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We propose an alternative fidelity measure (namely, a measure of the degree of similarity) between quantum states and benchmark it against a number of properties of the standard Uhlmann-Jozsa fidelity. This measure is a simple function of…

Josza's definition of fidelity for a pair of (mixed) quantum states is studied in the context of two types of operator algebras. The first setting is mainly algebraic in that it involves unital C$^*$-algebras $A$ that possess a faithful…

Quantum Physics · Physics 2016-11-23 Douglas Farenick , Samuel Jaques , Mizanur Rahaman

We propose a fidelity measure for quantum channels in a straightforward analogy to the corresponding mixed-state fidelity of Jozsa. We describe properties of this fidelity measure and discuss some applications of it to quantum information…

Quantum Physics · Physics 2007-05-23 Maxim Raginsky

Applications of quantum technology often require fidelities to quantify performance. These provide a fundamental yardstick for the comparison of two quantum states. While this is straightforward in the case of pure states, it is much more…

Quantum fidelity is a central tool in quantum information, quantifying how much two quantum states are similar. Here we propose a limit formula for the quantum fidelity between a mixed state and a pure state. As an example of an…

Quantum Physics · Physics 2014-10-13 Gaetana Spedalieri , Christian Weedbrook , Stefano Pirandola

The fidelity of two pure states (also known as transition probability) is a symmetric function of two operators, and well-founded operationally as an event probability in a certain preparation-test pair. Motivated by the idea that the…

Quantum Physics · Physics 2009-11-06 Andreas Winter

Various fidelity measures can be defined between two quantum processes especially when at least one of them is non-unitary. In this paper we consider two such measures of state averaged process fidelity, put forward an efficient procedure…

Mathematical Physics · Physics 2011-11-11 Joydip Ghosh

When applied to different input states, an imperfect quantum operation yields output states with varying fidelities, defined as the absolute square of their overlap with the desired states. We present an expression for the distribution of…

Quantum Physics · Physics 2009-02-26 Line Hjortshoj Pedersen , Niels Martin Moller , Klaus Molmer

Fidelity is a figure of merit widely employed in quantum technology in order to quantify similarity between quantum states and, in turn, to assess quantum resources or reconstruction techniques. Fidelities higher than, say, 0.9 or 0.99, are…

Quantum Physics · Physics 2015-06-17 Matteo Bina , Antonio Mandarino , Stefano Olivares , Matteo G. A. Paris

Fidelity mechanics is formalized as a framework to investigate quantum critical phenomena in quantum many-body systems. This is achieved by introducing fidelity temperature to properly quantify quantum fluctuations, which, together with…

Strongly Correlated Electrons · Physics 2017-09-29 Huan-Qiang Zhou , Qian-Qian Shi , Yan-Wei Dai

We calculate the trade-off between the quality of estimating the quantum state of an ensemble of identically prepared qubits and the minimum level of disturbance that has to be introduced by this procedure in quantum mechanics. The…

Quantum Physics · Physics 2009-11-07 Konrad Banaszek , Igor Devetak

Quantum fidelity estimation is essential for benchmarking quantum states and processes on noisy quantum devices. While stabilizer operations form the foundation of fault-tolerant quantum computing, non-stabilizer resources further enable…

Quantum Physics · Physics 2025-06-17 Zhiping Liu , Kun Wang , Xin Wang

Transition Probability (fidelity) for pairs of density operators can be defined as "functor" in the hierarchy of "all" quantum systems and also within any quantum system. The introduction of "amplitudes" for density operators allows for a…

Quantum Physics · Physics 2016-04-08 Armin Uhlmann

We consider several definitions of the quantum Wasserstein distance based on an optimization over general bipartite quantum states with given marginals. Then, we examine the quantities obtained after the optimization is carried out over…

Quantum Physics · Physics 2026-05-15 Géza Tóth , József Pitrik

Fidelity is a fundamental measure for the closeness of two quantum states, which is important both from a theoretical and a practical point of view. Yet, in general, it is difficult to give good estimates of fidelity, especially when one…

Quantum Physics · Physics 2022-03-31 András Gilyén , Alexander Poremba

Fidelity is crucial for characterizing transformations of quantum states under various quantum channels, which can be served as a fundamental tool in resource theories. Firstly, we define an $\alpha$-$z$-fidelity as a significant quantity…

Quantum Physics · Physics 2025-07-08 Xiaojing Yan , Xiao Sun , Mingming Du , Jiashan Tang

Present-day quantum devices require precise implementation of desired quantum channels. To characterize the quality of implementation one uses the average operation fidelity $F$, defined as the fidelity between an initial pure state and its…

Quantum Physics · Physics 2024-03-18 Igor Chełstowski , Grzegorz Rajchel-Mieldzioć , Karol Życzkowski

Quantum fidelity is one of the most important measures of similarity between mixed quantum states. However, the usual formulation is cumbersome and hard to understand when encountering the first time. This work shows in a novel, elegant…

Quantum Physics · Physics 2023-10-11 Adrian Müller

In this paper, we introduce a new alternative quantum fidelity for quantum states which perfectly satisfies all Jozsas axioms and is zero for orthogonal states. By employing this fidelity, we derive an improved bound for quantum speed limit…

Quantum Physics · Physics 2017-02-22 Abbas Ektesabi , Naghi Behzadi , Esfandyar Faizi

Quantifying coherence is an essential endeavor for both quantum foundations and quantum technologies. In this paper, we put forward a quantitative measure of coherence by following the axiomatic definition of coherence measures introduced…

Quantum Physics · Physics 2017-07-06 C. L. Liu , Da-Jian Zhang , Xiao-Dong Yu , Qi-Ming Ding , Longjiang Liu
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