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1.
function for the squeezed atomic coherent state in entangled state representation and some of its applications 下载免费PDF全文
Based on the Einstein, Podolsky, and Rosen (EPR) entangled state representation, this paper introduces the wave function for the squeezed atomic coherent state (SACS), which turns out to be just proportional to a single-variable ordinary Hermite polynomial of order 2j. As important applications of the wave function, the Wigner function of the SACS and its marginal distribution are obtained and the eigenproblems of some Hamiltonians for the generalized angular momentum system are solved. 相似文献
2.
《中国物理 B》2021,30(9):90308-090308
The quantum speed limit time for quantum system under squeezed environment is studied. We consider two typical models, the damped Jaynes–Cummings model and the dephasing model. For the damped Jaynes–Cummings model under squeezed environment, we find that the quantum speed limit time becomes larger with the squeezed parameter r increasing and indicates symmetry about the phase parameter value θ = π. Meanwhile, the quantum speed limit time can also be influenced by the coupling strength between the system and environment. However, the quantum speed limit time for the dephasing model is determined by the dephasing rate and the boundary of acceleration region that interacting with vacuum reservoir can be broken when the squeezed environment parameters are appropriately chosen. 相似文献
3.
Wave function for the squeezed atomic coherent state in entangledstate representation and some of its applications 下载免费PDF全文
Based on the Einstein, Podolsky, and Rosen (EPR) entangled
state representation, this paper introduces the wave function for
the squeezed atomic coherent state (SACS), which turns out to be
just proportional to a single-variable ordinary Hermite polynomial
of order 2j. As important applications of the wave function,
the Wigner function of the SACS and its marginal distribution are
obtained and the eigenproblems of some Hamiltonians for the
generalized angular momentum system are solved. 相似文献
4.
《中国物理 B》2019,(4)
We theoretically investigate the phase sensitivity with parity measurement on a Mach–Zehnder interferometer with a coherent state combined with a squeezed number state. Within a constraint on the total mean photon number, we find, via parity measurement, that the mixing of a coherent state and squeezed number state can give better phase sensitivity than mixing a coherent state and squeezed vacuum state when the phase shift deviates from the optimal phase φ= 0. In addition,we show that the classical Fisher information for parity measurement saturates the quantum Fisher information when the phase shift approaches to zero. Thus, the quantum Crame′r–Rao bound can be reached via the parity measurement in the case of φ= 0. 相似文献
5.
Squeezed state of light has drawn an enormous attention in information processing and digital communication since it has broken the quantum limit of noise. Here we have analytically investigated the interactions among coherent and vacuum squeezed states of light, interaction among coherent vacuum and squeezed states of light, and that between phase and amplitude squeezed states of light signals. Hence we established the nature of the resulting interaction with the help of photon statistics. 相似文献
6.
We carried out a study of statistical properties of a squeezed coherent state superposition (SCSS) evolving under a thermal reservoir at zero and finite temperature. Our results reveal some peculiarities not noticed by previous studies, which were mainly focused on ideal (lossless) properties of SCSS. Our main results indicate the existence of realistic parameters for which SCSS, at zero absolute, remains sub-Poissonian or squeezed asymptotically, while, at finite temperature, we found that SCSS only loses its squeezing or sub-Poissonian character at large times as compared with the time needed to the SCSS become a complete mixture. 相似文献
7.
Mallet F Castellanos-Beltran MA Ku HS Glancy S Knill E Irwin KD Hilton GC Vale LR Lehnert KW 《Physical review letters》2011,106(22):220502
We perform state tomography of an itinerant squeezed state of the microwave field prepared by a Josephson parametric amplifier (JPA). We use a second JPA as a preamplifier to improve the quantum efficiency of the field quadrature measurement from 2% to 36%±4%. Without correcting for the detection inefficiency we observe a minimum quadrature variance which is 68(-7)(+9)% of the variance of the vacuum. We reconstruct the state's density matrix by a maximum likelihood method and infer that the squeezed state has a minimum variance less than 40% of the vacuum, with uncertainty mostly caused by calibration systematics. 相似文献
8.
