Strong coupling of ionizing transitions

Abstract

We demonstrate that a ionising transition can be strongly coupled to a photonic resonance. The strong coupling manifests itself with the appearance of a narrow optically active resonance below the ionisation threshold. Such a resonance is due to electrons transitioning into a novel bound state created by the collective coupling of the electron gas with the vacuum field of the photonic resonator. Applying our theory to the case of bound-to-continuum transitions in microcavity-embedded doped quantum wells, we show how those strong-coupling features can be exploited as a novel knob to tune both optical and electronic properties of semiconductor heterostructures.

Oscillating bound states for a giant atom

“…In contrast to bound states arising from an impurity protected by an energy gap [51][52][53][54][55][56][57][58], the bound states we find here appear inside the continuous energy spectrum. Therefore, it is possible to manipulate (catch or release) propagating photons/phonons in the waveguide by tuning the dark-mode condition [Eq.…”

“…The physical origin of the non-Markovianity is typically the coupling to a structured bath causing information backflow from the environment [44][45][46]. These systems can exhibit nonexponential relaxation [47,48] and bound states [34,[49][50][51][52][53][54][55][56][57][58][59][60], which can be harnessed for quantum simulations [61,62]. Here, we realize non-Markovianity in a single giant atom by engineering the time delays between coupling points to be comparable to the relaxation time [63,64].…”

Chemistry in Quantum Cavities: Exact Results, the Impact of Thermal Velocities, and Modified Dissociation

“…Another interesting result with relevance for polaritonic chemistry is the formation of bound polaritonic states below 41 , 42 and above the proton dissociation limit of H 2 + (see green region in Figure 4 ). Because we treat the nuclei/ions quantum-mechanically, we do not have to approximate the Born–Oppenheimer surfaces in our present approach for a simple picture of dissociation.…”

Excitons bound by photon exchange

“…Nonperturbative light-matter interaction in solidstate devices has been investigated as a pathway to tune optoelectronic properties of materials [2,3]. A recent theoretical work [4] predicted that, when the doped quantum wells are embedded in a photonic cavity, emission-reabsorption processes of cavity photons can generate an effective attractive interaction which binds electrons and holes together, leading to the creation of an intraband bound exciton.…”

“…demonstrated in inorganic microcavities, where it can be observed as a change of the exciton radius [10,11]. The question on whether such a mechanism can be pushed to the extreme, non-perturbatively modifying the excitation wavefunction and creating localised bound states from delocalised ones, has recently been theoretically investigated, leading to the prediction of discrete resonances appearing below the continuum ionization threshold for large enough values of the light-matter coupling strengths [4]. The lower edge of the continuum corresponds to free electrons with no kinetic energy.…”