A millisecond quantum memory for scalable quantum networks

Abstract

Two independent experiments that demonstrate memories for single quantum excitations with storage times of the order of a millisecond—two orders of magnitude longer than reported so far—should help to bring practical long-distance quantum-communication networks a step closer. Scalable quantum-information processing requires the capability of storing quantum states1,2. In particular, a long-lived storable and retrievable quantum memory for single excitations is of key importance to long-distance quantum communication with atomic ensembles and linear optics3,4,5,6,7. Although atomic memories for classical light8 and continuous variables9 have been demonstrated with millisecond storage time, lifetimes of only around 10 μs have been reported for quantum memories storing single excitations10,11,12,13. Here we present an experimental investigation into extending the storage time of quantum memory for single excitations. We identify and isolate distinct mechanisms responsible for the decoherence of spin waves in atomic-ensemble-based quantum memories. By exploiting magnetic-field-insensitive states—so-called clock states—and generating a long-wavelength spin wave to suppress dephasing, we succeed in extending the storage time of the quantum memory to 1 ms. Our result represents an important advance towards long-distance quantum communication and should provide a realistic approach to large-scale quantum information processing.

Cite this article

Zhao, B., Chen, YA., Bao, XH. et al. A millisecond quantum memory for scalable quantum networks. Nature Phys 5, 95–99 (2009). https://doi.org/10.1038/nphys1153

View full text

>> Full Text:   A millisecond quantum memory for scalable quantum networks