Wilson JH Nuttall AH Prater RA 《The Journal of the Acoustical Society of America》2006,120(6):3627-3634
An innovative noise suppression algorithm, called the coherent onion peeler (COP) (patent detained) is derived by minimizing the error in the coherent subtraction of the data from a single plane wave model. The COP solution "collapses" for all beamforming algorithms to the same solution at the complex hydrophone FFT level. Thus, any beamformer can be applied to the residual FFTs after the COP has been applied. The COP is applied to the strongest interferer first and the residual FFTs represent the acoustic field with this interferer coherently "peeled back" like the outer skin of an onion. This procedure can be repeated any number of times to coherently suppress the noise from all interferers present. A new nonadaptive beamformer is developed that "blends" together the best beam pattern properties of conventional beamforming (CBF) near array design frequency and the generalized fourier integral method (GFIM) at very low frequencies (VLF). In between these frequency extremes, the GFIM-CBF Blend (patent pending) (G-C Blend) is a frequency-dependent weighted average of both individual beamformers. COP and G-C Blend are applied to the broadband noise emitted by the tow ship, which severely degrades the performance of the towed array; COP reduced this broadband noise by over 19 dB in a single pass. 相似文献
9.
Time evolution of a squeezed chaotic field in an amplitude damping channel when used as a generating field for a squeezed number state 下载免费PDF全文
《中国物理 B》2015,(7)
We investigate how an optical squeezed chaotic field(SCF) evolves in an amplitude dissipation channel. We have used the integration within ordered product of operators technique to derive its evolution law. We also show that the density operator of SCF can be viewed as a generating field of the squeezed number state. 相似文献
10.
A scheme for the optimal Gaussian cloning of coherent light states at the interface between light and atoms is proposed. The distinct feature of this proposal is that the clones are stored in an atomic quantum memory, which is important for applications in quantum communication. The atomic quantum cloning machine requires only a single passage of the light pulse through the atomic ensembles followed by the measurement of a light quadrature and an appropriate feedback, which renders the protocol experimentally feasible. An alternative protocol, where one of the clones is carried by the outgoing light pulse, is discussed in connection with eavesdropping on quantum key distribution. 相似文献
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It is found that a coherent state of the cavity field can be generated in a micromaser with injected atoms in a coherent superposition of the upper and lower states. The dependence of the density matrix elements of the field on the number of injected atoms indicates that due to the same initial atomic coherence the emission of separately injected single atoms in the cavity is a cooperative process.Dedicated to Prof. Asim Barut on the occasion of his 65th birthday. Physicist, philosopher, friend of man, here indeed is a role model for us all. 相似文献
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15.
Properties of field quantum entropy evolution in the Jaynes--Cummings model with initial squeezed coherent states field 下载免费PDF全文
The properties of the field quantum entropy evolution in a system of
a single-mode squeezed coherent state field interacting with a
two-level atom is studied by utilizing the complete quantum theory,
and we focus our attention on the discussion of the influences of
field squeezing parameter $\gamma $, atomic distribution angle
$\theta $ and coupling strength $g$ between the field and the atom
on the properties of the evolution of field quantum entropy. The
results obtained from numerical calculation indicate that the
amplitude of oscillation of field quantum entropy evolution
decreases with the increasing of squeezing parameter $\gamma $, and
that both atomic distribution angle $\theta $ and coupling strength
$g$ between the field and the atom can influence the periodicity of
field quantum entropy evolution. 相似文献
16.
We propose a new two-mode squeezed coherent state representation |z1, z2〉g which is characteristic of the correlation between the squeezing and the displacement. Based on it and using the technique of integration within an ordered product of operators we obtain a generalized two-mode Fresnel operator (GTFO), which is an image of the mapping from (z1, z2) to in |z1, z2〉g representation. The matrix element of GTFO in the coordinate representation leads to a generalized two-dimensional Collins formula (Huygens-Fresnel integration transformation describing optical diffraction) in entangled form. 相似文献
17.
A scheme is proposed for the teleportation of an unknown atomic state. The scheme is based on the resonant interaction of atoms with a coherent cavity field. The mean photon-number of the cavity field is much smaller than one and thus the cavity decay can be effectively suppressed. Another advantage of the scheme is that only one cavity is required. 相似文献
18.
卢道明 《原子与分子物理学报》2007,24(1):183-187
利用T-C模型研究了耦合二能级原子与相干态光场相互作用系统中场熵的演化规律,数值计算结果表明:场熵的演化受原子间耦合强度和光场初始平均光子数的变化的影响. 相似文献
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J. H. Li 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,42(3):467-473
We theoretically study the features of the spontaneous emission
spectra in a coherently driven cold four-level atomic system with
a cyclic configuration. It is shown that a few interesting
phenomena such as spectral-line narrowing, spectral-line
enhancement, and spectral-line suppression can be realized in our
system. Interestingly enough, the spectral-line enhancement and
suppression can be controlled just by appropriately modulating the
phase, the frequency, and the intensity of an external coherent
magnetic field, respectively. This investigation may find
applications in high-precision spectroscopy.
An erratum to this article is available at . 相似文献