共查询到20条相似文献,搜索用时 15 毫秒
1.
Wang Kaige A. Sinatra L.A. Lugiato 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,12(2):339-349
We present a simple method, based on the quantum regression theorem, to calculate the quantum correlation spectra for two
optical beams in the linearized fluctuation regime. As an application, we discuss the dynamical instability, the squeezing
spectra and the QND properties of a crossed Kerr-type dispersive model.
Received 30 August 1999 and Received in final form 4 July 2000 相似文献
2.
Y. Zhang K. Kasai M. Watanabe 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,21(3):361-366
We propose a novel quantum switch teleportation with a continuous variable, which can teleport a quantum state to two different
receivers alternatively, using a pair of two-mode squeezed lights as the quantum switching to manipulate the transmission
route. In this scheme, the EPR entangled beams shared by sender and receivers are produced by mixing a pair of two-mode squeezed
lights on one beamsplitter and separating them by using a polarizing beam splitter. The teleportation capability of this system
is examined by the criteria proposed by Ralph and Lam [#!ralph!#] from a small signal quantum optical point of view.
Received 20 May 2002 / Received in final form 29 July 2002 Published online 24 September 2002
RID="a"
ID="a"e-mail: zhangyun@crl.go.jp 相似文献
3.
Y. Shih 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,22(3):485-493
One of the most surprising consequences of quantum mechanics is the entanglement of two or more distant particles. Even though
we still have questions in regard to fundamental issues of the entangled quantum systems, quantum entanglement has started
to play important roles in practical applications. Quantum imaging is one of the hot topics. Quantum imaging has many interesting
features which are useful for different applications. For example, quantum imaging can be nonlocal, which is useful for secure
two-dimensional information transfer. Quantum imaging can reach a much higher spatial resolution comparing with classical
imaging, even beyond the diffraction limit, which is useful for lithography and other microsystem fabrication technology.
It is not a violation of the uncertainty principle, however, a quantum mechanical multi-particle phenomenon.
Received 30 August 2002 / Received in final form 11 November 2002 Published online 4 February 2003 相似文献
4.
R. Migliore A. Messina A. Napoli 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,13(3):585-588
We prove that a mesoscopic Josephson junction, irradiated with a quantum superposition of two -out of phase optical coherent states, exhibits an experimentally observable sensitivity to the quantum coherences of the
field state.
Received 1 June 1999 and Received in final form 30 July 1999 相似文献
5.
S.M. Barnett C. Fabre A. Maıtre 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,22(3):513-519
We compare two high sensitivity techniques which are used to measure very small displacements of physical objects by optical
techniques: the interferometric devices, measuring longitudinal phase shifts, and the devices used to monitor transverse displacement
of light beams. We detail the differences and the similarities for the quantum limits on the resolution of both systems. In
both cases squeezed light can be used to resolve beyond the standard quantum limit and number correlated states allow us to
reach the “Heisenberg” limit.
Received 12 September 2002 Published online 21 January 2003 相似文献
6.
L. Vernac M. Pinard V. Josse E. Giacobino 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,18(1):129-135
Using a quantum theory for an ensemble of two- or three-level atoms driven by electromagnetic fields in an optical cavity,
we show that the various spins associated with the atomic ensemble can be squeezed. Two kinds of squeezing are obtained: on
the one hand self-spin squeezing when the input fields are coherent ones and the atomic ensemble exhibits a large non-linearity;
on the other hand squeezing transfer when one of the incoming fields is squeezed.
Received 14 August 2001 and Received in final form 7 November 2001 相似文献
7.
Paulina Marian Tudor A. Marian 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,11(2):257-265
We analyze the transient nonclassical behaviour of a single-mode field whose interaction with an environment is governed by
the quantum optical master equation. Our analytic method makes use of the generalized characteristic function of the field
state. First, we find a time at which all squeezing effects disappear by decoherence regardless of the initial state of the
mode. In the case of an input even coherent state, an unusual modification of higher-order squeezing at low values of thermal
mean occupancy transferred to the field is found and discussed. For the same initial state, we also perform a comprehensive
analysis of the mixing process during the interaction with the reservoir. We prove that a maximum in the evolution of the
2-entropy of the attenuated mode exists on condition that its initial mean photon number exceeds the mean occupancy of the
reservoir. This transient mixing enhancement can be considered as a quantum effect of the initial state on the mode damping.
Received 22 April 1999 and Received in final form 2 November 1999 相似文献
8.
9.
