Showing papers by "Jeffrey H. Shapiro published in 2011"
TL;DR: In this paper, the spatial resolution, image contrast, and signal-to-noise ratio of a ghost imaging system were derived for rough-surfaced targets that create fully developed speckle in their returns and Kolmogorov-spectrum turbulence that is uniformly distributed along all propagation paths.
Abstract: Recent work has indicated that ghost imaging may have applications in standoff sensing. However, most theoretical work has addressed transmission-based ghost imaging. To be a viable remote-sensing system, the ghost imager needs to image rough-surfaced targets in reflection through long, turbulent optical paths. We develop, within a Gaussian-state framework, expressions for the spatial resolution, image contrast, and signal-to-noise ratio of such a system. We consider rough-surfaced targets that create fully developed speckle in their returns and Kolmogorov-spectrum turbulence that is uniformly distributed along all propagation paths. We address both classical and nonclassical optical sources, as well as a computational ghost imager.
94 citations
01 Dec 2011
TL;DR: In this article, the authors proposed a method to solve a set of problems with the U.S. Army Research Office grant No. W911NF-05-1-0197.
Abstract: United States. Army Research Office. Multidisciplinary University Research Initiative (Grant No. W911NF-05-1-0197)
87 citations
TL;DR: In this paper, the effect of turbulence on quantum ghost imaging was investigated and it was shown that by decoupling the entangled photon source from the ghost-imaging central image plane, the authors were able to dramatically increase the ghost image quality.
Abstract: We investigate the effect of turbulence on quantum ghost imaging. We use entangled photons and demonstrate that for a specific experimental configuration the effect of turbulence can be greatly diminished. By decoupling the entangled photon source from the ghost-imaging central image plane, we are able to dramatically increase the ghost-image quality. When imaging a test pattern through turbulence, this method increases the imaged pattern visibility from $V=0.15\ifmmode\pm\else\textpm\fi{}0.04$ to $0.42\ifmmode\pm\else\textpm\fi{}0.04$.
77 citations
TL;DR: The asymptotic capacity at low input powers of an average-power limited or anAverage- and peak- power limited discrete-time Poisson channel is considered.
Abstract: The asymptotic capacity at low input powers of an average-power limited or an average- and peak-power limited discrete-time Poisson channel is considered. For a Poisson channel whose dark current is zero or decays to zero linearly with its average input power e, capacity scales like e log 1/e for small e. For a Poisson channel whose dark current is a nonzero constant, capacity scales, to within a constant, like e log log 1/e for small e.
56 citations
TL;DR: In this paper, a detailed theoretical analysis to the setup and results reported in the experiment are considered. But the results are limited to entangled photons with a finite correlation area and a turbulence model beyond the phase screen approximation.
Abstract: Atmospheric turbulence generally affects the resolution and visibility of an image in long-distance imaging. In a recent quantum ghost imaging experiment [P. B. Dixon et al., Phys. Rev. A 83, 051803 (2011)], it was found that the effect of the turbulence can nevertheless be mitigated under certain conditions. This paper gives a detailed theoretical analysis to the setup and results reported in the experiment. Entangled photons with a finite correlation area and a turbulence model beyond the phase screen approximation are considered.
37 citations
TL;DR: Sub-Rayleigh resolution by a factor proportional to [ln(Nmax /N)]1/2 is demonstrated through unstructured scanning of a focused classical beam across an object and dynamic application of a threshold N less than the maximum count level N.
Abstract: Diffraction from a finite-diameter entrance pupil imposes the Rayleigh bound on the spatial resolution achievable by a conventional imaging system We demonstrate resolution beyond this limit through unstructured scanning of a focused laser beam across an object together with dynamic application of a threshold N less than the maximum count level Nmax Experimental results show sub-Rayleigh resolution enhancement by a factor of [ln(Nmax/N)]1/2
27 citations
TL;DR: Shapiro et al. as mentioned in this paper evaluated the effect of scintillation arising from propagation through atmospheric turbulence on the sift and error probabilities of a quantum key distribution (QKD) system that uses the weak-laser-pulse version of the Bennett-Brassard 1984 protocol.
