One of the hurdles faced in the construction of a quantum computer is how to move qubits around inside. According to an NIST news release, NIST's Joint Quantum Institute joined forces with researchers at Princenton to solve this problem by creating a "quantum bus". Physicist Jacob Taylor explains the problem this way:
"In order to couple qubits, we need to be able to move information about one to the other. There are a few ways that this can be done and they usually involve moving around the particles themselves, which is very difficult to do quickly without destabilizing their spins - which are carrying the information - or transferring information about the spins to light. While this is easier than moving the particles themselves, the interaction between light and matter is generally very weak."
Their solution uses the latter method. First, they combined spin-orbit qubits with circuit quantum electrodynamics. The resulting device couples the spins of electrons trapped in an indium-arsenide quantum dot with the electron's positions. This allows the magnetic field of the qubit (which now reflects the spins), to interact with microwave photons moving in a superconducting cavity. In effect, they've got half of a bus - the spin information is moved from the qubit to a photon. So you can't buy that quantum brain for your robot just yet. They still need to get the spin information from the photon into another qubit at the other end of the bus. For a more detailed explanation of the work, with schematics and links to papers, see the JQI news release. A Princeton news release also mentions the work.