Broadband and efficient Quantum Memory Using ac Stark Gradient Echo Memory

Abstract

A quantum state light-storage, using a virtual magnetic field through the ac Stark effect is proposed to combine the high overall storage efficiency and large bandwidth employing room temperature atomic vapor. In this approach, which was called the ac Stark Gradient Echo Memory (ASGEM), it has been shown the possibility to employ about a nanosecond ac Stark pulse far detuned (∼ 127 THz) from D1 line of rubidium and create an atomic media with the possibility to store a photon with about a GHz bandwidth with storage and retrieval efficiency of more than 90%. A contour plot of efficiency as a function of gradient field strength and optical depth, based on three-level Maxwell-Bloch equations, simulated for a better understanding of experimental parameter optimization.

Readout-Integrated Time-Bin Qutrit Analyzer for Echo-Based Quantum Memories

“…It should be noted that this approach works equally well for all possible optical rephasing strategies, including both first in first out (FIFO), e.g., AFC [30], and first in last out (FILO), e.g., CRIB, GEM [25][26][27], protocols, as for all of them coherences that are mapped earlier to the |g ↔ |e are emitted earlier by the memory. The PRA is particularly useful for measuring time-bin qubits when the photons have a very long coherence time > 100 ns.…”

“…For on-demand and temporally multimode quantum memories like controlled reversible inhomogeneous broadening (CRIB) and gradient echo memory (GEM) [25][26][27], revival of silenced echo (ROSE) [28,29], or atomic frequency comb (AFC) spin-wave storage [30], an equivalent action can be performed by means of two successive partial readouts of a stored time-bin qubit [19]. We consider that the memory implements on demand storage by using a λ system consisting of two ground states the coherence is mapped back onto |g − |e by another π pulse (read pulse) and, subsequently, re-emitted as a flying photon based on a process that is dependent on the particular protocol in use.…”

A readout-integrated time-bin qutrit analyzer for echo-based quantum memories

“…For on-demand and temporally multi-mode quantum memories like CRIB/GEM [22][23][24], ROSE [25,26] or AFC spin-wave storage [27,28], an equivalent action can be performed by means of two successive partial readouts of a stored time-bin qubit [19]. We consider a quantum memory consisting of a lambda system with a long-lived spin transition |g −|s and two optical transition, |s −|e and |g − |e .…”