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We present a detailed discussion of a general theory of phase-space distributions, introduced recently by the authors [J. Phys. A {\bf 31}, L9 (1998)]. This theory provides a unified phase-space formulation of quantum mechanics for physical…

Quantum Physics · Physics 2009-10-31 C. Brif , A. Mann

Quantum operations represented by completely positive maps encompass many of the physical processes and have been very powerful in describing quantum computation and information processing tasks. We introduce the notion of relative phase…

Quantum Physics · Physics 2007-05-23 Arun K. Pati

We formulate dynamical phase transitions in subsystems embedded in larger quantum systems. Introducing the entanglement echo as an overlap of the initial and instantaneous entanglement ground states, we show its analytic structure after a…

Quantum Physics · Physics 2021-06-21 Kim Pöyhönen , Teemu Ojanen

Determining the physically accessible unitary dynamics of a quantum system under finite Hamiltonian resources is a central problem in quantum control and Hamiltonian engineering. Dynamical Lie algebras (DLAs) provide the fundamental link…

Quantum Physics · Physics 2026-03-06 Yanying Liang , Ruibin Xu , Mao-Sheng Li , Haozhen Situ , Zhu-Jun Zheng

We study relaxation times, also called mixing times, of quantum many-body systems described by a Lindblad master equation. We in particular study the scaling of the spectral gap with the system length, the so-called dynamical exponent,…

Statistical Mechanics · Physics 2015-10-30 Marko Znidaric

The relationship between quantum phase transition and complex geometric phase for open quantum system governed by the non-Hermitian effective Hamiltonian with the accidental crossing of the eigenvalues is established. In particular, the…

Quantum Physics · Physics 2008-11-26 Alexander I. Nesterov , S. G. Ovchinnikov

The Van der Waals equation (VdW-EoS) is a prototype equation of state for realistic systems, because it contains the excluded volume and the particle interactions. Additionally, the simulated annealing (and the similar simulated…

Soft Condensed Matter · Physics 2016-09-30 Peter Friedel

In this work, we show that ma-QAOA is equivalent to a restriction of continuous-time quantum walks on dynamic graphs. We then show it is universal for computation by finding the appropriate $B$ and $C$ operators and angles that implement…

Quantum Physics · Physics 2022-09-02 Rebekah Herrman

We explore the main processes involved in the evolution of general quantum systems by means of Diagrams of States, a novel method to graphically represent and analyze how quantum information is elaborated during computations performed by…

Quantum Physics · Physics 2009-12-02 Sara Felloni , Alberto Leporati , Giuliano Strini

This work presents a unified perspective on thermal equilibrium and quantum dynamics by examining the simplest quantum system, a qubit, as a minimal model. We show that both the thermal partition function and the Loschmidt amplitude can be…

Quantum Physics · Physics 2026-03-02 Manmeet Kaur , Somendra M. Bhattacharjee

The Lindblad equation describes the dissipative time evolution of a density matrix that characterizes an open quantum system in contact with its environment. The widespread ensemble interpretation of a density matrix requires its time…

Quantum Physics · Physics 2020-09-04 Bernd Fernengel , Barbara Drossel

Quantum phase estimation plays a central role in quantum simulation as it enables the study of spectral properties of many-body quantum systems. Most variants of the phase estimation algorithm require the application of the global unitary…

We report dynamical quantum phase transition portrait in the alternating field transverse XY spin chain with Dzyaloshinskii-Moriya interaction by investigating singularities in the Loschmidt echo and the corresponding rate function after a…

Quantum Physics · Physics 2020-06-16 Stav Haldar , Saptarshi Roy , Titas Chanda , Aditi Sen De , Ujjwal Sen

In quantum dynamics, the Loschmidt amplitude is analogous to the partition function in the canonical ensemble. Zeros in the partition function indicate a phase transition, while the presence of zeros in the Loschmidt amplitude indicates a…

Quantum Physics · Physics 2025-04-10 Mingtao Xu , Wei Yi , De-Huan Cai

We investigate a class of one-dimensional, exactly solvable anisotropic XY spin-1/2 models in an alternating transverse magnetic field from an entanglement perspective. We find that a physically motivated Lie-algebraic generalized…

Statistical Mechanics · Physics 2017-08-23 Shusa Deng , Gerardo Ortiz , Lorenza Viola

Using the mapping of the Fokker-Planck description of classical stochastic dynamics onto a quantum Hamiltonian, we argue that a dynamical glass transition in the former must have a precise definition in terms of a quantum phase transition…

Statistical Mechanics · Physics 2010-08-10 Claudio Castelnovo , Claudio Chamon , David Sherrington

Non-analyticities in the logarithm of the Loschmidt echo, known as dynamical quantum phase transitions [DQPTs], are a recently introduced attempt to classify the myriad of possible phenomena which can occur in far from equilibrium closed…

Quantum Gases · Physics 2022-12-15 Colin Rylands , Emil A. Yuzbashyan , Victor Gurarie , Aidan Zabalo , Victor Galitski

At the heart of quantum technology development is the control of quantum systems at the level of individual quanta. Mathematically, this is realised through the study of Hamiltonians and the use of methods to solve the dynamics of quantum…

Quantum Physics · Physics 2022-10-24 Sofia Qvarfort , Igor Pikovski

We give a general introduction to quantum phase transitions in strongly-correlated electron systems. These transitions which occur at zero temperature when a non-thermal parameter $g$ like pressure, chemical composition or magnetic field is…

Strongly Correlated Electrons · Physics 2009-11-07 M. Lavagna

We propose an experimentally feasible scheme to achieve quantum computation based on a pair of orthogonal cyclic states. In this scheme, quantum gates can be implemented based on the total phase accumulated in cyclic evolutions. In…

Quantum Physics · Physics 2009-11-07 Shi-Liang Zhu , Z. D. Wang
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