Quantum control and information processing

We review the recent developments in quantum control and its contribution to quantum information processing.     

Quantum criticality from Fisher information

Quantum Information Processing - Physical constraints make it challenging to implement and control many-body interactions. For this reason, designing quantum information processes with Hamiltonians...     

Quantum Fisher information for moving three-level atom

Quantum information technology largely relies on a precious and fragile resource, call quantum entanglement, which exhibits a highly nontrivial manifestation of the coherent superposition of states of composite quantum systems. In this article, we discuss the correlation between the quantum entanglement measured by the von Neumann entropy and atomic quantum Fisher information by taking account the case of moving three-level atom. Our results show that there is a monotonic relation between the atomic quantum Fisher information and entanglement in the case of non-moving atom. On the other hand, we find that the atomic quantum Fisher information and entanglement exhibit an opposite changement behavior during the time evolution in the presence of atomic motion.     

面向输电线故障信息传输的多播路由

针对无线传感器网络应用于输电线路故障传输时存在通信代价高、实时性差的问题,提出一种输电线路故障传输多播路由算法(MRFT)。抽象出输电线路故障信息传输网络模型;根据时延最短路径树(SPT)的最大端到端时延确定多播树时延上限,将时延上限边接入多播树;设计最小代价启发函数将剩余叶子节点接入多播树。仿真结果表明,与KPP算法相比,MRFT算法构造的多播树在多播树时延、端到端时延方差和多播树代价3个方面均有良好表现。该算法能够有效保证输电线路故障信息传输的实时性,降低通信代价。     

A game with errors in information transmission

We consider a hierarchical game for two players with possible errors in information exchanges. We compute the maximal guaranteed result for the top level player. We consider certain qualitative features of the resulting problems and discover their relation with coding theory problems.     

Quantum demultiplexer of quantum parameter-estimation information in quantum networks

The quantum demultiplexer is constructed by a series of unitary operators and multipartite entangled states. It is used to realize information broadcasting from an input node to multiple output nodes in quantum networks. The scheme of quantum network communication with respect to phase estimation is put forward through the demultiplexer subjected to amplitude damping noises. The generalized partial measurements can be applied to protect the transferring efficiency from environmental noises in the protocol. It is found out that there are some optimal coherent states which can be prepared to enhance the transmission of phase estimation. The dynamics of state fidelity and quantum Fisher information are investigated to evaluate the feasibility of the network communication. While the state fidelity deteriorates rapidly, the quantum Fisher information can be enhanced to a maximum value and then decreases slowly. The memory effect of the environment induces the oscillations of fidelity and quantum Fisher information. The adjustment of the strength of partial measurements is helpful to increase quantum Fisher information.     

Some mathematical questions of theory of information transmission

A survey talk given by M.S. Pinsker at the Summer Seminar on Information Theory and Statistical Methods of Automatic Control, Prague, May 25–June 4, 1965, was published in Kybernetika journal of the Czech Academy of Sciences (1966, vol. 2, no. 2, pp. 117–146). By the courtesy of the editors of Kybernetika, we are allowed to publish an abridged version of the talk, which concisely and clearly exposes final mathematical results that underlie Shannon’s information theory. The content of the talk is deeply intertwined with the author’s works. The talk is almost unknown to Russian readers, and with this publication we fill this gap, thereby paying tribute to our outstanding scientist and friend.     

Enhancement of information transmission efficiency by synaptic failures

Many synapses have a high percentage of synaptic transmission failures. I consider the hypothesis that synaptic failures can increase the efficiency of information transmission across the synapse. I use the information transmitted per vesicle release about the presynaptic spike train as a measure of synaptic transmission efficiency and show that this measure can increase with the synaptic failure probability. I analytically calculate the Shannon mutual information transmitted across two model synapses with probabilistic transmission: one with a constant probability of vesicle release and one with vesicle release probabilities governed by the dynamics of synaptic depression. For inputs generated by a non-Poisson process with positive autocorrelations, both synapses can transmit more information per vesicle release than a synapse with perfect transmission, although the information increases are greater for the depressing synapse than for a constant-probability synapse with the same average transmission probability. The enhanced performance of the depressing synapse over the constant-release-probability synapse primarily reflects a decrease in noise entropy rather than an increase in the total transmission entropy. This indicates a limitation of analysis methods, such as decorrelation, that consider only the total response entropy. My results suggest that synaptic transmission failures governed by appropriately tuned synaptic dynamics can increase the information-carrying efficiency of a synapse.     

