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Rotationally Invariant Proof of Bell’s Theorem Without Inequalities for 4k-Dimensional (k=1,2,...) Systems 下载免费PDF全文
We present rotationally invariant proof of Bell‘s theorem without inequalities for spin-(2N 1)/2system (N = 2k-1,k = 1, 2, 3, 4...) with only two particles, which is a generalization of Cabello‘s study [Phys. Rev. A 67 (2003)032107]. 相似文献
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We propose a decoy state quantum key distribution scheme with odd coherent state which follows sub-Poissonian distributed photon count and has low probability of the multi-photon event and vacuum event in each pulse. The numerical calculations show that our scheme can improve efficiently the key generation rate and secure communication distance. Fhrthermore, only one decoy state is necessary to approach to the perfect asymptotic limit with infinite decoy states in our scheme, but at least two decoy states are needed in other scheme. 相似文献
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Design of quantum VQ iteration and quantum VQ encoding algorithm taking O(√N) steps for data compression 下载免费PDF全文
Vector quantization (VQ) is an important data compression
method. The key of the encoding of VQ is to find the closest vector among
N vectors for a feature vector. Many classical linear search algorithms
take $O(N)$ steps of distance computing between two vectors. The quantum VQ iteration and corresponding quantum VQ encoding algorithm that takes
$O(\sqrt N )$ steps are presented in this paper. The unitary operation of
distance computing can be performed on a number of vectors simultaneously
because the quantum state exists in a superposition of states. The quantum VQ iteration comprises three oracles, by contrast many quantum algorithms have only one oracle, such as Shor's factorization algorithm and Grover's algorithm. Entanglement state is generated and used, by contrast the state in Grover's algorithm is not an entanglement state. The quantum VQ iteration is a rotation over subspace, by contrast the Grover iteration is a rotation over global space. The quantum VQ iteration extends the Grover iteration to the more complex search that requires more oracles. The method of the quantum VQ iteration is universal. 相似文献
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本文从波动性和粒子性两方面详细分析了平衡辐射场的性质,给出了更清晰、更容易被学生理解的平衡辐射场的波粒二象性图像. 相似文献
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In quantum mechanics, the expectation value of an operator can be measured by using the projective measurement, ifthe coupling between the measured system and pointer is strong enough. However in the weak coupling regime, the pointercan not show all the eigenvalue of the physical quantity directly due to the overlapping among the pointer states, whichmakes the measurement of the expectation value difficult. In this paper, we propose an expectation value measurementmethod in the weak coupling regime inspired by the weak measurement scheme. Compared to the projective measurement,our scheme has two obvious advantages. Experimentally we use the internal state and motional state of a single trapped40Ca+ to establish the measurement scheme and realize the proof of principle demonstration of the scheme. 相似文献
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Recently, Zhou et al. [Phys. Rev. A 79 (2009) 044304] proposed a scheme for transferring three-dimensional quantum states between remote atomic qubits confined in cavities connected by fibers through adiabatic passage. In order to avoid the decoherence due to spontaneous emission, Zhou et al. utilized the large detuning atom-field interaction. In the present paper, we discuss the influence of dissipation on the scheme in both the resonant atom-field interaction case and the large detuning case. We numerically analyze the success probability and the transferring fidelity. It is shown that the resonant case is a preferable choice for the technique of the stimulated Raman adiabatic passage (STIRAP) due to the shorter operation time and the smaller probability of dissipation. 相似文献