Publications
274 results found
Kim MS, Allen L, Loudon R, 1994, Quantum theory of radiation pressure on a dielectric slab, Physical Review A, Vol: 50, Pages: 3614-3626, ISSN: 1050-2947
BUZEK V, GANTSOG T, KIM M, 1994, PRODUCTION OF MACROSCOPIC SCHRODINGER CAT STATES FROM WEAK QUANTIZED CAVITY FIELDS INTERACTING WITH ATOMS DRIVEN BY CLASSICAL FIELDS, JOURNAL OF MODERN OPTICS, Vol: 41, Pages: {1625-1635}-{1625-1635}, ISSN: 0950-0340
We show that macroscopic superposition (Schrodinger cat) states of a quantized single-mode cavity field can be produced via the interaction of this field with a two-level atom which is driven by a classical field even for small initial intensities of the quantized cavity mode. We show that with a properly chosen driving field an almost pure superposition state with arbitrary amplitudes and phases of component states can be produced.
LEE K, KIM M, BUZEK V, 1994, AMPLIFICATION OF MULTICOMPONENT SUPERPOSITIONS OF COHERENT STATES OF LIGHT WITH QUANTUM AMPLIFIERS, JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS, Vol: 11, Pages: {1118-1129}-{1118-1129}, ISSN: 0740-3224
We analyze statistical properties of multicomponent superpositions of coherent states of light amplified by quantum-mechanical amplifiers with reduced quantum fluctuations. We show that sub-Poissonian (i.e., amplitude-squeezed) amplifiers can transform any initial superposition of coherent states of light into a nonclassical state with a high degree of sub-Poissonian photon statistics. Simultaneously the shape of the photon-number distribution of the initial state of light is preserved but shifted toward higher photon numbers. On the other hand, we show that phase-sensitive (i.e., quadrature-squeezed) amplifiers may preserve the initial reduction of quadrature fluctuations (quadrature squeezing). We show that by using amplifiers with reduced quantum noise one can, in principle, control the influence of the noise transferred from the amplifier to the system.
KIM M, BUZEK V, KIM M, 1994, GENERATION OF PHASE-SENSITIVE NONCLASSICAL EFFECTS VIA DECAY OF LIGHT INTO A PHASE-INSENSITIVE ENVIRONMENT, PHYSICS LETTERS A, Vol: 186, Pages: {283-288}-{283-288}, ISSN: 0375-9601
We show that phase-sensitive nonclassical effects can be transiently produced via decay of a field mode into a heat bath. In particular, we analyze the time evolution of the fourth-order squeezing of the field mode and we show that under certain conditions the light field which initially was not fourth-order squeezed may exhibit this nonclassical effect. We have found general conditions under which the reduction of higher-order moments of quadrature operators can be observed and eventually the fourth-order squeezing can be produced.
Kim MS, Kim MG, Lee KS, 1994, Squeezing Properties of Jaynes-Cummings Fields in Heat Baths, Journal of Modern Optics, Vol: 41, Pages: 569-580, ISSN: 0950-0340
MOYACESSA H, BUZEK V, KIM MS, et al., 1993, INTRINSIC DECOHERENCE IN THE ATOM-FIELD INTERACTION, PHYSICAL REVIEW A, Vol: 48, Pages: 3900-3905, ISSN: 1050-2947
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- Citations: 155
Kim MS, 1993, Dissipation and Amplification of Jaynes-Cummings Superposition States, Journal of Modern Optics, Vol: 40, Pages: 1331-1350, ISSN: 0950-0340
Park B, Kim MS, Kim YD, et al., 1993, Charge-transfer effect on surface-enhanced second-harmonic generation, The Journal of Physical Chemistry, Vol: 97, Pages: 5080-5084, ISSN: 0022-3654
KIM MS, DEOLIVEIRA FAM, KNIGHT PL, 1990, THE INTERACTION OF DISPLACED NUMBER STATE AND SQUEEZED NUMBER STATE FIELDS WITH 2-LEVEL ATOMS, 9TH UNITED KINGDOM CONF ON QUANTUM ELECTRONICS, Publisher: TAYLOR & FRANCIS LTD, Pages: 659-669, ISSN: 0950-0340
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- Citations: 16
