Light storage for one second in room-temperature alkali vapor

Abstract

Light storage, the controlled and reversible mapping of photons onto long-lived states of matter, enables memory capability in optical quantum networks. Prominent storage media are warm alkali vapors due to their strong optical coupling and long-lived spin states. In a dense gas, the random atomic collisions dominate the lifetime of the spin coherence, limiting the storage time to a few milliseconds. Here we present and experimentally demonstrate a storage scheme that is insensitive to spin-exchange collisions, thus enabling long storage times at high atomic densities. This unique property is achieved by mapping the light field onto spin orientation within a decoherence-free subspace of spin states. We report on a record storage time of 1 s in room-temperature cesium vapor, a 100-fold improvement over existing storage schemes. Furthermore, our scheme lays the foundations for hour-long quantum memories using rare-gas nuclear spins.

Coherence Properties of Molecular Single Photons for Quantum Networks

“…Furthermore, the photons can be used in implementing a robust and long-lasting storage and retrieval scheme in atomic gases [17,37]-one of the next evident goals in experimental quantum hybridization. The method of utilizing a one-port analysis or a quantum eraser will be used as a further characterization step beyond a characterization in the common HongOu-Mandel experiments.…”

“…Being very versatile and robust, hot atomic vapors are ideally suited for this task. They are not only suitable as efficient quantum memories [17], but also allow for the implementation of GHz-wide Faraday filters [15]. The latter are based on the optical interaction of linear polarized light with the nondegenerate Zeeman sublevels in an atomic vapor.…”

Demonstration of slow light in rubidium vapor using single photons from a trapped ion

“…These light-matter interfaces may be used as necessary communication tools, such as to synchronise photon arrival times for entanglement distribution. Trapped ions are strong candidates for communication nodes owing to their long qubit life time [1] and high fidelity ion-photon entanglement [2], whilst neutral atoms are versatile quantum systems, useful as memories [3,4,5], for photon storage [6] or tunable photon delay via slow light [7,8]. Development of these two quantum technologies has largely proceeded in separate tracks, partly due to their disparate wavelengths of operation, but combining these platforms offers a compelling hybrid quantum system for use in quantum networking and distributed quantum computing.…”

Power narrowing: counteracting Doppler broadening in two-color transitions

“…As Doppler broadening is an inhomogeneous dephasing mechanism, one can potentially counteract it by introducing additional velocity-dependent shifts [10][11][12][13][14]. Here we study the counteraction of Doppler broadening by velocity dependent light-shifts and identify an important class of systems where such counteraction occurs naturally, without a need for additional auxiliary fields.Coherent two-photon processes, such as Raman transitions, two-photon absorption, and electromagnetically induced transparency (EIT), are at the heart of many quantum-optics protocols, ranging from quantum light sources and memories [15][16][17][18] to sensing and quantum nonlinear optics [19]. The canonical example of a three-level system employed for these processes is the Λ configuration, where two longlived ground states are coupled via an intermediate excited state.…”