Abstract: The effect of scintillation, arising from propagation through atmospheric turbulence, on the sift and error probabilities of a quantum key distribution (QKD) system that uses the weak-laser-pulse version of the Bennett-Brassard 1984 (BB84) protocol is evaluated Two earth-space scenarios are examined: satellite-to-ground and ground-to-satellite transmission Both lie in the far-field power-transfer regime This work complements previous analysis of turbulence effects in near-field terrestrial BB84 QKD [J H Shapiro, Phys Rev A 67, 022309 (2003)] More importantly, it shows that scintillation has virtually no impact on the sift and error probabilities in earth-space BB84 QKD, something that has been implicitly assumed in prior analyses for that application This result contrasts rather sharply with what is known for high-speed laser communications over such paths, in which deep, long-lived scintillation fades present a major challenge to high-reliability operation
22 citations
16 Oct 2011
TL;DR: In this article, the capacity of optically reading classical data from a coded target was investigated, and it was shown that non-classical sources can outperform classical sources, yielding higher throughput and photon efficiency, and lower implementation complexity.
Abstract: We investigate quantum limits on the capacity of optically reading classical data from a coded target, and show that non-classical sources can outperform classical sources, yielding higher throughput and photon efficiency, and lower implementation complexity.
21 citations
TL;DR: In this article, the effect of turbulence on quantum ghost imaging was investigated using entangled photons in several experimental configurations and it was shown that for a novel configuration, the effects of turbulence can be greatly diminished.
Abstract: We investigate the effect of turbulence on quantum ghost imaging. We use entangled photons in several experimental configurations and demonstrate that for a novel configuration, the effect of turbulence can be greatly diminished.
15 citations
TL;DR: The first (to the authors' knowledge) far-field ghost images formed with phase-sensitive classical-state light and compare them with ghost images of the same object formed with conventional phase-insensitive classical- state light are reported.
Abstract: We report the first (to our knowledge) far-field ghost images formed with phase-sensitive classical-state light and compare them with ghost images of the same object formed with conventional phase-insensitive classical-state light. To generate signal and reference beams with phase-sensitive cross correlation, we used a pair of synchronized spatial light modulators that imposed random, spatially varying, anticorrelated phase modulation on the outputs from 50-50 beam splitting of a laser beam. In agreement with theory, we found the phase-sensitive image to be inverted, whereas the phase-insensitive image is erect, with both having comparable spatial resolutions and signal-to-noise ratios.
12 citations
10 Jul 2011
TL;DR: In this paper, a series of field demonstrations of high-bandwidth optical free-space links were performed at MIT Lincoln Laboratory, and the results showed near-unity correlation coefficients in all air-to-ground tests.
Abstract: Since 2008, MIT Lincoln Laboratory has performed a series of field demonstrations of high-bandwidth optical free-space links. Bi-directional scintillation fading measurements have shown near-unity correlation coefficients in all air-to-ground tests.
TL;DR: In this article, a balanced homodyne LADAR receiver employing a phase-sensitive amplifier (PSA) was used to increase the detection efficiency to nearly 100% in target discrimination and imaging applications.
Abstract: We demonstrate a balanced-homodyne LADAR receiver employing a phase-sensitive amplifier (PSA) to raise the
effective photon detection efficiency (PDE) to nearly 100%. Since typical LADAR receivers suffer from losses in the
receive optical train that routinely limit overall PDE to less than 50% thus degrading SNR, PSA can provide significant
improvement through amplification with noise figure near 0 dB. Receiver inefficiencies arise from sub-unity quantum
efficiency, array fill factors, signal-local oscillator mixing efficiency (in coherent receivers), etc. The quantum-enhanced
LADAR receiver described herein is employed in target discrimination scenarios as well as in imaging applications. We
present results showing the improvement in detection performance achieved with a PSA, and discuss the performance
advantage when compared to the use of a phase-insensitive amplifier, which cannot amplify noiselessly.
TL;DR: In this paper, the authors proposed a Quantum Sensors Program (AFRL Contract FA8750-09-C-0194) with the U.S. Defense Advanced Research Projects Agency (DARPA).
Abstract: United States. Defense Advanced Research Projects Agency. Quantum Sensors Program (AFRL Contract FA8750-09-C-0194)
01 May 2011
TL;DR: In this paper, the authors proposed an InPho-based approach to solve the problem of in-Pho in-flight communication for the Defense Advanced Research Projects Agency (DARPA DSO-InPho Grant No. W911NF-10-1-0404.
Abstract: United States. Defense Advanced Research Projects Agency (DARPA DSO InPho Grant No. W911NF-10-1-0404)
Posted Content•
TL;DR: In this paper, Chen et al. showed that semiclassical photodetection theory does indeed explain the anticorrelation found by Chen and Emmerich in their experiment with a Mach-Zehnder interferometer.
