A spectral hole memory for light at the single photon level

• Published in: arXiv.org 2016-04
• Main Authors: Kutlu Kutluer, Pascual-Winter, María Florencia, Dajczgewand, Julian, Ledingham, Partick M, Mazzera, Margherita, Chanelière, Thierry, de Riedmatten, Hugues
• Format: Article
• Language: English
• Subjects: Crystals; Group velocity; Optical memory (data storage); Optical pulses; Optical pumping; Photons; Quantum theory; Solid state; Spectra
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1509.03145

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\(_2\)SiO\(_5\) 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 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 \(5 \,\mathrm{mm}\)-long crystal. We also show that our device works at the single photon level by storing and retrieving \(3\,\mathrm{\mu s}\)-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 \((9\pm1)\times 10^{-3}\) photons per pulse in a detection window of \(4\,\mathrm{\mu s}\) leading to a signal-to-noise ratio of \(33 \pm 4\) for an average input photon number of 1, making our device promising for long-lived storage of non-classical light.