Patent ID: 8891282

Claim:
A quantum memory intended to store an incoming quantum light pulse, comprising: an ensemble of atoms embedded in a storage medium; and at least one light source for emitting towards the storage medium first, second and third light pulses, the first light pulse carrying quantum information to be stored; wherein the at least one light source is adapted for emitting second and third light pulses which are such that a photon echo substantially carrying quantum information stored by the first light pulse is emitted by the ensemble of atoms after emission of the third light pulse, and wherein the at least one light source is adapted for emitting the third light pulse at a time greater than twice the time interval between emission of the first and second light pulses, for emitting second and third light pulses with an intensity and time/frequency profile such that they rotate substantially simultaneously the Bloch vectors of the atoms of the ensemble by an angle of π , and is further adapted such that the following conditions are met: (i) (|2{right arrow over (k 2 )}−{right arrow over (k 1 )}|−|{right arrow over (k)}|)·L>π (ii) (|{right arrow over (k 1 )}+2({right arrow over (k 3 )}−{right arrow over (k 2 )})|−|{right arrow over (k)}|)·L<<π (iii) wherein {right arrow over (k)} 1 , {right arrow over (k)} 2 , and {right arrow over (k)} 3 are the wave vector of first, second and third light pulses, respectively, L is the length of the crystal, and |{right arrow over (k)}|=|{right arrow over (k)} 1 |=|{right arrow over (k)} 2 | (where the operator |.| designates the modulus of a vector).