DEOLIVEIRA FAM, KIM MS, KNIGHT PL, et al., 1990, PROPERTIES OF DISPLACED NUMBER STATES, PHYSICAL REVIEW A, Vol: 41, Pages: 2645-2652, ISSN: 1050-2947
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- Citations: 277
Kim MS, Deoliveira FAM, Knight PL, 1990, The interaction of displaced number state and squeezed number state fields with 2-level atoms, Journal of Modern Optics, Vol: 37, Pages: 659-669, ISSN: 0950-0340
KIM M, DEOLIVEIRA F, KNIGHT P, 1989, PROPERTIES OF SQUEEZED NUMBER STATES AND SQUEEZED THERMAL STATES, PHYSICAL REVIEW A, Vol: 40, Pages: {2494-2503}-{2494-2503}, ISSN: 1050-2947
KIM MS, DEOLIVEIRA FAM, KNIGHT PL, 1989, PHOTON NUMBER DISTRIBUTIONS FOR SQUEEZED NUMBER STATES AND SQUEEZED THERMAL STATES, OPTICS COMMUNICATIONS, Vol: 72, Pages: 99-103, ISSN: 0030-4018
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- Citations: 59
KIM MS, KNIGHT PL, 1989, PHOTON CORRELATIONS AND SUCCESSIVE EMISSION, PHYSICAL REVIEW A, Vol: 40, Pages: 215-227, ISSN: 1050-2947
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- Citations: 24
KIM MS, DEOLIVEIRA FAM, KNIGHT PL, 1989, SIMULTANEOUS JUMPS IN 2 2-LEVEL ATOMS, OPTICS COMMUNICATIONS, Vol: 70, Pages: 473-477, ISSN: 0030-4018
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- Citations: 27
KIM MS, KNIGHT PL, 1987, QUANTUM-JUMP TELEGRAPH NOISE AND MACROSCOPIC INTENSITY FLUCTUATIONS, PHYSICAL REVIEW A, Vol: 36, Pages: 5265-5270, ISSN: 1050-2947
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- Citations: 36
KIM MS, KNIGHT PL, WODKIEWICZ K, 1987, CORRELATIONS BETWEEN SUCCESSIVELY EMITTED PHOTONS IN RESONANCE FLUORESCENCE, OPTICS COMMUNICATIONS, Vol: 62, Pages: 385-388, ISSN: 0030-4018
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- Citations: 30
REMPE G, WALTHER H, KLEIN N, 1987, OBSERVATION OF QUANTUM COLLAPSE AND REVIVAL IN A ONE-ATOM MASER, PHYSICAL REVIEW LETTERS, Vol: 58, Pages: 353-356, ISSN: 0031-9007
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- Citations: 1296
Kim MS, Antesberger G, Bodendorf CT, et al., Scheme for direct observation of the Wigner characteristic function in cavity QED, PHYSICAL REVIEW A, Vol: 58, Pages: {R65-R68}-{R65-R68}, ISSN: 1050-2947
We suggest a quantum state reconstruction scheme. Our proposal is applicable to the field inside a microwave cavity as well as to the harmonic motion of a trapped atom. It will be shown that the inversion of two-level atoms after a resonant interaction with a coherently displaced quantum state is directly related to the Wigner characteristic function of the initial state. This method neither requires the preparation of atoms in a quantum superposition of the upper and lower energy levels nor heavy numerical processing of the measured data. We demonstrate the reconstruction scheme for the example of a Schrodinger-cat superposition state.
KIM M, BUZEK V, DECAY OF QUANTUM COHERENCES UNDER THE INFLUENCE OF A THERMAL HEATBATH - SCHRODINGER CAT STATES AT FINITE TEMPERATURE, JOURNAL OF MODERN OPTICS, Vol: 39, Pages: {1609-1614}-{1609-1614}, ISSN: 0950-0340
Recently several methods have been proposed for generation of superposition (Schrodinger cat) states in microwave cavities. At microwave frequencies thermal photons can significantly affect statistical properties of superposition states. In the present letter we study the influence of a thermal heatbath on non-classical properties of quantum superposition states. We show that at non-zero temperatures the loss of quantum coherences is much faster than at zero temperature and that the sensitivity of the quantum coherence to the presence of thermal photons can lead to some difficulties in the preparation of Schrodinger cat states in microwave cavities unless the temperature of the microwave cavity is sufficiently low.
