Showing papers by "Jeffrey H. Shapiro published in 2003"

Capacity of wireless optical communications

Abstract: We consider the ergodic capacity and capacity-versus-outage probability of direct-detection optical communication through a turbulent atmosphere using multiple transmit and receive apertures. We assume shot-noise-limited operation in which detector outputs are doubly stochastic Poisson processes whose rates are proportional to the sum of the transmitted powers, scaled by lognormal random fades, plus a background noise. In the high and low signal-to-background ratio regimes, we show that the ergodic capacity of this fading channel equals or exceeds that for a channel with deterministic path gains. Furthermore, knowledge of these path gains is not necessary to achieve capacity when the signal-to-background ratio is high. In the low signal-to-background ratio regime, path-gain knowledge provides minimal capacity improvement when using a moderate number of transmit apertures. We also develop expressions for the capacity-versus-outage probability in the high and low signal-to-background ratio regimes, by means of a moment-matching approximation to the distribution for the sum of lognormal random variables. Monte Carlo simulations show that these capacity-versus-outage approximations are quite accurate for moderate numbers of apertures.

Near-field turbulence effects on quantum-key distribution

Abstract: Bounds on average power transfer over a near-field optical path through atmospheric turbulence are used to deduce bounds on the sift and error probabilities of a free-space quantum-key distribution system that uses the Bennett-Brassard 1984 (BB84) protocol. It is shown that atmospheric turbulence imposes at most a modest decrease in the sift probability and a modest increase in the conditional probability of error given that a sift event has occurred.

Wireless optical communications via diversity reception and optical preamplification

Abstract: Atmospheric optical communication systems that use optical preamplifiers and diversity reception to combat the effects of atmospheric turbulence are addressed. The effects of atmospheric turbulence, background light, source extinction ratio, amplified spontaneous emission, and receiver thermal noise are considered in a context of a semiclassical photon-counting approach. The particular diversity techniques that are investigated include aperture averaging, linear combining, and adaptive optics. Numerical results, obtained using a conditional Gaussian approximation, quantify the link margin improvement due to optical preamplification and diversity reception.

Quantum Gaussian noise

Abstract: In semiclassical theory, light is a classical electromagnetic wave and the fundamental source of photodetection noise is the shot effect arising from the discreteness of the electron charge. In quantum theory, light is a quantum-mechanical entity and the fundamental source of photodetection noise comes from measuring the photon-flux operator. The Glauber coherent states are Gaussian quantum states which represent classical electromagnetic radiation. Quantum photodetection of these states yields statistics that are indistinguishable from the corresponding Poisson point-process results of semiclassical photodetection. Optical parametric interactions, however, can be used to produce other Gaussian quantum states, states whose photodetection behavior cannot be characterized semiclassically. A unified analytical framework is presented for Gaussian-state photodetection that includes the full panoply of nonclassical effects that have been produced via parametric interactions.

