There are many advantages in using light to encode quantum information. Due to a relatively small coupling with their environment, decoherence is less severe on photons than other systems, and high precision measure- ment and many techniques for the manipulation of non classical light are available in the lab.
Quantum Information (QI) was mostly formulated in terms of qubits, finite dimensional quantum systems analog to the classical bits. In Quantum Optics (QO), this corresponds to the single-photon (or few photons) regime. Many protocols have also been translated to infite dimensional systems, corresponding to the continous- variable regime in QO. This is the case of the measurement-based paradigm for quantum computation, in which information is processed via local measurements on an entangled resource state (cluster state), which is pre- pared starting from a multimode squeezed state. The basic measurements required in the optical setting are homodyne measurements. Our group has developed a setup in which an optical parametric oscillator syn- chronously pumped by a pulsed laser (SPOPO) produces a multimode squeezed state which is then measured by multimode homodyne detection.
The main goal of my research project is to explore the potential of this setup for quantum information process- ing. On the one hand I focus on the use of simple non-Gaussian operations, such as photon subtraction from squeezed states, for quantum computation and quantum information processing in general. This is motivated by recent proposals to introduce mode-selective photon addition/subtraction to the SPOPO setup, but the re- sults may be of interest in other setups as well, since these are among the simplest non-Gaussian operations to do in the lab. On the other hand I study how the properties of the output of the SPOPO are affected by the spectral/temporal shape of the pulses in the pump beam and how pulse-shaping can be used to engineer the squeezing and the correlations in the output beam. The ultimate goal is to combine all this to realize interest- ing QI protocols with minimal or no modifications to the existing experimental setup or to propose sensible modifications.
Talks : Partenariat équipe QI