Rephasing efficiency of sequences of phased pulses in spin-echo and light-storage experiments

Abstract

We investigate the rephasing efficiency of sequences of phased pulses for spin echoes and light storage by electro-magnetically induced transparency (EIT). We derive a simple theoretical model and show that the rephasing efficiency is very sensitive to the phases of the imperfect rephasing pulses. The obtained efficiency differs substantially for spin echoes and EIT light storage, which is due to the spatially retarded coherence phases after EIT light storage. Similar behavior is also expected for other light storage protocols with spatial retardation or for rephasing of collective quantum states with an unknown/undefined phase, e.g., as relevant in single photon storage. We confirm the predictions of our theoretical model by experiments in a Pr

Efficient and robust signal sensing by sequences of adiabatic chirped pulses

“…We use the pulses' relative phases to correct for such and other errors (see Appendix B), e.g., using the popular XY, KDD, or UR sequences [22][23][24][25]49,51]. These are based on composite pulses and improve population transfer and rephasing [22,49,50,52].…”

“…For example, we can choose the phases of the individual RAP pulses to correspond to the popular XY, KDD, or UR sequences [22,23,49,51]. These are based on composite pulses, which have been shown to improve the efficiency of population transfer and rephasing with imperfect RAP pulses [22,49,50,52].…”

“…The propagator of a pulse (not necessarily RAP) in the bare basis can be parameterized by [22,51,52]…”

“…For example, imperfect adiabaticity due to, e.g., fast change in the mixing angle or insufficient pulse area, can make = 0. Such errors can be compensated by applying phased sequences of pulses, where the phases of the subsequent pulses are chosen to cancel the errors of the individual pulses up to a certain order [22,51,52]. If the pulses are time separated, the propagator of the whole cycle [free evolution for time τ /2 − pulse− free evolution for time τ /2] changes by taking α → α = α + τ , where we assumed that the detuning variation is constant during one [τ /2 − pulse − τ /2] period.…”

“…Adiabatic chirped pulses perform robust population flips by rapid adiabatic passage (RAP) even with inhomogeneous broadening, a weak driving field, and significant amplitude fluctuations [35][36][37][38][39]. They have been applied for rephasing [40][41][42][43][44][45] and combined with composite pulses [46][47][48] for improved population transfer [49][50][51][52].…”