共查询到20条相似文献,搜索用时 15 毫秒
1.
Li-juan Xu 《Optics Communications》2011,284(13):3335-3344
We investigate the nonclassicality of two-mode photon-added squeezed vacuum state (TPASV) and its decoherence in a thermal environment according to the sub-Poissonian statistics and the negative region of Wigner function (WF). Based on the fact that the TPASV can be seen as a squeezed Hermite polynomial excitation state, we further obtain a compact expression for the normalization factor of TPASV, i.e., a Jacobi polynomial of the squeezing parameter. We also derive the explicit expression of WF of TPASV and then the decoherence effect on this state is also discussed by deriving the time evolution of the WF and its negative region. 相似文献
2.
By applying the bosonic creation operator to squeezed
vacuum states, this paper introduces a new kind of quantum states:
photon-added squeezed vacuum states. It also presents an
experimental approach to prepare these states, and investigates
their quantum statistical properties by the numerical method. The
results indicate that these states reveal some interesting
non-classical properties, such as anti-bunching effects,
squeezing effects and negativities of the relevant Wigner
functions. 相似文献
3.
The states
|A
1
A
2 are considered, where the operators
are associated with a unitary representation of the groupSp(4,), and the two-mode Glauber coherent states |A
1
A
2> are joint eigenstates of the destruction operatorsa
1 anda
2 for the two independent oscillator modes. We show that they are ordinary coherent states with respect to new operatorsb
1 andb
2, which are themselves general linear (Bogolibov) transformations of the original operatorsa
1,a
2 and their hermitian conjugatesa
1
,a
2
. We further show how they may be regarded as the most general two-mode squeezed states. Most previous work on two-mode squeezed states appears to be based on more restrictive definitions than our own, and thereby reduces to special cases which are unified within our treatment. 相似文献
4.
We provide a class of inequalities whose violation shows the presence of entanglement in two-mode systems. We initially consider observables that are quadratic in the mode creation and annihilation operators and find conditions under which a two-mode state is entangled. Further examination allows us to formulate additional conditions for detecting entanglement. We conclude by showing how the methods used here can be extended to find entanglement in systems of more than two modes. 相似文献
5.
Quantum cryptography using any two nonorthogonal states 总被引:6,自引:0,他引:6
Bennett CH 《Physical review letters》1992,68(21):3121-3124
6.
A Gaussian degree of entanglement for a symmetric two-mode Gaussian
state can be defined as its distance to the set of all separable two-mode Gaussian
states. The principal property that enables us to evaluate both Bures distance and relative entropy between symmetric two-mode
Gaussian
states is the diagonalization of their covariance matrices under the same beam-splitter transformation. The multiplicativity
property of the Uhlmann fidelity and the additivity of the relative entropy allow one to finally deal with a single-mode optimization
problem in both cases. We find that only
the Bures-distance Gaussian entanglement
is consistent with the exact entanglement of formation. 相似文献
7.
8.
9.
10.
We prove the unconditional security of the Bennett 1992 protocol, by using a reduction to an entanglement distillation protocol initiated by a local filtering process. The bit errors and the phase errors are correlated after the filtering, and we can bound the amount of phase errors from the observed bit errors by an estimation method involving nonorthogonal measurements. The angle between the two states shows a trade-off between accuracy of the estimation and robustness to noises. 相似文献
11.
《Physics letters. A》2019,383(25):3069-3073
In this work we propose a scheme in the context of superconducting cavities to unambiguously discriminate non-orthogonal quantum field states when one of them is one of the four Bell states. The present work, which generalizes an earlier proposal [1] dealing with non-entangled states, also makes use of a single high Q cavity, a sample of three-level atoms, Ramsey zones and selective detectors, thus consisting of an oversimplification from the experimental view. 相似文献
12.
