We work at the boundary between Quantum Optics and Cold Atom physics.
We use 4-wave mixing in a rubidium vapour to generate beams that are entangled in their quadratures as well as in their transverse spatial degrees of freedom. These light fields, dubbed "quantum images", have subtle quantum correlations in their phases and their amplitudes that depends on the position in their transverse profiles. They could be used for the imaging of hard to see (transparent) objects, accurate beam positioning, or quantum cryptography.
- Figure: 4-wave mixing in a rubidium vapour. Two pump photons are converted into one probe photon and one conjugate photon, generating strong correlations between the probe and the conjugate.
Atomic quantum memories
The entangled beams created by 4-wave mixing are resonant with a rubidium transition. This allows us to envision the creation of quantum information processing (QIP) systems (for quantum communications, quantum computations, etc.) where light plays the role of information carrier and atoms the role of a memory. The challenge is to transfer quantum information from a beam of light to a collection of atoms, and to transfer it back to the light at a later time. The development of long-lived quantum memories is of paramount importance to the nascent field of QIP, and cold atoms in optical lattices are good candidates to provide a flexible and controllable testing ground for the implementation of new ideas toward this goal.