Abstract: Recently, Chen \em et al \rm.\ [Phys. Rev. A 84, 033835 (2011)] reported observation of anticorrelated photon coincidences in a Mach-Zehnder interferometer whose input light came from a mode-locked Ti:sapphire laser that had been rendered spatially incoherent by passage through a rotating ground-glass diffuser. They provided a quantum-mechanical explanation of their results, which ascribes the anticorrelation to two-photon interference. They also developed a classical-light treatment of the experiment, and showed that it was incapable of explaining the anticorrelation behavior. Here we show that semiclassical photodetection theory---i.e., classical electromagnetic fields plus photodetector shot noise---does indeed explain the anticorrelation found by Chen \em et al \rm.\ The key to our analysis is proper accounting for the disparate time scales associated with the laser's pulse duration, the speckle-correlation time, the interferometer's differential delay, and the duration of the photon-coincidence gate. Our result is consistent with the long-accepted dictum that laser light which has undergone linear-optics transformations is classical-state light, so that the quantum and semiclassical theories of photodetection yield quantitatively identical results for its measurement statistics. The interpretation provided by Chen \em et al \rm. for their observations implicitly contradicts that dictum
TL;DR: In this article, the authors show that the classical phase-sensitive light produces ghost images most closely mimicking those obtained with biphotons, and derive the spatial resolution, image contrast, and signal-to-noise ratio of a standoff-sensing ghost imager, taking into account target-induced speckle.
Abstract: The theory of partial coherence has a long and storied history in classical statistical optics. The vast majority
of this work addresses fields that are statistically stationary in time, hence their complex envelopes only have
phase-insensitive correlations. The quantum optics of squeezed-state generation, however, depends on nonlinear
interactions producing baseband field operators with phase-insensitive and phase-sensitive correlations. Utilizing
quantum light to enhance imaging has been a topic of considerable current interest, much of it involving biphotons,
i.e., streams of entangled-photon pairs. Biphotons have been employed for quantum versions of optical coherence
tomography, ghost imaging, holography, and lithography. However, their seemingly quantum features have been
mimicked with classical-state light, questioning wherein lies the classical-quantum boundary. We have shown,
for the case of Gaussian-state light, that this boundary is intimately connected to the theory of phase-sensitive
partial coherence. Here we present that theory, contrasting it with the familiar case of phase-insensitive partial
coherence, and use it to elucidate the classical-quantum boundary of ghost imaging. We show, both theoretically
and experimentally, that classical phase-sensitive light produces ghost images most closely mimicking those
obtained with biphotons, and we derive the spatial resolution, image contrast, and signal-to-noise ratio of a
standoff-sensing ghost imager, taking into account target-induced speckle.
TL;DR: In this paper, the authors show that the quantum enhancements afforded by SVI and phasesensitive additive amplification (PSA) can improve the spatial resolution of a soft-aperture, homodyne-detection laser-radar (ladar) system.
Abstract: Theory has shown [1] that the quantum enhancements afforded by squeezed-vacuum injection (SVI) and phasesensitive
amplification (PSA) can improve the spatial resolution of a soft-aperture, homodyne-detection laserradar
(ladar) system. Here we show they can improve the range resolution of such a ladar system. In particular,
because an experimental PSA-enhanced system is being built whose slow photodetectors imply multi-pulse
integration, we develop range-measurement theory that encompasses its processing architecture. We allow the
target to have an arbitrary mixture of specular and speckle components, and present computer simulation results
demonstrating the range-resolution improvement that accrues from quantum enhancement with PSA.
TL;DR: An ultrashort-pulse system is not a solution for high-data-rate FSO communication through fog, because, at best, it will reproduce on average the energy-transfer performance of a wavelength-optimized quasimonochromatic system.
Abstract: The use of ultrashort (femtosecond duration) light pulses for line-of-sight free-space optical (FSO) communication through fog is receiving increasing attention. Assuming that the transmitter power is low enough to preclude nonlinear interactions, and that scattering-induced multipath spread is less than the reciprocal of the scattering-induced Doppler spread, it is shown that the average transmitter-to-receiver fractional energy transfer of an ultrafast FSO system cannot exceed that of a quasimonochromatic (nanosecond pulse duration) system operating at the optimum wavelength within the ultrafast system’s spectrum. Thus, an ultrashort-pulse system is not a solution for high-data-rate FSO communication through fog, because, at best, it will reproduce on average the energy-transfer performance of a wavelength-optimized quasimonochromatic system.
