Spectral-hole memory for light at the single-photon level

Kutlu Kutluer, María Florencia Pascual-Winter, Julian Dajczgewand, Patrick M. Ledingham, Margherita Mazzera, Thierry Chanelière, Hugues de Riedmatten
2016 Physical Review A  
We demonstrate a solid state spin-wave optical memory based on stopped light in a spectral hole. A long lived narrow spectral hole is created by optical pumping in the inhomogeneous absorption profile of a Pr^3+:Y_2SiO_5 crystal. Optical pulses sent through the spectral hole experience a strong reduction of their group velocity and are spatially compressed in the crystal. A short Raman pulse transfers the optical excitation to the spin state before the light pulse exits the crystal, effectively
more » ... stopping the light. After a controllable delay, a second Raman pulse is sent, which leads to the emission of the stored photons. We reach storage and retrieval efficiencies for bright pulses of up to 39 % in a 5 mm-long crystal. We also show that our device works at the single photon level by storing and retrieving 3 μ s-long weak coherent pulses with efficiencies up to 31 %, demonstrating the most efficient spin-wave solid state optical memory at the single-photon level so far. We reach an unconditional noise level of (9±1)× 10^-3 photons per pulse in a detection window of 4 μ s leading to a signal-to-noise ratio of 33 ± 4 for an average input photon number of 1, making our device promising for long-lived storage of non-classical light.
doi:10.1103/physreva.93.040302 fatcat:i4wldxlnafes5fhnntlzim5hgi