {Schwedes, Christian and Peik, E and von Zanthier, Joachim and Nevsky, Alexander and Walther, Herbert},
doi = {10.1007/s00340-002-1075-5},
faupublication = {no},
journal = {Applied Physics B-Lasers and Optics},
month = {Jan},
pages = {143-147},
peerreviewed = {Yes},
title = {{Narrow}-bandwidth diode-laser-based blue and ultraviolet light source},
volume = {76},
year = {2003}
}
@article{faucris.121747824,
abstract = {We report measurements of the isotope shifts of the 3d(6)4s(2) a (5)D(4)-3d(6)4s4p z (5)F(5)(o) Fe I resonance line at 372 nm between all four stable isotopes (54)Fe, (56)Fe, (57)Fe, and (58)Fe, as well as the complete hyperfine structure of that line for (57)Fe, the only stable isotope having a nonzero nuclear spin. The field and specific mass shift coefficients of the transition have been derived from the data, as well as the experimental value for the hyperfine structure magnetic dipole coupling constant A of the excited state of the transition in (57)Fe: A(3d(6)4s4p z (5)F(5)(o)) = 81.69(86) MHz. The measurements were carried out by means of high-resolution Doppler-free laser saturated absorption spectroscopy in a Fe-Ar hollow cathode discharge cell using both natural and enriched iron samples. The measured isotope shifts and hyperfine constants are reported with uncertainties at the percent leve},
author = {Krins, S. and Oppel, Steffen and Huet, N. and von Zanthier, Joachim and Bastin, T.},
doi = {10.1103/PhysRevA.80.062508},
faupublication = {yes},
journal = {Physical Review A},
peerreviewed = {Yes},
title = {{Isotope} shifts and hyperfine structure of the {Fe} {I} 372-nm resonance line},
volume = {80},
year = {2009}
}
@article{faucris.116532284,
abstract = {We have measured the absolute frequency of the In-115(+) 5s(2) S-1(0)-5s5p P-3(0) clock transition at 236.5 nm with an accuracy of 3.3 parts in 10(11). For this measurement, a frequency synthesis chain was used which links the indium clock transition to a methane-stabilized He-Ne laser at 3.39 mu m and a Nd:YAG laser at 1064 nm whose second harmonic was locked to a hyperfine component in molecular iodine. A frequency gap in the chain of 1.43 THz at 850 nm was bridged with the help of an optical frequency comb generator. The frequency of the In-115(+) clock transition was determined to 1 267 402 452 914(41) kHz, where the accuracy is limited by the uncertainty of the iodine reference. This measurement represents an improvement of more than three orders of magnitude in accuracy compared to previous measurements of the line. (C) 1999 Elsevier Science B.V. All rights reserved.},
author = {von Zanthier, Joachim and Abel, J and Becker, Thomas and Fries, M and Peik, E and Walther, Herbert and Holzwarth, R and Reichert, J and Udem, Thomas and Hänsch, Theodor and Nevsky, Alexander and Skvortsov, M N and Bagayev, S N},
doi = {10.1016/S0030-4018(99)00253-9},
faupublication = {no},
journal = {Optics Communications},
keywords = {single ion trapping;optical frequency standard;frequency chain;absolute frequency measurement},
pages = {57-63},
peerreviewed = {Yes},
title = {{Absolute} frequency measurement of the {In}-115(+) 5s(2 1){S}(0)-5s5p {P}-3(0) transition},
volume = {166},
year = {1999}
}
@article{faucris.119200224,
abstract = {We propose to use multiphoton interferences from statistically independent light sources in combination with linear optical detection techniques to enhance the resolution in imaging. Experimental results with up to five independent thermal light sources confirm this approach to improve the spatial resolution. Since no involved quantum state preparation or detection is required, the experiment can be considered an extension of the Hanbury Brown-Twiss experiment for spatial intensity correlations of order N > 2. DOI: 10.1103/PhysRevLett.109.2336},
author = {Oppel, Steffen and Büttner, Teresa and Kok, P. and von Zanthier, Joachim},
doi = {10.1103/PhysRevLett.109.233603},
faupublication = {yes},
journal = {Physical Review Letters},
peerreviewed = {Yes},
title = {{Superresolving} {Multiphoton} {Interferences} with {Independent} {Light} {Sources}},
volume = {109},
year = {2012}
}
@article{faucris.121781264,
abstract = {We discuss a simple search problem which can be pursued with different methods, either on a classical or on a quantum basis. The system is represented by a chain of trapped ions. The ion to be searched for is a member of that chain, consisting, however, of an isotopic species different from the others. It is shown that classical imaging may lead to the final result as fast as quantum imaging. However, for the discussed case the quantum method gives more flexibility and higher precision when the number of ions considered in the chain increases. In addition, interferences are observable even when the distances between the ions are smaller than half a wavelength of the incident light.},
