A simple scheme for expanding photonic cluster states for quantum information

Research paper by Pruet Kalasuwan, Gabriel Mendoza, Anthony Laing, Tomohisa Nagata, Jack Coggins, Mark Callaway, Shigeki Takeuchi, Andre Stefanov, Jeremy L. O'Brien

Indexed on: 22 Mar '10Published on: 22 Mar '10Published in: Quantum Physics


We show how an entangled cluster state encoded in the polarization of single photons can be straightforwardly expanded by deterministically entangling additional qubits encoded in the path degree of freedom of the constituent photons. This can be achieved using a polarization--path controlled-phase gate. We experimentally demonstrate a practical and stable realization of this approach by using a Sagnac interferometer to entangle a path qubit and polarization qubit on a single photon. We demonstrate precise control over phase of the path qubit to change the measurement basis and experimentally demonstrate properties of measurement-based quantum computing using a 2 photon, 3 qubit cluster state.