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Superconducting phase qubits with shadow-evaporated Josephson junctions 被引量:5
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作者 宿非凡 刘伟洋 +7 位作者 徐晖凯 邓辉 李志远 田野 朱晓波 郑东宁 吕力 赵士平 《Chinese Physics B》 SCIE EI CAS CSCD 2017年第6期61-65,共5页
We develop a fabrication process for the superconducting phase qubits in which Josephson junctions for both the qubit and superconducting quantum interference device(SQUID) detector are prepared by shadow evaporatio... We develop a fabrication process for the superconducting phase qubits in which Josephson junctions for both the qubit and superconducting quantum interference device(SQUID) detector are prepared by shadow evaporation with a suspended bridge. Al junctions with areas as small as 0.05 μm^2 are fabricated for the qubit, in which the number of the decoherencecausing two-level systems(TLS) residing in the tunnel barrier and proportional to the junction area are greatly reduced. The measured energy spectrum shows no avoided crossing arising from coherent TLS in the experimentally reachable flux bias range of the phase qubit, which demonstrates the energy relaxation time T1 and dephasing time Tφ on the order of 100 ns and 50 ns, respectively. We discuss several possible origins of decoherence from incoherent or weakly-coupled coherent TLS and further improvements of the qubit performance. 展开更多
关键词 superconducting phase qubit two-level system DECOHERENCE shadow evaporated junction
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Efficient Atomic One-Qubit Phase Gate Realized by a Cavity QED and Identical Atoms System
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作者 何勇 姜年权 《Communications in Theoretical Physics》 SCIE CAS CSCD 2010年第1期97-99,共3页
We present a scheme to implement a one-qubit phase gate with a two-level atom crossing an optical cavity in which some identical atoms are trapped. One can conveniently acquire an arbitrary phase shift of the gate by ... We present a scheme to implement a one-qubit phase gate with a two-level atom crossing an optical cavity in which some identical atoms are trapped. One can conveniently acquire an arbitrary phase shift of the gate by properly choosing the number of atoms trapped in the cavity and the velocity of the atom crossing the cavity. The present scheme provides a very simple and efficient way for implementing one-qubit phase gate. 展开更多
关键词 qubit phase gate two-level atom cavity QED phase shift identical atoms unitary transformation
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Geometric quantum discord and Berry phase between two charge qubits coupled by a quantum transmission line
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作者 朱汉杰 张国锋 《Chinese Physics B》 SCIE EI CAS CSCD 2014年第12期55-58,共4页
Geometric quantum discord(GQD) and Berry phase between two charge qubits coupled by a quantum transmission line are investigated. We show how GQDs evolve and investigate their dependencies on the parameters of the s... Geometric quantum discord(GQD) and Berry phase between two charge qubits coupled by a quantum transmission line are investigated. We show how GQDs evolve and investigate their dependencies on the parameters of the system.We also calculate the energy and the Berry phase and compare them with GQD, finding that there are close connections between them. 展开更多
关键词 geometric quantum discord(GQD) Berry phase charge qubits
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Control of purity and entanglement for two spatially two-separated qubits via phase damping
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作者 A.S.F.Obada H.A.Hessian +1 位作者 A.B.A.Mohamed M.Hashem 《Chinese Physics B》 SCIE EI CAS CSCD 2012年第10期115-121,共7页
