US Patent 7332738 - Phase shift coupling for quantum state readout

http://www.freepatentsonline.com/7332738.html

Quantum computing depends on the entangling of states such as spin or polarization of fundamental particles such that there is a certain degree of information sharing between physically separated particles. D-Wave has taken the lead in patents in this area focusing on quantum computers formed using superconducting materials and one of the problems that they are trying to solve is maintaining entanglement during a readout process. This patent teaches a method in which readout is facilitated by the use of a charge device which has a quantum state entangled with that of a phase device. Claim 1 reads:

1. A method for reading out the quantum state of a mesoscopic phase device, the method comprising: coherently coupling said mesoscopic phase device to a mesoscopic charge device using a phase shift device; and measuring the quantum state of said mesoscopic charge device.