author = {Agarwal, Girish S. and Ariunbold, Gombojav O and von Zanthier, Joachim and Walther, Herbert},
doi = {10.1103/PhysRevA.70.063816},
faupublication = {yes},
journal = {Physical Review A},
peerreviewed = {Yes},
title = {{Nonclassical} imaging for a quantum search of trapped ions},
volume = {70},
year = {2004}
}
@article{faucris.206102871,
abstract = {Intensity correlation microscopy (ICM), which is prominently known through antibunching microscopy or super-resolution optical fluctuation imaging (SOFI), provides super-resolution through a correlation analysis of antibunching of independent quantum emitters or temporal fluctuations of blinking fluorophores. For correlation order m the PSF in the signal is effectively taken to the mth power, and is thus directly shrunk by the factor root m. Combined with deconvolution, a close to linear resolution improvement of factor m can be obtained. Yet, analysis of high correlation orders is challenging, which limits the achievable resolutions. Here we propose to use three dimensional structured illumination along with mth-order correlation analysis to obtain an enhanced scaling of up to m + m = 2m. Including the stokes shift or plasmonic sub-wavelength illumination enhancements beyond 2m can be achieved. Hence, resolutions far below the diffraction limit and with already low correlation orders in full 3D imaging, can potentially be achieved. Since ICM operates in the linear regime our approach may be particularly promising for enhancing the resolution in biological imaging at low illumination levels. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement},
author = {Classen, Anton and von Zanthier, Joachim and Agarwal, G. S.},
doi = {10.1364/OE.26.027492},
faupublication = {yes},
journal = {Optics Express},
pages = {27492-27503},
peerreviewed = {Yes},
title = {{Analysis} of super-resolution via {3D} structured illumination intensity correlation microscopy},
volume = {26},
year = {2018}
}
@article{faucris.116528104,
abstract = {A frequency comparison and an absolute frequency measurement of iodine stabilized frequency-doubled Nd:YAG lasers at 532 nm has been performed at the Max-Planck-Institute for Quantum Optics. Two independent I-2-stabilized laser systems, one assembled at the Institute of Laser Physics, Novosibirsk, Russia, the other at the Physikalisch-Technische Bundesanstalt, Braunschweig, Germany were investigated. Using a phase-coherent frequency chain, the absolute frequency of the I-2-stabilized lasers has been compared to a CH4-stabilized He-Ne laser at 3.39 mum which has been calibrated against an atomic cesium fountain clock. A new value for the R(56)32-0:a(10) component, recommended by the Comite International des Poids et Mesures for the realization of the meter [Metrologia 30 (1993/1994) 523; Metrologia 36 (1999) 211], has been obtained with reduced uncertainty. Improved absolute frequency values of the R(56)32-0 and P(54)32-0 iodine absorption lines together with the hyperfine line separations are presented. (C) 2001 Elsevier Science B.V. All rights reserved.},
author = {Nevsky, Alexander and Holzwarth, R and Reichert, J and Udem, Thomas and Hänsch, Theodor and von Zanthier, Joachim and Walther, Herbert and Schnatz, H and Riehle, Fritz and Pokasov, Pavel and Skvortsov, M N and Bagayev, S N},
doi = {10.1016/S0030-4018(01)01190-7},
faupublication = {no},
journal = {Optics Communications},
keywords = {iodine spectroscopy;optical frequency standard;absolute frequency measurement;frequency chain},
pages = {263-272},
peerreviewed = {Yes},
title = {{Frequency} comparison and absolute frequency measurement of {I}-2-stabilized lasers at 532 nm},
volume = {192},
year = {2001}
}
@article{faucris.116523484,
abstract = {We propose a technique capable of imaging a distinct physical object with sub-Rayleigh resolution in an ordinary far-field imaging setup using single-photon sources and linear optical tools only. We exemplify our method for the case of a rectangular aperture and two or four single-photon emitters obtaining a resolution enhanced by a factor of 2 or 4, respectivel},
author = {Thiel, Christoph and Bastin, T. and von Zanthier, Joachim and Agarwal, G. S.},
