Abstract: A quantum memory device includes an atomic ensemble (4) and a signal source of electromagnetic radiation (10) for generating modes to be stored and having a frequency corresponding to an off-resonant transition between first and second states in the atomic ensemble. The quantum memory device also includes a control source of electromagnetic radiation (12) for generating electromagnetic radiation having a frequency corresponding to an off-resonant atomic transition between second and third states in the atomic ensemble; the third state has a higher energy than the second state which has a higher energy than the first state. The signal source and the control source create a coherent excitation of the transition between the first state and the third state such that the atomic ensemble stores the signal source modes, and the control source subsequently stimulates emission of the stored modes from the atomic ensemble.

Abstract: A quantum memory device includes an atomic ensemble (4) and a signal source of electromagnetic radiation (10) for generating modes to be stored and having a frequency corresponding to an off-resonant transition between first and second states in the atomic ensemble. The quantum memory device also includes a control source of electromagnetic radiation (12) for generating electromagnetic radiation having a frequency corresponding to an off-resonant atomic transition between second and third states in the atomic ensemble; the third state has a higher energy than the second state which has a higher energy than the first state. The signal source and the control source create a coherent excitation of the transition between the first state and the third state such that the atomic ensemble stores the signal source modes, and the control source subsequently stimulates emission of the stored modes from the atomic ensemble.

Abstract: An electromagnetic frequency converter includes an atomic ensemble; one or more first sources (6, 8) of electromagnetic radiation (P, R) to be incident upon the atomic ensemble to excite atomic valence electrons from a ground state to a first Rydberg state; one or more second sources (6, 14) of electromagnetic radiation (A, C) to be incident upon the atomic ensemble to excite atomic valence electrons from an excited state to a second Rydberg state; a first input (20) and/or output (26) for electromagnetic radiation (L) to be incident upon the atomic ensemble from the first input or received from the atomic ensemble at the first output; and a second input (14) and/or output (24) for electromagnetic radiation (M) to be incident upon the atomic ensemble from the second input or received from the atomic ensemble at the second output.

Abstract: An electromagnetic frequency converter includes an atomic ensemble; one or more first sources (6, 8) of electromagnetic radiation (P, R) to be incident upon the atomic ensemble to excite atomic valence electrons from a ground state to a first Rydberg state; one or more second sources (6, 14) of electromagnetic radiation (A, C) to be incident upon the atomic ensemble to excite atomic valence electrons from an excited state to a second Rydberg state; a first input (20) and/or output (26) for electromagnetic radiation (L) to be incident upon the atomic ensemble from the first input or received from the atomic ensemble at the first output; and a second input (14) and/or output (24) for electromagnetic radiation (M) to be incident upon the atomic ensemble from the second input or received from the atomic ensemble at the second output.