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A highly anticipated use of quantum computers is the simulation of complex quantum systems including molecules and other many-body systems. One promising method involves directly applying a linear combination of unitaries (LCU) to…

Quantum Physics · Physics 2022-02-02 Richard Meister , Simon C. Benjamin , Earl T. Campbell

The limits of direct unitary transformation of many-fermion Hamiltonians are explored. Practical application of such transformations requires that effective many-body interactions be discarded over the course of a calculation. The…

Strongly Correlated Electrons · Physics 2010-03-15 Jonathan E. Moussa

The dynamical evolution of squeezing correlations in an ultracold Bose-Einstein distributed across two modes is investigated theoretically in the framework of the Bose-Hubbard model. It is shown that the eigenstates of the Hamiltonian do…

Quantum Gases · Physics 2015-05-18 C. Bodet , J. Estève , M. K. Oberthaler , T. Gasenzer

When can a quantum system of finite dimension be used to simulate another quantum system of finite dimension? What restricts the capacity of one system to simulate another? In this paper we complete the program of studying what simulations…

Quantum Physics · Physics 2009-11-10 Michael J. Bremner , Dave Bacon , Michael A. Nielsen

We develop a truncated Hamiltonian method to investigate the dynamics of the $(1+1)d~\phi^4$ theory following quantum quenches. The results are compared to two different semi-classical approaches, the self-consistent Gaussian approximation…

Statistical Mechanics · Physics 2022-01-12 D. Szász-Schagrin , I. Lovas , G. Takács

Simulation of quantum chemistry is expected to be a principal application of quantum computing. In quantum simulation, a complicated Hamiltonian describing the dynamics of a quantum system is decomposed into its constituent terms, where the…

Quantum Physics · Physics 2020-03-04 Yingkai Ouyang , David R. White , Earl T. Campbell

We study a variation of the Trotter-Suzuki decomposition, in which a Hamiltonian exponential is approximated by an ordered product of two-qubit operator exponentials such that the Trotter step size is enhanced for a small number of terms.…

Quantum Physics · Physics 2023-04-10 Finn Lasse Buessen , Dvira Segal , Ilia Khait

We study a class of self-adjoint operators defined on the direct sum of two Hilbert spaces: a finite dimensional one called sometimes a ``small subsystem'' and an infinite dimensional one -- a ``reservoir''. The operator, which we call a…

Mathematical Physics · Physics 2009-11-11 Jan Derezinski , Wojciech De Roeck

Starting from a general, microscopic fermion-to-boson mapping that preserves Hermitian conjugation, we discuss truncations of the boson Fock space basis. We give conditions under which the exact boson images of finite fermion operators are…

Nuclear Theory · Physics 2008-11-26 Calvin W. Johnson , Joseph N. Ginocchio

In the preceding Comment [1] it was claimed that the third-order Hamiltonian obtained in our original paper [2] is not Hermitian for general situations when considering time-dependence and the way of deriving the effective third-order…

Quantum Physics · Physics 2024-02-21 Wenjun Shao , Chunfeng Wu , Xun-Li Feng

We present a general method by which linear quantum Hamiltonian dynamics with exponentially many degrees of freedom is replaced by approximate classical nonlinear dynamics with the number of degrees of freedom (phase space dimensionality)…

Quantum Physics · Physics 2018-08-01 Jonathan Wurtz , Anatoli Polkovnikov , Dries Sels

We study the unitary dynamics and the thermalization properties of free-fermion-like Hamiltonians after a sudden quantum quench, extending the results of S. Ziraldo et al. [Phys. Rev. Lett. 109, 247205 (2012)]. With analytical and numerical…

Disordered Systems and Neural Networks · Physics 2013-02-22 Simone Ziraldo , Giuseppe E. Santoro

Multifractal dimensions allow for characterizing the localization properties of states in complex quantum systems. For ergodic states the finite-size versions of fractal dimensions converge to unity in the limit of large system size.…

Statistical Mechanics · Physics 2019-10-30 Arnd Bäcker , Masudul Haque , Ivan M. Khaymovich

The discretization approximation method commonly used to simulate the dynamics of quantum system coupled to the environment in continuum often suffers from the periodically partial recovery of initial state because of the effect of finite…

Quantum Physics · Physics 2025-05-07 H. T. Cui , Y. A. Yan , M. Qin , X. X. Yi

Hamiltonian Truncation Methods are a useful numerical tool to study strongly coupled QFTs. In this work we present a new method to compute the exact corrections, at any order, in the Hamiltonian Truncation approach presented by Rychkov et…

High Energy Physics - Theory · Physics 2016-05-25 J. Elias-Miro , M. Montull , M. Riembau

Stochastic methods offer an effective way to suppress coherent errors in quantum simulation. In particular, the randomized compilation protocol may reduce circuit depth by randomly sampling Hamiltonian terms rather than following the…

Quantum Physics · Physics 2026-05-15 Yu-Xia Wu , Yun-Zhuo Fan , Dan-Bo Zhang

In contrast to lattice systems where powerful numerical techniques such as matrix product state based methods are available to study the non-equilibrium dynamics, the non-equilibrium behaviour of continuum systems is much harder to…

Statistical Mechanics · Physics 2019-03-20 Tibor Rakovszky , Márton Mestyán , Mario Collura , Márton Kormos , Gábor Takács

The study of real-time dynamics of fermions remains one of the last frontiers beyond the reach of classical simulations and is key to our understanding of quantum behavior in chemistry and materials, with implications for quantum…

Quantum Gases · Physics 2025-11-05 Matteo D'Anna , Jannes Nys , Juan Carrasquilla

We describe a simple, efficient method for simulating Hamiltonian dynamics on a quantum computer by approximating the truncated Taylor series of the evolution operator. Our method can simulate the time evolution of a wide variety of…

Quantum Physics · Physics 2015-03-06 Dominic W. Berry , Andrew M. Childs , Richard Cleve , Robin Kothari , Rolando D. Somma

We show how discrete squeezed states in an $N^{2}$-dimensional phase space can be properly constructed out of the finite-dimensional context. Such discrete extensions are then applied to the framework of quantum tomography and quantum…

Quantum Physics · Physics 2011-11-09 Marcelo A. Marchiolli , Maurizio Ruzzi , Diogenes Galetti