Experimental Study of a Quantum Memory Protocol: Revival of Silenced Echo and Superradiance

An optical quantum memory protocol is implemented in schemes of silenced echo revival in a 167Er3+:Y2SiO5 crystal at a telecommunication wavelength. The signal pulse recovery efficiency is 13% at a storage time of 60 μs for the optimum intensity of rephasing laser pulses. With a further increase in the laser pulse intensity, a superradiance pulse appears, causing a decrease in the signal pulse recovery efficiency. A way of improving the quantum memory efficiency by further increasing the pulse area of rephasing pulses is discussed.