Soliton Squeezing in a Mach-Zehnder Fiber Interferometer

A new scheme for generating amplitude squeezed light by means of soliton self-phase modulation is experimentally demonstrated. By injecting 180-fs pulses into an equivalent Mach-Zehnder fiber interferometer, a maximum noise reduction of $4.4 \pm 0.3$ dB is obtained ($6.3 \pm 0.6$ dB when corrected for losses). The dependence of noise reduction on the interferometer splitting ratio and fiber length is studied in detail.Comment: 5 pages, 4 figure

Generation and manipulation of squeezed states of light in optical networks for quantum communication and computation

We analyze a fiber-optic component which could find multiple uses in novel information-processing systems utilizing squeezed states of light. Our approach is based on the phenomenon of photon-number squeezing of soliton noise after the soliton has propagated through a nonlinear optical fiber. Applications of this component in optical networks for quantum computation and quantum cryptography are discussed.Comment: 12 pages, 2 figures; submitted to Journal of Optics

Nonclassical correlations in damped quantum solitons

Using cumulant expansion in Gaussian approximation, the internal quantum statistics of damped soliton-like pulses in Kerr media are studied numerically, considering both narrow and finite bandwidth spectral pulse components. It is shown that the sub-Poissonian statistics can be enhanced, under certain circumstances, by absorption, which damps out some destructive interferences. Further, it is shown that both the photon-number correlation and the correlation of the photon-number variance between different pulse components can be highly nonclassical even for an absorbing fiber. Optimum frequency windows are determined in order to realize strong nonclassical behavior, which offers novel possibilities of using solitons in optical fibers as a source of nonclassically correlated light beams.Comment: 15 pages, 11 PS figures (color

Intermittent random walks for an optimal search strategy: One-dimensional case

We study the search kinetics of an immobile target by a concentration of randomly moving searchers. The object of the study is to optimize the probability of detection within the constraints of our model. The target is hidden on a one-dimensional lattice in the sense that searchers have no a priori information about where it is, and may detect it only upon encounter. The searchers perform random walks in discrete time n=0,1,2, ..., N, where N is the maximal time the search process is allowed to run. With probability \alpha the searchers step on a nearest-neighbour, and with probability (1-\alpha) they leave the lattice and stay off until they land back on the lattice at a fixed distance L away from the departure point. The random walk is thus intermittent. We calculate the probability P_N that the target remains undetected up to the maximal search time N, and seek to minimize this probability. We find that P_N is a non-monotonic function of \alpha, and show that there is an optimal choice \alpha_{opt}(N) of \alpha well within the intermittent regime, 0 < \alpha_{opt}(N) < 1, whereby P_N can be orders of magnitude smaller compared to the "pure" random walk cases \alpha =0 and \alpha = 1.Comment: 19 pages, 5 figures; submitted to Journal of Physics: Condensed Matter; special issue on Chemical Kinetics Beyond the Textbook: Fluctuations, Many-Particle Effects and Anomalous Dynamics, eds. K.Lindenberg, G.Oshanin and M.Tachiy

Mode structure and photon number correlations in squeezed quantum pulses

The question of efficient multimode description of optical pulses is studied. We show that a relatively very small number of nonmonochromatic modes can be sufficient for a complete quantum description of pulses with Gaussian quadrature statistics. For example, a three-mode description was enough to reproduce the experimental data of photon number correlations in optical solitons [S. Spalter et al., Phys. Rev. Lett. 81, 786 (1998)]. This approach is very useful for a detailed understanding of squeezing properties of soliton pulses with the main potential for quantum communication with continuous variables. We show how homodyne detection and/or measurements of photon number correlations can be used to determine the quantum state of the multi-mode field. We also discuss a possible way of physical separation of the nonmonochromatic modes.Comment: 14 pages, 4 figures; minor revisions of the text, new references; to appear in the Phys. Rev.

Soliton back-action evading measurement using spectral filtering

We report on a back-action evading (BAE) measurement of the photon number of fiber optical solitons operating in the quantum regime. We employ a novel detection scheme based on spectral filtering of colliding optical solitons. The measurements of the BAE criteria demonstrate significant quantum state preparation and transfer of the input signal to the signal and probe outputs exiting the apparatus, displaying the quantum-nondemolition (QND) behavior of the experiment.Comment: 5 pages, 5 figure

TIME DOMAIN CORRELATIONS AND GATED DETECTION OF QUANTUM SOLITONS

We study the time-domain quantum-noise properties of solitons in optical fibers. Perturbation theory, including quantum description of the continuum, is used to derive a complete analytical expression for the second-order correlator of the amplitude quadrature in time domain. This correlator is subsequently used to calculate the photon-number noise reduction below the standard quantum limit by means of a time-gating filter. For propagation distances up to three soliton periods, the length at which the best noise reduction occurs, a square band-reject time filter is found to produce approximately 3.2 dB of squeezing

Time Domain Correlations and Gated Detection of Quantum Solitons

this paper, we derive analytical expressions for the quantum-noise correlators of the time-domain soliton quadratures from their frequency-domain counterparts, taking into account complete contribution of the Quantum Communications and Measurement, ed. by P. Kumar et al., Plenum Press, New York, in press. continuum

Прогностична роль клінічних даних і молекулярно-біологічних тканинних маркерів при великофракційному передопераційному опроміненні раку гортані

Cancer of the larynx ranks 10th among men in the general structure of Ukraine. The problem of the treatment of this disease is far from being solved. Alternative methods of treatment and prognosis are being searched for. We used large-fractional preoperative irradiation of cancer of the larynx, studied the main clinical features and tumor markers indicators which can be used for prediction and feasibility selection of a method of treatment.Рак гортани занимает 10-ое место среди мужчин в общей структуре Украины. Проблема лечения этой патологии далека от разрешения. Проводится поиск альтернативных методов лечения и прогноза заболевания. Нами применено крупнофракционное предоперационное облучение рака гортани, изучены основные клинические проявления и онкомаркеры, показатели которых могут использоваться для прогноза и выбора целесообразности того или иного метода лечения.Рак гортані посідає 10-те місце серед чоловіків у загальній структурі України. Проблема лікування цієї патології далека від вирішення. Проводиться пошук альтернативних методів лікування і прогнозу захворювання. Нами застосовано великофракційне передопераційне опромінення раку гортані, вивчено основні клінічні прояви, онкомаркери, показники якихможуть використовуватися для прогнозу та вибору доцільності того чи іншого методу лікування