For a diatomic molecule interacting with an off-resonant laser field it is shown how quantum vacuum fluctuations of the electromagnetic field act via spontaneous Raman processes on the molecular rotational degree of freedom. Furthermore, the inclusion of the molecule's centre-of-mass and the treatment of associated photon recoil effects is outlined. The obtained results form a basis for describing the combined centre-of-mass and rotational dynamics of the molecule in off-resonant, spatially varying laser fields, such as in the laser focus forming a dipole trap.
The application of stochastic cooling to trapped atoms is theoretically studied. We develop a quantum-field approach and investigate the fundamental limits of stochastic cooling, being determined by quantum-noise effects such as atom-number fluctuations and measurement back action. Moreover, using a spatially resolved operation, acting only on a fraction of the atomic cloud, is shown to lead to additional noise effects.
We implement the Bernstein-Vazirani algorithm on a 15-bit register encoding 2<sup>15</sup>-1 elements using optics. The apparatus is efficient in that the physical size of the apparatus scales linearly with the size (i.e. number of digits) of the register. We demonstrate also that the algorithm may be performed not only without entanglement, as Meyer has indicated, but also with a computational basis that does not consist of orthogonal states, and that this coding is the source of the efficiency of the algorithm. This raises several questions: is this the only algorithm that makes use of these simplifying features, or do all quantum Oracles in fact require exponential resources for their construction?