- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Strong Coupling of a Single Photon to a Magnetic Vortex
摘要： Strong light-matter coupling means that cavity photons and other type of matter excitations are coherently exchanged. It is used to couple different qubits (matter) via a quantum bus (photons) or to communicate different type of excitations, e.g., transducing light into phonons or magnons. An unexplored, so far, interface is the coupling between light and topologically protected particle-like excitations as magnetic domain walls, skyrmions or vortices. Here, we show theoretically that a single photon living in a superconducting cavity can be strongly coupled to the gyrotropic mode of a magnetic vortex in a nanodisc. We combine numerical and analytical calculations for a superconducting coplanar waveguide resonator and different realizations of the nanodisc (materials and sizes). We show that, for enhancing the coupling, constrictions fabricated in the resonator are crucial, allowing to reach the strong coupling in CoFe discs of radius 200 ? 400 nm having resonance frequencies of few GHz. The strong coupling regime permits to coherently exchange a single photon and quanta of vortex gyration. Thus, our calculations show that the device proposed here serves as a transducer between photons and gyrating vortices, opening the way to complement superconducting qubits with topologically protected spin-excitations like vortices or skyrmions. We finish by discussing potential applications in quantum data processing based on the exploitation of the vortex as a short-wavelength magnon emitter.
关键词： cavity quantum electrodynamics,topological magnetism,coplanar waveguide resonators,nanoresonator,Magnetic vortex,light-matter interaction
更新于2025-09-23 15:19:57
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Gauge ambiguities imply Jaynes-Cummings physics remains valid in ultrastrong coupling QED
摘要： Ultrastrong-coupling between two-level systems and radiation is important for both fundamental and applied quantum electrodynamics (QED). Such regimes are identified by the breakdown of the rotating-wave approximation, which applied to the quantum Rabi model (QRM) yields the apparently less fundamental Jaynes-Cummings model (JCM). We show that when truncating the material system to two levels, each gauge gives a different description whose predictions vary significantly for ultrastrong-coupling. QRMs are obtained through specific gauge choices, but so too is a JCM without needing the rotating-wave approximation. Analysing a circuit QED setup, we find that this JCM provides more accurate predictions than the QRM for the ground state, and often for the first excited state as well. Thus, Jaynes-Cummings physics is not restricted to light-matter coupling below the ultrastrong limit. Among the many implications is that the system's ground state is not necessarily highly entangled, which is usually considered a hallmark of ultrastrong-coupling.
关键词： quantum Rabi model,circuit QED,gauge invariance,Jaynes-Cummings model,ultrastrong coupling,quantum electrodynamics
更新于2025-09-19 17:15:36
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Ehrenfest+R dynamics. I. A mixed quantum–classical electrodynamics simulation of spontaneous emission
摘要： The dynamics of an electronic system interacting with an electromagnetic field is investigated within mixed quantum–classical theory. Beyond the classical path approximation (where we ignore all feedback from the electronic system on the photon field), we consider all electron–photon interactions explicitly according to Ehrenfest (i.e., mean-field) dynamics and a set of coupled Maxwell–Liouville equations. Because Ehrenfest dynamics cannot capture certain quantum features of the photon field correctly, we propose a new Ehrenfest+R method that can recover (by construction) spontaneous emission while also distinguishing between electromagnetic fluctuations and coherent emission.
关键词： quantum electrodynamics,electromagnetic field,Ehrenfest dynamics,spontaneous emission,mixed quantum-classical theory
更新于2025-09-19 17:15:36
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[IEEE 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - Rome, Italy (2019.6.17-2019.6.20)] 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - Interaction between Microwave and Mesoscopic Circuits in Cavity-circuit Quantum Electrodynamics
摘要： Mesoscopic electric circuits can exhibit a large number of effects relevant to quantum mechanics, quantum electrodynamics and quantum statistics. The topic presented here can be identified as an analog of conventional cavity quantum electrodynamics, where the quantum objects are multilevel atoms and quantized optical fields (photons), namely, a theoretical subject called “cavity-circuit quantum electrodynamics”, where the atoms are replaced with quantum mesoscopic circuits, will be developed. We will study the quantum characteristics of the interaction between the quantum mesoscopic circuits and the quantized electromagnetic field at microwave frequencies. These issues include quantum entangled eigenstates of two coupled mesoscopic circuits, time evolution of the circuit energy quanta (governed by the time-dependent Schr?dinger equation) and entanglement transfer between external photons and mesoscopic circuit energy quanta. Since there is inevitable electromagnetic interaction such as mutual capacitance and inductance coupling between two neighboring circuits, the quantum effects resulting from the aforementioned quantized circuit coupling would unavoidably affect the relevant processes in quantum computing devices and hence they deserve consideration in some issues of quantum information.
关键词： Quantum computing,Microwave photons,Quantum entanglement,Mesoscopic circuits,Quantum electrodynamics
更新于2025-09-19 17:13:59
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Quantum stabilization of microcavity excitation in a coupled microcavitya??half-cavity system
摘要： We analyze the quantum dynamics of a two-level emitter in a resonant microcavity with optical feedback provided by a distant mirror (i.e., a half cavity) with a focus on stabilizing the emitter-microcavity subsystem. Our treatment is fully carried out in the framework of cavity quantum electrodynamics. Specifically, we focus on the dynamics of a perturbed subradiant state of the emitter-microcavity subsystem to ascertain its stability (existence of time oscillatory solutions around the candidate state) or lack thereof. In particular, we find conditions under which multiple feedback modes of the half cavity contribute to the stability, showing certain analogies with the Lang-Kobayashi equations, which describe a laser diode subject to classical optical feedback.