Fluctuations and Noise in Photonics and Quantum Optics

Abstract: This Special Issue of Journal of Optics B: Quantum and Semiclassical Optics brings together the contributions of various researchers working on theoretical and experimental aspects of fluctuational phenomena in photonics and quantum optics. The topics discussed in this issue extend from fundamental physics to applications of noise and fluctuational methods from quantum to classical systems, and include: ? Quantum measurement ? Quantum squeezing ? Solitons and fibres ? Gravitational wave inferometers ? Fluorescence phenomena ? Cavity QED ? Photon statistics ? Noise in lasers and laser systems ? Quantum computing and information ? Quantum lithography ? Teleportation. This Special Issue is published in connection with the SPIE International Symposium on Fluctuations and Noise, held in Santa Fe, New Mexico, on 1-4 June 2003. The symposium contained six parallel conferences, and the papers in this Special Issue are connected to the conference entitled `Fluctuations and Noise in Photonics and Quantum Optics'. This was the first in a series of symposia organized with the support of the SPIE that have greatly contributed to progress in this area. The co-founders of the symposium series were Laszlo B Kish (Texas AM as can be seen in the collection of papers, he was certainly present in spirit. In honour of his creativity and pioneering work in this field, we have dedicated this Special Issue to him. The first item is an obituary reflecting on his life and work. The first technical paper in this issue represents Hermann's last sole author publication; a special thanks is due to A P Flitney for organizing this manuscript into publishable form. We thank the members of the International Programme Committee, listed below, and all those who contributed to making the event such a success. At this point we take the opportunity to express our gratitude to both the authors and reviewers, for their unfailing efforts in preparing and ensuring the high quality of the papers in this Special Issue. International Programme Committee David A Cardimona?Air Force Research Laboratory, USA Howard Carmichael?University of Auckland, New Zealand Carlton M Caves?University of New Mexico, Albuquerque, USA Peter D Drummond?University of Queensland, St Lucia, Australia Paul J Edwards?University of Canberra, Australia Luca Gammaitoni?Universit? degli Studi di Perugia, Italy Brage Golding?Michigan State University, East Lansing, USA Gabriela Gonzalez?Louisiana State University, Baton Rouge, USA Guangcan Guo?University of Science and Technology of China, Hefei, China Salman Habib?Los Alamos National Laboratory, NM, USA Murray Hamilton?University of Adelaide, Australia Bei-Lok Hu?University of Maryland/College Park, USA Daniel K Johnstone?Virginia Commonwealth University, Richmond, USA Franz X K?rtner?Massachusetts Institute of Technology, Cambridge, USA Prem Kumar?Northwestern University, Evanston, IL, USA Zachary Lemnios?DARPA, Arlington, VA, USA Gerd Leuchs?Friedrich-Alexander Universit?t Erlangen--N?rnberg, Germany Hideo Mabuchi?California Institute of Technology, Pasadena, USA Peter W Milonni?Los Alamos National Laboratory, NM, USA Adrian C Ottewill?University College Dublin, Ireland Martin B Plenio?Imperial College, London, UK Rajeev J Ram?Massachusetts Institute of Technology, Cambridge, USA Farhan Rana?Massachusetts Institute of Technology, Cambridge, USA Peter R Smith?Loughborough University of Technology, UK Rodney S Tucker?University of Melbourne, Australia Howard M Wiseman?Griffith University, Brisbane, Australia Stuart A Wolf?DARPA, Arlington, VA, USA Anton Zeilinger?University of Vienna, Austria Xi-Cheng Zhang?Rensselaer Polytechnic Institute, Troy, NY, USA

Error models for long-distance qubit teleportation

Abstract: A recent proposal for realizing long-distance, high-fidelity qubit teleportation is reviewed. This quantum communication architecture relies on an ultrabright source of polarization-entangled photons plus a pair of trapped-atom quantum memories, and it is compatible with long-distance transmission over standard telecommunication fiber. Models are developed for assessing the effects of amplitude, phase, and frequency errors in the entanglement source, as well as fiber loss and imperfect polarization restoration, on the throughput and fidelity of the system.

Toward target recognition from synthetic aperture radar imagery using electromagnetics-based signatures

Abstract: We develop a theory of target detection and classification from physics-based synthetic aperture radar (SAR) signatures. The target-return and clutter-return models are developed from electromagnetic theory. Both stripmap-mode and spotlight-mode SARs are treated. Adaptive-resolution processors, conventional SAR processors, and optimum likelihood-ratio target detectors are presented for multicomponent target detection, and their receiver operating characteristics are compared. Similarly, conventional and optimum likelihood-ratio processors are used for multicomponent target classification. We develop upper and lower bounds and present Monte Carlo simulations for the probabilities of correct classification.

Ultrabright tunable photon-pair source with total-flux polarization-entanglement

Abstract: We demonstrate a continuous-wave dual-pump tunable source of polarization-entangled photons that requires no spectral or spatial filtering and emits ten times more pairs per mW of pump than pervious sources.

Error models and error mitigation for long-distance high-fidelity quantum secret sharing

Abstract: A quantum communication architecture is being developed for long-distance, high-fidelity transmission and storage of Greenberger-Horne-Zeilinger states. This system uses an ultrabright narrowband source of polarization-entangled photons plus trapped-atom quantum memories, and it is compatible with long-distance transmission over standard telecommunication fiber. An error model for the preceding architecture is derived, and the use of quantum error correction or entanglement purification protocols to improve the performance of this quantum communication system is also discussed.

Generation of polarization entanglement from a PPKTP parametric downconverter

Abstract: We have generated polarization-entangled photon pairs from a type-II phase-matched periodically poled KTP parametric downconverter with collinear outputs. Bell's inequality was violated with a value of 2.57 /spl plusmn/ 0.03.

Progress toward long-distance, high-fidelity quantum communication

Abstract: A team of researchers from the Massachusetts Institute of Technology and Northwestern University is developing a system for achieving long-distance, high-fidelity teleportation and long-duration quantum storage. This paper will report recent progress that has been made in architectural studies, entanglement sources, and quantum memory.