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51.
In the paper we introduce stopping times for quantum Markov states. We study algebras and maps corresponding to stopping times, give a condition of strong Markov property and give classification of projections for the property of accessibility. Our main result is a new recurrence criterium in terms of stopping times (Theorem 1 and Corollary 2). As an application of the criterium we study how, in Section 6, the quantum Markov chain associated with the one-dimensional Heisenberg (usually non-Markovian) process, obtained from this quantum Markov chain by restriction to a diagonal subalgebra, is such that all its states are recurrent. We were not able to obtain this result from the known recurrence criteria of classical probability.Supported by GNAFA-CNR, Bando n. 211.01.25. 相似文献
52.
Summary Radiation inhibition in the many-atom Jaynes-Cummings model being a consequence of cooperative as well as cavity detuning
effects is examined. Numerical solutions for the time evolution of the atomic population inversion exhibiting quasi-stationary
behaviour are presented. Furthermore, the cooperative energy shift of these quasi-stationary states is numerically computed
by using a special projection operator.
The authors of this paper have agreed to not receive the proofs for correction. 相似文献
53.
54.
55.
56.
In this paper, by using properties of quantum controlled-not
manipulation and entanglement states, we have designed a novel (2,
3) quantum threshold scheme based on the Greenberger- Horne
-Zeilinger (GHZ) state. The proposed scheme involves two phases,
i.e. a secret sharing phase and a secret phase. Detailed proofs
show that the proposed scheme is of unconditional security. Since
the secret is shared among three participants, the proposed scheme
may be applied to quantum key distribution and secret sharing. 相似文献
57.
磁场对非对称量子点中极化子性质的影响 总被引:3,自引:1,他引:3
采用线性组合算符和幺正变换方法研究磁场对非对称量子点中弱耦合磁极化子性质的影响.导出了非对称量子点中弱耦合磁极化子的振动频率、基态能量和基态结合能随量子点的横向和纵向有效受限长度、磁场和电子-声子耦合强度的变化关系.数值计算结果表明:非对称量子点中弱耦合磁极化子的基态能量和基态结合能随量子点的横向和纵向有效受限长度的增加而迅速增大.随回旋频率的增加而增大,随电子-声子耦合强度的增加而减小. 相似文献
58.
We have investigated the evolution of the atomic quantum entropy and the entanglement of atom-photon in the system with competing k-photon and l-photon transitions by means of fully quantum theory, and examined the effects of competing photon numbers (k and l), the relative coupling strength between the atom and the two-mode field (A/g), and the initial photon number of the field on the atomic quantum entropy and the entanglement of atom-photon. The results show that the multiphoton competing transitions or the large relative coupling strength can lead to the strong entanglement between atoms and photons. The maximal atom-photon entanglement can be prepared via the appropriate selection of system parameters and interaction time. 相似文献
59.
Michael Devereux 《Foundations of Physics Letters》2003,16(1):41-55
Using an isolated measurement process, we calculate the effect measurement has on entropy for the multi-cylinder Szilard engine. We find that the system of cylinders possesses an entropy associated with cylinder total energy states, and that it records information transferred at measurement. Contrary to other's results, we find that the apparatus loses entropy due to measurement. The Second Law of Thermodynamics may be preserved if Maxwell's demon gains entropy moving the engine partition. 相似文献
60.
The frame of classical probability theory can be generalized by enlarging the usual family of random variables in order to encompass nondeterministic ones. This leads to a frame in which two kinds of correlations emerge: the classical correlation that is coded in the mixed state of the physical system and a new correlation, to be called probabilistic entanglement, which may occur also at pure states. We examine to what extent this characterization of correlations can be applied to quantum mechanics. Explicit calculations on simple examples outline that a same quantum state can show only classical correlations or only entanglement depending on its statistical content; situations may also arise in which the two kinds of correlations compensate each other. 相似文献