Abstract
We report on the experimental demonstration of an optical spin-wave memory, based on the atomic frequency comb (AFC) scheme, where the storage efficiency is strongly enhanced by an optical cavity. The cavity is of low finesse, but operated in an impedance matching regime to achieve high absorption in our intrinsically low-absorbing Eu3+:Y2SiO5 crystal. For storage of optical pulses as an optical excitation (AFC echoes), we reach efficiencies of 53% and 28% for 2 μs and 10 μs delays, respectively. For a complete AFC spin-wave memory we reach an efficiency of 12%, including spin-wave dephasing, which is a 12-fold increase with respect to previous results in this material. This result is an important step towards the goal of making efficient and long-lived quantum memories based on spin waves, in the context of quantum repeaters and quantum networks.
Highlights
Quantum information science seeks to develop methods and techniques that would allow us to perform certain tasks that cannot be achieved with conventional techniques based on classical physics
We report on the experimental demonstration of an optical spin-wave memory, based on the atomic frequency comb (AFC) scheme, where the storage efficiency is strongly enhanced by an optical cavity
These experiments have only implemented a partial version of that scheme, where the photon is stored solemnly as a optical excitation, called two-level AFC echo without applying any optical-to-spin conversion, in which case the AFC memory is equivalent to a fixed optical delay line
Summary
Quantum information science seeks to develop methods and techniques that would allow us to perform certain tasks that cannot be achieved with conventional techniques based on classical physics. To date most reported work at the SPL using REIC memories have been based on the atomic frequency comb (AFC) method [12,13,14,15,16,17]. These experiments have only implemented a partial version of that scheme, where the photon is stored solemnly as a optical excitation, called two-level AFC echo without applying any optical-to-spin conversion, in which case the AFC memory is equivalent to a fixed optical delay line. The implementation of the optical-to-spin conversion is crucial for AFC quantum memories, called spin-wave AFC memory because it allows to read out the memory on demand
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