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Conductance Oscillations through an Aharonov Bohm Ring with a quantum gate

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Advances in Manufacturing 1999年第3期3卷 203-207页

作者： SHI Yao ming CHEN Hang de XU Shi yue (College of Sciences, Shanghai University) CHEN Hao (Department of Physics, Fudan University) College of Sciences Shanghai UniversityCHEN HaoDepartment of Physics Fudan University

Based on a one dimensional quantum wave guide theory, we investigate the ballistic conductance through an Aharonov Bohm ring with a quantum gate. The analytical expression of the conductance is exactly obtained as the function of magnetic flux penetrating the ring and Fermi energy of indcident electrons. When Fermi energy equals that of bound states in the isolated stub, the conductance is fixed at a constant value which is only determined by the geometric structure of the ring system. We have found that there are a new kind of conductance oscillations for some special mesoscopic ring systems. As Fermi energy of incident electrons crosses that of bound state in the isolated stub, the conductance oscillations have no abrupt change of phase by π and are in phase. This striking feature is not in ageement with that of previous experiments and theories. The mechanism causing this new feature is discussed.

关键词： conductance oscillation A B ring quantum gate

Three-qubit quantum-gate operation with an SQUID in a cavity

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Chinese Physics B 2012年第6期21卷 213-215页

作者：石惠敏於亚飞张智明 Laboratory of Nanophotonic Functional Materials and Devices Laboratory of Quantum Information TechnologySouth China Normal University

We propose a method of realizing a three-qubit quantum gate with a superconducting quantum interference device（SQUID） in a *** this proposal,the gate operation involves the SQUID ground-states and the Fock states of cavity modes b and *** two field-modes act as the controlling qubits,and the two SQUID states form the target *** only the metastable lower levels are involved in the gate operation,the gate is not affected by the SQUID decay rates.

关键词： SQUID quantum gate C^2-Phase gate C^2-Not gate

Shortcut-based quantum gates on superconducting qubits in circuit QED

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Chinese Physics B 2021年第8期30卷 535-542页

作者： Zheng-Yin Zhao Run-Ying Yan Zhi-Bo Feng School of Science Xuchang UniversityXuchang 461000China

Construction of optimal gate operations is significant for quantum *** an efficient scheme is proposed for performing shortcut-based quantum gates on superconducting qubits in circuit quantum electrodynamics(QED).Two four-level artificial atoms of Cooper-pair box circuits,having sufficient level anharmonicity,are placed in a common quantized field of circuit QED and are driven by individual classical *** the effect of cross resonance,one-qubit NOT gate and phase gate in a decoupled atom can be implemented using the invariant-based shortcuts to *** the assistance of cavity bus,a one-step SWAP gate can be obtained within a composite qubit-photon-qubit system by inversely engineering the classical *** further consider the gate realizations by adjusting the microwave *** the accessible decoherence rates,the shortcut-based gates have high *** present strategy could offer a promising route towards fast and robust quantum computation with superconducting circuits experimentally.

关键词： superconducting qubit circuit QED quantum gate shortcuts to adiabaticity

A Scheme for Simulation of quantum gates by Abelian Anyons

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Communications in Theoretical Physics 2011年第11期56卷 873-876页

作者：沈尧艾青龙桂鲁 State Key Laboratory of Low-Dimensional quantum Physics and Department of Physics Tsinghua University Tsinghua National Laboratory for Information Science and Technology

Anyons can be used to realize quantum computation, because they are two-level systems in two dimensions. In this paper, we propose a scheme to simulate single-qubit gates and CNOT gate using Abelian anyons in the Kitaev model. Two pairs of anyons （six spins） are used to realize single-qubit gates, while ten spins are needed for the CNOT gate. Based on these quantum gates, we show how to realize the Grover algorithm in a two-qubit system.

关键词： fractional statistics anyon quantum gate

Elementary quantum gates Based on Intrinsic Interaction Hamiltonian

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Communications in Theoretical Physics 2006年第1X期46卷 69-72页

作者： CHEN Jing YU Chang-Shui SONG He-Shan Department of Physics Dalian University of Technology Dalian 116023 China

A kind of new operators, the generalized pseudo-spin operators are introduced and a universad intrinsic Hamiltonian of two-qubit interaction is studied in terms of the generalized pseudo-spin operators. A fundamental quantum gate U（θ） is constructed based on the universal Hamiltonian and shown that the roles of the new quantum gate U （θ） is equivalent, functionally, to the joint operation of Hadamard and C-Not gates.