01 May 2011
TL;DR: In this article, an unstructured scanning of a focused classical beam across an object and dynamic application of a threshold N less than the maximum count level N max was demonstrated. But the resolution of the beam was limited to a factor proportional to [ln(N max /N)]1/2.
Abstract: Sub-Rayleigh resolution by a factor proportional to [ln(N max /N)]1/2 is demonstrated through unstructured scanning of a focused classical beam across an object and dynamic application of a threshold N less than the maximum count level N max .
01 Oct 2011
TL;DR: In-Pho Grant No. W911NF-10-1-0404 as discussed by the authors was provided by the U.S. Defense Advanced Research Projects Agency (DARPA).
Abstract: United States. Defense Advanced Research Projects Agency. System Science Division. Defense Sciences Office (InPho Grant No. W911NF-10-1-0404)
01 Sep 2011
TL;DR: Shapiro et al. as mentioned in this paper evaluated the effect of scintillation on the sift and error probabilities of a weak-laser-pulse version of the Bennett-Brassard 1984 (BB84) protocol.
Abstract: The effect of scintillation, arising from propagation through atmospheric turbulence, on the sift and error probabilities of a quantum key distribution (QKD) system that uses the weak-laser-pulse version of the Bennett-Brassard 1984 (BB84) protocol is evaluated. Two earth-space scenarios are examined: satellite-to-ground and ground-to-satellite transmission. Both lie in the far-field power-transfer regime. This work complements previous analysis of turbulence effects in near-field terrestrial BB84 QKD [J. H. Shapiro, Phys. Rev. A 67, 022309 (2003)]. More importantly, it shows that scintillation has virtually no impact on the sift and error probabilities in earth-space BB84 QKD, something that has been implicitly assumed in prior analyses for that application. This result contrasts rather sharply with what is known for high-speed laser communications over such paths, in which deep, long-lived scintillation fades present a major challenge to high-reliability operation.
01 May 2011
TL;DR: A two-way entanglement-based communication protocol resilient to high loss and noise is implemented and efficient communication that is secure against passive eavesdropping is possible.
Abstract: A two-way entanglement-based communication protocol resilient to high loss and noise is implemented. Even though the entanglement is lost during transmission, efficient communication that is secure against passive eavesdropping is possible.
TL;DR: In this paper, Chen et al. showed that the photon-coincidence counting experiments can be fully explained with semiclassical photodetection theory, in which light is taken to be a classical electromagnetic wave, and the discreteness of the electron charge leads to shot noise as the fundamental photodeterection noise.
Abstract: Recently, Chen \em et al\rm.\ [New J. Phys. {\bf 13} (2011) 083018] presented experimental results, accompanied by quantum-mechanical analysis, showing that the quantum interference behavior of Bell states could be simulated in a modified Mach-Zehnder interferometer whose inputs are pseudothermal light beams obtained by passing laser light through a rotating ground-glass diffuser. Their experiments and their theory presumed low-flux operation in which the simulated quantum interference is observed via photon-coincidence counting. We first show that the Chen \em et al\rm.\ photon-coincidence counting experiments can be fully explained with semiclassical photodetection theory, in which light is taken to be a classical electromagnetic wave, and the discreteness of the electron charge leads to shot noise as the fundamental photodetection noise. We then use semiclassical photodetection theory to show that the \em same\rm\ simulated quantum interference pattern can be observed in high-flux operation, when photocurrent cross-correlation is used instead of photon-coincidence counting.
Posted Content•
TL;DR: In this article, the effect of turbulence on quantum ghost imaging was investigated and it was shown that by decoupling the entangled photon source from the ghost imaging central image plane, the authors were able to dramatically increase the ghost image quality.
Abstract: We investigate the effect of turbulence on quantum ghost imaging. We use entangled photons and demonstrate that for a novel experimental configuration the effect of turbulence can be greatly diminished. By decoupling the entangled photon source from the ghost imaging central image plane, we are able to dramatically increase the ghost image quality. When imaging a test pattern through turbulence, this method increased the imaged pattern visibility from V = 0.14 +/- 0.04 to V = 0.29 +/- 0.04.
01 May 2011
TL;DR: In this paper, the authors demonstrate far-field ghost imaging with phase-sensitive classical light whose anti-phase correlation between the signal and reference beams is imposed by two spatial light modulators.
Abstract: We demonstrate for the first time far-field ghost imaging with phase-sensitive classical light whose anti-phase correlation between the signal and reference beams is imposed by two spatial light modulators.