Two teams have forged the first chip-based version of a quantum bus, a tool for mixing and swapping information between qubits. The bus is a squiggly wire between two superconducting loops, which served as qubits. When activated, a qubit loop transfers its superposition to the wire in the form of a microwave photon. Raymond Simmonds of the National Institute of Standards and Technology in Boulder, Colo., who led one of the teams, got a seven-millimeter-long wire to store a photon for more than one microsecond. Rob Schoelkopf of Yale University and his group performed a similar trick with a longer wire that mixed a single quantum state between two qubits. To make a quantum computer, though, the researchers will have to keep the superconducting qubits stable or coherent for longer periods.
This article was originally published with the title "A Qubit Bus"