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Recently, the notion of a quantum acceleration limit has been proposed for any unitary time evolution of quantum systems governed by arbitrary nonstationary Hamiltonians. This limit articulates that the rate of change over time of the…

Quantum Physics · Physics 2026-05-29 Carlo Cafaro , Walid Redjem , Paul M. Alsing , Newshaw Bahreyni , Christian Corda

We show how one can asymptotically reach the Heisenberg limit in quantum Hamiltonian learning without entanglement, globally coherent measurements, or dynamical control, using only local quantum operations. Our protocol uses…

Quantum Physics · Physics 2025-12-02 Bora Baran , Timothy Heightman

We study time evolution of entanglement between two qubits, which are part of a larger system, after starting from a random initial product state. We show that, due to randomness in the initial product state, entanglement is present only…

Quantum Physics · Physics 2008-08-15 Marko Znidaric

We establish three impossibility results regarding our knowledge of the quantum state of the universe. Suppose the universal quantum state is a typical unit vector in a high-dimensional subspace $\mathscr{H}_0$ of Hilbert space…

Quantum Physics · Physics 2026-01-27 Eddy Keming Chen , Roderich Tumulka

We demonstrate that the task of determining an unknown quantum state can be accomplished efficiently by making a sequential measurement of two observables $\hat{A}$ and $\hat{B}$, provided that the two observables are chosen in such a way…

Quantum Physics · Physics 2013-10-22 Antonio Di Lorenzo

I explore the possibility that a quantum system S may be described completely by the combination of its standard quantum state $|\psi\rangle$ and a (hidden) quantum state $|\phi\rangle$ (that lives in the same Hilbert space), such that the…

Quantum Physics · Physics 2015-06-16 S. J. van Enk

Entanglement of pure states of bipartite quantum systems has been shown to have a unique measure in terms of the von Neumann entropy of the reduced states of either of its subsystems. The measure is established under entanglement…

Quantum Physics · Physics 2007-05-23 Garry Bowen , Nilanjana Datta

Quantum phase transitions are usually observed in ground states of correlated systems. Remarkably, eigenstate phase transitions can also occur at finite energy density in disordered, isolated quantum systems. Such transitions fall outside…

Disordered Systems and Neural Networks · Physics 2015-09-16 A. Chandran , C. R. Laumann , V. Oganesyan

The characterization of ensembles of many-qubit random states and their realization via quantum circuits are crucial tasks in quantum-information theory. In this work, we study the ensembles generated by quantum circuits that randomly…

Statistical Mechanics · Physics 2026-03-18 Dávid Szász-Schagrin , Michele Mazzoni , Bruno Bertini , Katja Klobas , Lorenzo Piroli

Quantum entanglement in systems of identical particles is often obscured by the interplay between exchange-induced correlations and the operational framework used to define entanglement. To study the role of exchange statistics, we propose…

Quantum Physics · Physics 2026-04-22 M. F. V. Oliveira , F. A. B. F. de Moura , M. L. Lyra , G. M. A. Almeida

The ordinary time-dependent perturbation theory of quantum mechanics, that describes the interaction of a stationary system with a time-dependent perturbation, predicts that the transition probabilities induced by the perturbation are…

Quantum Physics · Physics 2017-10-11 S. Longhi , G. Della Valle

We investigate the role of a statistical complexity measure to assign equilibration in isolated quantum systems. While unitary dynamics preserve global purity, expectation values of observables often exhibit equilibration-like behavior,…

Quantum Physics · Physics 2025-08-14 Marcos G. Alpino , Tiago Debarba , Reinaldo O. Vianna , André T. Cesário

The restricted numerical range $W_R(A)$ of an operator $A$ acting on a $D$-dimensional Hilbert space is defined as a set of all possible expectation values of this operator among pure states which belong to a certain subset $R$ of the of…

Stochastic dynamics of a quantum system driven by $N$ statistically independent random sudden quenches in a fixed time interval is studied. We reveal that with growing $N$ the system approaches a deterministic limit indicating…

Quantum Physics · Physics 2018-08-15 Marcin Łobejko , Jerzy Dajka , Jerzy Łuczka

In quantum information geometry, the curvature of von-Neumann entropy and relative entropy induce a natural metric on the space of mixed quantum states. Here we use this information metric to construct a random matrix ensemble for states…

Quantum Physics · Physics 2026-01-26 Harry J. D. Miller

We pursue the view that quantum theory may be an emergent structure related to large space-time scales. In particular, we consider classical Hamiltonian systems in which the intrinsic proper time evolution parameter is related through a…

General Relativity and Quantum Cosmology · Physics 2014-11-17 Hans-Thomas Elze

We investigate convergence properties of discrete-time semigroup quantum dynamics, including asymptotic stability, probability and speed of convergence to pure states and subspaces. These properties are of interest in both the analysis of…

Quantum Physics · Physics 2015-06-22 Giuseppe Ilario Cirillo , Francesco Ticozzi

In this paper, we study the behaviour of the output of pure entangled states after being transformed by a product of conjugate random unitary channels. This study is motivated by the counterexamples by Hastings and Hayden-Winter to the…

Mathematical Physics · Physics 2019-02-27 Benoit Collins , Motohisa Fukuda , Ion Nechita

We study the effect that the SU(2) symmetry, and the rich Hilbert space structure that it generates in lattice spin systems, has on the average entanglement entropy of highly excited eigenstates of local Hamiltonians and of random pure…

Quantum Physics · Physics 2023-12-04 Rohit Patil , Lucas Hackl , George R. Fagan , Marcos Rigol

We consider scattering processes where a quantum system is comprised of an inner subsystem and of a boundary, and is subject to Haar-averaged random unitaries acting on the boundary-environment Hilbert space only. We show that, regardless…

Quantum Physics · Physics 2023-08-30 Michele Avalle , Alessio Serafini