We propose a scheme to implement quantum controlled NOT gate and quantum phase gate in an optomechanical system based on phonon blockade. For appropriate choices of system parameters, fidelities of both the quantum gate operations are very close to unity in the absence of dissipation. Using recently achieved experimental values in a mechanical resonator coupled to a microwave cavity, we show that the quantum gate can be realized experimentally with very high fidelity.
A proposal for a conditional definition of the Swap Gate
为了实现量子逻辑运算,量子计算(QC)要求其基本工具和概念必须遵守物理定律。QC中的一个基本概念是条件量子动力学\cite{barenco},有时称为受控幺正操作\cite{kumar},它由条件“If-Then”语句建立。最著名的例子是c-not门,它在计算基础上运行如下:\textit{If the control qubit is set to $% |1>$, then apply the single qubit quantum NOT gate on the target. Otherwise, if the control qubit is set to $|0>$, then the target qubit is unchanged}。这个门代表了条件量子动力学的范例,其中目标量子位的翻转以控制量子位的状态为条件。其他门也是以类似的条件演化方式定义的;例如,控制相位门\cite{paulo1}。然而,据我们所知,这种条件量子动力学尚未被用来定义SWAP门。在这里,我们提出了一个可能的条件定义,在If-Then语句的形式,在两个量子比特的情况下,构建一个交换门。这个定义提出了两类分类,这取决于必须经历条件量子动力学的量子比特的数量。
We propose a family of microwave-activated entangling gates on two capacitively coupled fluxonium qubits. A microwave pulse applied to either qubit at a frequency near the half-frequency of the $|00\rangle - |11\rangle$ transition induces two-photon Rabi oscillations with a negligible leakage outside the computational subspace, owing to the strong anharmonicity of fluxoniums. By adjusting the drive frequency, amplitude, and duration, we obtain the gate family that is locally equivalent to the fermionic-simulation gates such as $\sqrt{\rm SWAP}$-like and controlled-phase gates. The gate error c…
We present a novel method to realize a multi-target-qubit controlled phase gate with one microwave photonic qubit simultaneously controlling $n-1$ target microwave photonic qubits. This gate is implemented with $n$ microwave cavities coupled to a superconducting flux qutrit. Each cavity hosts a microwave photonic qubit, whose two logic states are represented by the vacuum state and the single photon state of a single cavity mode, respectively. During the gate operation, the qutrit remains in the ground state and thus decoherence from the qutrit is greatly suppressed. This proposal requires onl…
Proposals for experimentally realizing quantum-autonomous gates
Joint Center for Quantum Information and Computer Science, NIST and University of Maryland(量子信息与计算机科学联合中心,美国国家标准与技术研究院和马里兰大学);Department of Physics, University of Maryland(马里兰大学物理系);Department of Physics, Harvard University(哈佛大学物理系);Atominstitut, Technische Universität Wien(维也纳工业大学原子研究所);Institute for Quantum Optics and Quantum Information, IQOQI Vienna, Austrian Academy of Sciences(奥地利科学院维也纳量子光学与量子信息研究所);Joint Quantum Institute, University of Maryland(马里兰大学联合量子研究所);Duke Quantum Center and Department of Physics, Duke University(杜克大学杜克量子中心及物理系);National Quantum Laboratory (QLab), University of Maryland(马里兰大学国家量子实验室(QLab));Department of Microtechnology and Nanoscience, Chalmers University of Technology(查尔姆斯理工大学微技术与纳米科学系);Institute for Physical Science and Technology, University of Maryland(马里兰大学物理科学与技术研究所)
Alternative scheme for two-qubit conditional phase gate by adiabatic passage under dissipation
我们检查最近的一个建议[H。Goto和K。Ichimura Phys. Rev. A 70,012305(2004)]中描述的方法,用于在自发发射和腔衰减的影响下通过绝热通道的受控相位门。我们证明了上述建议的修改可以用于在两量子比特Grover搜索中生成必要的条件相位门。在门控期间没有来自原子激发态和腔模的光子泄漏的条件下,数值分析了绝热通过的两量子比特条件相位门的成功概率和保真度.我们提出的门控方案和以前的方案之间的比较表明,Goto和Ichimura的方案是一种替代的和可行的方式在光学腔制度的两个量子位门,并可以推广到多量子位门的原则。
High-fidelity quantum gates are essential for large-scale quantum computation. However, any quantum manipulation will inevitably affected by noises, systematic errors and decoherence effects, which lead to infidelity of a target quantum task. Therefore, implementing high-fidelity, robust and fast quantum gates is highly desired. Here, we propose a fast and robust scheme to construct high-fidelity holonomic quantum gates for universal quantum computation based on resonant interaction of three-level quantum systems via shortcuts to adiabaticity. In our proposal, the target Hamiltonian to induce …
We propose a single-step implementation of a muti-target-qubit controlled phase gate with one cat-state qubit (\textit{cqubit}) simultaneously controlling $n-1$ target \textit{cqubits}. The two logic states of a \textit{cqubit} are represented by two orthogonal cat states of a single cavity mode. In this proposal, the gate is implemented with $n$ microwave cavities coupled to a superconducting transmon qutrit. Because the qutrit remains in the ground state during the gate operation, decoherence caused due to the qutrit's energy relaxation and dephasing is greatly suppressed. The gate implement…
Hybrid qubits have recently drawn intensive attention in quantum computing. We here propose a method to implement a universal controlled-phase gate of two hybrid qubits via two three-dimensional (3D) microwave cavities coupled to a superconducting flux qutrit. For the gate considered here, the control qubit is a microwave photonic qubit (particle-like qubit), whose two logic states are encoded by the vacuum state and the single-photon state of a cavity, while the target qubit is a cat-state qubit (wave-like qubit), whose two logic states are encoded by the two orthogonal cat states of the othe…
Universal quantum gates lie at the heart of designing quantum computer. We construct two compact quantum circuits to implement post-selected controlled-phase-flip (CPF) gate and Toffoli gate with linear optics assisted by one and two single photons, respectively. The current existing maximum success probability of 1/4 for linear optical CPF gate is achieved by resorting to an ancillary single photon rather than an entangled photon pair or two single photons. Remarkably, our Toffoli gate is accomplished with current maximum success probability of 1/30 without using additional entangled photon p…
Universal quantum gates are the core elements in quantum information processing. We design two schemes to realize more general (SWAP)$^{1/m}$ and controlled--(swap)$^{1/m}$ gates (for integer $m\geq1$) by directing flying single photons to solid--state quantum dots. The parameter $m$ is easily controlled by adjusting two quarter--wave plates and one half--wave plate. Additional computational qubits are not required to construct the two gates. Evaluations of the gates indicate that our proposals are feasible with current experimental technology.
We propose a deterministic SWAP gate for spatially encoded qubits. The gate is constructed from waveguide crossings, Mach Zender Interferometers and phase shifters providing the gate reconfigurability. Through manipulating the phase of the phase shifters, we can apply either the SWAP or identity gates. As an essential element of nearest neighbor qubit networks, the SWAP gate has a simple structure and presents minimal overhead, making it viable for universal quantum computation.
Implementations of quantum and classical gates with linear optical devices and photon number quantum non-demolition measurement for polarization encoded qubits