Kim MS, Sanders BC, Squeezing and antisqueezing in homodyne measurements, PHYSICAL REVIEW A, Vol: 53, Pages: {3694-3697}-{3694-3697}, ISSN: 1050-2947
Squeezing the signal field or the local oscillator can improve the accuracy of homodyne detection. We show that an equivalence exists between antisqueezing the signal field and squeezing the local oscillator state. The importance of this result is illustrated in two contexts: a homodyne measurement of squeezing and the reconstruction of the wave function.
Janszky J, Kim MG, Kim MS, Quasiprobabilities and the nonclassicality of fields, PHYSICAL REVIEW A, Vol: 53, Pages: {502-506}-{502-506}, ISSN: 1050-2947
The existence of positive well-defined quasiprobabilities is known to be related to the measure of nonclassicality for a given field state. We test the coincidence of the loss of well-known nonclassical properties with the appearance of the positive well-defined quasiprobabilities for various fields influenced by phase-insensitive reservoirs. For Gaussian fields the appearance of a positive Glauber-Sudarshan P function coincides with the loss of nonclassical properties in quadrature fluctuations and in photon statistics. We find that when an initial Fock state dissipates or is amplified the initial field loses its nonclassicality in photon statistics before the P function becomes positive, which is different from the Gaussian field. The Wigner function may be positive even when the decaying Fock state is sub-Poissonian. For the amplification of the Pock state, however, the Wigner function is positive only when the field is super-Poissonian. For the dissipation and amplification of the Fock state the point when a certain quasiprobability function becomes positive definite depends only on the average number of photons N of the heat bath.
KIM M, IMOTO N, PHASE-SENSITIVE RESERVOIR MODELED BY BEAM-SPLITTERS, PHYSICAL REVIEW A, Vol: 52, Pages: {2401-2410}-{2401-2410}, ISSN: 1050-2947
The superposition of input fields in a lossless beam splitter is studied in the Schrodinger picture by using the convolution of the positive P representations, and the convolution law for these representations is extended to other quasiprobability functions such as the Wigner and Q functions. We show that the reservoir can be modeled by an infinite array of beam splitters, and we use the convolution law and this model to derive the Fokker-Planck equation for a system coupled with a phase-sensitive reservoir. Solving this equation shows that a phase-sensitive attenuation and amplification can be described by the superposition of two independent quantum fields, one of which is the initial signal field and the other the squeezed thermal noise field representing the reservoir.
BUZEK V, KIM M, KIM M, ENTROPIC UNCERTAINTY RELATIONS FOR OPERATIONAL PHASE-SPACE MEASUREMENT, JOURNAL OF THE KOREAN PHYSICAL SOCIETY, Vol: 28, Pages: {529-533}-{529-533}, ISSN: 0374-4884
We introduce entropic measures of uncertainty related to operational phase-space probability density distributions. With the help of these entropies, we find the entropic uncertainty relation for the position ((q) over cap) and the momentum ((p) over cap) operators of a quantum-mechanical system in the form S-Psi Phi((q)) + S-Psi Phi((p)) greater than or equal to S-Psi Phi((q,p)) greater than or equal to k(B). The fundamental lower bound on the entropic uncertainty relation is equal to the Boltzmann constant k(B).
SANDERS B, LEE K, KIM M, OPTICAL HOMODYNE MEASUREMENTS AND ENTANGLED COHERENT STATES, PHYSICAL REVIEW A, Vol: 52, Pages: {735-741}-{735-741}, ISSN: 1050-2947
BUZEK V, KIM M, KIM M, DESCRIPTION OF THE INFLUENCE OF A RESERVOIR VIA COARSE-GRAINING IN PHASE-SPACE, JOURNAL OF THE KOREAN PHYSICAL SOCIETY, Vol: 28, Pages: {123-127}-{123-127}, ISSN: 0374-4884
We show that the Q-function of a single-mode field which is attenuated or amplified by a phase-sensitive environment can be expressed through a coarse-grained Q-function with time-dependent coarse-graining parameters. This fact can be utilized for simulation of the decay of quantum systems into various environments. In particular, we have derived an analytical expression describing the time-evolution of the Q-function of the initial Fock state which decays into a phase-sensitive reservoir.