Control of purity and entanglement of two two-qubits dispersively coupled to a field with a reservoir are investigated.Initially the qubits are entangled,while the field is either in a coherent state or a statistical ... Control of purity and entanglement of two two-qubits dispersively coupled to a field with a reservoir are investigated.Initially the qubits are entangled,while the field is either in a coherent state or a statistical mixture of two coherent states.For an alternative entanglement measure we calculate the negativity of the eigenvalues of the partially transposed density matrix.A measure related to the mutual entropy,namely the index of entropy,is employed to measure the entanglement.Its results agree well with the negativity.It is found that the entanglement and purity have strong sensitivity to phase damping.The asymptotic behaviour of the states of the field,the two two-qubits,and the total system fall into mixed states. 展开更多
关键词 ENTANGLEMENT phase damping PURITY separated qubits
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A geometric phase for superconducting qubits under the decoherence effect
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作者 S.Abdel-Khalek K.Berrada +1 位作者 Mohamed A.El-Sayed M.Abel-Aty 《Chinese Physics B》 SCIE EI CAS CSCD 2013年第10期88-93,共6页
We propose a relaxation rate or dissipative cavity-based parameters that can be used as indicators of the stationary limit of a mixed state geometric phase. We perform our considerations for the system of a supercondu... We propose a relaxation rate or dissipative cavity-based parameters that can be used as indicators of the stationary limit of a mixed state geometric phase. We perform our considerations for the system of a superconducting qubit in an open transmission line or interacting with a dissipative cavity. This system is very useful for performing an effective quantum computation by exhibiting the long collapse time of the geometric phase. It is shown that the geometric phase in the stationary limit does not depend on interaction time if the decay time exceeds an upper bound. 展开更多
关键词 superconducting-qubit meometric phase mixed state DECOHERENCE
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Resonant interaction scheme for GHZ state preparation and quantum phase gate with superconducting qubits in a cavity
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作者 刘欣 廖庆洪 +2 位作者 方光宇 王月媛 刘树田 《Chinese Physics B》 SCIE EI CAS CSCD 2014年第2期124-128,共5页
A scheme is proposed to generate GHZ state and realize quantum phase gate for superconducting qubits placed in a microwave cavity. This scheme uses resonant interaction between the qubits and the cavity mode, so that ... A scheme is proposed to generate GHZ state and realize quantum phase gate for superconducting qubits placed in a microwave cavity. This scheme uses resonant interaction between the qubits and the cavity mode, so that the interaction time is short, which is important in view of decoherence. In particular, the phase gate can be realized simply with a single interaction between the qubits and the cavity mode. With cavity decay being considered, the fidelity and success probability are both very close to unity. 展开更多
关键词 superconducting qubits GHZ state phase gate
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Direct implementation of a scalable non-local multi-qubit controlled phase gate via optical fibres and adiabatic passage
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作者 汤耀祥 林秀敏 +2 位作者 林功伟 陈立波 黄秀花 《Chinese Physics B》 SCIE EI CAS CSCD 2008年第12期4388-4395,共8页
