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Efficient measures to determine similarity of quantum states, such as the fidelity metric, have been widely studied. In this paper, we address the problem of defining a similarity measure for quantum operations that can be…

Quantum Physics · Physics 2022-11-23 Yiyou Chen , Hideyuki Miyahara , Louis-S. Bouchard , Vwani Roychowdhury

A profound comprehension of quantum entanglement is crucial for the progression of quantum technologies. The degree of entanglement can be assessed by enumerating the entangled degrees of freedom, leading to the determination of a parameter…

Quantum Physics · Physics 2025-04-16 Liang Xiong , Nung-sing Sze

Quantum memories represent one of the main ingredients of future quantum communication networks. Their certification is therefore a key challenge. Here we develop efficient certification methods for quantum memories. Considering a…

Quantum Physics · Physics 2023-11-17 Pavel Sekatski , Jean-Daniel Bancal , Marie Ioannou , Mikael Afzelius , Nicolas Brunner

There is growing interest in developing rigorous tests of quantumness that are feasible even before practical quantum advantages become a reality. Such tests not only aim to certify the quantum nature of a system but also serve as…

Quantum Physics · Physics 2025-10-13 Anna Schroeder , Lucas B. Vieira , Jan Nöller , Nikolai Miklin , Mariami Gachechiladze

Efficient verification of multipartite quantum states is crucial to many applications in quantum information processing. By virtue of Schmidt decomposition and mutually unbiased bases, here we propose a universal protocol to verify…

Quantum Physics · Physics 2026-03-04 Yunting Li , Huangjun Zhu

In this paper, we study $k$-positivity and Schmidt number under standard orthogonal group symmetries. The Schmidt number is a natural quantification of entanglement in quantum information theory. First of all, we exhibit a complete…

Quantum Physics · Physics 2023-07-21 Sang-Jun Park , Sang-Gyun Youn

We derive a universal performance limit for coherent quantum control in the presence of modeled and unmodeled uncertainties. For any target unitary $W$ that is implementable in the absence of error, we prove that the worst-case (and hence…

Quantum Physics · Physics 2025-07-14 Robert L. Kosut , Daniel A. Lidar , Herschel Rabitz

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

Unitarity randomized benchmarking (URB) is an experimental procedure for estimating the coherence of implemented quantum gates independently of state preparation and measurement errors. These estimates of the coherence are measured by the…

Quantum Physics · Physics 2019-01-17 Bas Dirkse , Jonas Helsen , Stephanie Wehner

We report the first complete characterization of single-qubit and two-qubit gate fidelities in silicon-based spin qubits, including cross-talk and error correlations between the two qubits. To do so, we use a combination of standard…

Scalable and fault-tolerant quantum computation will require error correction. This will demand constant measurement of many-qubit observables, implemented using a vast number of CNOT gates. Indeed, practically all operations performed by a…

Quantum Physics · Physics 2018-10-16 Andreas Peter , Daniel Loss , James R. Wootton

We introduce a measure of average dimensionality (or coherence) for high-dimensional quantum devices. This includes sets of quantum measurements, steering assemblages, and quantum channels. For measurements and channels, our measure…

Quantum Physics · Physics 2023-06-22 Thomas Cope , Roope Uola

We present a measure of quantum entanglement which is capable of quantifying the degree of entanglement of a multi-partite quantum system. This measure, which is based on a generalization of the Schmidt rank of a pure state, is defined on…

Quantum Physics · Physics 2016-09-08 J. Eisert , H. -J. Briegel

A Quantum Computer is a new type of computer which can solve problems such as factoring and database search very efficiently. The usefulness of a quantum computer is limited by the effect of two different types of errors, decoherence and…

Quantum Physics · Physics 2007-05-23 Kevin M. Obenland , Alvin M. Despain

Analog quantum simulation allows for assessing static and dynamical properties of strongly correlated quantum systems to high precision. To perform simulations outside the reach of classical computers, accurate and reliable implementations…

How to find universal sets quantum gates (gates whose composition can form any othergate within a given range) is an important part of the development of quantum computation science that has been explored in the past with success. However,…

Quantum Physics · Physics 2021-10-19 Carlos Efrain Quintero Narvaez

Benchmarking large-scale quantum gates, typically involving multiple native two-qubit and singlequbit gates, is crucial in quantum computing. Global fidelity, encompassing information about intergate correlations, offers a comprehensive…

We propose a method to reliably and efficiently extract the fidelity of many-qubit quantum circuits composed of continuously parametrized two-qubit gates called matchgates. This method, which we call matchgate benchmarking, relies on…

Quantum Physics · Physics 2022-02-22 Jonas Helsen , Sepehr Nezami , Matthew Reagor , Michael Walter

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 --…

Learning problems involving quantum data are natural candidates for demonstrating an advantage in quantum machine learning. Recent results indicate that, for certain tasks and under noiseless conditions, coherent processing of quantum data…