Patent ID: 7180645

Claim:
An apparatus for generating a quantum state of a two-qubit system including two qubits, each qubit being represented by a detector probability, where the probability is based upon N samples of a system in which a particle invariably travels through one of two paths, the apparatus comprising: a first beam splitter configured to receive a first particle of two particles having no correlation with each other, and to output the first particle into two paths in a superposition; and an interferometer configured to implement an interaction-free measurement, wherein an interaction-free measurement is a probability measurement method defined as: the condition when, after the N samples of the system containing the two particles, the probability of detection of a particle after N samples by a detector is about P C =cos 2 θ sin 2 θ, wherein N is defined as N=1/(1−P B )=1/(1−cos 4 θ), wherein θ is a characteristic of the first beam splitter, wherein P=cos 4 θ, and wherein the interferometer is configured to receive a second particle of the two particles and the output of the first beam splitter and generates a Bell state with asymptotic probability 1.