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Mean-field molecular dynamics based on path integrals is used to approximate canonical quantum observables for particle systems consisting of nuclei and electrons. A computational bottleneck is the sampling from the Gibbs density of the…

Numerical Analysis · Mathematics 2023-11-30 Xin Huang , Petr Plechac , Mattias Sandberg , Anders Szepessy

We construct a simple translationally invariant, nearest-neighbor Hamiltonian on a chain of 10-dimensional qudits that makes it possible to realize universal quantum computing without any external control during the computational process.…

Quantum Physics · Physics 2009-11-13 Daniel Nagaj , Pawel Wocjan

We study classical Hamiltonian systems in which the intrinsic proper time evolution parameter is related through a probability distribution to the physical time, which is assumed to be discrete. - This is motivated by the ``timeless''…

General Relativity and Quantum Cosmology · Physics 2015-06-25 H. -T. Elze

We show that quantum optical systems preserving the total number of excitations admit a simple classification of possible resonant transitions (including effective), which can be classified by analizying the free Hamiltonian and the…

Quantum Physics · Physics 2007-05-23 A. B. Klimov , I. Sainz

Without wasting time and effort on philosophical justifications and implications, we write down the conditions for the Hamiltonian of a quantum system for rendering it mathematically equivalent to a deterministic system. These are the…

Quantum Physics · Physics 2020-06-09 Gerard t Hooft

Time-driven quantum systems are important in many different fields of physics like cold atoms, solid state, optics, etc. Many of their properties are encoded in the time evolution operator which is calculated by using a time-ordered product…

These lecture notes introduce some simple effective Hamiltonians (also known as semi-empirical models) that have widespread applications to solid state and molecular systems. They are aimed as an introduction to a beginning graduate…

Chemical Physics · Physics 2016-09-08 B. J. Powell

Hamiltonian learning is an important procedure in quantum system identification, calibration, and successful operation of quantum computers. Through queries to the quantum system, this procedure seeks to obtain the parameters of a given…

Quantum Physics · Physics 2023-08-25 Arkopal Dutt , Edwin Pednault , Chai Wah Wu , Sarah Sheldon , John Smolin , Lev Bishop , Isaac L. Chuang

In the variational approach to quantum statistics, a smearing formula describes efficiently the consequences of quantum fluctuations upon an interaction potential. The result is an effective classical potential from which the partition…

Quantum Physics · Physics 2008-11-26 Hagen Kleinert , Werner Kuerzinger , Axel Pelster

We derive out a complete series expression of Hamiltonian eigenvalues without any approximation and cut in the general quantum systems based on Wang's formal framework \cite{wang1}. In particular, we then propose a calculating approach of…

Quantum Physics · Physics 2009-11-12 Zhou Li , An Min Wang

We propose a hybrid quantum-classical algorithm for approximating the ground state and ground state energy of a Hamiltonian. Once the Ansatz has been decided, the quantum part of the algorithm involves the calculation of two overlap…

Quantum Physics · Physics 2020-10-13 Kishor Bharti

We address the issue of coupling variables which are essentially classical to variables that are quantum. Two approaches are discussed. In the first (based on collaborative work with L.Di\'osi), continuous quantum measurement theory is used…

General Relativity and Quantum Cosmology · Physics 2009-10-31 J. J. Halliwell

We reelaborate on a general method for obtaining effective Hamiltonians that describe different nonlinear optical processes. The method exploits the existence of a nonlinear deformation of the su(2) algebra that arises as the dynamical…

Quantum Physics · Physics 2009-11-07 A. B. Klimov , J. L. Romero , J. Delgado , L. L. Sanchez-Soto

A Hamiltonian approach to the solution of the Vlasov-Poisson equations has been developed. Based on a nonlinear canonical transformation, the rapidly oscillating terms in the original Hamiltonian are transformed away, yielding a new…

Accelerator Physics · Physics 2008-11-26 Stephan I. Tzenov , Ronald C. Davidson

We derive the effective Hamiltonian $H - \mu N$ for open quantum systems with varying particle number from first principles within the framework of non-relativistic quantum statistical mechanics. We prove that under physically motivated…

Mathematical Physics · Physics 2026-02-26 Benedikt M. Reible , Luigi Delle Site

In the context of a two-parameter $(\alpha, \beta)$ deformation of the canonical commutation relation leading to nonzero minimal uncertainties in both position and momentum, the harmonic oscillator spectrum and eigenvectors are determined…

Mathematical Physics · Physics 2008-11-26 C. Quesne , V. M. Tkachuk

Quantum computing has recently been emerging in theoretical chemistry as a realistic avenue meant to offer computational speedup to challenging eigenproblems in the context of strongly-correlated molecular systems or extended materials.…

Quantum Physics · Physics 2026-03-05 Joachim Knapik , Bruno Senjean , Benjamin Lasorne , Yohann Scribano

We demonstrate that the dynamics of an open quantum system can be calculated efficiently and with predefined error, provided a basis exists in which the system-environment interactions are local and hence obey the Lieb-Robinson bound. We…

Quantum Physics · Physics 2015-03-19 Giulia Gualdi , Christiane P. Koch

Complete characterization of states and processes that occur within quantum devices is crucial for understanding and testing their potential to outperform classical technologies for communications and computing. However, solving this task…

Quantum Physics · Physics 2020-05-07 E. S. Tiunov , V. V. Tiunova , A. E. Ulanov , A. I. Lvovsky , A. K. Fedorov

Simple constructions and protocols are demonstrated to allow the implementation of universal quantum computation on an arbitrarily large quantum system by controlling a fixed number of spins, vastly reducing the engineering requirements in…

Quantum Physics · Physics 2009-04-23 Alastair Kay