This paper presents a direct implementation scheme of the non-local multi-qubit controlled phase gate by using optical fibres and adiabatic passage. The smaller operation number for implementing the multi-qubit contro... This paper presents a direct implementation scheme of the non-local multi-qubit controlled phase gate by using optical fibres and adiabatic passage. The smaller operation number for implementing the multi-qubit controlled phase gate and needlessness for addressing individually save physical resource and lower the difficulties of experiment. Mean- while, the scheme is immune from some decoherence effects such as the atomic spontaneous emission and fibre loss. In principle, it is scalable. 展开更多
关键词 adiabatic passage multi-qubit controlled phase gate
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Implementation of a nonlocal N-qubit conditional phase gate using the nitrogen–vacancy center and microtoroidal resonator coupled systems
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作者 曹聪 刘刚 +1 位作者 张茹 王川 《Chinese Physics B》 SCIE EI CAS CSCD 2014年第4期113-117,共5页
Implementation of a nonlocal multi-qubit conditional phase gate is an essential requirement in some quantum infor- mation processing (QIP) tasks. Recently, a novel solid-state cavity quantum electrodynamics (QED) ... Implementation of a nonlocal multi-qubit conditional phase gate is an essential requirement in some quantum infor- mation processing (QIP) tasks. Recently, a novel solid-state cavity quantum electrodynamics (QED) system, in which the nitrogen-vacancy (NV) center in diamond is coupled to a microtoroidal resonator (MTR), has been proposed as a poten- tial system for hybrid quantum information and computing. By virtue of such systems, we present a scheme to realize a nonlocal N-qubit conditional phase gate directly. Our scheme employs a cavity input-output process and single-photon interference, without the use of any auxiliary entanglement pair or classical communication. Considering the currently available technologies, our scheme might be quite useful among different nodes in quantum networks for large-scaled QIP. 展开更多
关键词 N-qubit conditional phase gate nitrogen-vacancy center microtoroidal resonator
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An Aharonov-Anandan phase gate in the sub-Hilbert space of a coupling flux qubits system
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作者 郑国林 邓辉 +3 位作者 吴玉林 王新强 陈莺飞 郑东宁 《Chinese Physics B》 SCIE EI CAS CSCD 2012年第7期146-151,共6页
We study two flux qubits with a parameter coupling scenario. Under the rotating wave approximation, we truncate the 4-dimensional Hilbert space of a coupling flux qubits system to a 2-dimensional subspace spanned by t... We study two flux qubits with a parameter coupling scenario. Under the rotating wave approximation, we truncate the 4-dimensional Hilbert space of a coupling flux qubits system to a 2-dimensional subspace spanned by two dressed states |01} and |10}. In this subspace, we illustrate how to generate an Aharnov Anandan phase, based on which, we can construct a NOT gate (as effective as a C-NOT gate) in this coupling flux qubits system. FinMly, the fidelity of the NOT gate is also calculated in the presence of the simulated classical noise. 展开更多
关键词 Aharonov Anandan phase sub-Hilbert space coupling flux qubits
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Scheme for implementing an economical phase-covariant quantum cloning machine of distant atomic qubits with single-photon interference
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作者 周彦辉 王磊 赖晓磊 《Chinese Physics B》 SCIE EI CAS CSCD 2013年第5期132-135,共4页
