Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userA Quick Introduction to the strong coupling regime of Cavity Quantum Electrodynamics: applications and fundamental quantum theory
105
0
0.0
(
0
)
Authors
Nathan D. Poulin
Ask ChatGPT about the research
No Arabic abstract
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 has been indispensable. From the quantization of the atom and field within a superconducting cavity, a unique realm of EPR type entanglement has emerged. In this way, dynamical evolution of the system in the strong coupling regime is intimately tied with the coupling of an atom with a single resonant or non-resonant mode within the cavity. More specifically, the cavity can be prepared so that the atom is detected in a desired state. Here, the essentials of the strong coupling regime of Cavity Quantum Electrodynamics (QED) are reviewed for cavities tuned with a single atomic transition. A brief introduction of the systems is followed by an approach of the more striking effects, leading towards Ramsey Interferometry and Quantum Non-Demolition measurements as means for quantum gate protocol. Because the integrity of the atom and photon states is important for the advancement of quantum computation, a brief discussion of the decoherence problems is also presented. This document is meant to introduce the topic in a way that makes it easily accessible to those working in closely related areas of physics, and to highlight key applications and some basic questions concerning decoherence and the measurement problem.
rate research
Read More
We study a generic cavity-QED system where a set of (artificial) two-level dipoles is coupled to the electric field of a single-mode LC resonator. This setup is used to derive a minimal quantum mechanical model for cavity QED, which accounts for both dipole-field and direct dipole-dipole interactions. The model is applicable for arbitrary coupling strengths and allows us to extend the usual Dicke model into the non-perturbative regime of QED, where the dipole-field interaction can be associated with an effective finestructure constant of order unity. In this regime, we identify three distinct classes of normal, superradiant and subradiant vacuum states and discuss their characteristic properties and the transitions between them. Our findings reconcile many of the previous, often contradictory predictions in this field and establish a common theoretical framework to describe ultrastrong coupling phenomena in a diverse range of cavity-QED platforms.
We report on spectra of circuit-quantum-electrodynamics (QED) systems in an intermediate regime that lies between the ultrastrong and deep-strong-coupling regimes, which have been reported previously in the literature. Our experimental results, along with numerical simulations, demonstrate that as the coupling strength increases, the spectrum of a circuit-QED system undergoes multiple qualitative transformations, such that several coupling regimes are identified, each with its own unique spectral features. The different spectral transformations can be related to crossings between energy level differences and to changes in the symmetries of the energy eigenstates. These results allow us to use qualitative spectral features to infer certain properties and parameters of the system.
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 quantum optics and the basis of photon-photon and atom-atom entangling gates. At microwave frequencies, success in cQED has had a transformative effect. At optical frequencies, the gates are potentially much faster and the photons can propagate over long distances and be easily detected, ideal features for quantum networks. Following pioneering work on single atoms, solid-state implementations are important for developing practicable quantum technology. Here, we embed a semiconductor quantum dot in a microcavity. The microcavity has a $mathcal{Q}$-factor close to $10^{6}$ and contains a charge-tunable quantum dot with close-to-transform-limited optical linewidth. The exciton-photon coupling rate $g$ exceeds both the photon decay rate $kappa$ and exciton decay rate $gamma$ by a large margin ($g/gamma=14$, $g/kappa=5.3$); the cooperativity is $C=2g^{2}/(gamma kappa)=150$, the $beta$-factor 99.7%. We observe pronounced vacuum Rabi oscillations in the time-domain, photon blockade at a one-photon resonance, and highly bunched photon statistics at a two-photon resonance. We use the change in photon statistics as a sensitive spectral probe of transitions between the first and second rungs of the Jaynes-Cummings ladder. All experiments can be described quantitatively with the Jaynes-Cummings model despite the complexity of the solid-state environment. We propose this system as a platform to develop optical-cQED for quantum technology, for instance a photon-photon entangling gate.
We experimentally realize an optical fiber ring resonator that includes a tapered section with subwavelength-diameter waist. In this section, the guided light exhibits a significant evanescent field which allows for efficient interfacing with optical emitters. A commercial tunable fiber beam splitter provides simple and robust coupling to the resonator. Key parameters of the resonator such as its out-coupling rate, free spectral range, and birefringence can be adjusted. Thanks to the low taper- and coupling-losses, the resonator exhibits an unloaded finesse of F=75+/-1, sufficient for reaching the regime of strong coupling for emitters placed in the evanescent field. The system is ideally suited for trapping ensembles of laser-cooled atoms along the nanofiber section. Based on measured parameters, we estimate that the system can serve as a platform for optical multimode strong coupling experiments. Finally, we discuss the possibilities of using the resonator for applications based on chiral quantum optics.
We derive analytical formulas for the forward emission and side emission spectra of cavity-modified single-photon sources, as well as the corresponding normal-mode oscillations in the cavity quantum electrodynamics (QED) strong-coupling regime. We investigate the effects of pure dephasing, treated in the phase-diffusion model based on a Wiener-Levy process, on the emission spectra and normal-mode oscillations. We also extend our previous calculation of quantum efficiency to include the pure dephasing process. All results are obtained in the Weisskopf-Wigner approximation for an impulse-excited emitter. We find that the spectra are broadened, the depths of the normal-mode oscillations are reduced and the quantum efficiency is decreased in the presence of pure dephasing.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
