One of the building blocks for the next generation of quantum computing and communications systems is a way of storing and regenerating photonic qubits. These are generally encoded in the polarisation of photons.
To date, physicists have done this by transferring the qubit from a photon to an ensemble of quantum particles such as a crystal lattice or a small cloud of atoms.
Today, Holger Specht and pals at the Max Planck Institute for Quantum Optics in Garching, Germany, have gone one better. They've found a way to store the qubit from a polarised photon in a single atom of rubidium and then release it again later.
The trick here is first to find an atom with the suitable two-level state that will absorb photons in the right way and second, to find a way to force the photon to give up its qubit to the atom.
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