25 research outputs found
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 dB is obtained ( 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