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This paper considers the control landscape of quantum transitions in multi-qubit systems driven by unitary transformations with single-qubit interaction terms. The two-qubit case is fully analyzed to reveal the features of the landscape…

Quantum Physics · Physics 2009-10-09 Renan Cabrera , Herschel Rabitz

The inability of Schrodinger's unitary time evolution to describe measurement of a quantum state remains a central foundational problem. It was recently suggested that the unitarity of Schrodinger dynamics can be spontaneously broken,…

The time evolution of the trace distance between two states of an open quantum system may increase due to initial system-environment correlations, thus exhibiting a breakdown of distance contractivity of the reduced dynamics. We analyze how…

Quantum Physics · Physics 2016-08-14 Jerzy Dajka , Jerzy Łuczka , Peter Hänggi

When a system is driven across a continuous phase transition, the density of topological defects demonstrates a power-law scaling behavior versus the quenching rate, as predicted by Kibble-Zurek mechanism. In this study, we generalized this…

Quantum Physics · Physics 2024-06-27 Lingzi Huang , Menghua Deng , Chen Sun , Fuxiang Li

Consider the question: what statistical ensemble corresponds to minimal prior knowledge about a quantum system ? For the case where the system is in fact known to be in a pure state there is an obvious answer, corresponding to the unique…

Quantum Physics · Physics 2009-10-31 Michael J. W. Hall

A realist description of our universe requires a twofold concept of locality. On one hand, there are the strictly Einstein-local interactions which generate the time evolution. On the other hand, the quantum state space calls for a…

Quantum Physics · Physics 2013-08-27 Andreas O. Tell

We show that superpositions of classical states in quantum gravity with fixed topology can lead to new classical states with a different topology. We study this phenomenon in a particular limit of the LLM geometries. In this limit, the UV…

High Energy Physics - Theory · Physics 2018-01-17 David Berenstein , Alexandra Miller

Extending hyperuniformity from classical to quantum fluctuations in electron systems yields a framework that identifies quantum phase transitions and reveals underlying gap structures through the quantum weight. We study long-wavelength…

Strongly Correlated Electrons · Physics 2026-01-27 Junmo Jeon , Shiro Sakai

We consider the problem of determining the state of a quantum system given one or more readings of the expectation value of an observable. The system is assumed to be a finite dimensional quantum control system for which we can influence…

Quantum Physics · Physics 2009-11-10 Domenico D'Alessandro

An unknown quantum state of a single system cannot be discovered, as a measured system is reprepare: it jumps into an eigenstate of the measured observable. This impossibility of finding the quantum state and other symptoms usually blamed…

Quantum Physics · Physics 2013-11-05 Wojciech H. Zurek

The number of parameters describing a quantum state is well known to grow exponentially with the number of particles. This scaling clearly limits our ability to do tomography to systems with no more than a few qubits and has been used to…

The different time-dependent distances of two arbitrarily close quantum or classical-statistical states to a third fixed state are shown to imply an experimentally relevant notion of state sensitivity to initial conditions. A quantitative…

Quantum Physics · Physics 2007-05-23 Gonzalo Garcia de Polavieja

We demonstrate that the unitary dynamics of a multi-qubit system can display hypersensitivity to initial state perturbation. This contradicts the common belief that the classical approach based on the exponential divergence of initially…

Quantum Physics · Physics 2023-07-28 Andrzej Grudka , Paweł Kurzyński , Adam S. Sajna , Jan Wójcik , Antoni Wójcik

We formulate a discrete two-state stochastic process with elementary rules that give rise to Born statistics and reproduce the probabilities from the Schr\"odinger equation under an associated Hamiltonian matrix, which we identify. We…

Quantum Physics · Physics 2023-09-19 Themis Matsoukas

This manuscript gathers and subsumes a long series of works on using QW to simulate transport phenomena. Quantum Walks (QWs) consist of single and isolated quantum systems, evolving in discrete or continuous time steps according to a…

Quantum Physics · Physics 2021-12-23 Giuseppe Di Molfetta

The measurement problem is the issue of explaining how the objective classical world emerges from a quantum one. Here we take a different approach. We assume that there is an objective classical system, and then ask that the standard rules…

Quantum Physics · Physics 2025-10-13 Isaac Layton , Jonathan Oppenheim , Zachary Weller-Davies

In quantum mechanical experiments one distinguishes between the state of an experimental system and an observable measured in it. Heuristically, the distinction between states and observables is also suggested in scattering theory or when…

Quantum Physics · Physics 2015-05-20 Arno Bohm , Peter W. Bryant

We investigate a ''quantum microscope'' for qubits based on nonlinear discrete-time chaotic dynamics, which exponentially amplifies the initially small fidelity of a pair of states to a large saturation value ( $\sim$ 1/2), thereby pushing…

Quantum Physics · Physics 2026-04-14 Sourav Paul , Anant Vijay Varma , Yogesh N. Joglekar , Sourin Das

We consider a two-level quantum system (qubit) which is continuously measured by a detector. The information provided by the detector is taken into account to describe the evolution during a particular realization of measurement process. We…

Mesoscale and Nanoscale Physics · Physics 2009-10-31 Alexander N. Korotkov

An understanding of quantum theory in terms of new, underlying descriptions capable of explaining the existence of non-classical correlations, non-commutativity of measurements and other unique and counter-intuitive phenomena remains still…

Quantum Physics · Physics 2025-05-12 Yasmin Navarrete , Sergio Davis