Crossover from a delocalized to localized atomic excitation in an atom–waveguide interface

Abstract

An atom–waveguide system, which presents one of the quantum interfaces that enable strong couplings between light and atoms, can support tightly-confined guided modes of light. In this distinctive quantum interface, we theoretically investigate the crossover from a delocalized to localized atomic excitation under long-range dipole–dipole interactions and lattice disorders. Both localization lengths of the excitation distributions and power-law scalings of dissipative von Neumann entanglement entropy show signatures of this crossover. We further calculate numerically the level statistics of the underlying non-Hermitian Hamiltonian, from which as the disorder strength increases, the gap ratio decreases and the intrasample variance increases before reaching respective saturated values. The mean gap ratio in the deeply localized regime is close to the one from Poisson statistics along with a relatively large intrasample variance, whereas in the nondisordered regime, a significant level repulsion emerges. Our results provide insights to study the non-ergodic phenomenon in an atom–waveguide interface, which can be potentially applied to photon storage in this interface under dissipations.

Chiral-coupling-assisted refrigeration in trapped ions

“…This collective interaction [24] is ubiquitous in any lightmatter-interacting quantum interface [25], which can manifest a giant frictional force for atoms in an optical cavity [26] or form optically bound pairs of atoms in free space [27,28]. The reciprocal nature of these light-induced dipoledipole interactions can be further modified and controlled in an atom-waveguide interface [29][30][31][32][33][34], making the chiral quantum optical setup [35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50] a novel scheme for exploration of motional refrigeration in optomechanical systems [51,52].…”

Microwave cavity-free hole burning spectroscopy of Er$^{3+}$:Y$_2$SiO$_5$ at millikelvin temperatures

“…Ability to effectively control the electronic spins with the propagating microwave signals [11][12][13][14][15] , which can couple to the same spins in broad frequency range, will pave the way to a large variety of microwave quantum mem-ory schemes including more than two electronic levels. The atomic frequency comb (AFC) protocol is one of the most promising quantum memory protocols established in optics [16][17][18] , which can be realized on two electronic levels as well as extended to a third longer living state also allowing for frequency domain multiplexing storage protocols 19,20 .…”