关键词： quantum gate intrinsic Hamiltonian

quantum information processing with nitrogen–vacancy centers in diamond

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Chinese Physics B 2018年第2期27卷 114-126页

作者：刘刚钦潘新宇 Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences (CAS) Beijing 100190 China Department of Physics The Chinese University of Hong Kong Shatin New Territories Hong Kong China Collaborative Innovation Center of quantum Matter Belting 100871 China CA S Center of Excellence in Topological quantum Computation Beijing 100190 China

Nitrogen-vacancy （NV） center in diamond is one of the most promising candidates to implement room temperature quantum computing. In this review, we briefly discuss the working principles and recent experimental progresses of this spin qubit. These results focus on understanding and prolonging center spin coherence, steering and probing spin states with dedicated quantum control techniques, and exploiting the quantum nature of these multi-spin systems, such as superposition and entanglement, to demonstrate the superiority of quantum information processing. Those techniques also stimulate the fast development of NV-based quantum sensing, which is an interdisciplinary field with great potential applications.

关键词： nitrogen-vacancy center quantum information processing spin coherence quantum gate

Transmission Modulated by quantumgatein AharonovCasher Ring

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Advances in Manufacturing 1999年第4期3卷 274-278页

作者： SHI Yao ming XU Shi Yue CHEN Hang de (College of Sciences, Shanghai University) CHEN Hao (Department of Physics, Fudan University) College of Sciences Shanghai University Department of Physics Fudan University

We study the electron transmission tuned by quantum gate in an Aharonov Casher (AC) ring. Transmission probability is obtained as a function of the normalized textured electric fields and Fermi energy. We find that modulating electron wavefunction in the stub can drastically affects electron transmission through the ring system. As Fermi energy crosses every eigenenergy of the isolated stub, the phases of both anomalous and periodic oscillations of the AC conductance generally have abrupt change by π. On two sides of several special Fermi energies, both anomalous and periodic oscillations have no abrupt phase change and are in phase. The detailed characteristics of the anomalous oscillations are dependent on the difference between the tilt angle of the spin and that of textured electric field. By modulating external magnetic field applied to the stub, we present AC oscillations of spin polarized conductance within adiabatic limit.

关键词： AC phase quantum gate spin polarized conductance

quantum Information Processing in a Coupled Cavity Array

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Communications in Theoretical Physics 2008年第12期50卷 1312-1316页

作者： LI Jian ZOU Jian SHAO Bin Department of Physics Beijing Institute of Technology Beijing 100（}81 China

We consider a one-dimensional array of L identical coupled cavities,and each cavity is doped with atwo-level ***,it has been developed in several varieties by the newest *** find that theone-qubit quantum state can be perfectly transferred through the cavity array,and the entanglement between the firsttwo qubits can also be transferred to the last two *** addition,we successfully realized the entangling gate andswap gate in the coupled cavity array.

关键词： state transfer entanglement transfer quantum gate coupled cavity array

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采用控制理论方法制备量子门

采用控制理论方法制备量子门

作者： Bilal Riaz 中国科学技术大学

学位级别：硕士

本论文的重点是利用控制理论和工程方法实现量子门。由于量子门的实现对于实现量子计算机的实现非常重要,控制量子门系统的量子系统方法对量子计算机的实现非常重要。本文基于Lyapunov方法研究了—个量子比特量子门的实现,并采用最优控... 详细信息

本论文的重点是利用控制理论和工程方法实现量子门。由于量子门的实现对于实现量子计算机的实现非常重要,控制量子门系统的量子系统方法对量子计算机的实现非常重要。本文基于Lyapunov方法研究了—个量子比特量子门的实现,并采用最优控制方法实现了两个量子比特量子门。为了实现—个量子位量子门,我们采用了基于Lyapunov的方法,这是因为—个量子位系统是最简单的量子系统,—个量子位系统的演化要么位于布洛赫球体上要么在其内部,这非常简单,几何结构,这类系统的演化类似于球体上或球体内的经典旋转。多量子比特量子系统不同于—个量子比特系统,因为我们不能将它们的演化看作是球上的演化,这是由于相互作用的结果导致多量子比特量子系统的纠缠,这是我们的主要原因没有将我们的Lyapunov方法扩展到多量子位系统。为了实现多量子比特量子系统的相干控制,最广泛采用的方法是最优量子控制。基于最优控制的策略具有的优点是,在实现中也可以考虑诸如控制频带限制和幅度限制的实验性约束。因此,对于两个量子位量子门合成,我们应用了最佳控制方法如Krotov方法,GRAPE,CRAB以及CRAB和GRAPE的组合。在本论文中,对于具有Ising型漂移的封闭两个量子比特量子系统的可控非门的制备,所有这些方法都进行了研究和比较。本文还表明,基于梯度的量子门设计优化控制方法比非梯度方法有更好的表现。

关键词： Lyapunov Method quantum gate CRAB GRAPE Krotov Method