doi = {10.1103/PhysRevA.80.013820},
faupublication = {yes},
journal = {Physical Review A},
peerreviewed = {Yes},
title = {{Sub}-{Rayleigh} quantum imaging using single-photon sources},
volume = {80},
year = {2009}
}
@article{faucris.119130704,
abstract = {An experimental and theoretical study of laser sideband cooling of a trapped ion in a radiofrequency trap is presented. The influence of the micromotion in the time-dependent potential of a Paul trap can lead to a counterintuitive situation, where sideband cooling is possible for positive values of the laser detuning, i.e., for a laser frequency that is higher than the resonance frequency of the ion at rest. The cooling rate and the capture range are calculated in a semiclassical model. Experimental results of laser sideband cooling at positive detuning are demonstrated with a single trapped In+ ion stored in a miniature Paul trap.},
author = {Schwedes, Christian and Becker, Thomas and von Zanthier, Joachim and Walther, Herbert and Peik, E},
doi = {10.1103/PhysRevA.69.053412},
faupublication = {no},
journal = {Physical Review A},
peerreviewed = {Yes},
title = {{Laser} sideband cooling with positive detuning},
volume = {69},
year = {2004}
}
@article{faucris.200908515,
abstract = {Interference of light fields, first postulated by Young, is one of the fundamental pillars of physics. Dirac extended this observation to the quantum world by stating that each photon interferes only with itself. A precondition for interference to occur is that no welcher-weg information labels the paths the photon takes; otherwise, the interference vanishes. This remains true, even if two-photon interference is considered, e.g., in the Hong-Ou-Mandel-experiment. Here, the two photons interfere only if they are indistinguishable, e.g., in frequency, momentum, polarization, and time. Less known is the fact that two-photon interference and photon indistinguishability also determine the photon statistics in the overlapping light fields of two independent sources. As a consequence, measuring the photon statistics in the far field of two independent sources reveals the degree of indistinguishability of the emitted photons. In this Letter, we prove this statement in theory using a quantum mechanical treatment. We also demonstrate the outcome experimentally with a simple setup consisting of two statistically independent thermal light sources with adjustable polarizations. We find that the photon statistics vary indeed as a function of the polarization settings, the latter determining the degree of welcher-weg information of the photons emanating from the two sources. (C) 2018 Optical Society of America.},
author = {Mehringer, Thomas and Mährlein, Simon and von Zanthier, Joachim and Agarwal, Girish},
doi = {10.1364/OL.43.002304},
faupublication = {yes},
journal = {Optics Letters},
pages = {2304-2307},
peerreviewed = {Yes},
title = {{Photon} statistics as an interference phenomenon},
volume = {43},
year = {2018}
}
@article{faucris.116519964,
abstract = {We investigate two-photon entangled states using two important degrees of freedom of the electromagnetic field, namely orbital angular momentum (OAM) and spin angular momentum. For photons propagating in the same direction we apply the idea of entanglement duality and develop schemes to do entanglement sorting based on either OAM or polarization. In each case the entanglement is tested using appropriate witnesses. We finally present generalizations of these ideas to three-and four-photon entangled state},
author = {Bhatti, Daniel and von Zanthier, Joachim and Agarwal, G. S.},
doi = {10.1103/PhysRevA.91.062303},
faupublication = {yes},
journal = {Physical Review A},
peerreviewed = {Yes},
title = {{Entanglement} of polarization and orbital angular momentum},
volume = {91},
year = {2015}
}
@article{faucris.201392095,
abstract = {We report on prime number decomposition by use of the Talbot effect, a well-known phenomenon in classical near field optics whose description is closely related to Gauss sums. The latter are a mathematical tool from number theory used to analyze the properties of prime numbers as well as to decompose composite numbers into their prime factors. We employ the well-established connection between the Talbot effect and Gauss sums to implement prime number decompositions with a novel approach, making use of the longitudinal intensity profile of the Talbot carpet. The new algorithm is experimentally verified and the limits of the approach are discussed. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement},
