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Entanglement-assisted quantum error correcting codes (EAQECCs) can be derived from arbitrary classical linear codes. However, it is a very difficult task to determine the number of entangled states required. In this work, using the method…

Information Theory · Computer Science 2020-04-22 Liangdong Lu , Wenping Ma , Luobin Guo

We perform a comprehensive analysis of the set of parameters $\{r_{i}\}$ that provide the energy distribution of pure qutrits that evolve towards a distinguishable state at a finite time $\tau$, when evolving under an arbitrary and…

Quantum Physics · Physics 2021-07-28 Francisco J. Sevilla , Andrea Valdés-Hernández , Alan J. Barrios

Research in quantum information science aims to surpass the scaling limitations of classical information processing. From a physicist's perspective, performance improvement involves a physical speedup in the quantum domain, achieved by…

Quantum Physics · Physics 2024-07-10 Farha Yasmin , Jan Sperling

The quantum speed limit indicates the maximal evolution speed of the quantum system. In this work, we determine speed limits on the informational measures, namely the von Neumann entropy, maximal information, and coherence of quantum…

Quantum Physics · Physics 2022-06-16 Brij Mohan , Siddhartha Das , Arun Kumar Pati

A visualization for dynamics of a qudit spin vector in a time-dependent magnetic field is realized by means of mapping a solution for a spin vector on the three-dimensional spherical curve (vector hodograph). The obtained results obviously…

Quantum Physics · Physics 2017-11-22 E. A. Ivanchenko

Geometric quantum mechanics aims to express the physical properties of quantum systems in terms of geometrical features preferentially selected in the space of pure states. Geometric characterisations are given here for systems of one, two,…

Quantum Physics · Physics 2007-06-13 Dorje C. Brody , Anna C. T. Gustavsson , Lane P. Hughston

A quantum clock cannot be modeled as a point mass moving along a single geodesic if it is in a state with nonzero position fluctuations. Instead, it is an extended object subject to tidal forces and a superposition of time dilations at…

Quantum Physics · Physics 2025-03-11 Joseph Balsells , Martin Bojowald

This letter analyzes the limits that quantum mechanics imposes on the accuracy to which spacetime geometry can be measured. By applying the physics of computation to ensembles of clocks, as in GPS, we present a covariant version of the…

Quantum Physics · Physics 2012-07-09 Seth Lloyd

The speed limit of quantum state transfer (QST) in a system of interacting particles is not only important for quantum information processing, but also directly linked to Lieb-Robinson-type bounds that are crucial for understanding various…

Quantum Physics · Physics 2023-11-28 Casey Jameson , Bora Basyildiz , Daniel Moore , Kyle Clark , Zhexuan Gong

We use a specific geometric method to determine speed limits to the implementation of quantum gates in controlled quantum systems that have a specific class of constrained control functions. We achieve this by applying a recent theorem of…

Quantum Physics · Physics 2014-07-09 Benjamin Russell , Susan Stepney

Distance to Uncontrollability is a crucial concept in classical control theory. Here, we introduce Quantum Distance to Uncontrollability as a measure how close a universal quantum system is to a non-universal one. This allows us to provide…

Quantum Physics · Physics 2022-04-06 Daniel Burgarth , Jeff Borggaard , Zoltán Zimborás

Quantum machine learning (QML) seeks to exploit the intrinsic properties of quantum mechanical systems, including superposition, coherence, and quantum entanglement for classical data processing. However, due to the exponential growth of…

Quantum Physics · Physics 2025-10-09 Timothy Heightman , Edward Jiang , Ruth Mora-Soto , Maciej Lewenstein , Marcin Płodzień

In the semiclassical limit of open ballistic quantum systems, we demonstrate the emergence of instantaneous decay modes guided by classical escape faster than the Ehrenfest time. The decay time of the associated quasi-bound states is…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Henning Schomerus , Jakub Tworzydlo

We study time-optimal protocols for controlling quantum systems which show several avoided level crossings in their energy spectrum. The structure of the spectrum allows us to generate a robust guess which is time-optimal at each crossing.…

Quantum Physics · Physics 2015-11-18 P. M. Poggi , F. C. Lombardo , D. A. Wisniacki

We design several examples of constrained, symmetric quantum circuit dynamics that generate non-equilibrium steady states. The qubit networks maintain local memory of the initial conditions and display inhomogeneous subsystem dynamics over…

Quantum Physics · Physics 2025-05-02 Unnati Akhouri , Sarah Shandera , Jackson Henry

A centipede made of $N$ quantum walkers on a one-dimensional lattice is considered. The distance between two consecutive legs is either one or two lattice spacings, and a global constraint is imposed: the maximal distance between the first…

Statistical Mechanics · Physics 2017-05-24 Pascal Grange

The notion of "closed systems" in Quantum Mechanics is discussed. For this purpose, we study two models of a quantum-mechanical system $P$ spatially far separated from the "rest of the universe" $Q$. Under reasonable assumptions on the…

Mathematical Physics · Physics 2015-05-06 Jérémy Faupin , Jürg Fröhlich , Baptiste Schubnel

An open quantum system with multiple levels coupled to a bosonic environment at zero temperature is investigated systematically using the non-Markovian quantum-state-diffusion (QSD) method [W. T. Strunz, L. Di\'osi, and N. Gisin, Phys. Rev.…

Quantum Physics · Physics 2012-04-10 Jun Jing , Xinyu Zhao , J. Q. You , Ting Yu

Transforming an initial quantum state into a target state through the fastest possible route---a quantum brachistochrone---is a fundamental challenge for many technologies based on quantum mechanics. Here, we demonstrate fast coherent…

Quantum linear system algorithms (QLSAs) can provide exponential speedups for the solution of linear systems, but the growth of the condition number for finite element problems can eliminate the exponential speedup. QLSAs are also incapable…

Quantum Physics · Physics 2024-04-12 Osama Muhammad Raisuddin , Suvranu De
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