Patent ID: 7075438

Claim:
A method of verifying the position of a tagging device, the method comprising: (A) storing response information in a quantum state of a quantum entity, the quantum entity comprising an entangled pair; (B) separating the entangled pair into first and second entangled particles; (C) conveying the first and second entangled particles to first and second emitters respectively; (D) emitting the first and second particles of the entangled pair respectively from the first and second emitters to the tagging device; (E) recombining the first and second entangled particles in the tagging device to determine the response information; (F) transmitting a signal from the tagging device to at least one of a plurality of detectors; (G) detecting and recording the arrival time of the signal at the or each receiving detector, the or each receiving detector being selected on the basis of the determined response information; and (H) comparing the arrival time of the signal at the or each receiving detector with an expected arrival time of the signal for the or each expected receiving detector; wherein matching the expected and actual signal arrival time for an expected detector verifies the position of the tagging device.