共查询到20条相似文献,搜索用时 48 毫秒
1.
Protection of entanglement from disturbance of the environment is an essential task in quantum information processing. We investigate the effect of the weak measurement and reversal (WMR) on the protection of the entanglement for an arbitrarily entangled two-qubit pure state from these three typical quantum noisy channels, i.e., amplitude damping channel, phase damping channel and depolarizing quantum channel. Given the parameters of the Bell-like initial qubits’ state |ψ〉 = a|00〉 + d|11〉, it is found that the WMR operation indeed helps for protecting distributed entanglement from the above three noisy quantum channels. But for the Bell-like initial qubits’ state |?〉 = b|01〉 + c|10〉, the WMR operation only protects entanglement in the amplitude damping channel, not for the phase damping and depolarizing quantum channels. In addition, we discuss how the concurrence and the success probability behave with adjusting the weak or the reversal weak measurement strength. 相似文献
2.
In this paper, we propose a scheme for quantum information splitting based on the non-maximally entangled four-qubit state in order to realize the splitting of the specific two-qubit state |ψ〉 A B =x|00〉+y|11〉. The information splitter will safely share an state to the receiver with help of the controller. Through introducing an auxiliary system and applying several appropriate unitary transformations the information receiver can reconstruct the original state sent by the information splitter. Due to the non-maximally entangled four-qubit state, the total probability that the receiver obtains the original information is P. Furthermore, we discuss the relationship between the successful splitting probability and the concurrence of the entangled state and get a specific expression. In addition, the scheme is tested against external and internal attacks, and we define a function to characterise the security with the concurrence of the entanglement. 相似文献
3.
Xiang-Guo Meng Ji-Suo Wang Hua-Chao Gao 《International Journal of Theoretical Physics》2016,55(8):3630-3636
Exploiting the thermo entangled state approach, we successfully solve the master equation for describing the single-mode cavity driven by an oscillating external field in the heat reservoir and then get the analytical time-evolution rule for the density operator in the infinitive Kraus operator-sum representation. It is worth noting that the Kraus operator M l, m is proved to be a trace-preserving quantum operation. As an application, the time-evolution for an initial coherent state ρ |β〉 = |β〉〈β| in such an environment is investigated, which shows that the initial coherent state decays to a new mixed state as a result of thermal noise, however the coherence can still be reserved for amplitude damping. 相似文献
4.
Rui He Hong-Yi Fan Jun Song Jun Zhou 《International Journal of Theoretical Physics》2016,55(7):3329-3337
We propose a new optical field named Laguerre-polynomial-weighted two-mode squeezed state. We find that such a state can be generated by passing the l-photon excited two-mode squeezed vacuum state Cla?lS2|00〉 through an single-mode amplitude damping channel. Physically, this paper actually is concerned what happens when both excitation and damping of photons co-exist for a two-mode squeezed state, e.g., dessipation of photon-added two-mode squeezed vacuum state. We employ the summation method within ordered product of operators and a new generating function formula about two-variable Hermite polynomials to proceed our discussion. 相似文献
5.
Cunjin Liu Fang Jia Lihua Gong Qin Guo 《International Journal of Theoretical Physics》2017,56(9):2763-2773
A scheme for teleporting an arbitrary tripartite entangled state is proposed when three bipartite entangled states (|η〉) with continuous variables are used as quantum channels. Quantum teleportation can be carried out successfully if the receiver adopts an appropriate unitary transformation. The calculation is greatly simplified by virtue of the Schmidt decompositions of both tripartite entangled state |p t ,χ 2,χ 3〉 and |η〉. Any tripartite state which can be expanded in terms of |p t ,χ 2,χ 3〉 may be teleported in this way due to the completeness of |p t ,χ 2,χ 3〉. 相似文献
6.
Population dynamics of excited atoms in dissipative cavities is investigated in this work. We present a method of controlling populations of excited atoms in dissipative cavities. For the initial state |ee〉AB|00〉ab, the repopulation of excited atoms can be obtained by using atom-cavity couplings and non-Markovian effects after the atomic excited energy decays to zero. For the initial state |gg〉AB|11〉ab, the two atoms can also be populated to the excited states from the initial ground states by using atom-cavity couplings and non-Markovian effects. And the stronger the atom-cavity coupling or the non-Markovian effect is, the larger the number of repopulation of excited atoms is. Particularly, when the atom-cavity coupling or the non-Markovian effect is very strong, the number of repopulation of excited atoms can be close to one in a short time and will tend to a steady value in a long time. 相似文献
7.
