Abstract:
Linear optics (LO) has been demonstrated to be an optimal system for quantum computation and information.
Classical polarimetry makes available efficient and accurate ways to
prepare and measure the polarisation of optical fields; transposing to
the single-photon level, these correspond to preparation and
measurement of qubits. The hardest task to achieve with single photons
is to realise a nonlinear interaction of these very weak fields, for
the implementation of quantum gates. This issue can be partially
overcome by resorting to linear devices, measurement and
post-selection; by this technique, a controlled-NOT gate has been
successfully demonstrated. The next challenge is to extend the
technique to slightly more complex quantum circuits. In this talk I
will discuss the first steps in this direction: the demonstration of a
three-qubit Toffoli gate,
and the realisation of a quantum control protocol which relies on the
possibility of supplementing the action of the gate with classical
feedback.
Joint Quantum Optics/AMO Seminar and QUINF Seminar
(PLEASE NOTE NON-STANDARD DATE AND PLACE)