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DC measurement of dressed states in a coupled 100?GHz resonator system using a single quasiparticle transistor as a sensitive microwave detector
摘要： We report on the on-chip detection of microwaves in the frequency range around 100 GHz. For the purpose of detection, we employ a discrete transport channel triggered in a superconducting single-electron transistor by photon-assisted tunneling of quasiparticles. The technique is applied to observe the spectrum of the dressed states of a model circuit quantum electrodynamics system consisting of a superconducting coplanar resonator coupled to a Josephson oscillator. The dressed states appear as typical resonance anticrossing exhibiting, in our case, an expectedly wide frequency splitting corresponding to the Jaynes–Cummings coupling strength, g=p (cid:2) 10 GHz. Due to the high decay rate, c (cid:2) 20–40 GHz, in the very transparent Josephson junctions used, the strong coupling limit, g (cid:3) c, which is required for qubit operation, is not achieved, and the photon population in the resonator is low, hni < 1. Remarkably, the continuous readout of the low population states demonstrates the high microwave sensitivity of the detector.
关键词： photon-assisted tunneling,dressed states,superconducting single-electron transistor,circuit quantum electrodynamics,microwave detection
更新于2025-09-12 10:27:22
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Normal-mode splitting in coupled high-Q microwave cavities
摘要： Three-dimensional radio frequency cavities demonstrate excellent frequency selectivity and, as such, are known for their use in RF ?lters. These cavities have potential applications in quantum information science, precision displacement metrology, and quantum electrodynamics. Additionally, coupled cavities that form a spectral doublet allow for parametric gain when incorporating mechanical elements. Here, we investigate normal-mode splitting in a pair of quarter-wave stub microwave cavities at room temperature and cryogenic environments in order to identify coupling mechanics for normal and superconducting systems. Superconducting quarter-wave stub cavities with a resonant frequency of 10 GHz are made from reactor-grade niobium and exhibit Q ranging from 105 to 109. We varied cavity-to-cavity coupling to observe several normal-mode splittings of increasing peak separation until we observed a mode crossing. The minimum observed peak separation was 7 MHz for room temperature tests and 200 kHz for cryogenic tests. We also report on values of an intrinsic quality factor for the tuning cavity as a dielectric rod is translated along its symmetry axis. The realization of coupled superconducting radio frequency (SRF) cavities of this type is a necessary step toward implementation of parametric SRF-mechanical gain.
关键词： normal-mode splitting,superconducting radio frequency cavities,quantum electrodynamics,parametric gain,high-Q microwave cavities
更新于2025-09-12 10:27:22
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Properties of quantum dots coupled to plasmons and optical cavities
摘要： Quantum electrodynamics is rapidly finding a set of new applications in thresholdless lasing, photochemistry, and quantum entanglement due to the development of sophisticated patterning techniques to couple nanoscale photonic emitters with photonic and plasmonic cavities. Colloidal and epitaxial semiconductor nanocrystals or quantum dots (QDs) are promising candidates for emitters within these architectures but are dramatically less explored in this role than are molecular emitters. This perspective reviews the basic physics of emitter-cavity coupling in the weak-to-strong coupling regimes, describes common architectures for these systems, and lists possible applications (in particular, photochemistry), with a focus on the advantages and issues associated with using QDs as the emitters.
关键词： plasmonic cavities,photochemistry,quantum electrodynamics,quantum dots,photonic cavities
更新于2025-09-11 14:15:04
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AIP Conference Proceedings [AIP Publishing PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON ADVANCES AND APPLICATIONS IN PLASMA PHYSICS (AAPP 2019) - St. Petersburg, Russia (18–20 September 2019)] PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON ADVANCES AND APPLICATIONS IN PLASMA PHYSICS (AAPP 2019) - Resonant laser-assisted process of the electron-positron pairs annihilation and production
摘要： A resonant laser-assisted process of the electron-positron pairs annihilation and production is studied theoretically. The second order in fine structure constant process in the laser field transforms into two consistent processes of first order in the fine structure constant: laser-assisted annihilation of initial electron-positron pair into intermediate photon and laser-assisted production of final electron-positron pair by intermediate photon under resonant conditions when virtual photon becomes real. It is demonstrated that the resonant conditions for initial pair include the excess of certain combination of the electron and positron energies over threshold energy and narrow angle between momenta of electron and positron. The same holds true for the final pair. Also, final positron emission angle can vary from zero to some maximum value. It is shown that energies of the final particles depend on this angle and can take from one to two values. A resonant differential cross section of the studied process is obtained. It is shown that the resonant differential cross section can significantly exceed the corresponding cross section without an external field (Bhabha cross section). The project calculations may be experimentally verified by the scientific facilities of pulsed laser radiation (SLAC, FAIR, XFEL, ELI, XCELS).
关键词： electron-positron pairs,annihilation,laser field,production,quantum electrodynamics,resonant laser-assisted process,resonant differential cross section
更新于2025-09-11 14:15:04
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Multiple colliding laser pulses as a basis for studying high-field high-energy physics
摘要： Apart from maximizing the strength of optical electromagnetic fields achievable at high-intensity laser facilities, the collision of several phase-matched laser pulses has been identified theoretically as a trigger of and way to study various phenomena. These range from the basic processes of strong-field quantum electrodynamics to the extraordinary dynamics of the generated electron-positron plasmas. This has paved the way for several experimental proposals aimed at both fundamental studies of matter at extreme conditions and the creation of particle and radiation sources. Because of the unprecedented capabilities of such sources, they have the potential to open up new opportunities for experimental studies in nuclear and quark-gluon physics. We perform here a systematic analysis of different regimes and opportunities achievable with the concept of multiple colliding laser pulses, for both current and upcoming laser facilities. We reveal that several distinct regimes could be within reach of multi-petawatt laser facilities.
