Quantum deflection of ultracold atoms by ideal mirrors

Abstract

We study the effect of deflection of narrow quantum wave packets from atomic mirrors. If the initial mean value of the momentum is less than the momentum uncertainty, then the mean value of the momentum gradually increases with time at the expense of the energy of quantum fluctuations, due to the effective quantum nonlocal interaction with the boundary, so that essential part (more than half) of the energy of quantum fluctuations can be transformed into the kinetic energy of the center of the wave packet. The evolution of different kinds of packets is analyzed in detail in the case of a free motion in a half-space confined with an ideal impenetrable boundary (including the coordinate and momentum probability distributions, the Wigner quasiprobability, the invariant uncertainty product, etc.). For arbitrary mirrors (totally reflecting or partially transparent) we have obtained general expressions describing the asymptotical behavior of initial narrow packets. A possibility of the verification of the effect in experiments with light ultracold atoms is discussed.