author = {Pelka, Karl and Graf, Jasmin and Mehringer, Thomas and von Zanthier, Joachim},
doi = {10.1364/OE.26.015009},
faupublication = {yes},
journal = {Optics Express},
pages = {15009-15014},
peerreviewed = {Yes},
title = {{Prime} number decomposition using the {Talbot} effect},
volume = {26},
year = {2018}
}
@article{faucris.121760804,
abstract = {We present a physical setup with which it is possible to produce arbitrary symmetric long-lived multiqubit entangled states in the internal ground levels of photon emitters, including the paradigmatic Greenberger-Horne-Zeilinger and W states. In the case of three emitters, where each tripartite entangled state belongs to one of two well-defined entanglement classes, we prove a one-to-one correspondence between well-defined sets of experimental parameters, i.e., locally tunable polarizer orientations, and multiqubit entanglement classes inside the symmetric subspac},
author = {Bastin, T. and Thiel, Christoph and von Zanthier, Joachim and Lamata, Lucas and Solano, E. and Agarwal, G. S.},
doi = {10.1103/PhysRevLett.102.053601},
faupublication = {yes},
journal = {Physical Review Letters},
peerreviewed = {Yes},
title = {{Operational} {Determination} of {Multiqubit} {Entanglement} {Classes} via {Tuning} of {Local} {Operations}},
volume = {102},
year = {2009}
}
@article{faucris.121757724,
abstract = {We propose a method for generating all symmetric Dicke states, either in the long-lived internal levels of N massive particles or in the polarization degrees of freedom of photonic qubits, using linear optical tools only. By means of a suitable multiphoton detection technique, erasing Welcher-Weg information, our proposed scheme allows the generation and measurement of an important class of entangled multiqubit state},
author = {Thiel, Christoph and von Zanthier, Joachim and Bastin, Thierry and Solano, Enrique and Agarwal, Girish S.},
doi = {10.1103/PhysRevLett.99.193602},
faupublication = {yes},
journal = {Physical Review Letters},
peerreviewed = {Yes},
title = {{Generation} of symmetric dicke states of remote qubits with linear optics},
volume = {99},
year = {2007}
}
@article{faucris.120976504,
abstract = {An experimental study of sideband laser cooling of trapped ions in miniature radio-frequency traps is presented. In+ ions are laser cooled by exciting the narrow intercombination line 5s(2) S-1(0) --> 5s5p (3)p(1), which shows resolved sidebands due to the vibrational motion of the ions in the trap. The influence of the micromotion at the frequency of the oscillating trapping field is investigated. Heating processes through coupling with the trapping held occur for certain regions of negative laser detuning. A method of bichromatic sideband cooling is introduced that combines efficient cooling from high temperatures with the possibility of reaching low mean vibrational quantum numbers [n]<1 by using narrow optical transitions. This technique allows recording of high-resolution excitation spectra of the cooling transition in the Lamb-Dicke regime and thus determination of [n]. Single ions as well as two-ion Coulomb crystals have been cooled to temperatures below 100 mu K, and population of the ground state of motion to more than 50% over long time scales is demonstrated. These values are close to the lower limit for the detection of vibrational excitation with the present method. [S1050-2947(99)08407-3].},
author = {Peik, E and Abel, J and Becker, Thomas and von Zanthier, Joachim and Walther, Herbert},
faupublication = {no},
journal = {Physical Review A},
pages = {439-449},
peerreviewed = {Yes},
title = {{Sideband} cooling of ions in radio-frequency traps},
volume = {60},
year = {1999}
}
@article{faucris.123636084,
abstract = {A method for gaining information about the phonon-number moments and the generalized nonlinear and linear quadratures in the motion of trapped ions (in particular, position and momentum) is proposed, valid inside and outside the Lamb-Dicke regime. It is based on the measurement of first time derivatives of electronic populations, evaluated at the motion-probe interaction time tau = 0. In contrast to other state-reconstruction proposals, based on measuring Rabi oscillations or dispersive interactions, the present scheme can be performed resonantly at infinitesimal short motion-probe interaction times, remaining thus insensitive to decoherence processes.},
author = {Bastin, Thierry and von Zanthier, Joachim and Solano, Enrique},
doi = {10.1088/0953-4075/39/3/020},
faupublication = {yes},
