Particle Optics

Jian Wei Tay, Magnus T. L. Hsu, Warwick P. Bowen

Particle sensing in optical tweezers systems provides information on the position, velocity, and force of the specimen particles. The conventional quadrant detection scheme is applied ubiquitously in optical tweezers experiments to quantify these parameters. In this paper, we show that quadrant detection is nonoptimal for particle sensing in optical tweezers and propose an alternative optimal particle sensing scheme based on spatial homodyne detection. A formalism for particle sensing in terms of transverse spatial modes is developed and numerical simulations of the efficacies of both quadrant and spatial homodyne detection are shown. We demonstrate that 1 order of magnitude improvement in particle sensing sensitivity can be achieved using spatial homodyne over quadrant detection.

Časlav Brukner, Anton Zeilinger

Stationary matter wave optics and stationary light optics are equivalent when we consider one-particle systems in vacuum. We show that, in contrast, stationary optics of energy-entangled particles is completely different for matter waves and for light. This difference is illustrated comparing the two-particle interference patterns exhibited by matter waves and by light, respectively. The time-independent probability for simultaneous detection of the two massive particles or of the two photons is strikingly nonequivalent.

O. Steinmann

M. H. Urin

An attempt to formulate the optical model of particle-hole-type excitations (including giant resonances) is undertaken. The model is based on the Bethe--Goldstone equation for the particle-hole Green function. This equation involves a specific energy-dependent particle-hole interaction that is due to virtual excitation of many-quasiparticle configurations and responsible for the spreading effect. After energy averaging, this interaction involves an imaginary part. The analogy between the single-quasiparticle and particle-hole optical models is outlined.