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Overlap-based distinguishability measures, such as fidelity- or Chernoff-type quantities, play a central role in quantum sensing and quantum illumination. In strongly lossy and fluctuating environments, however, these quantities may become…

Quantum Physics · Physics 2026-04-21 Arnaud Coatanhay , Angélique Drémeau

We report a new metric of quantum states. This metric is build up from super-fidelity, which has deep connection with the Uhlmann-Jozsa fidelity and plays an important role in quantifying entanglement. We find that the new metric possess…

Quantum Physics · Physics 2009-08-24 Zhi-Hao Ma , Fu-Lin Zhang , Zhi-Hua Chen , Jing-Ling Chen

We introduce a coherence susceptibility method, based on the fact that it signals quantum fluctuations, for identifying quantum phase transitions, which are induced by quantum fluctuations. This method requires no prior knowledge of order…

Quantum Physics · Physics 2016-08-18 Jin-Jun Chen , Jian Cui , Yu-Ran Zhang , Heng Fan

We study the dynamical fidelity $\mathcal{F} (t)$ and the Loschmidt echo $\mathcal{L} (t)$, following a periodic driving of the transverse magnetic field of a quantum Ising chain (back and forth across the quantum critical point) by…

Quantum Physics · Physics 2015-06-18 Shraddha Sharma , Angelo Russomanno , Giuseppe E. Santoro , Amit Dutta

We investigate distinguishability (measured by fidelity) of the initial and the final state of a qubit, which is an object of the so-called nonideal quantum measurement of the first kind. We show that the fidelity of a nonideal measurement…

Quantum Physics · Physics 2007-05-23 Miroljub Dugic , Milan M. Cirkovic

The fidelity susceptibility measures sensitivity of eigenstates to a change of an external parameter. It has been fruitfully used to pin down quantum phase transitions when applied to ground states (with extensions to thermal states). Here…

Disordered Systems and Neural Networks · Physics 2020-04-10 Piotr Sierant , Artur Maksymov , Marek Kuś , Jakub Zakrzewski

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

We train convolutional neural networks to predict whether or not a set of measurements is informationally complete to uniquely reconstruct any given quantum state with no prior information. In addition, we perform fidelity benchmarking…

Quantum sensing is one of the arenas that exemplifies the superiority of quantum technologies over their classical counterparts. Such superiority, however, can be diminished due to unavoidable noise and decoherence of the probe. Thus,…

Quantum Physics · Physics 2023-10-25 V. Montenegro , M. G. Genoni , A. Bayat , M. G. A. Paris

Fidelity is one of the most widely used quantities in quantum information that measure the distance of quantum states through a noisy channel. In this paper, we introduce a quantum analogy of computation tree logic (CTL) called QCTL, which…

Logic in Computer Science · Computer Science 2023-10-20 Ming Xu , Jianling Fu , Jingyi Mei , Yuxin Deng

Automatic differentiation is an invaluable feature of machine learning and quantum machine learning software libraries. In this work it is shown how quantum automatic differentiation can be used to solve the condensed-matter problem of…

Quantum Physics · Physics 2022-11-29 Olivia Di Matteo , R. M. Woloshyn

We describe how to use the fidelity decay as a tool to characterize the errors affecting a quantum information processor through a noise generator $G_{\tau}$. For weak noise, the initial decay rate of the fidelity proves to be a simple way…

Quantum Physics · Physics 2015-06-26 Benjamin Lévi , Cecilia C. López , Joseph Emerson , D. G. Cory

The computational power of real-world quantum computers is limited by errors. When using quantum computers to perform algorithms which cannot be efficiently simulated classically, it is important to quantify the accuracy with which the…

Quantum Physics · Physics 2024-01-18 Avi Vadali , Rutuja Kshirsagar , Prasanth Shyamsundar , Gabriel N. Perdue

In this article, we study the high order term of the fidelity of the Heisenberg chain with next-nearest-neighbor interaction and analyze its connection with quantum phase transition of Beresinskii-Kosterlitz-Thouless type happened in the…

Quantum Physics · Physics 2009-03-27 Li Wang , Shi-Jian Gu , Shu Chen

Quantum state comparison, utilizing metrics like fidelity and trace distance, underpins the assessment of quantum networks within quantum information theory. While recent research has expanded theoretical understanding, incorporating error…

Quantum Algebra · Mathematics 2024-04-18 John T. M. Campbell , Nicola Marchetti , John Dooley , Indrakshi Dey

Combining tensor network techniques with quantum autoregressive moving average models, we quantify the effects of time-correlated noise on quantum algorithms and predict their performance at scale. As a paradigmatic test case, we examine…

Quantum Physics · Physics 2026-03-06 Amit Jamadagni , Gregory Quiroz , Eugene Dumitrescu

We propose an optimal method exploiting second order quantum phase transitions to perform high precision measurements of the control parameter at criticality. Our approach accesses the high fidelity susceptibility via the measurement of…

Quantum Physics · Physics 2019-06-05 Luca Pezzè , Andreas Trenkwalder , Marco Fattori

Stable quantum computation requires noisy results to remain bounded even in the presence of noise fluctuations. Yet non-stationary noise processes lead to drift in the varying characteristics of a quantum device that can greatly influence…

Quantum Physics · Physics 2023-07-12 Samudra Dasgupta , Travis S. Humble

We derive a computable analytical formula for the quantum fidelity between two arbitrary multimode Gaussian states which is simply expressed in terms of their first- and second-order statistical moments. We also show how such a formula can…

Quantum Physics · Physics 2015-12-23 Leonardo Banchi , Samuel L. Braunstein , Stefano Pirandola

A general relation between quantum phase transitions and the second derivative of the fidelity (or the "fidelity susceptibility") is proposed. The validity and the limitation of the fidelity susceptibility in characterizing quantum phase…

Quantum Physics · Physics 2007-11-09 Min-Fong Yang