Investigating mesoscopic circuits with entangled state representations

By employing the continuous parameter entangled state representations, we investigate the energy level and the wave function for a capacitively and mutual-inductively coupled LC mesoscopic circuit. It is found that investigating the meso- scopic circuit in such representations can bring us the following conveniences. Firstly, the dynamical equation is naturally transformed into a single-variable differential equation. Secondly, the center-of-mass kinetic energy is included in the energy level of the system. Thus it is instructive to introduce the entangled state representation into the investigation of mesoscopic circuits.     

Investigating mesoscopic circuits with the entangled state representations

By employing the continuous parameter entangled state representations, we investigate the energy level and the wave function for a capacitively and mutual-inductively coupled LC mesoscopic circuit. It is found that investigating the mesoscopic circuit in such representations can bring us the following conveniences. Firstly, the dynamical equation is naturally transformed into a single-variable differential equation. Secondly, the center-of-mass kinetic energy is included in the energy level of the system. Thus it is instructive to introduce the entangled state representation into the investigation of mesoscopic circuits.     

Quantum mechanical photoncount formula derived by entangled state representation

By introducing the thermo entangled state representation,we derive four new photocount distribution formulas for a given light field density operator.It is shown that these new formulas,which are convenient to calculate the photocount,can be expressed as integrations over a Laguerre-Gaussian function with a characteristic function,Wigner function,Q-function and P-function,respectively.     

介观RLC电路在热真空态下的量子涨落

利用热场动力学的方法研究了介观RLC电路在具有热噪声的真空态下电荷和磁通(电流)的量子涨落.从而得到了有限温度下这一电路在热真空态下的量子涨落与温度的关系.结果表明,介观RLC电路的量子涨落不仅与电路中的元件参量和电路的共振频率ω有关,而且与温度T有关.温度越高,介观RLC电路的量子噪声越大 关键词： 介观RLC电路 热真空态 量子涨落     

热克尔态下介观LC电路的量子涨落

基于介观电容可看作介观隧道结的物理事实，利用旋波近似方法，对介观LC电路进行量子化处理，量子化后介观LC电路系统等效为一个克尔系统.再利用热场动力学理论方法 研究了介观LC电路在有限温度时热克尔态下电荷和磁通的量子涨落，并对结果进行了讨 论. 关键词： 介观LC电路 热克尔态 量子涨落     

Quantum fluctuation of mesoscopic distributed parameter circuits

Under the Born－von-Karmann periodic boundary condition, we propose a quantization scheme for a non-dissipative distributed parameter circuit (a uniform transmission line). Quantum fluctuations of charge and current in the vacuum state are investigated by adopting the canonical transformation and unitary transformation method. Our results indicate that in distributed parameter circuits, quantum fluctuations, which also have distributed properties, are related to both the circuit parameters and the positions and the mode of signals.     

量子力学纠缠态表象

扼要介绍了笔者近期提出的纠缠态表象的性质与应用。     

Quantum state reconstruction by entangled measurements

We address quantum state reconstruction for d-dimensional systems based on measuring, on the system of interest and a probe, of a single entangled observable defined on the bipartite system/probe Hilbert space. We show that the statistics of the measurement and the knowledge of the probe preparation suffice to reliably reconstruct the density matrix of the system, as well as the expectation value of any desired operator, including those not corresponding to observable quantities. The statistical robustness of the reconstruction is examined and a method is developed to minimize statistical errors by tuning the probe preparation. Numerical simulations of the whole reconstruction procedure are also presented for qubit systems.     

Bloch wave oscillation and Coulomb blockade in mesoscopic electric circuits

The quantum theory for mesoscopic electric circuits with charge discreteness is briefly described. The Schrödinger equation of the mesoscopic electric circuit with an external source which is the time function has been proposed. The Bloch wave oscillation and Coulomb blockade in the mesoscopic electric circuit have been addressed.     

