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原子吸收谱线展宽对原子光激发有较大的影响.在速率方程理论中人们通常将原子谱线的均匀展宽和非均匀展宽都归于原子谱线的线型函数.本文提出了一种将均匀展宽和非均匀展宽区别处理的原子激发计算方法,并指出当激发光与原子作用时间短于原子热运动平均碰撞时间时,这种区别对待均匀展宽和非均匀展宽的做法是十分必要的.并将文中提出的新方法应用于一个二能级原子跃迁过程的计算,计算结果显示两种方法具有很大差别. 相似文献
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原子吸收谱线展宽对原子光激发有较大的影响.在速率方程理论中人们通常将原子谱线的均匀展宽和非均匀展宽都归于原子谱线的线型函数.本文中提出了一种将均匀展宽和非均匀展宽区别处理的原子激发计算方法,并指出当激发光与原子作用时间短于原子热运动平均碰撞时间时,这种区别对待均匀展宽和非均匀展宽的做法是十分必要的.文中还将本文提出的新方法应用于一个二能级原子跃迁过程的计算,计算结果显示两种方法具有很大差别. 相似文献
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分析了多普勒展宽和多普勒频移区别,讨论了高斯拟合和弦积分线形分布的差异。利用多道光学分析仪(OSMA)测量HT-6M托卡马克限制器前Hα线形分布,通过高斯拟合由多普勒展宽和多普勒频移分别得出等离子温度和粒子入射速度。 相似文献
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量子存储器是光子与物质系统之间的接口,允许存入和读出加载了量子信息的光子,是构建实用化量子网络的核心器件.基于稀土掺杂晶体可以实现固态的量子存储器,较长的相干时间和较宽的存储带宽使其成为目前最有潜力的量子物理系统之一.本文综述近年来基于稀土掺杂晶体的多模式固态量子存储方面的实验进展.主要内容包括频率自由度的多模式量子存储、时间自由度的多模式量子存储、空间自由度的多模式量子存储和多个自由度并行复用的多模式量子存储.在多自由度复用的多模式存储的基础上进一步介绍基于量子存储器的量子模式变换和实时的任意操作.该系列工作为构建高速率的实用化量子网络奠定基础,其中超越存储器本身的脉冲操作功能还有望在未来量子信息处理过程中获得广泛的应用. 相似文献
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A novel quantum memory scheme is proposed for quantum data buses in scalable quantum computers by using adjustable interaction. Our investigation focuses on a hybrid quantum system including coupled flux qubits and a nitrogen–vacancy center ensemble. In our scheme, the transmission and storage(retrieval) of quantum state are performed in two separated steps, which can be controlled by adjusting the coupling strength between the computing unit and the quantum memory. The scheme can be used not only to reduce the time of quantum state transmission, but also to increase the robustness of the system with respect to detuning caused by magnetic noises. In comparison with the previous memory scheme, about 80% of the transmission time is saved. Moreover, it is exemplified that in our scheme the fidelity could achieve 0.99 even when there exists detuning, while the one in the previous scheme is 0.75. 相似文献
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We propose a scheme to suppress the laser phase noise without increasing the optomechanical single-photon coupling strength.In the scheme,the parametric amplification terms,created by Kerr and Duffing nonlinearities,can restrain laser phase noise and strengthen the effective optomechanical coupling,respectively.Interestingly,decreasing laser phase noise leads to increasing thermal noise,which is inhibited by bringing in a broadband-squeezed vacuum environment.To reflect the superiority of the scheme,we simulate quantum memory and stationary optomechanical entanglement as examples,and the corresponding numerical results demonstrate that the laser phase noise is extremely suppressed.Our method can pave the way for studying other quantum phenomena. 相似文献
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Uncertainty relations take a crucial and fundamental part in the frame of quantum theory, and are bringing on many marvelous applications in the emerging field of quantum information sciences. Especially, as entropy is imposed into the uncertainty principle, entropy‐based uncertainty relations lead to a number of applications including quantum key distribution, entanglement witness, quantum steering, quantum metrology, and quantum teleportation. Herein, the history of the development of the uncertainty relations is discussed, especially focusing on the recent progress with regard to quantum‐memory‐assisted entropic uncertainty relations and dynamical characteristics of the measured uncertainty in some explicit physical systems. The aims are to help deepen the understanding of entropic uncertainty relations and prompt further explorations for versatile applications of the relations on achieving practical quantum tasks. 相似文献