By means of cavity-assisted photon interference, a simple scheme is proposed to implement a symmetric economical phase-covariant quantum cloning machine of two remote qubits, with each in a separate cavity. With our p... By means of cavity-assisted photon interference, a simple scheme is proposed to implement a symmetric economical phase-covariant quantum cloning machine of two remote qubits, with each in a separate cavity. With our present scheme, a high-fidelity cloning machine is realized. Our scheme may be quite useful in terms of distributed quantum information processing. 展开更多
关键词 economical phase-covariant quantum cloning machine distant atomic qubits single-photon inter-ference
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基于参数化角编码的量子K-means算法
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作者 冯微军 郭躬德 林崧 《量子电子学报》 CAS CSCD 北大核心 2024年第1期113-124,共12页
结合K-means算法和角编码技术,提出了一种无需量子随机存储(QRAM)的量子K-means算法。该算法利用量子操作的并行性,仅需对数数量的时间复杂度就能完成数据的加载;并且通过对输入数据进行参数预处理操作,确定数据分量的参数阈值,解决了... 结合K-means算法和角编码技术,提出了一种无需量子随机存储(QRAM)的量子K-means算法。该算法利用量子操作的并行性,仅需对数数量的时间复杂度就能完成数据的加载;并且通过对输入数据进行参数预处理操作,确定数据分量的参数阈值,解决了样本不同特征尺度差异的问题。该算法由编码数据、相似度度量、量子最小值搜索和质心迭代更新四个主要步骤组成,细致描述了这些步骤所涉及的算子和线路构建,并对关键线路进行了仿真模拟。实验结果和经典预测结果一致,验证了所提量子K-means算法的可靠性。此外,理论分析表明所提出算法相比于经典算法在运行时间上有平方级加速。 展开更多
关键词 量子光学 量子K-means算法 角编码 量子相位估计 多量子比特交换测试
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一类三量子比特X态的几何量子失协
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作者 卫佳宁 段周波 张钧 《数学物理学报(A辑)》 CSCD 北大核心 2024年第5期1144-1152,共9页
基于[Phys Rev Lett,124,110401(2020)]中提出的多体量子失协的定义,该文通过测量诱导给出了依赖于四个实参数的一类三量子比特X态的几何量子失协解析表达式,并给出了该类态几何量子失协的等高图.作为应用,该文研究了相位翻转信道下三... 基于[Phys Rev Lett,124,110401(2020)]中提出的多体量子失协的定义,该文通过测量诱导给出了依赖于四个实参数的一类三量子比特X态的几何量子失协解析表达式,并给出了该类态几何量子失协的等高图.作为应用,该文研究了相位翻转信道下三量子比特X态几何量子失协的动力学行为. 展开更多
关键词 几何量子失协 三量子比特X态 相位翻转信道
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Definite Answer for Riemann Hypothesis Zeta 3/2 Function Provided by New Material Yb2Si2O7 in Quantum Mechanics
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作者 Hung-Te Henry Su Po-Han Lee 《Journal of Modern Physics》 2024年第9期1409-1429,共21页
This paper indicates the problem of the famous Riemann hypothesis (RH), which has been well-verified by a definite answering method using a Bose-Einstein Condensate (BEC) phase. We adopt mathematical induction, mappin... This paper indicates the problem of the famous Riemann hypothesis (RH), which has been well-verified by a definite answering method using a Bose-Einstein Condensate (BEC) phase. We adopt mathematical induction, mappings, and laser photons governed by electromagnetically induced transparency (EIT) to examine the existence of the RH. In considering the well-developed as Riemann zeta function, we find that the existence of RH has a corrected and self-consistent solution. Specifically, there is the only one pole at s = 1 on the complex plane for Riemann’s functions, which generalizes to all non-trivial zeros while s > 1. The essential solution is based on the BEC phases and on the nature of the laser photon(s). This work also incorporates Heisenberg commutators [ x^,p^]=1/2in the field of quantum mechanics. We found that a satisfactory solution for the RH would be incomplete without the formalism of Heisenberg commutators, BEC phases, and EIT effects. Ultimately, we propose the application of qubits in connection with the RH. 展开更多
关键词 BEC phases EIT Heisenberg Commutators Laser Photons qubitS Riemann Hypothesis
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Quantization of the double-qubit structure and quantum computation
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作者 梁宝龙 王继锁 《Chinese Physics B》 SCIE EI CAS CSCD 2007年第10期3097-3103,共7页