U. Leonhardt T. Kiss P. Piwnicki 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,7(3):413-423
Impressive pictures of moving Bose-Einstein condensates have been taken using phase-contrast imaging [M.R. Andrews et al., Science 273, 84 (1996)]. We calculate the quantum backaction of this measurement technique, assuming the absence of residual absorption.
We find that the condensate gets gradually depleted at a universal rate that is proportional to the light intensity and to
the inverse cube of the optical wave length. The fewer atoms are condensed the higher is the required intensity to see a picture,
and, consequently, the higher is the induced backaction. To describe the quantum physics of phase-contrast imaging we put
forward a new approach to quantum-optical propagation. We develop an effective field theory of paraxial optics in a fully
quantized atomic medium.
Received 25 February 1999 相似文献
10.
M. Pelton C. Santori G.S. Solomon O. Benson Y. Yamamoto 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,18(2):179-190
Current quantum cryptography systems are limited by the attenuated coherent pulses they use as light sources: a security loophole
is opened up by the possibility of multiple-photon pulses. By replacing the source with a single-photon emitter, transmission
rates of secure information can be improved. We have investigated the use of single self-assembled InAs/GaAs quantum dots
as such single-photon sources, and have seen a tenfold reduction in the multi-photon probability as compared to Poissonian
pulses. An extension of our experiment should also allow for the generation of triggered, polarization-entangled photon pairs.
The utility of these light sources is currently limited by the low efficiency with which photons are collected. However, by
fabricating an optical microcavity containing a single quantum dot, the spontaneous emission rate into a single mode can be
enhanced. Using this method, we have seen 78% coupling of single-dot radiation into a single cavity resonance. The enhanced
spontaneous decay should also allow for higher photon pulse rates, up to about 3 GHz.
Received 8 July 2001 and Received in final form 25 August 2001 相似文献
11.
传统的螺旋相位板是一种利用沿方位角方向介质材料高度递增实现对光束相位调控产生涡旋光束的光学器件,由于这种特殊的几何结构特征使其不能通过相位板的叠加而调控出射光束所携带的角量子数.本文基于坐标变换方法将介质材料沿方位角方向折射率不变而高度递增的传统螺旋相位板变换为一种介质材料沿方位角方向高度不变而折射率递增的平板式螺旋相位板.通过理论分析与数值模拟,发现本文所设计的平板式螺旋相位板不仅与传统螺旋相位板一样能够产生高质量的涡旋光束,而且平板式螺旋相位板的高度和涡旋光束携带的角量子数可以根据介质材料的折射率选取而任意调节.为了实际应用的需要,可以通过叠加多层平板式螺旋相位板以获得不同角量子数的涡旋光束.这种平板式螺旋相位板在光传输、光通信等领域具有广阔的潜在应用价值. 相似文献
12.
E. Brambilla A. Gatti L.A. Lugiato M.I. Kolobov 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,15(1):127-135
We analyze theoretically spatial structures appearing in the far diffraction zone of the electromagnetic field emitted in
the cavityless parametric down-conversion. We investigate in detail the spatial correlation functions of intensity and demonstrate
the existence of strong quantum correlations between the regions of the far field symmetrical with respect to the optical
axis. Our simplified model allows us to obtain analytical results for some limiting cases. We demonstrate that in the limit
of small diffraction and ideal quantum efficiency of photodetection the noise reduction in the photocurrent difference between
symmetrical regions in the far diffraction field becomes complete at zero frequency of photocurrent fluctuations.
Received 5 February 2001 and Received in final form 11 April 2001 相似文献
13.
量子纠缠是一种重要的量子资源,在多个空间分离的量子存储器间建立确定性的量子纠缠,然后在用户控制的时刻将所存储的量子纠缠转移到量子信道中进行信息的分发和传送,这对于实现量子信息网络是至关重要的.本文介绍了用光学参量放大器制备与铷原子D1吸收线对应的非经典光场,而且在三个空间分离的原子系综中确定性量子纠缠的产生、存储和转移.利用电磁感应透明光和原子相互作用的原理,将制备的多组分光场纠缠态模式映射到三个远距离的原子系综以建立原子自旋波之间的纠缠.然后,存储在原子系综中的纠缠态通过三个量子通道,纠缠态的量子噪声被转移到三束空间分离的正交纠缠光场.三束释放的光场间纠缠的存在验证了该系统具有保持多组分纠缠的能力.这个方案实现了三个量子节点间的纠缠,并且可以直接扩展到具有更多节点的量子网络,为未来实现大型量子网络通信奠定了基础. 相似文献
14.