journal = {Journal of Physics B-Atomic Molecular and Optical Physics},
pages = {685-693},
peerreviewed = {Yes},
title = {{Measure} of phonon-number moments and motional quadratures through infinitesimal-time probing of trapped ions},
volume = {39},
year = {2006}
}
@article{faucris.116806404,
abstract = {Single laser-cooled ions stored in radiofrequency traps are the atomic systems which allow the highest resolution in optical or microwave spectroscopy. A narrow transition in such an ion can serve as a reference for a frequency standard of extremely high accuracy and stability. In view of this application we study the 5 S-55 P clock transition in a single trapped In ion at a wavelength of 237 nm [1]. This transition is highly immune to systematic frequency shifts. A frequency control at the millihertz level is expected leading to a residual relative uncertainty at the level of 10. For realizing the standard it is necessary to compare its absolute frequency to other known frequencies, at best to the present primary frequency standard, the cesium atomic clock. We report on the comparison of the In clock transition to a methane-stabilized He-Ne laser at 3.39 μ.m. This laser was calibrated before the measurement against an atomic cesium fountain clock. A frequency gap of 37 THz at the fourth harmonic of the He-Ne standard was bridged by a frequency comb generated by a mode-locked femtosecond laser. The frequency of the clock transition was determined to 1267402452899.92 (0.23) kHz where the accuracy of the measurement is limited by the uncertainty of the He-Ne standard.},
author = {von Zanthier, Joachim and Becker, Thomas and Eichenseer, M and Nevsky, Alexander and Schwedes, Christian and Peik, E and Walther, Herbert and Holzwarth, R and Reichert, J and Udem, Thomas and Hänsch, Theodor and Pokasov, Pavel and Skvortsov, M N and Bagayev, S N},
faupublication = {no},
journal = {Laser Physics},
pages = {1117-1119},
peerreviewed = {Yes},
title = {{Absolute} frequency measurement of the {In}+ clock transition with a mode-locked femtosecond laser},
url = {https://www.scopus.com/inward/record.url?partnerID=HzOxMe3b&scp=0035486352&origin=inward},
volume = {11},
year = {2001}
}
@article{faucris.117676064,
abstract = {We observe interference in the light scattered from trapped Ca-40(+) ion crystals. By varying the intensity of the excitation laser, we study the influence of elastic and inelastic scattering on the visibility of the fringe pattern and discriminate its effect from that of the ion temperature and wave-packet localization. In this way we determine the complex degree of coherence and the mutual coherence of light fields produced by individual atoms. We obtain interference fringes from crystals consisting of two, three, and four ions in a harmonic trap. Control of the trapping potential allows for the adjustment of the interatomic distances and thus the formation of linear arrays of atoms serving as a regular grating of microscopic scatterer},
author = {Wolf, Sebastian and Wechs, Julian and von Zanthier, Joachim and Schmidt-Kaler, Ferdinand},
doi = {10.1103/PhysRevLett.116.183002},
faupublication = {yes},
journal = {Physical Review Letters},
peerreviewed = {Yes},
title = {{Visibility} of {Young}'s {Interference} {Fringes}: {Scattered} {Light} from {Small} {Ion} {Crystals}},
url = {http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.116.183002},
volume = {116},
year = {2016}
}
@article{faucris.121751564,
abstract = {We quantitatively investigate the non-classicality and non-locality of a whole new class of mixed disparate quantum and semiquantum photon sources at the quantum-classical boundary. The latter include photon-added thermal and photon-added coherent sources, experimentally investigated recently by Zavatta et al (2009 Phys. Rev. Lett. 103 140406). The key quantity in our investigations is the visibility of the corresponding photon-photon correlation function. We present explicit results on the violations of the Cauchy-Schwarz inequality-which is a measure of non-classicality-as well as of Bell-type inequalitie},
author = {Wiegner, Ralph and von Zanthier, Joachim and Agarwal, G. S.},
doi = {10.1088/0953-4075/44/5/055501},
faupublication = {yes},
journal = {Journal of Physics B-Atomic Molecular and Optical Physics},
peerreviewed = {Yes},
title = {{Quantum} interference and non-locality of independent photons from disparate sources},
volume = {44},
year = {2011}
}
@article{faucris.120056464,
