A Long-Term Memory for Light

The ability to store light while keeping its quantum coherence properties (e.g., entanglement) plays an important role in quantum information science. It makes it possible to build quantum memories for light, which could become crucial elements in many quantum information processing schemes based on the use of photons, from quantum communication networks to quantum computing protocols. A critical parameter for applications is the duration over which light can be stored. For example, the distribution of quantum bits over complex quantum information networks, and their storage for further manipulation, might require quantum memories with storage time from a few seconds to a few minutes. Writing in Physical Review Letters, Georg Heinze at the University of Darmstadt, Germany, and colleagues report an important step towards this goal by demonstrating a solid-state coherent optical memory capable of storing a classical light pulse, and even a full image, for a duration of more than one minute—the longest light-storage time reported in any system to date [1].