Quantum and optical technology

Abstract:

A single photon, delocalized over two optical modes, is characterized by means of quantum homodyne tomography. The reconstructed four-dimensional density matrix extends over the entire Hilbert space and thus reveals, for the first time, complete information about the dual-rail optical quantum bit as a state of the electromagnetic field. The experimental data violate the Bell inequality albeit with a loophole similar to the detection loophole in photon counting experiments.

Abstract:

Remote state preparation of single-mode photonic quantum bits in a counter intuitive scheme was discussed. An electromagnetic field quadrature measurement was performed. The measurements collapses the nonlocal single-photon state into a superposition of the single-photon and vacuum states in the other mode. It was found that the preparation efficiency of the resulting qubit can be higher than that of the initial single photon.

Abstract:

An electromagnetic field quadrature measurement, performed on one of the modes of the nonlocal single-photon state alpha|1,0>-beta|0,1>, collapses it into a superposition of the single-photon and vacuum states in the other mode. We use this effect to implement remote preparation of arbitrary single-mode photonic qubits conditioned on observation of a preselected quadrature value. The preparation efficiency of the resulting qubit can be higher than that of the initial single photon.