abstract = {We report nonclassical aspects of the collective behavior of two atoms in a cavity by investigating the photon statistics and photon distribution over a very broad domain of parameters. Starting with the dynamics of two atoms radiating in phase into the cavity, we study the photon statistics for arbitrary interatomic phases as revealed by the second-order intensity correlation function at zero time, g((2))(0), and the Mandel Q parameter. We find that the light field can be tuned from antibunched to (super-) bunched as well as nonclassical to classical behavior by merely modifying the atomic position. The highest nonclassicality in the sense of the smallest Q parameter is found when spontaneous emission, cavity decay, coherent pumping, and atom-cavity coupling are of comparable magnitude. We introduce a quantum version of the negative binomial distribution with its parameters directly related to Q and g(2)(0) and discuss its range of applicability. We also examine the Klyshko parameter, which highlights the nonclassicality of the photon distribution.},
author = {Pleinert, Marc-Oliver and von Zanthier, Joachim and Agarwal, G. S.},
doi = {10.1103/PhysRevA.97.023831},
faupublication = {yes},
journal = {Physical Review A},
peerreviewed = {Yes},
title = {{Phase} control of the quantum statistics of collective emission},
volume = {97},
year = {2018}
}
@article{faucris.111449844,
abstract = {We report on a novel pseudothermal light source based on laser light coupled into an optical multimode fiber. The setup is simple, low cost, exhibits inherently high directional light emission and allows for a flexible arrangement. By measuring the photon statistics and spatial two point intensity correlations in the far field we show that the setup exhibits all characteristics of a Gaussian random sourc},
author = {Mehringer, Thomas and Oppel, Steffen and von Zanthier, Joachim},
doi = {10.1007/s00340-017-6775-y},
faupublication = {yes},
journal = {Applied Physics B-Lasers and Optics},
peerreviewed = {Yes},
title = {{An} optical multimode fiber as pseudothermal light source},
volume = {123},
year = {2017}
}
@article{faucris.123744104,
abstract = {We report on the frequency stabilisation of a Nd:YAG laser at 946 nm to the Hertz-level. The laser will be used for ultra-high resolution spectroscopy of the 5s(2) S-1(0) - 5s5p P-3(0) transition in In+ and will ultimately serve as a local oscillator of an optical frequency standard based on a single trapped indium ion. To resolve the extremely narrow S-1(0) - P-3(0) resonance (natural linewidth 0.82 Hz) at 237 nm, the frequency-quadrupled Nd:YAG laser radiation has to be frequency stable at the Hertz-scale for measurement times up to several tens of seconds. We obtain the frequency stability of the laser by locking it onto an external reference cavity of high finesse, placed on an active vibration isolation platform. (C) 2002 Elsevier Science B.V. All rights reserved.},
author = {Nevsky, Alexander and Eichenseer, M and von Zanthier, Joachim and Walther, Herbert},
doi = {10.1016/S0030-4018(02)01763-7},
faupublication = {no},
journal = {Optics Communications},
pages = {91-100},
peerreviewed = {Yes},
title = {{A} {Nd} : {YAG} {Laser} with short-term frequency stability at the {Hertz}-level},
volume = {210},
year = {2002}
}
@article{faucris.120061964,
abstract = {We report a way of manipulating the spontaneous emission process leading to a spatial modulation of spontaneous decay. The effect is observed in the case of coherently driven atoms separated by less than a transition wavelength. It is quantified by Glauber's photon-photon second-order correlation function. We show that the photon arrival time, usually regarded as an entirely random process, depends not only on where a photon is detected but also on where a former photon had been recorded previously. Our results shed light on the unexpected consequences of state reduction and entanglement for the fundamental process of spontaneous emission.},
author = {von Zanthier, Joachim and Agarwal, Girish S. and Bastin, Thierry},
doi = {10.1103/PhysRevA.74.061802},
faupublication = {yes},
journal = {Physical Review A},
peerreviewed = {Yes},
title = {{Measurement}-induced spatial modulation of spontaneous decay and photon arrival times},
volume = {74},
year = {2006}
}
@article{faucris.109062184,
