Continuous Measurement of Atomic Motion

John E. Thomas, L. J. Wang

Jürgen Audretsch, Th. Konrad, Michael B. Mensky

Continuous weak or fuzzy measurement of the Rabi oscillation of a two level atom subjected to a $π-$pulse of a resonant light field is simulated numerically. We thereby address the question whether it is possible to measure characteristic features of the motion of the state of a single quantum system in real time. We compare two schemes of continuous measurement: continuous measurement with constant fuzziness and with fuzziness changing in the course of the measurement. Because the sensitivity of the Rabi atom to the influence of the measurement depends on the state of the atom, it is possible to optimize the continuous fuzzy measurement by varying its fuzziness.

Ralf Quadt, Matthew J. Collett, Daniel F. Walls

It is shown that the photocurrent measured using homodyne detection of the phase quadrature on the output field of a cavity gives information about the transverse motion of an atom passing through the standing light field inside the cavity. Monte Carlo simulation techniques are used which result in quantum trajectories of the system conditioned on the measured photocurrent, i.e., the photocurrent defines the backaction of the continuous measurement on the atomic motion.

W. L. Power, Martin Wilkens

Shohini Ghose, Paul M. Alsing, Ivan Deutsch +3 more

Summary form only given. The recovery of the classical limit in quantum systems that have underlying chaotic dynamics is a key question in current studies of the quantum to classical transition. Interaction with an environment results in decoherence that can cause the quantum Wigner function to approach the corresponding classical phase space distribution by suppressing quantum interference effects, but it fails to extract localized classical trajectories from the quantum dynamics. Such trajectories are crucial for quantifying chaos both theoretically and in experiments through the measure of the Lyapunov exponents. One can recover trajectories from the quantum dynamics through the process of continuous measurements when the record is retained. Ehrenfest s theorem guarantees that quantum systems that are well localized by the measurement effectively obey classical mechanics. We have studied the role of continuous measurement in recovering the classical chaotic dynamics of laser cooled atoms in a magneto-optical lattice of double wells.

J. L. Hanssen, Valery Milner, Todd P. Meyrath +1 more