论文标题
在相干和不连贯的基础上探索两分混合状态的量子特性
Exploring quantum properties of bipartite mixed states under coherent and incoherent basis
论文作者
论文摘要
量子相干性和量子纠缠是叠加原理的两种不同表现。在本文中,我们表明,用于估计连贯性的正确选择是可分离的基础。使用钟形基础估计的量子相干性并不代表系统中的连贯性,因为由于选择基础状态,系统存在连贯性。我们首先在使用铃铛状态和一个计算基础的两个状态制备的两个量子混合状态下计算纠缠和量子相干性。使用相干性的L1符号估算量子相干性,使用并发测量纠缠,并使用线性熵测量混合度。然后,我们在铃铛的基础上估计这些数量,并确定仅应在可分离的基础上测量连贯性,而纠缠和混合性可以在任何基础上测量。然后,我们计算这些混合状态的传送保真度,并找到国家的保真度大于经典隐性忠诚度的区域。我们还研究了违反贝尔-Chsh不平等的行为,以验证系统中的量子非局部相关性。通过从三方系统中获得的两分状态进行了对上述量子相关性,传送保真度和钟形不平等验证的估计,该估计是通过从三方系统中获得的两分状态进行的。我们发现,对于其中一些状态,即使没有违反贝尔·奇克(Bell-Chsh)的不平等现象,也可能会传送,这表明非局部性不是量子传送的必要条件。
Quantum coherence and quantum entanglement are two different manifestations of the superposition principle. In this article we show that the right choice of basis to be used to estimate coherence is the separable basis. The quantum coherence estimated using the Bell basis does not represent the coherence in the system, since there is a coherence in the system due to the choice of the basis states. We first compute the entanglement and quantum coherence in the two qubit mixed states prepared using the Bell states and one of the states from the computational basis. The quantum coherence is estimated using the l1-norm of coherence, the entanglement is measured using the concurrence and the mixedness is measured using the linear entropy. Then we estimate these quantities in the Bell basis and establish that coherence should be measured only in separable basis, whereas entanglement and mixedness can be measured in any basis. We then calculate the teleportation fidelity of these mixed states and find the regions where the states have a fidelity greater than the classical teleportation fidelity. We also examine the violation of the Bell-CHSH inequality to verify the quantum nonlocal correlations in the system. The estimation of the above mentioned quantum correlations, teleportation fidelity and the verification of Bell-CHSH inequality is also done for bipartite states obtained from the tripartite systems by the tracing out of one of their qubits. We find that for some of these states teleportation is possible even when the Bell-CHSH inequality is not violated, signifying that nonlocality is not a necessary condition for quantum teleportation.