abstract = {Incoherent scattering of photons off two remote atoms with a Lambda-level structure is used as a basic Young-type interferometer to herald long-lived entanglement of an arbitrary degree. The degree of entanglement, as measured by the concurrence, is found to be tunable by two easily accessible experimental parameters. Fixing one of them to certain values unveils an analog to the Malus' law. An estimate of the variation in the degree of entanglement due to uncertainties in an experimental realization is give},
author = {Schilling, Uwe and Thiel, Christoph and Solano, E. and Bastin, T. and von Zanthier, Joachim},
doi = {10.1103/PhysRevA.80.022312},
faupublication = {yes},
journal = {Physical Review A},
peerreviewed = {Yes},
title = {{Heralded} entanglement of arbitrary degree in remote qubits},
volume = {80},
year = {2009}
}
@article{faucris.208823608,
abstract = {Measuring the Mth-order intensity correlation function of light emitted by two statistically independent thermal light sources may display N00N-like interferences of arbitrary order N = Ma center dot 2. We show that via a particular choice of detector positions one can isolate M-photon quantum paths where either all M photons are emitted from the same source or Ma center dot 2 photons are collectively emitted by both sources. The latter superposition displays N00N-like oscillations with N = Ma center dot 2 which may serve, e.g., in astronomy, for imaging two distant thermal sources with Ma center dot 2-fold increased resolution. We also discuss slightly modified detection schemes improving the visibility of the N00N-like interference pattern and present measurements verifying the theoretical predictions.},
author = {Bhatti, Daniel and Classen, Anton and Oppel, Steffen and Schneider, Raimund and von Zanthier, Joachim},
doi = {10.1140/epjd/e2018-90371-8},
faupublication = {yes},
journal = {European Physical Journal D},
peerreviewed = {Yes},
title = {{Generation} of {N00N}-like interferences with two thermal light sources},
volume = {72},
year = {2018}
}
@article{faucris.204081880,
abstract = {We present a computer algorithm capable of simulating the photon stream and the corresponding temporal photon statistics of thermal light sources. The algorithm implements realistic experimental conditions, incorporating the relevant parameters of the source as well as of the detection process. The code is verified by comparing the temporal photon autocorrelation function computed from the simulations to the one measured with a real thermal light source. In view of the renewed interest for intensity interferometry in astronomy and the life sciences, such simulations become increasingly relevant. (C) 2018 Optical Society of America},
author = {Schneider, Raimund and Biernoth, Christoph and Hölzl, Johannes and Pscherer, André and von Zanthier, Joachim},
doi = {10.1364/AO.57.007076},
faupublication = {yes},
journal = {Applied Optics},
pages = {7076-7080},
peerreviewed = {Yes},
title = {{Simulating} the photon stream of a real thermal light source},
volume = {57},
year = {2018}
}
@article{faucris.121922724,
abstract = {The 5s(2 1)S(0)--> 5s5p P-3(0) transition of a single laser-cooled In-115(+) ion in a miniature radiofrequency trap is investigated as a possible optical frequency standard. This line at a frequency of 1267 THz (wavelength 236.5 nm) is highly immune to frequency shifts due to external perturbations so that the expected systematic uncertainties can be reduced to the millihertz level. Experimentally. we obtained a fractional resolution Deltav/v = 1.3 x 10(-13) (linewidth 170 Hz), limited by the frequency instability of the laser used for excitation. The g factor and the lifetime of the metastable P-3(0) level were measured as g(P-3(0)) = -9.87(5) x 10(-4) and tau(P-3(0)) = 0.195(8) s. Both values are in good agreement with perturbative calculations, based an hyperfine mixing between the P-1 and P-3 levels.},
author = {Becker, Thomas and von Zanthier, Joachim and Nevsky, Alexander and Schwedes, Christian and Skvortsov, M N and Walther, Herbert and Peik, E},
doi = {10.1103/PhysRevA.63.051802},
faupublication = {no},
journal = {Physical Review A},
peerreviewed = {Yes},
title = {{High}-resolution spectroscopy of a single {In}+ ion: {Progress} towards an optical frequency standard},
volume = {63},
year = {2001}
}
@article{faucris.121784124,
abstract = {We have used a single laser femtosecond (.)optical frequency synthesizer together with a widely tunable Nd:YAG laser to measure the absolute frequency of several absorption lines in molecular iodine around 532 nm. The use of two different repetition frequencies allows us to determine the number of modes used for the frequency measurement unambiguously. The lines also provide data for the determination of improved ro-vibrational constants of the iodine molecule.},
