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We report an efficient quantum algorithm for estimating the local density of states (LDOS) on a quantum computer. The LDOS describes the redistribution of energy levels of a quantum system under the influence of a perturbation. Sometimes…

Quantum Physics · Physics 2009-11-10 Joseph Emerson , Seth Lloyd , David Poulin , David Cory

We describe a scalable stochastic method for the experimental measurement of generalized fidelities characterizing the accuracy of the implementation of a coherent quantum transformation. The method is based on the motion reversal of random…

Quantum Physics · Physics 2009-11-11 Joseph Emerson , Robert Alicki , Karol Zyczkowski

We introduce a complex-extended continuum level density and apply it to one-dimensional scattering problems involving tunneling through finite-range potentials. We show that the real part of the density is proportional to a real "time…

Quantum Physics · Physics 2020-07-10 Pavel Stránský , Milan Šindelka , Michal Kloc , Pavel Cejnar

Some theorems on derivatives of the Coulomb density functional with respect to the coupling constant $\lambda$ are given. Consider an electron density $n_{GS}({\bf r})$ given by a ground state. A model Fermion system with the reduced…

Statistical Mechanics · Physics 2015-05-20 Koichi Kusakabe , Isao Maruyama

Understanding the thermodynamic properties of many-body quantum systems and their emergence from microscopic laws is a topic of great significance due to its profound fundamental implications and extensive practical applications. Recent…

Quantum Physics · Physics 2024-09-05 Antonio Palamara , Francesco Plastina , Antonello Sindona , Irene D'Amico

High-fidelity qubit readout is a fundamental requirement for practical quantum computing systems. In this work, we investigate methods to enhance the measurement fidelity of flux qubits via a quantum flux parametron-mediated readout scheme.…

Quantum Physics · Physics 2026-03-27 Yanjun Ji , Susanna Kirchhoff , Frank K. Wilhelm

Transition-metal centers are the active sites for many biological and inorganic chemical reactions. Notwithstanding this central importance, density-functional theory calculations based on generalized-gradient approximations often fail to…

Soft Condensed Matter · Physics 2009-11-11 Heather J. Kulik , Matteo Cococcioni , Damian A. Scherlis , Nicola Marzari

The fidelity per site between two ground states of a quantum lattice system corresponding to different values of the control parameter defines a surface embedded in a Euclidean space. The Gaussian curvature naturally quantifies quantum…

Statistical Mechanics · Physics 2007-11-30 Huan-Qiang Zhou , Jian-Hui Zhao , Hong-Lei Wang , Bo Li

An approximate analytical scheme of the dynamical mean field theory (DMFT) is developed for the description of the electron (ion) lattice systems with Hubbard correlations within the asymmetric Hubbard model where the chemical potentials…

Strongly Correlated Electrons · Physics 2009-11-11 Ihor V. Stasyuk , Orest B. Hera

We study fidelity and fidelity susceptibility by addition of entanglement of entropy in the one-dimensional quantum compass model in a transverse magnetic field numerically. The whole four recognized gapped regions in the ground state phase…

Strongly Correlated Electrons · Physics 2014-06-13 Mostafa Motamedifar , Somayyeh Nemati , Saeed Mahdavifar , Saber Farjami Shayesteh

Two electrons at the threshold of ionization represent a severe test case for electronic structure theory. A pseudospectral method yields a very accurate density of the two-electron ion with nuclear charge close to the critical value.…

Chemical Physics · Physics 2014-08-12 Paul E. Grabowski , Kieron Burke

We discuss a numerical analysis employing the density of partition function zeroes which permits effective distinction between phase transitions of first and second order, elucidates crossover between such phase transitions and gives a new…

Statistical Mechanics · Physics 2007-05-23 Wolfhard Janke , Ralph Kenna

We show how the use of variational states to approximate the ground state of a system can be employed to study a multi-mode Dicke model. One of the main contributions of this work is the introduction of a not very commonly used quantity,…

Quantum Physics · Physics 2020-06-19 L. F. Quezada , E. Nahmad-Achar

We propose an analytical model for the accurate calculation of size and density dependent quantum oscillations in thermodynamic and transport properties of confined and degenerate non-interacting Fermi gases. We provide a universal,…

Quantum Gases · Physics 2018-09-11 Alhun Aydin , Altug Sisman

The time evolution of probability density, the ground-state fidelity and the entanglement of a Bose-Fermi mixture in a 1D double well potential, are studied through the two mode approximation. We found that the behaviour of the quantum…

Quantum Physics · Physics 2022-08-23 R. Avella , J. Nisperuza , JP Rubio , D. Grajales

We study localization properties of continuously monitored dynamics and associated measurement-induced phase transitions in disordered quantum many-body systems on the basis of the quantum trajectory approach. By calculating the fidelity…

Statistical Mechanics · Physics 2023-06-09 Kazuki Yamamoto , Ryusuke Hamazaki

We study both static and transport properties of model quantum dots, employing density functional theory as well as (numerically) exact methods. For the lattice model under consideration the accuracy of the local-density approximation…

Mesoscale and Nanoscale Physics · Physics 2011-04-11 S. Schenk , P. Schwab , M. Dzierzawa , U. Eckern

We study slightly generalized quantum fidelity susceptibilities where the differential change in the fidelity is measured with respect to a different term than the one used for driving the system towards a quantum phase transition. As a…

Strongly Correlated Electrons · Physics 2013-04-30 Mischa Thesberg , Erik Sorensen

In the present work, we introduce a Self-Consistent Density-Functional Embedding technique, which leaves the realm of standard energy-functional approaches in Density Functional Theory and targets directly the density-to-potential mapping…

Computational Physics · Physics 2019-07-17 Uliana Mordovina , Teresa E. Reinhard , Iris Theophilou , Heiko Appel , Angel Rubio

In this paper we analyze the ground state phase diagram of a class of fermionic Hamiltonians by looking at the fidelity of ground states corresponding to slightly different Hamiltonian parameters. The Hamiltonians under investigation can be…

Quantum Physics · Physics 2009-11-13 M. Cozzini , P. Giorda , P. Zanardi