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We derive expressions for the zeroth and the first three spectral moment sum rules for the retarded Green's function and for the zeroth and the first spectral moment sum rules for the retarded self-energy of the inhomogeneous Bose-Hubbard…

Quantum Gases · Physics 2015-01-12 J. K. Freericks , V. Turkowski , H. R. Krishnamurthy , M. Knap

Relevant metrological scenarios involve the simultaneous estimation of multiple parameters. The fundamental ingredient to achieve quantum-enhanced performances is based on the use of appropriately tailored quantum probes. However, reaching…

A fixed time-step variational integrator cannot preserve momentum, energy, and symplectic form simultaneously for nonintegrable systems. This barrier can be overcome by treating time as a discrete dynamic variable and deriving adaptive…

Numerical Analysis · Mathematics 2022-08-17 Harsh Sharma , Jeff Borggaard , Mayuresh Patil , Craig Woolsey

Quantum transition amplitudes are formulated for a model system with local internal time, using path integrals. The amplitudes are shown to be more regular near a turning point of internal time than could be expected based on existing…

General Relativity and Quantum Cosmology · Physics 2017-12-19 M. M. Amaral , Martin Bojowald

Accurate computation of the Green's function is crucial for connecting experimental observations to the underlying quantum states. A major challenge in evaluating the Green's function in the time domain lies in the efficient simulation of…

Quantum Physics · Physics 2025-09-12 Lingyun Wan , Jie Liu , Jinlong Yang

The equilibration of two coupled reservoirs is studied using a Green function approach which is suitable for future development with the closed time path method. The problem is solved in two parameterizations, in order to demonstrate the…

High Energy Physics - Phenomenology · Physics 2009-11-07 Mark Burgess , Margaret Carrington , Gabor Kunstatter

The retardation and temperature effects in two-body collisions are studied. The collision integral with retardation effects is obtained on the base of the Kadanoff- Baym equations for Green functions in a form with allowance for reaching…

Nuclear Theory · Physics 2007-05-23 V. A. Plujko , O. M. Gorbachenko , M. O. Kavatsyuk

We present a symmetry-enabled direct quantum protocol for computing many-body Green's functions, a central tool for studying strongly correlated quantum systems. Our protocol relies only on native time evolution and straightforward…

Quantum Physics · Physics 2026-03-03 Changhao Yi , Cunlu Zhou

We investigate the possibility to assist the numerically ill-posed calculation of spectral properties of interacting quantum systems in thermal equilibrium by extending the imaginary-time simulation to a finite Schwinger-Keldysh contour.…

Strongly Correlated Electrons · Physics 2013-02-25 Andreas Dirks , Martin Eckstein , Thomas Pruschke , Philipp Werner

In this article, we present a concise and self-contained introduction to nonequilibrium statistical mechanics with quantum field theory by considering an ensemble of interacting identical bosons or fermions as an example. Readers are…

Statistical Mechanics · Physics 2014-11-20 Takafumi Kita

We perform a perturbative analysis for the nonequilibrium Green functions of the spinless Falicov-Kimball model in the presence of an arbitrary external time-dependent but spatially uniform electric field. The conduction electron…

Strongly Correlated Electrons · Physics 2009-11-11 V. Turkowski , J. K. Freericks

Fast and reliable manipulation with qubits is fundamental for any quantum technology. The implementation of these manipulations in physical systems is the focus of studies involving optimal control theory. Realistic physical devices are…

Quantum Physics · Physics 2025-03-28 Haoran Sun , Michael Galperin

Computational efficiency demands discretised, hierarchically organised, and individually adaptive time-step sizes (known as the block-step scheme) for the time integration of N-body models. However, most existing N-body codes adapt…

Instrumentation and Methods for Astrophysics · Physics 2017-09-20 Walter Dehnen

We examine several numerical techniques for the calculation of the dynamics of quantum systems. In particular, we single out an iterative method which is based on expanding the time evolution operator into a finite series of Chebyshev…

Strongly Correlated Electrons · Physics 2015-05-13 Holger Fehske , Jens Schleede , Gerald Schubert , Gerhard Wellein , Vladimir S. Filinov , Alan R. Bishop

We present an algorithm to compute Green's functions on quantum computers for interacting electron systems, which is a challenging task on conventional computers. It uses a continued fraction representation based on the Lanczos method,…

Quantum Physics · Physics 2022-12-07 Francois Jamet , Abhishek Agarwal , Ivan Rungger

The dynamical behaviour of many-body systems is often richer than what can be anticipated from their static properties. Here we show that in closed quantum systems this becomes evident by considering time-integrated observables as order…

Statistical Mechanics · Physics 2013-06-14 James M. Hickey , Sam Genway , Igor Lesanovsky , Juan P. Garrahan

For many quantum systems intended for information processing, one detects the logical state of a qubit by integrating a continuously observed quantity over time. For example, ion and atom qubits are typically measured by driving a cycling…

Quantum Physics · Physics 2023-10-03 Shawn Geller , Daniel C. Cole , Scott Glancy , Emanuel Knill

Bayesian estimation approaches, which are capable of combining the information of experimental data from different likelihood functions to achieve high precisions, have been widely used in phase estimation via introducing a controllable…

Quantum Physics · Physics 2021-07-02 Yuxiang Qiu , Min Zhuang , Jiahao Huang , Chaohong Lee

I review the way the many-body Green functions are used to renormalize the perturbation theory of correlated fermions. The Green functions are introduced to implement systematically dynamical corrections to the static mean-field theory. The…

Strongly Correlated Electrons · Physics 2021-09-21 Václav Janiš

This paper introduces an adaptive time splitting technique for the solution of stiff evolutionary PDEs that guarantees an effective error control of the simulation, independent of the fastest physical time scale for highly unsteady…

Numerical Analysis · Mathematics 2012-04-10 Stéphane Descombes , Max Duarte , Thierry Dumont , Violaine Louvet , Marc Massot