Quantum information approach to the azurite mineral frustrated quantum magnet

Quantum correlations are almost impossible to address in bulk systems. Quantum measures extended only to a few number of parties can be discussed in practice. In the present work, we study nonlocality for a cluster of spins belonging to a mineral whose structure is that of a quantum magnet. We reproduce at a much smaller scale the experimental outcomes, and then, we study the role of quantum correlations there. A macroscopic entanglement witness has been introduced in order to reveal nonlocal quantum correlations between individual constituents of the azurite mineral at nonzero temperatures. The critical point beyond which entanglement is zero is found at \(T_c < 1\,\mathrm{K}\).     

Quantum information processing in the neighborhood of a black hole

Natural Computing - Using an imperfectly prepared state, we show that in relativistic settings, the evolution of a massive spin-1/2 particle violates many standard assumptions made in quantum...     

Quantum information processing in self-assembled crystals of cold polar molecules

We discuss the implementation of quantum gate operations in a self-assembled dipolar crystal of polar molecules. Here qubits are encoded in long-lived spin states of the molecular ground state and stabilized against collisions by repulsive dipole–dipole interactions. To overcome the single site addressability problem in this high density crystalline phase, we describe a new approach for implementing controlled single and two-qubit operations based on resonantly enhanced spin–spin interactions mediated by a localized phonon mode. This local mode is created at a specified lattice position with the help of an additional marker molecule such that individual qubits can be manipulated by using otherwise global static and microwave fields only. We present a general strategy for generating state and time dependent dipole moments to implement a universal set of gate operations for molecular qubits and we analyze the resulting gate fidelities under realistic conditions. Our analysis demonstrates the experimental feasibility of this approach for scalable quantum computing or digital quantum simulation schemes with polar molecules.     

基于ARM/GPRS的宿舍信息发送系统

针对宿舍卫生和违规信息及时发送的需求,设计并实现了基于GPRS及Synchronization Services for ADO.NET同步技术的宿舍信息发送系统.该系统由服务器端、移动终端（采用基于ARM9的S3C2440微处理器）、GPRS网络和手机接收终端组成.ARM控制器通过串口向GPRS模块发送AT指令,将宿舍相关信息以短信形式发送至手机端,移动终端通过基于服务的同步技术实现与服务器端信息的同步.     

Zigbee芯片在信息传输中的应用

针对信息检测中遇到的有线布线困难及工程造价高等情况,给出了一种无线解决方案,利用满足Zigbee规范的无线收发芯片(CC2430)组成信息无线传输模块,给出了完整的系统设计及软件实现方案。     

Research of transmission information between symbol and packet terminals

Worked out algorithms control of data transmission for interaction symbol terminals with packet terminals and their basic characteristics are described.     

Measures for investigating the contextual modulation of information transmission

The aim of this paper is to show how information theoretic measures can be used to analyse and interpret the results of psychophysical experiments designed to search for conditions under which information from one source modulates the transmission of information from another source. We therefore use measures of mutual and conditional information to analyse systems with two inputs. The information transmitted by such a system can be split into three components depending on whether it is shared between the two inputs or is specific to each. We are concerned here with distinguishing systems that use one input to modulate transmission of information about the other from systems that simply add both inputs, and show how the three components provide evidence for distinguishing between additive and modulatory effects. We also report numerical simulations of the sampling biasses and variances of these measures as a function of the sample size and propose minimum sample sizes that should be used to overcome the bias.