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71.
Einsteins unpublished 1927 deterministic trajectory interpretation of quantum mechanics is critically examined, in particular with regard to the reason given by Einstein for rejecting his theory. It is shown that the aspect Einstein found objectionable—the mutual dependence of the motions of particles when the (many-body) wavefunction factorises—is a generic attribute of his theory but that this feature may be removed by modifying Einsteins method in either of two ways: using a suggestion of Grommer or, in a physically important special case, using a simpler technique. It is emphasized though that the presence or absence of the interdependence property does not determine the acceptability of a trajectory theory. It is shown that there are other grounds for rejecting Einsteins theory (and the two modified theories), to do with its domain of applicability and compatibility with empirical predictions. That Einsteins reason for rejection is not a priori grounds for discarding a trajectory theory is demonstrated by reference to an alternative deterministic trajectory theory that displays similar particle interdependence yet is compatible with quantum predictions.PACS: 03.65.Bz.Essay written in memory of J.T. Cushing. 相似文献
72.
We tell the tale of the first writing of a partial transpose, without guaranteeing historical authenticity.
Dedicated to Prof. Asher Peres, Haifa, on the occasion of his 70th birthday. 相似文献
73.
We study the entanglement properties of the output state of a universal cloning machine. We analyse in particular bipartite and tripartite entanglement of the clones, and discuss the classical limit of infinitely many output copies. 相似文献
74.
Yorick Hardy Willi-Hans Steeb Ruedi Stoop 《International Journal of Theoretical Physics》2003,42(12):2847-2853
Entangled quantum states are an important component of quantum computing techniques such as quantum error-correction, dense coding, and quantum teleportation. We describe how to generate fully entangled states in the Hilbert space C
N
C
N
starting from a unitary matrix and show that they form an orthonormal basis in this space. 相似文献
75.
提出了一个基于纠缠交换理论犤2~4犦的量子密钥分发协议。安全性分析证明此QKD协议是无条件安全,而且十分有效。 相似文献
76.
研究了多量子位Heisenberg模型中纠缠的时间演化特性, 并给出了平均纠缠度〈C〉和多体纠缠度Q的解析表达式. 结果发现无论是对〈C〉还是对Q随着时间t的不断增长, 它们均先线性的增大, 而后达到一近似稳定状态, 并绕一平衡值做无规则的上下震荡. 若进一步考察N〈C〉则还可以发现, 纠缠上下震荡的平衡值与Heisenberg链的长度几乎无关, 而仅由它们的次近邻耦合常数J决定. 相似文献
77.
78.
We investigate the entanglement of the three-qubit Heisenberg XXX chain in the presence of impurity and obtain the analytical expressions of the concurrence C. It is found that for impurity entanglement, C appears only when J
1 > J for J > 0, and J
1 > 0 for J < 0, and in these two regions C increases with the increase of J
1, so is the critical temperature T
c. When J
1 ≫ | J |, C reaches its maximum value 0.5 and T
c reaches the asymptotic value T
c = 3.41448J
1. For entanglement between the normal lattices, C appears only when J > 0 and −2J < J
1 < J, and initially increases with the increase of J
1 and arrives at the maximum value C
max = (e4J/T
−3)/(e4J/T
+ 3) before it decays to zero gradually, so is the critical temperature T
c with, however, the maximum value T
cmax = 4J/In3.
Supported by the Natural Science Research Project of Shaanxi Province (Grant No. 2004A15) 相似文献
79.
A theoretical framework is demonstrated to evaluate the degree of entanglement of bit states in quantum computing. Separability
of general superposition of Hilbert space unit vectors is discussed, and criteria in amplitude as well as in phase are derived.
By these criteria the possibility of different quantum gates such as controlled not (CN), controlled controlled not (CCN),
controlled rotation (CR), and controlled phase shift (CPS), to create the entanglement is examined. Furthermore, the selection
of measurement mode external to the quantum system is incorporated in the formula using Kronecker delta (δ
kx
), introducing the concept of dynamic entanglement. With this the process of wavefunction collapse upon measurement is understood as the result of the activation of the dynamic
entanglement. A firefly in a box model is used to show a pure state of ontological uncertainty, which is in a dynamically
entangled state in Hilbert space. 相似文献
80.
With some reviews on the investigations on the schemes for quantum state transfer based on spin systems, we discuss the quantum
dynamics of magnetically-controlled networks for Bloch electrons. The networks are constructed by connecting several tight-binding
chains with uniform nearest-neighbor hopping integrals. The external magnetic field and the connecting hopping integrals can
be used to control the intrinsic properties of the networks. For several typical networks, rigorous results are shown for
some specific values of external magnetic field and the connecting hopping integrals: a complicated network can be reduced
into a virtual network, which is a direct sum of some independent chains with uniform nearest-neighbor hopping integrals.
These reductions are due to the fermionic statistics and the Aharonov-Bohm effects. In application, we study the quantum dynamics
of wave packet motion of Bloch electrons in such networks. For various geometrical configurations, these networks can function
as some optical devices, such as beam splitters, switches and interferometers. When the Bloch electrons as Gaussian wave packets
input these devices, various quantum coherence phenomena can be observed, e.g., the perfect quantum state transfer without
reflection in a Y-shaped beam, the multi-mode entanglers of electron wave by star-shaped network, magnetically controlled
switches, and Bloch electron interferometer with the lattice Aharonov-Bohm effects. With these quantum coherent features,
the networks are expected to be used as quantum information processors for the fermion system based on the possible engineered
solid state systems, such as the array of quantum dots that can be implemented experimentally.
相似文献