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This note presents a simple formula for the average fidelity between a unitary quantum gate and a general quantum operation on a qudit, generalizing the formula for qubits found by Bowdrey et al [Phys. Lett. A 294, 258 (2002)]. This formula…

Quantum Physics · Physics 2009-11-07 Michael A. Nielsen

Superconducting qubits are a promising platform for building a larger-scale quantum processor capable of solving otherwise intractable problems. In order for the processor to reach practical viability, the gate errors need to be further…

Quantum computation is a topic of significant recent interest, with practical advances coming from both research and industry. A major challenge in quantum programming is dealing with errors (quantum noise) during execution. Because quantum…

Programming Languages · Computer Science 2018-12-04 Shih-Han Hung , Kesha Hietala , Shaopeng Zhu , Mingsheng Ying , Michael Hicks , Xiaodi Wu

As quantum processors grow, new performance benchmarks are required to capture the full quality of the devices at scale. While quantum volume is an excellent benchmark, it focuses on the highest quality subset of the device and so is unable…

We generalize the experimental success criterion for quantum teleportation/memory in continuous-variable quantum systems to be suitable for non-unit-gain condition by considering attenuation/amplification of the coherent-state amplitude.…

Quantum Physics · Physics 2008-09-29 Ryo Namiki , Masato Koashi , Nobuyuki Imoto

Verifying the correct functioning of quantum gates is a crucial step towards reliable quantum information processing, but it becomes an overwhelming challenge as the system size grows due to the dimensionality curse. Recent theoretical…

We study the effects of imperfections on the fidelity of the Toffoli gate recently realized in a circuit~QED setup using quantum control methods. The noise is introduced in the interqubits interactions. The coupling constants are no longer…

Quantum Physics · Physics 2016-08-03 J. Khatibi Moqadam , Renato Portugal , N. F. Svaiter , G. O. Corrêa

We investigate the problem of bounding the quantum process fidelity given bounds on the fidelities between target states and the action of a process on a set of pure input states. We formulate the problem as a semidefinite program and prove…

Quantum Physics · Physics 2018-11-28 Karl Mayer , Emanuel Knill

Contemporary methods for benchmarking noisy quantum processors typically measure average error rates or process infidelities. However, thresholds for fault-tolerant quantum error correction are given in terms of worst-case error rates --…

High-fidelity control of quantum bits is paramount for the reliable execution of quantum algorithms and for achieving fault-tolerance, the ability to correct errors faster than they occur. The central requirement for fault-tolerance is…

With the current interest in building quantum computers, there is a strong need for accurate and efficient characterization of the noise in quantum gate implementations. A key measure of the performance of a quantum gate is the minimum gate…

Quantum Physics · Physics 2020-08-26 Yiping Lu , Jun Yan Sim , Jun Suzuki , Berthold-Georg Englert , Hui Khoon Ng

Quantum feedback control is a technology which can be used to drive a quantum system into a predetermined eigenstate. In this article, sufficient conditions for the experiment parameters of a quantum feedback control process of a homodyne…

Quantum Physics · Physics 2007-05-23 Andreas de Vries

We study the distribution over measurement outcomes of noisy random quantum circuits in the low-fidelity regime. We show that, for local noise that is sufficiently weak and unital, correlations (measured by the linear cross-entropy…

Quantum Physics · Physics 2021-12-01 Alexander M. Dalzell , Nicholas Hunter-Jones , Fernando G. S. L. Brandão

Let $\eta_0$ be the supremum of those $\eta$ for which every poly-size quantum circuit can be simulated by another poly-size quantum circuit with gates of fan-in $\leq 2$ that tolerates random noise independently occurring on all wires at…

Quantum Physics · Physics 2007-05-23 Alexander A. Razborov

In this paper, we analyze the performance of randomized benchmarking protocols on gate sets under a variety of realistic error models that include systematic rotations, amplitude damping, leakage to higher levels, and 1/f noise. We find…

Quantum Physics · Physics 2014-07-08 Jeffrey M. Epstein , Andrew W. Cross , Easwar Magesan , Jay M. Gambetta

Motivated by rapid developments in the field of quantum computing and the increasingly diverse nature of qubits, we theoretically study the influence that quenched outside disturbances have in an intermediately long time limit. We consider…

Strongly Correlated Electrons · Physics 2024-07-19 Wesley Roberts , Michael Vogl , Gregory A. Fiete

High-fidelity logical \emph{T}-gate realization constitutes a core prerequisite for large-scale fault-tolerant quantum computing. However, conventional magic state distillation requires massive physical qubit overhead across successive…

Quantum Physics · Physics 2026-05-04 Cheng-Yun Ding , Li-Hua Zhang , Jian Zhou

Quantum error correction (QEC) is essential for realizing scalable quantum computation. However, when evaluating its benefits, most analyses assume idealized components, overlooking the imperfections inherent in realistic fault-tolerant…

Quantum Physics · Physics 2026-05-26 Lorenzo Valentini , Diego Forlivesi , Marco Chiani

This paper presents a framework for designing provably safe feedback controllers for sampled-data control affine systems with measurement and actuation uncertainties. Based on the interval Taylor model of nonlinear functions, a sampled-data…

Optimization and Control · Mathematics 2022-10-13 Yuhao Zhang , Sequoyah Walters , Xiangru Xu

Starting with the basic control system model often employed in NMR pulse design, we derive more realistic control system models taking into account effects such as off-resonant excitation for systems with fixed inter-qubit coupling…

Quantum Physics · Physics 2009-10-01 Sonia Schirmer