Bound states and entanglement generation in waveguide quantum electrodynamics

Abstract

We investigate the behavior of two quantum emitters (two-level atoms) embedded in a linear waveguide, in a quasi-one-dimensional configuration. Since the atoms can emit, absorb, and reflect radiation, the pair can spontaneously relax towards an entangled bound state, under conditions in which a single atom would instead decay. Exploiting the resolvent formalism, we analyze the properties of these bound states, which occur for resonant values of the interatomic distance, and discuss their relevance with respect to entanglement generation. The stability of such states close to the resonance is studied, as well as the properties of nonresonant bound states, whose energy is below the threshold for photon propagation

Enhancement of spontaneous entanglement generation via coherent quantum feedback

“…which means that the two-qubit reduced system evolves within the strong-coupling regime. This result is in contrast to previous studies [20][21][22][23][24]28], in which g eff and γ eff are of the same order (intermediate-coupling regime). Therefore, as γ L → γ R , the qubits can readily exchange quanta and get highly entangled, with the dissipation effect negligible.…”

Markovian and non-Markovian dynamics of quantum emitters coupled to two-dimensional structured reservoirs

“…This leads to perfect super/subradiance [23][24][25][26]39], which can be exploited for entanglement generation, self-organization of atoms or multiphoton generation among others [24,36,37,[40][41][42][43][44].…”

Long-lived entanglement of two multilevel atoms in a waveguide

“…and does not mix different sectors, belonging to different values of  . Due to this conservation law and the robustness of our approximations [47], our analysis applies equally well to a pair of harmonic oscillators and to a pair of (N+1)-level atoms (with equally spaced levels) in a waveguide. See figure 1.…”

“…However, the interplay between absorption, stimulated and spontaneous emission provides a quantum emitter with mirror-like properties [29,40,41]. Hence, a pair of emitters can confine the field in the region between them, yielding nontrivial bound states above the threshold for photon propagation, that can be exploited for their robust entanglement features [42][43][44][45][46][47].…”