Controlling the Position and Motion of a Single Atom in an Optical Cavity

Mojtaba Moazzezi, Yuri V. Rostovtsev

Thomas H. Fischer

An experiment is described where slow laser-cooled atoms are injected into a high-finesse optical cavity. Single atoms are trapped in the cavity light field and observed by measuring the light intensity transmitted through the cavity. Feedback-based methods are realized to extend the time the atom stays in the cavity. The influence of atoms on the cavity transmission and the light force on atoms in a cavity are also analyzed theoretically. This allows to study the motion of an atom in the cavity and to interpret the experimental transmission signals. The current limitations for the storage time are identified and a strategy to overcome them is suggested. Apart from that, a method is proposed which allows a two-dimensional position measurement of atoms in the cavity.

Alexander Kubanek, M. Koch, Christian Sames +4 more

T W Lynn, K Birnbaum, H J Kimble

Recent realizations of single-atom trapping and tracking in cavity QED open the door for feedback schemes which actively stabilize the motion of a single atom in real time. We present feedback algorithms for cooling the radial component of motion for a single atom trapped by strong coupling to single-photon fields in an optical cavity. Performance of various algorithms is studied through simulations of single-atom trajectories, with full dynamical and measurement noise included. Closed loop feedback algorithms compare favorably to open-loop "switching" analogs, demonstrating the importance of applying actual position information in real time. The high optical information rate in current experiments enables real-time tracking that approaches the standard quantum limit for broadband position measurements, suggesting that realistic active feedback schemes may reach a regime where measurement backaction appreciably alters the motional dynamics.

S. Nußmann

T. W. Lynn, Kevin M. Birnbaum, Harry J. Kimble

Recent realizations of single-atom trapping and tracking in cavity QED open the door for feedback schemes which actively stabilize the motion of a single atom in real time. We present feedback algorithms for cooling the radial component of motion for a single atom trapped by strong coupling to single-photon fields in an optical cavity. Performance of various algorithms is studied through simulations of single-atom trajectories, with full dynamical and measurement noise included. Closed loop feedback algorithms compare favorably to open-loop "switching" analogs, demonstrating the importance of applying actual position information in real time. The high optical information rate in current experiments enables real-time tracking that approaches the standard quantum limit for broadband position measurements, suggesting that realistic active feedback schemes may reach a regime where measurement backaction appreciably alters the motional dynamics.