BUZEK V, KIM M, DECAY WITHOUT LOSSES - MEAN-PHOTON-NUMBER DECAY AND SHANNON ENTROPY DECAY OF MICROMASER FIELDS VIA CONDITIONAL MEASUREMENTS, JOURNAL OF THE KOREAN PHYSICAL SOCIETY, Vol: 27, Pages: {215-220}-{215-220}, ISSN: 0374-4884
We investigate the dynamics of a lossless micromaser when a single-mode cavity field is resonantly coupled via one-photon transitions to two-level atoms crossing the cavity in a sequence. We analyze the statistical properties of the cavity field when the atoms after the interaction are conditionally measured, provided the interaction time is short. Namely, we select only those sequences wherein each atom after the interaction is measured in its initial state. We assume that the total sequence duration is smaller than the cavity decay time so that cavity losses can be neglected. We show that even though there is no direct transfer of the energy from the atoms to the field and vice versa, the mean photon number of the cavity field is reduced due to the conditional measurement. This energy ‘’decay” is accompanied by a reduction of the Shannon entropy of the field. We show that there exists an attractor state of the cavity field which is the Fock state with the smallest photon number which contributes to the initial state of the field. Finally, we find the remarkable result that the time evolution of a field initially prepared in a coherent state which is conditionally measured by the sequence of atoms is exactly the same as the time evolution of a coherent field decaying into a zero-temperature heat bath.
BUZEK V, GANTSOG T, KIM M, PHASE PROPERTIES OF SCHRODINGER CAT STATES OF LIGHT DECAYING IN PHASE-SENSITIVE RESERVOIRS, PHYSICA SCRIPTA, Vol: T48, Pages: {131-142}-{131-142}, ISSN: 0281-1847
We study phase properties of quantum mechanical superposition states decaying into phase-sensitive reservoirs. We show that the Wigner phase quasiprobability distribution reflects the quantum interference effects very well while the Pegg-Barnett and the Husimi phase probability distributions are quite insensitive with respect to the character of the quantum interference between component states. We study in detail phase properties of the even coherent state which decays into the thermal and the squeezed reservoirs. In thermal reservoirs the phase of the superposition state becomes randomized under the influence of thermal fluctuations. The higher the number of thermal photons the faster the randomization process is. On the other hand we show that depending on the relative phase between the superposition state and the phase-sensitive reservoir the process of phase randomization can be either enhanced or completely s suppressed.
BUZEK V, KIM M, GANTSOG T, QUANTUM PHASE DISTRIBUTIONS OF AMPLIFIED SCHRODINGER-CAT STATES OF LIGHT, PHYSICAL REVIEW A, Vol: 48, Pages: {3394-3397}-{3394-3397}, ISSN: 1050-2947
We study the phase properties of quantum superpositions of two coherent states (Schrodinger-cat states) amplified by phase-sensitive (squeezed) amplifiers. We show that a phase-sensitive amplifier with a properly chosen phase can preserve the phase distribution of the Schrodinger-cat-state input.
LEE K, KIM M, LEE S, et al., SQUEEZING PROPERTIES OF MULTICOMPONENT SUPERPOSITION STATES OF LIGHT, JOURNAL OF THE KOREAN PHYSICAL SOCIETY, Vol: 26, Pages: {197-204}-{197-204}, ISSN: 0374-4884
Interacting with a Kerr medium, an input coherent field evolves into a generalized coherent state. We show that at the interaction time lambdat = pi/N, where lambda is the nonlinear coupling coefficient, the generalized coherent state is transformed into a superposition of N coherent component states. Using the Wigner-function phase-space formalism, we show that the noise reduction takes place along rotated quadrature axes for the superposition states and for the generalized coherent states. The influence of a dissipative environment (vacuum reservoir) on the squeezing properties of these multicomponent superposition states is investigated. In the stationary limit, the noise is again reduced to the vacuum level. Deterioration of squeezing is related with the rapid decay of quantum coherences under the influence of the reservoir.
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