Researchers in Denmark have managed to store the states of two entangled light beams in a solid state memory.
In an optical quantum network, relay stations will be needed to guard against the odd data photon getting lost along the way. So far, researchers have used gas as the storage medium, but the team at The University of Copenhagen have succeeded in using impurities in diamond to capture the data.
From the announcement:
[In a gas-based system] a laser beam is sent into a vacuum chamber with a single gas atom. The atom reacts by sending out a single photon and a special phenomenon in the quantum world ensures that the photon is entangled with the atom. This entanglement or synchronization can be used to send information. The quantum information is stored in the polarization of light which can be right- or left-handed.
This handedness can be thought of as the equivalent of an ordinary computer's binary bits; 0 or 1.
"But a gas atom floats freely and it is difficult to trap it so you can hit it", explains Anders Sørensen, "therefore, we wanted to find a solution with a solid state atom which we could contain. Our solution was a diamond - not the diamond itself, which consists of carbon atoms, but tiny impurities in the diamond which consists of a single nitrogen atom".
The work is published in Nature Physics