Xiao-Juan Liu An Luo Zhao-Hui Peng Bing-Ju Zhou Ming-Wei Liu Chun-Xia Jia Chun-Lei Jiang 《International Journal of Theoretical Physics》2016,55(11):4740-4750
We investigate quantum echo control and Bell state swapping for two atomic qubits (TAQs) coupling to two-mode vacuum cavity field (TMVCF) environment via two-photon resonance. We discuss the effect of initial entanglement factor ?? and relative coupling strength R=g1/g2 on quantum state fidelity of TAQs, and analyze the relation between three kinds of quantum entanglement(C(ρa),C(ρf),S(ρa)) and quantum state fidelity, then reveal physical essence of quantum echo of TAQs. It is shown that in the identical coupling case R=1, periodic quantum echo of TAQs with π cycle is always produced, and the value of fidelity can be controlled by choosing appropriate ?? and atom-filed interaction time. In the non-identical coupling case R≠1, quantum echoes with periods of π, 2π and 4π can be formed respectively by adjusting R. The characteristics of quantum echo results from the non-Markovianity of TMVCF environment, and then we propose Bell state swapping scheme between TAQs and two-mode cavity field. 相似文献
8.
Jun Song Hong-Yi Fan Ye-Jun Xu Jun Zhou 《International Journal of Theoretical Physics》2011,50(6):1946-1952
By employing the technique of an integral within an ordered product (IWOP) of operators we recast the complex wavelet transform
to a matrix element of the two-mode squeezing-displacing operator U
2(μ,σ) between the mother wavelet vector 〈ψ| and the two-mode quantum state vector |f〉 to be transformed, i.e., we propose that 〈ψ|U
2(μ,σ)|f〉 can be considered as a new kind of spectra for analyzing |f〉, this may have some potential applications in quantum information and calculation. As an example, we numerically calculate
wavelet-transform spectrum for the Bell states, which may play a role of distinguishing them one from another. 相似文献
9.
10.
In this paper, we introduce a pair of mutually conjugate multipartite entangled state representations for defining the squeezing operator of entangled multipartite Sn(λ) which involves an n-mode bosonic operator realization of the SU(1,1) Lie algebra. This operator squeezes the multipartite entangled state in a natural way. We discuss the transform properties of aj and \(a_{j}^{\dagger }\) under the operation of Sn(λ) and derive the interaction Hamiltonian which can generate such an evolution. In addition, the corresponding multipartite squeezed vacuum state |λ〉 is obtained. Based on this, the variances of the n-mode quadratures in |λ〉 are evaluated and the violation of the Bell inequality for |λ〉 is examined by using the formalism of Wigner representation. 相似文献
11.
S?ren?Fournais Maria?Hoffmann-Ostenhof Thomas?Hoffmann-Ostenhof Thomas??stergaard?S?rensen 《Communications in Mathematical Physics》2009,289(1):291-310
We investigate the analytic structure of solutions of non-relativistic Schrödinger equations describing Coulombic many-particle systems. We prove the following: Let ψ(x) with \({{\bf x} = (x_{1},\dots, x_{N})\in \mathbb {R}^{3N}}\) denote an N-electron wavefunction of such a system with one nucleus fixed at the origin. Then in a neighbourhood of a coalescence point, for which x 1 = 0 and the other electron coordinates do not coincide, and differ from 0, ψ can be represented locally as ψ(x) = ψ (1)(x) + |x 1|ψ (2)(x) with ψ (1), ψ (2) real analytic. A similar representation holds near two-electron coalescence points. The Kustaanheimo-Stiefel transform and analytic hypoellipticity play an essential role in the proof. 相似文献
12.
Koji Nagata Tadao Nakamura Josep Batle Soliman Abdalla Ahmed Farouk 《International Journal of Theoretical Physics》2018,57(7):2116-2120
In the short contribution, we consider inequalities of confirming genuine multipartite entanglement. We have a better entanglement witness for a particular mixed state to test genuine multipartite entanglement. Our physical situation is that we measure Pauli observables σ x , σ y , and σ z per side. If the reduction factor is greater than 0.4, then we can confirm the measured quantum state is genuine multipartite entangled experimentally. 相似文献
13.
H. Haken H. Sauermann Ch. Schmid H. D. Vollmer 《Zeitschrift für Physik A Hadrons and Nuclei》1967,206(4):369-393
We start from quantum mechanical laser equations which were derived in a previous paper for an inhomogeneously broadened laser and which contain in particular the noise sources due to cavity losses, vacuum fluctuations, interaction with phonons and nonlasing photons and the pump. For the example of frequency locking caused by the nonlinear polarization we derive a quantum mechanical Langevin equation for the relative phase angleψ=2ψ 2 —ψ 1-ψ 3, whereψ 1,ψ 2,ψ 3, are the total phases of three axial modes which would be equally spaced in the unloaded cavity. In the resulting equation
$$\dot \psi = \delta - \beta \sin \psi + f(t)$$ 相似文献
14.
