Coherent transfer and retrieval of terahertz-bandwidth single photon pulses to a quantum dot ensemble at telecommunication wavelengths

We demonstrate the coherent transfer and on-demand retrieval of quantum state of telecom-wavelength ultrabroadband single photon pulse (terahertz range) to a collective excitation of a large number of quantum dots using photon-echo technique. The large inhomogeneous broadening of exciton energies in quantum dots, in conjunction with photon-echo technique, enables us to increase the acceptable spectral bandwidth of transferred single photon pulse from the current maximum of 5 gigahertz to 1 terahertz.