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《中国物理 B》2021,30(6):60305-060305
We generalize BB84 quantum key distribution(QKD) to the scenario where the receiver adopts a heralded quantum memory(QM). With the heralded QM, the valid dark count rate of the receiver's single photon detectors can be mitigated obviously, which will lower the quantum bit error rate, and thus improve the performance of decoy-state BB84 QKD systems in long distance range. Simulation results show that, with practical experimental system parameters, decoy-state BB84 QKD with QM can exhibit performance comparable to that of without QM in short distance range, and exhibit performance better than that without QM in long distance range. 相似文献
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Mucheng Guo Shuping Liu Weiye Sun Miaomiao Ren Fudong Wang Manjin Zhong 《Frontiers of Physics》2023,18(2):21303
Rare-earth doped crystals carry great prospect in developing ensemble-based solid state quantum memories for remote quantum communication and fast quantum processing applications. In recent years, with this system, remarkable quantum storage performances have been realized, and more exciting applications have been exploited, while the technical challenges are also significant. In this paper, we outlined the status quo in the development of rare-earth-based quantum memories from the point of view of different storage protocols, with a focus on the experimental demonstrations. We also analyzed the challenges and provided feasible solutions. 相似文献
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We generalize the conception of quantum leakage for the atomic collective excitation states. By making use of the atomic coherence
state approach, we study the influence of the atomic spatial motion on the symmetric collective states of 2-level atomic ensemble
due to inhomogeneous coupling. In the macroscopic limit, we analyze the quantum decoherence of the collective atomic state
by calculating the quantum leakage for a very large ensemble at a finite temperature. Our investigations show that the fidelity
of the atomic system will not be good in the case of atom numberN→∞. Therefore, quantum leakage is an inevitable problem in using the atomic ensemble as a quantum information memory. The
detailed calculations shed theoretical light on quantum processing using atomic ensemble collective qubit. 相似文献
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针对量子中继器短时间内难以应用于长距离量子密钥分配系统的问题, 提出了基于量子存储的长距离测量设备无关量子密钥分配协议, 分析了其密钥生成率与存储效率、信道传输效率和安全传输距离等参数间的关系, 研究了该协议中量子存储单元的退相干效应对最终密钥生成率的影响, 比较了经典测量设备无关量子密钥分配协议和基于量子存储的测量设备无关量子密钥分配协议的密钥生成率与安全传输距离的关系. 仿真结果表明, 添加量子存储单元后, 协议的安全传输距离由无量子存储的216 km增加至500 km, 且量子存储退相干效应带来的误码对最终的密钥生成率影响较小. 实验中可以采取调节信号光强度的方式提高测量设备无关量子密钥分配系统的密钥生成率, 为实用量子密钥分配实验提供了重要的理论参数. 相似文献
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量子技术,比如量子通信、量子计算,具有经典技术所不具有的优势.但是,作为量子技术基本元素的量子态往往极为脆弱,很容易受到外界环境的影响而丢失,而且量子态的制造和量子操作往往是概率性的.这种概率性使得远距离量子通信和大规模的量子计算很难实现,除非有量子存储器将这些随机产生的量子态缓存并同步起来.在过去的十几年中,量子存储在各种各样的存储方案中得到了研究,而且已经从最初的原理性演示逐步发展到了如今的近乎可实用化.现如今,量子存储领域追求的是可实用化,而判断一个存储器是否可以实用化的基本标准是:高存储效率、低噪音、长寿命(或者大的时间带宽积)和室温条件下运行.通过介绍多个具有代表性的存储方案,本文给出了量子存储领域的研究现状和发展趋势.其中基于室温原子系综的宽带量子存储因其装置简单、实用性更强而广受关注.但是由于噪音问题,直到最近才在实验室中实现可工作在室温环境中的宽带FORD (far off-resonance Duan-Lukin-Cirac-Zoller)量子存储和梯形量子存储.本文对多种存储方案的工作原理、优缺点进行了介绍,对FORD方案之所以能够成功进行了分析,还对量子存储的降噪方法进行了总结. 相似文献