A. B. Dzyubenko 《JETP Letters》2001,74(6):318-322
A novel unitary transformation of the Hamiltonian that allows one to partially separate the center-of-mass motion for charged electron-hole systems in a magnetic field is presented. The two-mode squeezed oscillator states that appear at the intermediate stage of the transformation are used for constructing a trial wave function of a two-dimensional charged magnetoexciton. 相似文献
13.
We investigate photon statistical properties of the multiple-photon-added two-mode squeezed coherent states(PATMSCS).We find that the photon statistical properties are sensitive to the compound phase involved in the TMSCS.Our numerical analyses show that the photon addition can enhance the cross-correlation and anti-bunching effects of the PATMSCS.Compared with that of the TMSCS,the photon number distribution of the PA-TMSCS is modulated by a factor that is a monotonically increasing function of the numbers of adding photons to each mode;further,that the photon addition essentially shifts the photon number distribution. 相似文献
14.
Feedback is proposed for distinguishing between two weak coherent states with phases differing by ∼π. The mutual nonorthogonality
of such states gives rise to a discrimination error, which can be reduced by using feedback. An optical quantum channel is
discussed where the input is classical information encoded in two weak coherent states. For a channel with feedback, the discrimination
error probability is calculated, and the mutual entropy that quantifies the fidelity between input and output is evaluated.
We find that the use of a feedback loop in a quantum communication channel can increase the mutual entropy when canonical
position or photon number is measured. 相似文献
15.
Rules are derived for graphical determination of the overlap integral of wave functions and matrix elements of operators of physical quantities. A calculation is made for four-electron atoms in the configuation 1s22s4s using nonorthogonal radial orbitals.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 7–11, March, 1981. 相似文献
16.
E. K. Bashkirov 《Russian Physics Journal》1996,39(2):107-110
The conditions have been found for the stationary evolution of the dispersion of the quadrature components of bosonic fields in the generalized two-mode model with two-boson interaction.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 3–6, February, 1996. 相似文献
17.
《中国物理 B》2019,(9)
We investigate the sensitivity of phase estimation in a Mach–Zehnder interferometer with photon-subtracted twomode squeezed vacuum states.Our results show that, for given initial squeezing parameter, both symmetric and asymmetric photon subtractions can further improve the quantum Cramér–Rao bound(i.e., the ultimate phase sensitivity), especially for single-mode photon subtraction.On the other hand, the quantum Cramér–Rao bound can be reached by parity detection for symmetric photon-subtracted two-mode squeezed vacuum states at particular values of the phase shift, but it is not valid for asymmetric photon-subtracted two-mode squeezed vacuum states.In addition, compared with the two-mode squeezed vacuum state, the phase sensitivity via parity detection with asymmetric photon-subtracted two-mode squeezed vacuum states will be getting worse.Thus, parity detection may not always be the optimal detection scheme for nonclassical states of light when they are considered as the interferometer states. 相似文献
18.
借助于双模压缩真空态在EPR纠缠态表象中的表示,研究了用双模压缩真空态作为量子通道 实现任意的单模和双模量子态的远程传输.
关键词:
量子隐形传态
EPR纠缠态
压缩真空态 相似文献
19.
Shi-Biao Zheng 《Physica A》1998,260(3-4)
We propose a scheme for generating superpositions of two pair coherent states of a two-mode field. In the scheme an atom is sent through a cavity initially in a pair coherent state. The state-selective measurement following the two-mode Raman process projects the two-mode field to a pair cat state. 相似文献
20.
Quantum entanglement and nonlocality properties of a family of
two-mode Gaussian pure states have been investigated. The results
show that the entanglement of these states is determined by both the
two-mode squeezing parameter and the difference of the two
single-mode squeezing parameters. For the same two-mode squeezing
parameter, these states show larger entanglement than the usual
two-mode squeezed vacuum state. The violation of Bell inequality
depends strongly on all the squeezing parameters of these states and
disappears completely in the limit of large squeezing. In
particular, these states can exhibit much stronger violation of
local realism than two-mode squeezed vacuum state in the range of
experimentally available squeezing values. 相似文献