author = {Holzwarth, R and Nevsky, Alexander and Zimmermann, Marcus and Udem, Thomas and Hänsch, Theodor and von Zanthier, Joachim and Walther, Herbert and Knight, J C and Wadsworth, William and Russell, Philip St John and Skvortsov, M N and Bagayev, S N},
doi = {10.1007/s003400100633},
faupublication = {no},
journal = {Applied Physics B-Lasers and Optics},
pages = {269-271},
peerreviewed = {Yes},
title = {{Absolute} frequency measurement of iodine lines with a femtosecond optical synthesizer},
volume = {73},
year = {2001}
}
@article{faucris.107167984,
abstract = {We investigate Dicke subradiance of N >= 2 distant quantum sources in free space, i.e., the spatial emission patterns of spontaneously radiating noninteracting multilevel atoms or multiphoton sources, prepared in totally antisymmetric states. We find that the radiated intensity is marked by a full suppression of spontaneous emission in particular directions. In resemblance to the analogous, yet inverted, superradiant emission profiles of N distant two-level atoms prepared in symmetric Dicke states, we call the corresponding emission patterns directional Dicke subradiance. We further derive that higher-order intensity correlations of the light emitted by statistically independent thermal light sources display the same directional Dicke subradiant behavior and show that it stems from the same interference phenomenon as in the case of quantum sources. We finally present measurements of directional Dicke subradiance for N = 2,...,5 distant thermal light sources corroborating the theoretical finding},
author = {Bhatti, Daniel and Schneider, Raimund and Oppel, Steffen and von Zanthier, Joachim},
doi = {10.1103/PhysRevLett.120.113603},
faupublication = {yes},
journal = {Physical Review Letters},
peerreviewed = {Yes},
title = {{Directional} {Dicke} {Subradiance} with {Nonclassical} and {Classical} {Light} {Sources}},
volume = {120},
year = {2018}
}
@article{faucris.123906684,
abstract = {The collective behavior of ensembles of atoms has been studied in-depth since the seminal paper of Dicke [Phys. Rev. 93, 99 (1954)], where he demonstrated that a group of emitters in collective states is able to radiate with increased intensity and modified decay rates in particular directions, a phenomenon that he called superradiance. Here, we show that the fundamental setup of two atoms coupled to a single-mode cavity can distinctly exceed the free-space super-radiant behavior, a phenomenon we call hyperradiance. The effect is accompanied by strong quantum fluctuations and surprisingly arises for atoms radiating out-of-phase, an alleged non-ideal condition where one expects subradiance. We are able to explain the onset of hyperradiance in a transparent way by a photon cascade taking place among manifolds of Dicke states with different photon numbers under particular out-of-phase coupling conditions. These theoretical results can be realized with current technology and should thus stimulate future experiments. (C) 2017 Optical Society of America},
author = {Pleinert, Marc-Oliver and von Zanthier, Joachim and Agarwal, Girish S.},
doi = {10.1364/OPTICA.4.000779},
faupublication = {yes},
journal = {Optica},
pages = {779-785},
peerreviewed = {Yes},
title = {{Hyperradiance} from collective behavior of coherently driven atoms},
volume = {4},
year = {2017}
}
@article{faucris.121782144,
abstract = {We demonstrate the existence of nonclassical correlations in the radiation of two atoms, that Lire coherently driven by a continuous laser source. The photon-photon correlations of the fluorescence light show a spatial interference pattern not present in a classical treatment, A feature of this phenomenon is that bunched and antibunched light is emitted in different spatial directions. The calculations are performed analytically. It is pointed out that the correlations are induced by state reduction due to the measurement process when the detection of the photons does not distinguish between the atoms. It is interesting to note that the phenomena shorn up even without any interatomic interaction.},
author = {Skornia, Christoph and von Zanthier, Joachim and Agarwal, Girish S. and Werner, E and Walther, Herbert},
doi = {10.1103/PhysRevA.64.063801},
faupublication = {no},
journal = {Physical Review A},
peerreviewed = {Yes},
title = {{Nonclassical} interference effects in the radiation from coherently driven uncorrelated atoms},
volume = {64},
year = {2001}
}