967 research outputs found
Maximum-likelihood algorithm for quantum tomography
Optical homodyne tomography is discussed in the context of classical image
processing. Analogies between these two fields are traced and used to formulate
an iterative numerical algorithm for reconstructing the Wigner function from
homodyne statistics.Comment: 7 pages LaTeX, contribution to proceedings of 6th central-european
workshop on quantum optic
Accuracy of Sampling Quantum Phase Space in Photon Counting Experiment
We study the accuracy of determining the phase space quasidistribution of a
single quantized light mode by a photon counting experiment. We derive an exact
analytical formula for the error of the experimental outcome. This result
provides an estimation for the experimental parameters, such as the number of
events, required to determine the quasidistribution with assumed precision. Our
analysis also shows that it is in general not possible to compensate the
imperfectness of the photodetector in a numerical processing of the
experimental data. The discussion is illustrated with Monte Carlo simulations
of the photon counting experiment for the coherent state, the one photon Fock
state, and the Schroedinger cat state.Comment: 11 pages REVTeX, 5 figures, uses multicol, epsfig, and pstricks.
Submitted to Special Issue of Journal of Modern Optics on Quantum State
Preparation and Measuremen
Testing single-photon wave packets by Hong-Ou-Mandel interference
We discuss characterization of single-photon wave packets by measuring
Hong-Ou-Mandel interference with a weak coherent pulse. A complete multimode
calculation is presented and effects of multiphoton terms in the coherent field
as well as the impact of source and detection imperfections are discussed.Comment: Submitted to IEEE conference proceedings: National Conference on
Telecommunication Technologies and Malaysia Conference on Photonics 200
Approaching the ultimate capacity limit in deep-space optical communication
The information capacity of an optical channel under power constraints is
ultimately limited by the quantum nature of transmitted signals. We discuss
currently available and emerging photonic technologies whose combination can be
shown theoretically to enable nearly quantum-limited operation of a noisy
optical communication link in the photon-starved regime, with the information
rate scaling linearly in the detected signal power. The key ingredients are
quantum pulse gating to facilitate mode selectivity, photon-number-resolved
direct detection, and a photon-efficient high-order modulation format such as
pulse position modulation, frequency shift keying, or binary phase shift keyed
Hadamard words decoded optically using structured receivers.Comment: 9 pages, 4 figures. Presented at Free-Space Laser Communications
XXXI, 4-6 February 2019, San Francisco, C
Nonlocality of the Einstein-Podolsky-Rosen state in the phase space
We discuss violation of Bell inequalities by the regularized
Einstein-Podolsky-Rosen (EPR) state, which can be produced in a quantum optical
parametric down-conversion process. We propose an experimental photodetection
scheme to probe nonlocal quantum correlations exhibited by this state.
Furthermore, we show that the correlation functions measured in two versions of
the experiment are given directly by the Wigner function and the Q function of
the EPR state. Thus, the measurement of these two quasidistribution functions
yields a novel scheme for testing quantum nonlocality.Comment: 10 pages LaTeX, contribution to proceedings of 6th central-european
workshop on quantum optic
Sampling quantum phase space with squeezed states
We study the application of squeezed states in a quantum optical scheme for
direct sampling of the phase space by photon counting. We prove that the
detection setup with a squeezed coherent probe field is equivalent to the
probing of the squeezed signal field with a coherent state. An example of the
Schroedinger cat state measurement shows that the use of squeezed states allows
one to detect clearly the interference between distinct phase space components
despite losses through the unused output port of the setup.Comment: 6 pages LaTeX. Submitted to Optics Expres
Direct measurement of spatial Wigner function with area-integrated detection
We demonstrate experimentally a novel technique for characterizing transverse
spatial coherence using the Wigner distribution function. The presented method
is based on measuring interference between a pair of rotated and displaced
replicas of the input beam with an area-integrating detector, and it can be
superior in regimes when array detectors are not available. We analyze the
quantum optical picture of the presented measurement for single-photon signals
and discuss possible applications in quantum information processing.Comment: 3 pages, REVTe
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