Shi-Biao Zheng Guang-Can Guo 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,1(1):105-107
We propose a method for preparing superpositions of coherent states of the motion of an ion in an anisotropic two-dimensional
trap, in which the ion is tightly bound in the y direction. In the scheme the ion is excited by two resonant laser beams with equal amplitude, propagating along the x and y directions, respectively. In the Dicke-Lamb limit, an initial coherent state of the ion motion can be converted into a superposition
of several coherent states on a circle through the laser-ion interactions and state-selective measurements on the ion.
Received: 30 May 1997 / Revised: 29 July 1997 / Accepted: 22 October 1997 相似文献
15.
A. Andreoni M. Bondani G.M. D'Ariano M.G.A. Paris 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,13(3):415-421
We propose a novel scheme for the joint generation of two squeezed beams at arbitrary frequencies ω
1 and ω
2. The scheme consists of two successive steps, both involving nonlinear interactions in χ(2) crystals. The dynamics of the setup is analyzed both quantum mechanically and classically within the parametric approximation.
An experimental implementation involving the fundamental and the harmonics of a Nd:YAG laser pulse, and β-BaB
2
O
4 nonlinear crystals is suggested.
Received 17 May 2000 and Received in final form 9 October 2000 相似文献
16.
C. Szwaj G.-L. Oppo A. Gatti L.A. Lugiato 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,10(3):433-448
Quantum images, that is inhomogeneous field distributions purely generated by quantum fluctuations, persist when passing from
the degenerate to the non-degenerate case of optical parametric oscillators (OPO). Below the threshold for parametric oscillation
where the near-field distributions are homogeneous both in intensity and phase, appropriate spatial correlation functions
anticipate the transverse spatial pattern that appears above threshold. In particular, the angular dependence of the far field
spatial correlation function is able to reveal the travelling-wave nature of the phase pattern above threshold typical of
nondegenerate OPOs. Cross-correlation functions between signal and idler intensities show clear evidence of the non-classical
nature of the output light.
Received 8 October 1999 相似文献
17.
《中国物理快报》2021,(9)
We experimentally demonstrate a low-noise phase-sensitive amplifier(PSA) scheme that is able to amplify bright entangled beams at a high level intensity gain of up to 4.4.Moreover,we demonstrate that the PSA scheme introduces much less uncorrelated extra noise to the entangled state than the phase-insensitive amplifier scheme with the same intensity gain.This PSA scheme has potential applications for quantum communication in continuous variable regimes. 相似文献
18.
Xie Chang-de Zhang Jing Pan Qing Jia Xiao-jun Peng Kun-chi 《Frontiers of Physics in China》2006,1(4):383-395
In this paper, we briefly introduce the basic concepts and protocols of continuous variable quantum communication, and then
summarize the experimental researches accomplished by our group in this field. The main features of quantum communication
systems used in our experiments are: (1) The bright entangled optical beams with the anticorrelated amplitude quadratures
and the correlated phase quadratures that serve as the entanglement resources and (2) The Bell-state direct detection systems
are utilized in the measurements of quantum entanglement and transmitted signals instead of the usually balanced homodyne
detectors. 相似文献
19.
O. Jedrkiewicz R. Loudon J. Jeffers 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,39(1):129-140
Previous work on the retrodictive theory of direct
detection is extended to cover the homodyne detection of coherent optical
signal states
and
. The retrodictive input state probabilities are obtained by
the application of Bayes' theorem to the corresponding predictive
distributions, based on the probability operator measure (POM) elements for
the homodyne process. Results are derived for the retrodictive information
on the complex amplitude of the signal field obtainable from the difference
photocount statistics of both 4-port and 8-port balanced homodyne detection
schemes. The local oscillator is usually assumed much stronger than the
signal but the case of equal strengths in 4-port detection is also
considered. The calculated probability distributions and error rates are
illustrated numerically for values of signal and local oscillator strengths
that extend from the classical to the quantum regimes. 相似文献
20.
A. Luis L.L. Sánchez-Soto 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,3(2):195-200
We reconsider the problem of the sum and difference of two angle variables in quantum mechanics. The spectra of the sum and
difference operators have widths of , but angles differing by are indistinguishable. This means that the angle sum and difference probability distributions must be cast into a range. We obtain probability distributions for the angle sum and difference and relate this problem to the representation
of nonbijective canonical transformations.
Received: 6 December 1997 / Revised: 15 April 1998 / Accepted: 7 May
1998 相似文献