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Large single-atom cooperativity in quantum systems is important for quantum information processing. Here, we propose to exponentially enhance the single-atom cooperativity parameter by exploiting the strongly localized effect of modes in…

Quantum Physics · Physics 2025-09-08 Qian Bin , Ying Wu , Jin-Hua Gao , Aixi Chen , Franco Nori , Xin-You Lü

The strong-coupling regime of cavity-quantum-electrodynamics (cQED) represents light-matter interaction at the fully quantum level. Adding a single photon shifts the resonance frequencies, a profound nonlinearity. cQED is a test-bed of…

We propose a scheme for generating a high-purity single photon on the basis of cavity quantum electrodynamics (QED). This scheme employs a four-level system including two excited states, two ground states, and two driving lasers; this…

Quantum Physics · Physics 2025-03-12 Seigo Kikura , Rui Asaoka , Masato Koashi , Yuuki Tokunaga

We introduce a simple scheme to efficiently compute photon exchange-correlation contributions due to the coupling to transversal photons as formulated in the newly developed quantum-electrodynamical density functional theory (QEDFT). Our…

Quantum Physics · Physics 2018-04-16 Johannes Flick , Christian Schäfer , Michael Ruggenthaler , Heiko Appel , Angel Rubio

Cavity quantum electrodynamics (QED) generalizations of time-dependent (TD) density functional theory (DFT) and equation-of-motion (EOM) coupled-cluster (CC) theory are used to model small molecules strongly coupled to optical cavity modes.…

Chemical Physics · Physics 2023-07-19 Marcus D. Liebenthal , Nam Vu , A. Eugene DePrince

Since the photon box gedanken experiments of several of the founding fathers of modern physics, considerable progress has been made in differentiating the quantum and classical worlds. In this pursuit, the cavity as an open quantum system…

Quantum Physics · Physics 2014-12-02 Nathan D. Poulin

Light-matter interaction with squeezed vacuum has received much interest for the ability to enhance the native interaction strength between an atom and a photon with a reservoir assumed to have an infinite bandwidth. Here, we study a model…

We investigate the time evolution of the photon-detection probability at various output ports of an all-fiber coupled cavity-quantum-electrodynamics (cavity-QED) system. The setup consists of two atoms trapped separately in the field of two…

Quantum Physics · Physics 2019-08-23 Ross Shillito , Nikolett Német , Scott Parkins

The reduced density matrix (RDM) plays a key role in quantum entanglement and measurement, as it allows the extraction of almost all physical quantities related to the reduced degrees of freedom. However, restricted by the degrees of…

Quantum Physics · Physics 2025-03-27 Bin-Bin Mao , Yi-Ming Ding , Zhe Wang , Shijie Hu , Zheng Yan

A cavity QED system is analyzed which duplicates the dynamics of a two-level atom in free space interacting exclusively with broadband squeezed light. We consider atoms in a three or four-level Lambda-configuration coupled to a high-finesse…

Quantum Physics · Physics 2009-11-07 Stephen Clark , Scott Parkins

We present a systematic study of the properties of systems composed of $N$ two-level quantum emitters coupled to a single cavity mode, for light-matter interaction strengths ranging from the weak to the ultrastrong and deep-strong coupling…

Phenomenological approaches to photon loss have long been the workhorse of cavity-QED, but prove inadequate in the presence of sufficiently broadband light-matter interactions. We present a rigorous and ab initio derivation of a quantum…

Quantum Physics · Physics 2025-08-01 Chris Gustin , Juanjuan Ren , Sebastian Franke , Stephen Hughes

We propose a way of obtaining effective low energy Hubbard-like model Hamiltonians from ab initio Quantum Monte Carlo calculations for molecular and extended systems. The Hamiltonian parameters are fit to best match the ab initio two-body…

Strongly Correlated Electrons · Physics 2015-08-06 Hitesh J. Changlani , Huihuo Zheng , Lucas K. Wagner

The technique of quantum electrodynamics (QED) calculations of energy levels in the helium atom is reviewed. The calculations start with the solution of the Schr\"odinger equation and account for relativistic and QED effects by perturbation…

Atomic Physics · Physics 2021-07-14 Vladimir A. Yerokhin , Vojtech Patkos , Krzysztof Pachucki

In this work we give a comprehensive derivation of an exact and numerically feasible method to perform ab-initio calculations of quantum particles interacting with a quantized electromagnetic field. We present a hierachy of…

The field of cavity quantum electrodynamics (QED) has seen a recent resurgence of interest in few- and many-body physics owing to the realization that the breaking of symmetries and the presence of disorder can give rise to entirely new…

In this work, we present a stochastic variational calculation (SVM) of energies and wave functions of few particle systems coupled to quantum fields in cavity QED. The light-matter coupled system is described by the Pauli-Fierz Hamiltonian.…

Mesoscale and Nanoscale Physics · Physics 2022-01-05 Alexander Ahrens , Chenhang Huang , Matt Beutel , Cody Covington , Kalman Varga

Collective light-matter interactions have been used to control chemistry and energy transfer, yet accessible approaches that combine ab initio methodology with large many-body quantum optical systems are missing due to the fast increase in…

Quantum Physics · Physics 2024-08-27 Frieder Lindel , Dominik Lentrodt , Stefan Yoshi Buhmann , Christian Schäfer

Studies of ultracold atoms in optical lattices link various disciplines, providing a playground where fundamental quantum many-body concepts, formulated in condensed-matter physics, can be tested in much better controllable atomic systems,…

Quantum Physics · Physics 2007-11-22 Igor. B. Mekhov , Christoph Maschler , Helmut Ritsch

Cavity quantum electrodynamics (cQED) harnesses light-matter interactions to produce nonclassical light states. However, a fundamental challenge lies in simultaneously achieving Purcell enhancement and tailored wavefront control within a…