S. N. Molotkov 《JETP Letters》2005,81(11):599-604
The extreme admissible error probability at the receiving end to which the secure key distribution is possible has been found. This result takes into account all possible attacks on the distributed key, including those that involve large quantum memory and the capability of an eavesdropper to perform collective measurements simultaneously over the entire transmitted sequence of quantum states. The critical error is independent of the parameters of a particular attack and is determined only in terms of the overlapping degree ε = |〈u1|u0〉¦ of information states and the fundamental functions of classical and quantum information theories. The latter functions are the capacity H(Q) of a classical binary communication channel and classical capacity \(\bar C(\varepsilon )\) of a binary quantum communication channel. The key compression degree after error correction is also expressed in terms of only the classical capacity \(\bar C(\varepsilon )\) of the quantum communication channel. 相似文献
15.
Andrei Khrennikov 《Journal of Russian Laser Research》2009,30(5):472-479
Already Schrödinger tried to proceed towards a purely wave theory of quantum phenomena. However, he should give up and accept Born’s probabilistic interpretation of the wave function. A simple mathematical fact was behind this crucial decision. The wave function of a composite system S = (S 1, S 2) belongs to the tensor product of two L2 spaces and not to their Cartesian product. It was impossible to consider it as a vector function ψ(x) = (ψ 1(x), ψ 2(x)), x ∈ R 3. Here we solved this problem. It is shown that there exists a mathematical formalism that provides a possibility to describe composite quantum systems without appealing to the tensor product of the Hilbert state space, and one can proceed with their Cartesian product. It may have important consequences for the understanding of entanglement and applications to quantum information theory. It seems that “quantum algorithms” can be realized on the basis of classical wave mechanics. However, the interpretation of the proposed mathematical formalism is a difficult problem and needs additional studies. 相似文献
16.
This paper discusses the thermal conductivityK of a dirty type II superconductor in the mixed state, for fields close to the upper critical field (H e2 orH e3) where the electronic component is dominant and easily separated. To order |Δ|2, the conductivity depends only on the space average 〈|Δ|2〉. Our formula is a generalisation of earlier results byMaki andAmbegaokar andGriffin for gapless superconductors. The slope\(\left( {\frac{{\partial K}}{{\partial H}}} \right)_{Hc2} \) is proportional to the slope of the magnetization curve\(\left( {\frac{{\partial K}}{{\partial H}}} \right)_{Hc2} \), the ratio of these two slopes being a universal function of temperature. These results are very different from the predictions of the “effective gap” model. 相似文献
17.
S. I. Manaenkov 《Physics of Particles and Nuclei Letters》2017,14(1):44-57
Exact solution for the electromagnetic field densities E and H of a dipole of uniformly accelerated point-charges with identical masses is discussed. It is shown that, for any fixed time t and a large distance R between the center of the dipole and the fieldpoint, |E| ~ R ?4, |H| ~ R ?5, while for large c|t| ~ R, |E| ~ |H| ~1/R as in spherical electromagnetic waves. Nevertheless, any irreversible radiation of electromagnetic waves is absent since the wave zone does not exist. 相似文献
18.
A. V. Derbin I. S. Drachnev I. S. Lomskaya V. N. Muratova N. V. Pilipenko D. A. Semenov L. M. Tukkhonen E. V. Unzhakov A. Kh. Khusainov 《JETP Letters》2018,108(8):499-503
Spectra of electrons from beta decays of 144Ce–144Pr nuclei have been measured and analyzed in order to find a contribution from a heavy neutrino. For the neutrino with the mass mνH in the interval of 150–350 keV, a new upper bound |UeH|2 ≤ (2?5) × 10?3 at 90% C.L. has been found for the mixing parameter. 相似文献
19.
If the present or upcoming searches for neutrinoless double beta ((ββ)0ν) decay give a positive result, the Majorana nature of massive neutrinos will be established. From the determination of the value of the (ββ)0ν-decay effective Majorana mass parameter (|〈m〉|), it would be possible to obtain information on the type of neutrino mass spectrum. Assuming 3-ν mixing and massive Majorana neutrinos, we discuss the information that a measurement of, or an upper bound on, |〈m〉| can provide on the value of the lightest neutrino mass m1. With additional data on the neutrino masses obtained in 3H β-decay experiments, it might be possible to establish whether the CP symmetry is violated in the lepton sector. This would require very high precision measurements. If CP invariance holds, the allowed patterns of the relative CP parities of the massive Majorana neutrinos would be determined. 相似文献
20.
We describe the inclusive Racah matrices for the first non-(anti)symmetric rectangular representation R = [2, 2] for quantum groups Uq(slN). Most of them have sizes 2, 3, and 4 and are fully described by the eigenvalue hypothesis. Of two 6 × 6 matrices, one is also described in this way, but the other one corresponds to the case of degenerate eigenvalues and is evaluated by the highest weight method. Together with the much harder calculation for R = [3, 1] and with the new method to extract exclusive matrices J and \(\overline J\) from the inclusive ones, this completes the story of Racah matrices for |R| ≤ 4 and allows one to calculate and investigate the corresponding colored HOMFLY polynomials for arbitrary 3-strand and arborescent knots. 相似文献