Quantum Memory Breaks Performance BarrierA new approach stores and retrieves quantum states with record reliability, paving the way for improved quantum information processing.
Faithfully storing an unknown quantum light state is essential to advanced quantum communication and distributed quantum computation applications. The required quantum memory must have high fidelity to improve the performance of a quantum network. Here we report the reversible transfer of photonic polarization states into collective atomic excitation in a compact solid-state device. The quantum memory is based on an atomic frequency comb (AFC) in rare-earth ion-doped crystals. We obtain up to 0.999 process fidelity for the storage and retrieval process of single-photon-level coherent pulse. This reliable quantum memory is a crucial step toward quantum networks based on solid-state devices.
The ability of storing and retrieving quantum states of light is an important experimental challenge in quantum information science. A powerful quantum memory for light is required in a quantum repeater, which would allow long distance (>500km) quantum communications. To be implemented in such application, the quantum memory must allow on-demand readout, with high fidelity and efficiency, and a long storage time. Additionally a multimode capacity (for temporal or spatial modes) would allow multiplexing. Our approaches focus on rare-earth doped crystals, i.e. solid state quantum memory. I present, in this work, our contributions for a solid-state quantum storage, with good performances in every criteria. In particular, I present the preservation of quantum entanglement during the storage, which paves the way for the implementation of quantum memories in quantum repeaters.
A key requirement for quantum information processing applications such as quantum communication or computation is the ability to reliably store, manipulate, and retrieve a piece of information, encoded, for example, in the polarization state of a single photon. Among the many routes presently being explored to achieve these goals is cavity quantum electrodynamics (c-QED), which entails trapping a single atom in a cavity and inducing it to interact with a single photon. In this vein, Boozer et al. show that they are able to imprint the state of a single photon onto a single trapped Cs atom, store it for an appreciable fraction of the lifetime of the atom in the trap, and then retrieve that information again sometime later in the form of another photon and send it on its way. They verify that the whole process is coherent, providing further support for c-QED-based systems as promising candidates for nodes in a quantum information processing network. — ISO