回音壁模式光学微腔传感研究进展

简要回顾了近几年回音壁模式光学微腔在传感研究中的应用,其涉及领域包括位移传感、力传感、加速度传感、质量传感、纳米粒子传感、温度传感、角速度传感和奇异点增强传感。对回音壁模式光学微腔在不同领域的传感机理进行了简单介绍,并且对重要的实验工作进行了介绍,指出了提高传感精度的重要因素,为之后的理论和实验研究提供了一定的参考。

专题导读 量子信息技术

以量子计算、量子通信和量子测量为代表的量子信息技术,是量子科技的重要组成部分,是对传统技术体系产生冲击、进行重构的重大颠覆性技术创新,将引领新一轮科技革命和产业变革发展方向,已成为全球主要国家及地区在前沿技术和未来产业领域加强布局推进的关注焦点。

量子计算机的研发进展与未来展望

量子计算机是直接以量子态进行信息处理的新型计算机。量子态具有叠加性,量子计算机具有并行性,对一个由n个量子比特组成的量子计算机的一次操作就是对其所包括的所有2^(n)个量子态的操作,由此可以完成经典计算机无法完成的任务。量子计算机在大数分解和无序数据库搜索问题上已经显示出超越经典计算机的能力。从2016年开始,以IBM为代表的跨国大公司进入这一领域,量子计算机的研发进入快速发展的新阶段。当前,超导量子计算体系发展迅速,达到近百量子比特的规模,率先实现超越经典计算的量子霸权,而拓扑量子计算体系、量子点量子计算体系、离子阱量子体系是其强劲的竞争体系。今后几年,量子计算机的硬件将继续迅速发展,不同方案将逐步拉开。量子计算机的操作系统已经初步建立,进入发展阶段。量子应用算法开始进入快速和大规模的研发阶段。世界各国均把量子计算机的研发作为国家战略,量子计算机的研发将会大大加速。

量子直接通信研究进展

量子直接通信是一种在量子信道直接传输机密信息的量子保密通信技术,与经典通信实现在噪声信道下的可靠通信不同,它可实现在既有噪声又有窃听信道下的可靠和安全通信。通过阐述量子直接通信的原理、20年来的主要发展阶段、由理论走向实用化过程中突破的技术难点,分析并展望了量子直接通信的未来发展与应用前景。

量子直接通信新进展与应用展望

量子直接通信是量子通信的重要形式之一,它是指利用量子态作为信息载体直接进行安全通信的技术。量子直接通信具有感知和防止窃听、兼容现有光通信网络、无需额外部署加密设施等特点,天然适合高密级的数据信息传输。介绍近年来量子直接通信的新进展,讨论量子直接通信在近期条件下的实施特点,展望其应用方向。

Invalidity of Geometrical Interpretation of F-Spin Structure of Nuclear Rotations by Otsuka’s View

In Otsuka's view of nuclear rotations neutrons and protons are not rotating around a common axis,but rather around separate axis.In this letter,we pointed out that this invalidates the geometrical interpretation of F-spin structure of the neutron-proton interacting boson model,where the angle between the axis of symmetries of neutron ellipsoid and proton ellipsoid is used to determine whether a state is F-spin symmetric or mixed symmetric.

Bang-bang control suppression of amplitude damping in a three-level atom

By using quantum bang-bang control technique,we studied the suppression of amplitude damping,or energy dissipation,in a three-level atom in various configurations.We have explicitly given the bang-bang control groups in three different configurations,and the pulse sequences for these bang-bang control operations.

Entanglement of linear cluster states in terms of averaged entropies

An entanglement measure,multiple entropy measures(MEMS) was proposed recently by using the geometric mean of partial entropies over all possible i-body combinations of the quantum system.In this work,we study the average subsystem von Neumann entropies of the linear cluster state and investigated the quantum entanglement of linear cluster states in terms of MEMS.Explicit results with specific particle numbers are calculated,and some analytical results are given for systems with arbitrary particle numbers.Compared with other example quantum states such as the GHZ states and W states,the linear cluster states are "more entangled" in terms of MEMS,namely their averaged entropies are larger than the GHZ states and W states.

Simulation of general three-body interactions in a nuclear magnetic resonance ensemble quantum computer

Three-body interaction plays an important role in many-body physics,and quantum computer is efficient in simulating many-body interactions. We have experimentally demonstrated the general three-body interactions in a three-qubit nuclear magnetic resonance ensemble quantum computer. Using a nuclear magnetic resonance computer we implemented general forms of three-body interactions including σ 1x σ z2 σ x3 and σ 1x σ z2 σ y3 . The results show good agreement between theory and experiment. We have also given a concise and practical formula for a general n-body interaction in terms of one-and two-body interactions.

Simulation of the four-body interaction in a nuclear magnetic resonance quantum information processor

The four-body interaction plays an important role in many-body systems, and it can exhibit interesting phase transition behaviors. In this letter, we report the experimental demonstration of a four-body interaction in a four-qubit nuclear magnetic resonance quantum information processor. The strongly modulating pulse is used to implement spin selective excitation. The results show a good agreement between theory and experiment.

Experimental implementation of a fixed-point duality quantum search algorithm in the nuclear magnetic resonance quantum system

In this work, we demonstrated a fixed-point quantum search algorithm in the nuclear magnetic resonance (NMR) system. We constructed the pulse sequences for the pivotal operations in the quantum search protocol. The experimental results agree well with the theoretical predictions. The generalization of the scheme to the arbitrary number of qubits has also been given.

Experimental quantum deletion in an NMR quantum information processor

We report an NMR experimental realization of a rapid quantum deletion algorithm that deletes marked states in an unsorted database.Unlike classical deletion,where search and deletion are equivalent,quantum deletion can be implemented with only a single query,which achieves exponential speed-up compared to the optimal classical analog.In the experimental realization,the GRAPE algorithm was used to obtain an optimized NMR pulse sequence,and the efficient method of maximum-likelihood has been used to reconstruct the experimental output state.

Control problems in quantum systems

The past decade or two has witnessed tremendous progress in theory and practice of quantum control technologies.Bridging different scientific disciplines ranging from fundamental particle physics to nanotechnology,the goal of quantum control has been to develop effective and efficient tools for common analysis and design,but more importantly would pave the way for future technological applications.This article briefly reviews basic quantum control theory from the perspective of modeling,analysis and design,as well as considers future research directions.

Efficient entanglement purification for doubly entangled photon state

In this paper,we present an efficient purification scheme that improves the efficiency of entanglement purification of the recently proposed entanglement purification scheme for doubly entangled photon states (Phys.Rev.A,2008,77:042315).This modified scheme contains the bit-flip error correction where all the photon pairs can be kept while all the bit-flip errors are corrected and the entanglement purification of phase-flip errors where a wavelength conversion process is used.This scheme has the advantage of high efficiency and a much lower minimum fidelity of the original state.It works under existing technology.

Editorial

Quantum communication and quantum computation are two major branches of quantum information.In quantum communication,principles of quantum physics provide us with the capability of on-site detection of eavesdropping(ODE).In quantum key distribution,random numbers are distributed between two remote parties.If an eavesdropper is found,then the communicated data will be discarded.If no eavesdropper is found,the transmitted data is then post-processed to a very high security level and used as keys.Quantum key distribution could not communicate secret message directly,because it cannot obliterate the information leakage before eavesdropper detection(OILBED).In quantum secure direct communication,not only eavesdropper can be found on-site,but also the obliteration of information leakage before eavesdropper detection can be realized.