A scheme for conditional quantum phase gate viabimodal cavity and a Λ-type three-level atom

We propose a scheme to implement a two-qubit conditional quantum phase gatefor the intracavity field viaa single three-level $\Lambda$-type atom driven by two modes in a high-Q cavity. The quantum information is encoded on the Fock states of the bimodal cavity. The gate's averaged fidelity is expected to reach $99.8\%$.     

Investigation of gate current in nano-scale MOSFETs by Monte Carlo solution of quantum Boltzmann equation

This paper investigates gate current through ultra-thin gate oxide of nano-scale metal oxide semiconductor field effect transistors (MOSFETs), using two-dimensional (2D) full-band self-consistent ensemble Monte Carlo method based on solving quantum Boltzmann equation. Direct tunnelling, Fowler--Nordheim tunnelling and thermionic emission currents have been taken into account for the calculation of total gate current. The 2D effect on the gate current is investigated by including the details of the energy distribution for electron tunnelling through the barrier. In order to investigate the properties of nano scale MOSFETs, it is necessary to simulate gate tunnelling current in 2D including non-equilibrium transport.     

Unconventional Geometric Phase Gate with Superconducting Quantum Interference Device Qubits in Cavity QED

In the system with superconducting quantum interference devices （SQUID） in cavity, a scheme for constructing two-qubit quantum phase gate via a conventional geometric phase-shift is proposed by using a quantized cavity field and classical microwave pulses. In this scheme, the gate operation is realized in the subspace spanned by the two lower flux states of the SQUID system mud the population operator of the excited state has no effect on it. Thus the effect of decoherence caused from the levels of the SQUID system is possible to minimize. Under cavity decay, our strictly numerical simulation shows that it is also possible to realize the unconventional geometric phase gate. The experimental feasibility is discussed in detail.     

All-optical realization of × NOR logic gate using chaotic semiconductor lasers under phase modulator control

The theoretical construction of the fundamental × NOR gate using two injection semiconductor laser diodes due to mutual coupling is presented. Two laser diodes that are commonly driven by a monochromatic light beam result in chaos; however, chaotic synchronization between the two lasers may be achieved by coupling them. The all-optical logic gate is finally implemented by synchronizing or un-synchronizing appropriately the two chaotic states under a phase modulator (PM) control. Numerical results validate the feasibility of the method.     

Block-free optical quantum Banyan network based on quantum state fusion and fission

Optical switch fabric plays an important role in building multiple-user optical quantum communication networks.Owing to its self-routing property and low complexity, a banyan network is widely used for building switch fabric. While,there is no efficient way to remove internal blocking in a banyan network in a classical way, quantum state fusion, by which the two-dimensional internal quantum states of two photons could be combined into a four-dimensional internal state of a single photon, makes it possible to solve this problem. In this paper, we convert the output mode of quantum state fusion from spatial-polarization mode into time-polarization mode. By combining modified quantum state fusion and quantum state fission with quantum Fredkin gate, we propose a practical scheme to build an optical quantum switch unit which is block free. The scheme can be extended to building more complex units, four of which are shown in this paper.     

MPT分子的荧光性质及其在实现逻辑功能中的应用

回顾了近年来作者在荧光分子开关的设计、合成、性质及其在数字信息处理中的应用等方面的研究进展．基于所制备的5-甲氧基-2-（2-吡啶基）-噻唑（2-MPT,1）及其系列衍生物具有荧光量子产率高、发光性质对所处化学环境敏感的基本特性,作者对相关体系的可控光谱性质进行了二进制的编码,实现了丰富的分子基二进制逻辑门和运算功能．结合微流芯片技术,对分子基数字信息处理系统的器件化进行了尝试．     

Preliminary shielding analysis for the CSNS target station monolith

The construction of the China Spallation Neutron Source （CSNS） has been initiated at Dongguan,Guangdong,China.In spallation neutron sources the target station monolith is contaminated by a large number of fast neutrons whose energies can be as large as those of the protons of the proton beam directed towards the tungsten target.A detailed radiation transport analysis of the target station monolith is important for the construction of the CSNS.The analysis is performed using the coupled Monte Carlo and multi-dimensional discrete ordinates method.Successful elimination of the primary ray effects via the two-dimensional uncollided flux and first collision source methodology is also illustrated.The dose at the edge of the monolith is calculated.The results demonstrate that the doses received by the hall staff members are below the required standard limit.     

基于非均匀外场的双量子比特自旋XYZ模型的swap门操作

自旋模型在实现量子信息处理中起着很重要的作用.将自旋之间的海森堡相互作用作为最基本量子比特之间的相互作用,将会使量子比特之间产生量子纠缠;同时忽略掉自旋之间相互作用的各向异性可直接用来实现(swap)n量子门,再配以单量子比特旋转门,可构成完备的量子计算基本门.事实上,各向异性相互作用是存在于任何固态材料中的,其对实现量子逻辑门的影响很值得研究.本文讨论了在非均匀外场下XYZ模型的双量子比特swap门的实现问题,给出非均匀外场以及各向异性相互作用导致的swap门操作的误差.