关键词： optical feedback,microcavity,Lang-Kobayashi equations,quantum dynamics,two-level emitter,cavity quantum electrodynamics,stability,subradiant state
更新于2025-09-19 17:13:59
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Dimer chains in waveguide quantum electrodynamics
摘要： We examine the propagation of single photons in periodic and disordered dimer chains coupled to one-dimensional chiral waveguides. Each dimer is composed of two dipole-coupled atoms. In the disordered setting, we separately treat two types of position disorder, namely in dimer length and in dimer separation. The focus of this study is to understand in what ways the interplay between dipole–dipole interactions and directionality of photon emission can impact the transport of single photons. Cold atoms trapped near optical fibers can serve as an experimentally realizable platform for the models that we consider.
关键词： Chiral quantum optics,Photon localization,Dipole–dipole interactions,Waveguide quantum electrodynamics,Position disorder
更新于2025-09-19 17:13:59
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Improving photon antibunching with two dipole-coupled atoms in whispering-gallery-mode microresonators
摘要： In the two-atom or multiatom system, the atoms can interact with each other through exchange of virtual photon. This kind of energy exchange is often referred as the dipole-dipole interaction (DDI). Here we consider this DDI system consisting of a pair of two-level atoms strongly coupled with a bimodal whispering-gallery-mode (WGM) microresonator which is driven by an external laser field. Our aim is to explore the photon correlation characteristics of the proposed architecture using realistic experimental parameter values. We compare in detail the quality of photon antibunching (i.e., the smallness of the second-order correlation function) from three involved configurations in cavity quantum electrodynamics (QED): (i) only one two-level atom, (ii) two far apart two-level atoms without DDI, and (iii) two DDI (dipole-coupled) two-level atoms are respectively coupled to the driven WGM microresonator through the evanescent field. We clearly show that the DDI between both atoms can distinctly enhance the photon antibunching even in the weak-coupling regime in configuration (iii) with feature-rich line shapes. We also find that the photon antibunching can be modulated by properly adjusting the atom-cavity coupling strength. In addition, we display that this strong photon antibunching is robust against the cooperative atomic decay. Our DDI-based cavity QED scheme may provide an alternative way to the construction of integrated on-chip single-photon sources.
关键词： photon antibunching,whispering-gallery-mode microresonators,single-photon sources,dipole-dipole interaction,cavity quantum electrodynamics
更新于2025-09-19 17:13:59
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The interplay of electron-photon and cavity-environment coupling on the electron transport through a quantum dot system
摘要： We theoretically investigate the characteristics of the electron transport through a two-dimensional a quantum dot system in the xy-plane coupled to a photon cavity and a photon reservoir, the environment. The electron-photon coupling, gγ, and the cavity-reservoir coupling, κ, are tuned to study the system in the weak, gγ ≤ κ, and the strong coupling regime, gγ > κ. An enhancement of current is both seen with increasing gγ and κ in the weak coupling regime for both x- and y-polarization of the photon field. This is a direct consequence of the Purcell effect. The current enhancement is due to the contribution of the photon replica states to the electron transport in which intraband transitions play an important role. The properties of the electron transport are drastically changed in the strong coupling regime with an x-polarized photon field in which the current is suppressed with increasing gγ, but it is still increasing with κ. This behavior of the current is related to the population of purely electronic states and depopulation of photon replica states.
关键词： Quantum master equation,Quantum Dot,Cavity-Quantum electrodynamics,Quantum transport,Purcell effect
更新于2025-09-16 10:30:52
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Fano resonance induced fast to slow light in a hybrid semiconductor quantum dot and metal nanoparticle system
摘要： We theoretically demonstrate the Fano resonance and the conversion from fast to slow light in a hybrid semiconductor quantum dot (SQDs)-metal nanoparticle (MNPs) with cavity quantum electrodynamics treatment. The absorption spectra of the weak probe field exhibit a series of asymmetric Fano line shapes and their related optical propagation properties, such as fast and slow light effects, are investigated based on the hybrid system for suitable parametric regimes. Further, the transparency windows (i.e. the absorption dip approaches zero) in the probe absorption spectra are accompanied by the rapid steep dispersion of the Fano resonance profile, which promises the slow or fast light effect, and even tunable fast-to-slow light propagation (or vice versa) can be achieved by controlling different parameter regimes. Therefore the investigation may indicate promising applications in quantum information processing based on the hybrid SQD-MNP system.
关键词： semiconductor quantum dots,cavity quantum electrodynamics (C-QED),metal nanoparticles,fast to slow light,Fano resonance
更新于2025-09-16 10:30:52
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Quantum light-matter interaction and controlled phonon scattering in a photonic Fano cavity
摘要： By using a Fano resonance as one of the mirrors in an optical cavity, a localized mode with a highly asymmetric line shape is obtained. Placing a single quantum emitter inside the cavity leads to a new regime of cavity quantum electrodynamics, where the light-matter interaction dynamics is fundamentally different from that observed in a conventional cavity with Lorenztian line shape. Furthermore, when the vibrational dynamics of the emitter is taken into account, an intricate phonon-photon interplay arises, and the optical interference induced by the Fano mirror signi?cantly alters the leakage of energy into vibrational modes. We demonstrate that this control mechanism improves the maximum attainable indistinguishability of emitted photons, as compared to an equivalent cavity with a conventional mirror.
关键词： phonon scattering,Quantum light-matter interaction,Fano cavity,photonic Fano cavity,cavity quantum electrodynamics
更新于2025-09-12 10:27:22