Nonexponential decay of a collective excitation in an atomic ensemble coupled to a one-dimensional waveguide

Abstract

We study the dynamics of a single excitation coherently shared among an ensemble of atoms and coupled to a one-dimensional wave guide. The coupling between the matter and the light field gives rise to collective phenomena such as superradiant states with an enhanced initial decay rate, but also to the coherent exchange of the excitation between the atoms. We find that the competition between the two phenomena provides a characteristic dynamics for the decay of the excitations, and remarkably exhibits an algebraic behavior, instead of the expected standard exponential one, for a large number of atoms. The analysis is first performed for a chiral waveguide, where the problem can be solved analytically. Remarkably, we demonstrate that a bidirectional waveguide exhibits the same behavior for large number of atoms and, therefore, it is possible to experimentally access characteristic properties of a chiral waveguide also within a bidirectional waveguide.

Observation of coherent coupling between super- and subradiant states of an ensemble of cold atoms collectively coupled to a single propagating optical mode

“…For a system that is prepared in the timed Dicke state, i.e., φ n (t = 0) = 1/ √ N , with n = 1, ..., N , and that then evolves freely, our model allows us to derive analytic expressions for φ n (t) and χ n (t), where the latter is proportional to the sum of the excited state amplitudes of the first n atoms: scaling of the observation time. In the limit β = 1, these results agree with calculations based on a master equation approach [19].…”

“…In addition, in cavity quantum electrodynamics the timed Dicke physics is at the basis of the assumptions of the Tavis-Cummings model [14,15], which describes collectively enhanced light-matter coupling between an atomic ensemble and a single mode cavity [16,17]. For these reasons, notable effort has been recently devoted to describe the time dynamics of extended ensembles [2,[18][19][20][21][22], a task which, unlike the standard Dicke model, needs to consider coupling between superand subradiant states, see Fig. 1(a).…”

Observation of superradiant bursts in waveguide QED

“…There, the waveguide mediates long-range dipole-dipole interactions between the emitters, which can be engineered to be almost unidirectional [19]. These unique interactions make the study of collective radiative effects in wQED an especially intriguing research direction [20][21][22][23][24][25][26][27].…”

Quantum correlations of localized atomic excitations in a disordered atomic chain

“…Therefore, it is challenging to unravel clear signatures of localization under a dissipative environment. In a setup of light-matter interacting quantum interface with collective dipole-dipole interactions [23,24], a strongly-coupled atom-waveguide system [25,26] presents subradiant dynamics [27][28][29] which sustains for a longer lifetime and thus suffices to simulate Anderson-like localization of a quenched single atomic excitation [30,31]. The atomwaveguide system has been shown to manifest mesoscopic entanglement [32], photon-photon correlations [33,34], longrange correlated spin dimers [35,36], and bounded multiatom excitations [37].…”