The quantization scheme of a double-qubit structure with superconducting quantum interference devices (SQUIDs) is given. By introducing unitary matrices and using spectral decompositions, the Hamiltonian operator of... The quantization scheme of a double-qubit structure with superconducting quantum interference devices (SQUIDs) is given. By introducing unitary matrices and using spectral decompositions, the Hamiltonian operator of the system is exactly formulated in compact forms in spin-1/2 notation. A scheme of designing controlled-phase-shift (CPS) gates is also proposed by using this circuit system. 展开更多
关键词 double-qubit QUANTIZATION spectral decomposition controlled-phase-shift
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量子神经网络在PID参数调整中的应用 被引量:4
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作者 曹茂俊 李盼池 肖红 《计算机工程》 CAS CSCD 北大核心 2011年第12期182-184,189,共4页
提出一种基于量子神经网络(QNNs)的比例积分微分(PID)参数在线调整方法。通过构造受控量子旋转门,给出一个量子神经元模型,其中包括输入量子比特相位的旋转角度和控制量2种设计参数。在此基础上提出一个量子神经网络模型,利用梯度下降... 提出一种基于量子神经网络(QNNs)的比例积分微分(PID)参数在线调整方法。通过构造受控量子旋转门,给出一个量子神经元模型,其中包括输入量子比特相位的旋转角度和控制量2种设计参数。在此基础上提出一个量子神经网络模型,利用梯度下降法设计该模型的学习算法,并将其用于PID参数的在线调整,实验结果表明,QNNs的调整能力及稳定性均优于反向传播网络。 展开更多
关键词 受控量子旋转门 量子神经元 量子神经网络 比例积分微分参数调整 量子比特相位
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超导电路的量子化方法 被引量:4
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作者 宿非凡 《物理与工程》 2021年第3期13-15,21,共4页
超导量子计算是当下世界范围内被广泛关注的研究课题之一,近年来许多文献报道了利用超导量子比特对特定物理过程的研究和仿真,在新近的一些工作里其应用范围已经超出了物理学研究范围,在化学、信息学等领域也得到了很好的结果。超导量... 超导量子计算是当下世界范围内被广泛关注的研究课题之一,近年来许多文献报道了利用超导量子比特对特定物理过程的研究和仿真,在新近的一些工作里其应用范围已经超出了物理学研究范围,在化学、信息学等领域也得到了很好的结果。超导量子计算器件首先要对超导电路进行量子化。本文针对超导量子计算芯片(量子比特)中的超导电路总结了一套规范、实用的量子化方法,并以此方法对位相量子比特超导电路进行了量子化并给出了其哈密顿量。本文思路与方法对新型量子比特或其他超导电路的设计与研究也有一定帮助。 展开更多
关键词 超导量子比特 约瑟夫森结 量子化 位相量子比特
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各向异性耦合量子位的几何相位
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作者 袁兵 梁麦林 张福林 《河南师范大学学报(自然科学版)》 CAS CSCD 北大核心 2007年第1期75-77,182,共4页
对于各项异性耦合的两个量子位,当外加磁场缓慢变化时,计算了该体系的几何相位.结果表明,各向异性对于几何相位有显著的影响,这使得几何相位与磁场各分量形成的立体角之间的关系不再成立.并且各向异性耦合还可以使在各向同性耦合情况下... 对于各项异性耦合的两个量子位,当外加磁场缓慢变化时,计算了该体系的几何相位.结果表明,各向异性对于几何相位有显著的影响,这使得几何相位与磁场各分量形成的立体角之间的关系不再成立.并且各向异性耦合还可以使在各向同性耦合情况下几何相位为0状态的几何相位不为0. 展开更多
关键词 量子位 几何相位 纠缠
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NMR和超导量子比特中的几何相位
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作者 张晓燕 张志颖 《长春理工大学学报(自然科学版)》 2013年第5期77-79,100,共4页
几何相因子只与系统的演化路径有关而与演化快慢无关,因而可以实现可容错量子计算。通过探测系统的几何相位,可以实现普适量子逻辑门。先介绍了绝热近似下的Berry相位和A-A相位,然后用坐标变换方法计算了核磁共振系统的几何相位。旋转... 几何相因子只与系统的演化路径有关而与演化快慢无关,因而可以实现可容错量子计算。通过探测系统的几何相位,可以实现普适量子逻辑门。先介绍了绝热近似下的Berry相位和A-A相位,然后用坐标变换方法计算了核磁共振系统的几何相位。旋转磁场下磁通量子比特哈密顿变化的总效果类似于一个自旋1/2粒子在旋转磁场中的行为,进而计算出相干脉冲下基于约瑟夫森结的超导磁通量子比特的几何相位,给定参数得到单比特量子逻辑门。 展开更多
关键词 几何相位 NMR 量子比特
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不对称外磁场下两量子比特系统的几何相
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作者 苏耀恒 陈爱民 +1 位作者 王军 李跃文 《河南科技大学学报(自然科学版)》 CAS 北大核心 2017年第2期79-83,共5页
研究了不对称旋转外磁场下具有XXZ型海森堡相互作用的两量子比特系统的几何相。考虑体系的绝热条件,利用数值模拟的方法得到量子比特系统的4个本征态的Berry相,研究了外加旋转磁场的极角以及量子比特之间相互作用的各向异性参数对4个本... 研究了不对称旋转外磁场下具有XXZ型海森堡相互作用的两量子比特系统的几何相。考虑体系的绝热条件,利用数值模拟的方法得到量子比特系统的4个本征态的Berry相,研究了外加旋转磁场的极角以及量子比特之间相互作用的各向异性参数对4个本征态的Berry相的影响。研究结果表明:当极角保持不变,各向异性参数由0增加至无穷大的过程中,系统的哈密顿量由一种极限下的含外场的XX模型经过中间的海森堡模型,逐渐演化为另外一种极限下的Ising模型。4个本征态的Berry相都有各自独特的变化规律,且极角越小几何相趋于稳定越快。通过对系统Berry相的研究,可以得到系统在不同参数区间对应的模型的转化,并对本征态的几何性质有更进一步的认识。 展开更多
关键词 量子信息 两量子比特系统 几何相 海森堡相互作用
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相干脉冲下磁通量子比特的几何量子计算
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作者 张晓燕 张志颖 《科学技术与工程》 北大核心 2013年第23期6667-6670,共4页
首先计算了旋转磁场下自旋1/2粒子的绝热几何相位。用微波电流脉冲控制量子比特,导致量子比特里产生振荡的磁场。这个效应可以通过一个扰动的哈密顿量增加到总哈密顿量里,对哈密顿量进行旋转变换,得到磁通量子比特哈密顿变化的总效果类... 首先计算了旋转磁场下自旋1/2粒子的绝热几何相位。用微波电流脉冲控制量子比特,导致量子比特里产生振荡的磁场。这个效应可以通过一个扰动的哈密顿量增加到总哈密顿量里,对哈密顿量进行旋转变换,得到磁通量子比特哈密顿变化的总效果类似于一个自旋1/2粒子在旋转磁场中的行为,进而计算出相干脉冲下磁通量子比特的几何相位,给定参数得到单比特量子逻辑门。最后简述了基于几何相位设计两比特受控非门。 展开更多
关键词 磁通量子比特 几何相位 量子逻辑门
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