关键词： high-field high-energy physics,quantum electrodynamics,multiple colliding laser pulses,electron-positron plasmas,particle and radiation sources
更新于2025-09-11 14:15:04
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Cavity quantum-electrodynamical polaritonically enhanced electron-phonon coupling and its influence on superconductivity
摘要： So far, laser control of solids has been mainly discussed in the context of strong classical nonlinear light-matter coupling in a pump-probe framework. Here, we propose a quantum-electrodynamical setting to address the coupling of a low-dimensional quantum material to quantized electromagnetic fields in quantum cavities. Using a prototypical model system describing FeSe/SrTiO3 with electron-phonon long-range forward scattering, we study how the formation of phonon polaritons at the two-dimensional interface of the material modifies effective couplings and superconducting properties in a Migdal-Eliashberg simulation. We find that through highly polarizable dipolar phonons, large cavity-enhanced electron-phonon couplings are possible, but superconductivity is not enhanced for the forward-scattering pairing mechanism due to the interplay between coupling enhancement and mode softening. Our results demonstrate that quantum cavities enable the engineering of fundamental couplings in solids, paving the way for unprecedented control of material properties.
关键词： phonon polaritons,electron-phonon coupling,superconductivity,cavity quantum electrodynamics,quantum materials
更新于2025-09-10 09:29:36
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Evolution of Atomic Entanglement for Different Cavity-Field Statistics in Single-Mode Two-Photon Process
摘要： We study the evolution of entanglement for a pair of two-level Rydberg atoms passing one after the other into an ideal cavity filled with a single mode radiation field. The atoms interact with the cavity field via two-photon transitions. The initial joint state of two atoms that enter the cavity one after the other is unentangled. Interactions intervened by the single mode cavity photon field brings out the final two-atom mixed entangled type state. We use the well known measure appropriate for the mixed states, i.e. the entanglement of formation to quantify the entanglement. We calculate the entanglement of formation of the joint two-atom state as a function of the Rabi angle, for the Fock state field, coherent field and thermal field respectively inside the cavity. The change in the magnitude of atomic entanglement with cavity photon number has been discussed.
关键词： cavity quantum electrodynamics,two-photon transitions,entanglement of formation,entanglement,Rydberg atoms
更新于2025-09-10 09:29:36
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Engineering Photon Delocalization in a Rabi Dimer with a Dissipative Bath
摘要： A Rabi dimer is used to model a recently reported circuit quantum electrodynamics system composed of two coupled transmission-line resonators with each being coupled to one qubit. In this study, a phonon bath is adopted to mimic the multimode micromechanical resonators and is coupled to the qubits in the Rabi dimer. The dynamical behavior of the composite system is studied by the Dirac–Frenkel time-dependent variational principle combined with the multiple Davydov D2 ans¨atze. Initially, all the photons are pumped into the left resonator, and the two qubits are in the down state coupled with the phonon vacuum. In the strong qubit–photon coupling regime, the photon dynamics can be engineered by tuning the qubit–bath coupling strength α and photon delocalization is achieved by increasing α. In the absence of dissipation, photons are localized in the initial resonator. Nevertheless, with moderate qubit–bath coupling, photons are delocalized with quasiequilibration of the photon population in two resonators at long times. In this case, high-frequency bath modes are activated by interacting with depolarized qubits. For strong dissipation, photon delocalization is achieved via frequent photon-hopping within two resonators and the qubits are suppressed in their initial down state.
关键词： Rabi dimer,photon delocalization,qubit–bath coupling,Davydov ans¨atze,quantum electrodynamics
更新于2025-09-10 09:29:36
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spectroscopy
摘要： We apply point-particle effective field theory to electronic and muonic 4He+ ions, and use it to identify linear combinations of spectroscopic measurements for which the theoretical uncertainties are much smaller than for any particular energy levels. The error is reduced because these combinations are independent of all short-range physics effects up to a given order in the expansion in the small parameters R/aB and Zα (where R and aB are the ion’s nuclear and Bohr radii). In particular, the theory error is not limited by the precision with which nuclear matrix elements can be computed, or compromised, by the existence of any novel short-range interactions, should these exist. These combinations of 4He measurements therefore provide particularly precise tests of quantum electrodynamics. The restriction to 4He arises because our analysis assumes a spherically symmetric nucleus, but the argument used is more general and extendable to both nuclei with spin, and to higher orders in R/aB and Zα.
关键词： 4He+ ions,spectroscopy,quantum electrodynamics,nuclear physics,effective field theory
更新于2025-09-10 09:29:36
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Self-energy shift of the energy levels of atomic hydrogen in photonic crystal medium
摘要： Corrections to the average kinetic energy of atomic electrons caused by the change in electron mass in the photonic crystal medium are investigated. Corresponding shift of energy levels of atoms placed in a photonic crystal is shown to be of order of the ordinary Lamb shift.
关键词： atomic hydrogen,photonic crystal,energy levels,Lamb shift,quantum electrodynamics
更新于2025-09-10 09:29:36