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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

Estimating a classical parameter encoded in the Hamiltonian of a quantum probe is a fundamental and well-understood task in quantum metrology. A textbook example is the estimation of a classical field's amplitude using a two-level probe, as…

Quantum Physics · Physics 2026-04-15 Ricard Ravell Rodríguez , Martí Perarnau-Llobet , Pavel Sekatski

Quantum imaginary-time evolution (QITE) is a promising tool to prepare thermal or ground states of Hamiltonians, as convergence is guaranteed when the evolved state overlaps with the ground state. However, its implementation using a a…

Quantum Physics · Physics 2025-01-20 Ioannis Kolotouros , David Joseph , Anand Kumar Narayanan

In randomized benchmarking of quantum logical gates, partial twirling can be used for simpler implementation, better scaling, and higher accuracy and reliability. For instance, for two-qubit gates, single-qubit twirling is easier to realize…

Quantum Physics · Physics 2022-06-22 Kirill Dubovitskii , Yuriy Makhlin

Quasiparticle interference imaging (QPI) provides a route to characterize electronic structure from real space images acquired using scanning tunneling microscopy. It emerges due to scattering of electrons at defects in the material. The…

Strongly Correlated Electrons · Physics 2025-11-12 Peter Wahl , Luke C. Rhodes , Carolina A. Marques

A physical system exposes to us in a real space, while its description often refers to its reciprocal momentum space. A connection between them can be established by exploring patterns of quasiparticles interference (QPI), which is…

Mesoscale and Nanoscale Physics · Physics 2019-11-13 Dan-Bo Zhang , Qiang Han , Z. D. Wang

Quantum Fisher information matrix (QFIM) is a cornerstone of modern quantum metrology and quantum information geometry. Apart from optimal estimation, it finds applications in description of quantum speed limits, quantum criticality,…

Quantum Physics · Physics 2018-04-16 Dominik Šafránek

The fidelity of quantum circuits (QC) is influenced by several factors, including hardware characteristics, calibration status, and the transpilation process, all of which impact their susceptibility to noise. However, existing methods…

Quantum Physics · Physics 2025-05-22 Yikai Mao , Shaswot Shresthamali , Masaaki Kondo

Quantum tomography is the main method used to assess the quality of quantum information processing devices, but its complexity presents a major obstacle for the characterization of even moderately large systems. The number of experimental…

Quantum Physics · Physics 2015-03-19 Marcus P. da Silva , Olivier Landon-Cardinal , David Poulin

We propose a quantum metrology protocol based on a two-step joint evolution of the probe system and an ancillary qubit and quantum measurement. With a proper initial state of the ancillary qubit and an optimized evolution time, the quantum…

Quantum Physics · Physics 2025-01-06 Peng Chen , Jun Jing

Quantum Fano inequality (QFI) in quantum information theory provides an upper bound to the entropy exchange by a function of the entanglement fidelity. We give various Fano-like upper bounds to the entropy exchange and QFI is a special case…

Quantum Physics · Physics 2013-02-22 Naresh Sharma

Quantum Fisher information (QFI) has potential applications in quantum metrology tasks. We investigate QFI when the consecutive actions of a quantum channel on the sequence of qubits have partial classical correlations. Our results showed…

Quantum Physics · Physics 2020-03-09 Ming-Liang Hu , Hui-Fang Wang

Quantum Darwinism explains the emergence of classical objectivity through the redundant encoding of pointer information in environmental fragments. However, existing diagnostics rely on arbitrary thresholds or structural assumptions that…

Quantum Physics · Physics 2026-02-03 Arda Batin Tank

Quantum machine learning (QML) models often require deep, parameterized circuits to capture complex frequency components, limiting their scalability and near-term implementation. We introduce \textit{Quantum Random Features} (QRF) and…

Quantum Physics · Physics 2026-01-30 Akitada Sakurai , Aoi Hayashi , William John Munro , Kae Nemoto

We address the use of simple quantum probes for the spectral characterization of classical noisy environments. In our scheme a qubit interacts with a classical stochastic field describing environmental noise and is then measured after a…

Quantum Physics · Physics 2014-03-21 Claudia Benedetti , Fabrizio Buscemi , Paolo Bordone , Matteo G. A. Paris

Quantum Fisher information matrix (QFIM) is a core concept in theoretical quantum metrology due to the significant importance of quantum Cram\'{e}r-Rao bound in quantum parameter estimation. However, studies in recent years have revealed…

Quantum Physics · Physics 2020-03-27 Jing Liu , Haidong Yuan , Xiao-Ming Lu , Xiaoguang Wang

We derive an algebraic framework which identifies the minimal information required to assess how well a quantum device implements a desired quantum operation. Our approach is based on characterizing only the unitary part of an open system's…

Quantum Physics · Physics 2013-10-10 Daniel M. Reich , Giulia Gualdi , Christiane P. Koch

Quantum parameter estimation with Hermitian systems has been applied in various fields, but there are relatively few results concerning non-Hermitian systems. Here, we study the quantum parameter estimation for general non-Hermitian…

Quantum Physics · Physics 2023-09-06 Xinglei Yu , Chengjie Zhang

Quantum metrology studies the ultimate limit of precision in estimating a physical quantity if quantum strategies are exploited. Here we investigate the evolution of a two-level atom as a detector which interacts with a massless scalar…

General Relativity and Quantum Cosmology · Physics 2015-01-28 Zehua Tian , Jieci Wang , Heng Fan , Jiliang Jing

Quantum technologies work by utilizing properties inherent in quantum systems such as quantum coherence and quantum entanglement and are expected to be superior to classical counterparts for solving certain problems in science and…

Quantum Physics · Physics 2023-04-10 Yusuke Hama , Hirofumi Nishi