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We develop a systematic framework for the quantum and thermal properties of a Klein-Gordon scalar field subject to an inverted harmonic potential $-{1\over2} m^2\omega^2 x^2$. Starting from a non-Hermitian momentum substitution $P \to P -…

Quantum Physics · Physics 2026-05-29 Kevin Hernández

Cosmological perturbation theory is a powerful tool to predict the statistics of large-scale structure in the weakly non-linear regime, but even at 1-loop order it results in computationally expensive mode-coupling integrals. Here we…

Cosmology and Nongalactic Astrophysics · Physics 2017-02-17 Xiao Fang , Jonathan A. Blazek , Joseph E. McEwen , Christopher M. Hirata

Squeezed states of the harmonic oscillator are a common resource in applications of quantum technology. If the noise is suppressed in a nonlinear combination of quadrature operators below threshold for all possible up-to-quadratic…

Quantum Physics · Physics 2023-06-13 Vojtěch Kala , Petr Marek , Radim Filip

We solve explicitly the two-dimensional harmonic oscillator and the harmonic oscillator in a background magnetic field in noncommutative phase-space without making use of any type of representation. A key observation that we make is that…

High Energy Physics - Theory · Physics 2009-08-03 Joseph Ben Geloun , Sunandan Gangopadhyay , Frederik G Scholtz

Solvability of the ubiquitous quantum harmonic oscillator relies on a spectrum generating osp(1|2) superconformal symmetry. We study the problem of constructing all quantum mechanical models with a hidden osp(1|2) symmetry on a given space…

High Energy Physics - Theory · Physics 2017-12-20 R. Bonezzi , O. Corradini , E. Latini , A. Waldron

A broadband multidimensional variational measurement allows overcoming the Standard Quantum Limit (SQL) of a classical mechanical force detection for a mechanical oscillator. In this measurement quantum back action, which perturbs the…

Non-Markovian quantum state diffusion (NMQSD) is a non-relativistic but otherwise exact theory which expresses the reduced density matrix of an arbitrary subsystem, interacting linearly with an uncoupled harmonic oscillator bath, as an…

Quantum Physics · Physics 2007-05-23 Joshua Wilkie , Ray Ng

We generalize the oscillator model of a particle interacting with a thermal reservoir by introducing arbitrary nonlinear couplings in the particle coordinates.The equilibrium positions of the heat bath oscillators are promoted to space-time…

High Energy Physics - Theory · Physics 2009-10-28 F. Illuminati , M. Patriarca , P. Sodano

We notice that PT symmetric non-Hermitian one dimensional simple Harmonic Oscillator under simultaneous transformation of co-ordinate and momentum with proper choice of positive oscillating frequency can reflect negative spectrum with well…

Quantum Physics · Physics 2018-03-19 Biswanath Rath

At high temperature the infrared modes of a weakly coupled quantum field theory can be treated nonperturbatively in real time using the classical field approximation. We use this to introduce a nonperturbative approach to the calculation of…

High Energy Physics - Phenomenology · Physics 2009-11-07 Gert Aarts

Through a set of generators that preserves the hermiticity and trace of density matrices, we analyze the damping of harmonic oscillator in open quantum systems into four modes, distinguished by their specific effects on the covariance…

Quantum Physics · Physics 2019-04-23 B. A. Tay

Wave packets for the Quantum Non-Linear Oscillator are considered in the Generalized Coherent State framerwork. To first order in the non-linearity parameter the Coherent State behaves very similarly to its classical counterpart. The…

Quantum Physics · Physics 2012-07-12 Subir Ghosh

In this paper, we study the statistical mechanics within the polymer quantization framework in the semiclassical regime. We apply a non-canonical transformation to the phase space variables. Then, we use this non-canonical transformation to…

General Relativity and Quantum Cosmology · Physics 2025-11-24 Kourosh Nozari , Hamed Ramezani

Phase-space representations based on coherent states (P, Q, Wigner) have been successful in the creation of stochastic differential equations (SDEs) for the efficient stochastic simulation of high dimensional quantum systems. However many…

Quantum Physics · Physics 2015-05-14 M. R. Hush , A. R. R. Carvalho , J. J. Hope

Classical Density Functional Theory (DFT) is a statistical-mechanical framework to analyze fluids, which accounts for nanoscale fluid inhomogeneities and non-local intermolecular interactions. DFT can be applied to a wide range of…

Computational Engineering, Finance, and Science · Computer Science 2017-02-07 Andreas Nold , Benjamin D. Goddard , Peter Yatsyshin , Nikos Savva , Serafim Kalliadasis

We present a study of photon statistics associated with high-order harmonic generation (HHG) involving one-mode and intermodal correlations of the high harmonic photons. The aim of the paper is to give insight into the nonclassical…

Quantum Physics · Physics 2021-09-15 Ákos Gombkötő , Péter Földi , Sándor Varró

For a weakly coupled quantum field at high temperature the classical approximation offers a possibility to gain insight into nonperturbative real-time dynamics. I use this to present a nonperturbative approach to the computation of spectral…

High Energy Physics - Lattice · Physics 2015-06-25 Gert Aarts

Intracavity and external third order correlations in the damped nondegenerate parametric oscillator are calculated for quantum mechanics and stochastic electrodynamics (SED), a semiclassical theory. The two theories yield greatly different…

Quantum Physics · Physics 2009-11-06 D. T. Pope , P. D. Drummond , W. J. Munro

We develop and analyze a fault-tolerant quantum algorithm for computing $n$-th order response properties necessary for analysis of non-linear spectroscopies of molecular and condensed phase systems. We use a semi-classical description in…

Quantum Physics · Physics 2024-04-23 Tyler Kharazi , Torin F. Stetina , Liwen Ko , Guang Hao Low , K. Birgitta Whaley

The von Neumann trace form of quantum statistical mechanics is transformed to an integral over classical phase space. Formally exact expressions for the resultant position-momentum commutation function are given. A loop expansion for wave…

Quantum Physics · Physics 2018-11-07 Phil Attard