量子力学混合态表象

在以往的文献中量子力学的表象都是纯态表象,在本文中我们从算符的合理排序和概率统计的正态分布思想出发,首次提出了量子力学混合态表象的概念,并证明了其完备性和正交性.量子力学混合态表象的优点是可以反映算符的多种表示以及其相应的排序规则.     

Quantum anonymous voting systems based on entangled state

Based on quantum entanglement, secure anonymous ballot systems are introduced to realize voting among numerous candidates in this paper. By searching individuals, each voter may cast a vote for his desired candidates of which number may be more than one. Therefore, the system based on the proposed algorithm may be applied voting among many candidates, such as a network ballot with the development of a quantum network. Finally, the security of the present scheme is investigated.     

Quantum waveguide theory for hole transport in mesoscopic structures

A quantum waveguide theory is proposed for hole transport in the mesoscopic structures, including the band mixing effect. We found that due to the interference between the ‘light’ hole and ‘heavy’ wave, the transmission and reflection coefficients oscillate more irregularly as a function of incident wave vector geometry parameters. Furthermore conversion between the heavy hole and light hole states occurs at the intersection.     

用非最大纠缠信道对任意二粒子纠缠态的量子秘密分享

提出一个对任意二粒子纠缠态在N者之间的量子秘密分享方案,该方案利用非最大纠缠Einstein-Podolsky-Rosen(EPR)对作为量子信道,利用广义的贝尔基进行测量.接收者通过引入辅助粒子,并对其做选择性测量,就会概率性地得到最初的量子态. 关键词： 非最大纠缠的Einstein-Podolsky-Rosen(EPR)对 广义的贝尔测量     

Quantum dense coding using a peculiar tripartite entangled state

Following a recent proposal ( Phys. Lett. A 346 (2005) 330) about quantum dense coding using a tripartite entangled GHZ state and W state, this paper proposes an experimentally feasible scheme for dense coding in cavity QED by using another peculiar tripartite entangled state. In the scheme the atoms interact simultaneously with a highly detuned cavity mode with the assistance of a classical field, the successful probability of dense coding scheme with this peculiar tripartite entangled state equals 1.     

Squeeze-swapping by Bell measurement studied in terms of the entangled state representation

By virtue of the entangled state representation(Hong-Yi Fan and J R Klauder 1994 Phys.Rev.A 49 704) and the two-mode squeezing operator’s natural representation(Hong-Yi Fan and Yue Fan 1996 Phys.Rev.A 54 958) we propose the squeeze-swapping mechanism which can generate quantum entanglement and new squeezed states of continuum variables.     

Quantum teleportation of arbitrary two-qubit state via entangled cavity fields

We propose a new protocol for quantum teleportation of an arbitrary two qubit state via continuous variables entangling channel. In our scheme two pairs of entangled light fields are employed. An outstanding characteristic of this scheme is that arbitrary state of two atoms is transmitted deterministically and directly to another pair of atoms without the help of the other atoms.     

Quantum state sharing with a genuinely entangled five-qubit state and Bell-state measurements

We construct several distinct schemes for tripartite Quantum state sharing (QSTS) of arbitrary single- and two-qubit states. Our schemes use genuinely entangled five-qubit state that has recently been introduced by Brown et al. [J. Phys. A 38 1119 (2005)] as the quantum channel. The Bell-state measurements and the single-qubit measurement are needed in our schemes. In comparison with the QSTS scheme using the same quantum channel [Phys. Rev. A 77 (2008) 032321], not joint measurement, which makes this scheme simpler than the latter.     

用纠缠态表象推导广义Ehrenfest定理

利用两粒子相对坐标和总动量的共同本征态|η〉构成的连续变量纠缠态表象,推导了转动系统的Ehrenfest定理,从而说明了在满足某些近似的情况下,量子力学不但能够与经典物理完美自洽,而且利用量子力学的规律可以导出相应的经典物理规律.