Sustained photon pulse revivals from inhomogeneously broadened spin ensembles

Abstract

A very promising recent trend in applied quantum physics is to combine the advantageous features of different quantum systems into what is called “hybrid quantum technology”. One of the key elements in this new field will have to be a quantum memory enabling to store quanta over extended periods of time. Systems that may fulfill the demands of such applications are comb‐shaped spin ensembles coupled to a cavity. Due to the decoherence induced by the inhomogeneous ensemble broadening, the storage time of these quantum memories is, however, still rather limited. Here we demonstrate how to overcome this problem by burning well‐placed holes into the spectral spin density leading to spectacular performance in the multimode regime. Specifically, we show how an initial excitation of the ensemble leads to the emission of more than a hundred well‐separated photon pulses with a decay rate significantly below the fundamental limit of the recently proposed “cavity protection effect”.

Introduction to the Dicke Model: From Equilibrium to Nonequilibrium, and Vice Versa

“… Such models were studied in a wider variety of contexts, including the effects of disorder on dynamical superradiance in a low Q cavity, the phase diagram of microcavity polaritons, solid state quantum memories, as well as for cold atom in optical cavities, accounting for the spatial variation of the cavity modes . Several works in this context have investigated the dynamics of an initially prepared state, using either brute force numerics for small systems, or matrix product state approaches . The existence of such disorder prevents the simplification of replacing individual spins by a collective spin operator, hence the need for efficient numerical methods to explore this enlarged Hilbert space .…”

Optimal control of non-Markovian dynamics in a single-mode cavity strongly coupled to an inhomogeneously broadened spin ensemble

“…In contrast to established echo techniques our scheme only involves low-intensity signals and therefore diminishes the influence of noise caused by writing and reading pulses. The applicability of our approach is also demonstrated in conjunction with a spectral hole-burning technique [26][27][28] that allows us to reach storage times going far beyond the dephasing time of the inhomogeneously broadened ensemble. Importantly, the Volterra equation exactly governs the resulting linear non-Markovian dynamics not only in the semiclassical but also in the pure quantum case for the particular situation without external drive, when all spins are initially in the ground state and the cavity contains initially a single photon [26,28,29].…”

A fast sparse spectral method for nonlinear integro-differential Volterra equations with general kernels

“…Integral equations involving Volterra operators occur in diverse applications in various disciplines of engineering [55,59] and finance and economics [3,37], as well as the natural sciences [9,20,28,30,31,35,44,58]. Beyond linear Volterra integral equations of first and second kinds, which respectively take the forms…”