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In recent proposals for achieving optical super-resolution, variants of the Quantum Fisher Information (QFI) quantify the attainable precision. We find that claims about a strong enhancement of the resolution resulting from coherence…

Quantum Physics · Physics 2019-11-14 Zdeněk Hradil , Jaroslav Řeháček , Luis Sánchez-Soto , Berthold-Georg Englert

Topological phase transitions in generic multiband systems are mediated by band-touching defects whose codimension -- the number of momentum directions along which the gap closes linearly -- varies across universality classes. Although…

Quantum Physics · Physics 2026-04-03 C. A. S. Almeida

This study investigates quantum-enhanced parameter estimation through continuous monitoring in open quantum systems that exhibit a dissipative time crystal phase. We first analytically derive the global quantum Fisher information (QFI) rate…

Quantum metrology promises precision beyond classical limits, yet environmental noise typically degrades the quantum resources required for such enhancement. In this work, we investigate frequency estimation in noisy continuous-variable…

Quantum Physics · Physics 2026-05-08 Ayan Patra , Manju , Aditi Sen De , Matteo G. A. Paris

In [Phys. Rev. Lett. 127, 023001 (2021)] a reduced density matrix functional theory (RDMFT) has been proposed for calculating energies of selected eigenstates of interacting many-fermion systems. Here, we develop a solid foundation for this…

Quantum Physics · Physics 2022-05-06 Julia Liebert , Federico Castillo , Jean-Philippe Labbé , Christian Schilling

Human experts cannot efficiently access the physical information of quantum many-body states by simply "reading" the coefficients, but have to reply on the previous knowledge such as order parameters and quantum measurements. In this work,…

Quantum Physics · Physics 2021-10-26 Xinran Ma , Z. C. Tu , Shi-Ju Ran

Exact simulations of quantum circuits (QCs) are currently limited to $\sim$50 qubits because the memory and computational cost required to store the QC wave function scale exponentially with qubit number. Therefore, developing efficient…

Quantum Physics · Physics 2025-02-18 Marco Bernardi

Quantum metrology studies the ultimate precision limit of physical quantities by using quantum strategy. In this paper we apply the quantum metrology technologies to the relativistic framework for estimating the deficit angle parameter of…

Quantum Physics · Physics 2022-08-11 Ying Yang , Jiliang Jing , Zehua Tian

We study the quantum Fisher information (QFI) of acceleration, in the open quantum systems, for a two-level atom with the circular motion coupled to a massless scalar field in the Minkowski vacuum without and with a reflecting boundary in…

General Relativity and Quantum Cosmology · Physics 2021-05-05 Zixu Zhao , Shuhang Zhang , Qiyuan Pan , Jiliang Jing

A new framework is formulated to study entanglement dynamics in many-body quantum systems along with an associated geometric description. In this formulation, called the Quantum Correlation Transfer Function (QCTF), the system's wave…

Quantum Physics · Physics 2025-04-22 Peyman Azodi , Herschel A Rabitz

Exceptional points (EPs) exhibit strongly enhanced spectral responses and are therefore promising candidates for sensing applications. Whether these non-Hermitian degeneracies provide a genuine advantage in the quantum regime has been the…

Quantum Physics · Physics 2026-03-12 Jan Wiersig , Stefan Rotter

Variational quantum algorithms are promising tools whose efficacy depends on their optimisation method. For noise-free unitary circuits, the quantum generalisation of natural gradient descent has been introduced and shown to be equivalent…

Quantum Physics · Physics 2023-09-12 Bálint Koczor , Simon C. Benjamin

In this contribution, quantum Fisher information is utilized to estimate the parameters of a central qubit interacting with a single-spin qubit. The effect of the longitudinal, transverse and the rotating strengths of the magnetic field on…

Quantum Physics · Physics 2018-04-04 N. Metwally

The fundamental metrological limits of temperature sensing in open quantum systems remain largely unresolved, particularly regarding the role of non-Gaussian quantum resources. In this letter, we establish analytic bounds on the quantum…

Quantum Physics · Physics 2025-12-04 Pritam Chattopadhyay

We evaluate the density matrix of an arbitrary quantum mechanical system in terms of the quantities pertinent to the solution of the time-dependent density functional theory (TDDFT) problem. Our theory utilizes the adiabatic connection…

Mesoscale and Nanoscale Physics · Physics 2019-09-04 Vladimir U. Nazarov

The expected decrease in system inertia and frequency stability motivates the development and maintenance of dynamic system models by Transmission System Operators. However, some dynamic model parameters can be unavailable due to market…

Signal Processing · Electrical Eng. & Systems 2025-05-27 Dawn Virginillo , Asja Derviškadić , Mario Paolone

We investigate how relative phase information, encoded by a single qubit $H\,\varphi\,H$ gate sequence, is reflected in the quantum Fisher information (QFI) under noisy dynamics. Within a collision model framework, algorithmically prepared…

Quantum Physics · Physics 2025-09-23 S. Elham Mousavigharalari , Deniz Türkpençe

The quantum Cram\'er-Rao bound sets a fundamental limit on the accuracy of unbiased parameter estimation in quantum systems, relating the uncertainty in determining a parameter to the inverse of the quantum Fisher information. We…

We establish one-body reduced density-matrix functional theory for the canonical ensemble in a finite basis set at an elevated temperature. Including temperature guarantees differentiability of the universal functional by occupying all…

Mathematical Physics · Physics 2023-02-22 Sarina M. Sutter , Klaas J. H. Giesbertz

We use two fundamental theoretical frameworks to study the finite-size (shell) properties of the unitary gas in a periodic box: 1) an ab initio Quantum Monte Carlo (QMC) calculation for boxes containing 4 to 130 particles provides a precise…

Quantum Gases · Physics 2011-06-27 Michael McNeil Forbes , Stefano Gandolfi , Alexandros Gezerlis