Strongly coupled cavity QED and the precision measurement of single atoms

Cavity quantum electrodynamics (QED) provides an enhanced interaction between single atoms and the cavity. The strongly coupled cavity QED system enables us to sense and track the position of single atoms in real time. With the tilted asymmetric TEM10 cavity modes, one can eliminate of the degenerate trajectory of a single atom and determine the trajectory of single atoms with an improved spatial resolution.

We have also experimentally demonstrated the strong coupling between single atoms and the higher order Hermite-Gaussian transverse modes in a high-finesse optical micro-cavity. Compared to the usual low-order symmetric transverse modes, multiple lobes and the asymmetric spatial pattern of the titled modes provide more information about the motion of single atoms in the cavity. The motional information can be extracted from the measured transmission spectra, which includes the velocities and the positions of the atoms in vertical and off-axis directions. As a sensitive single atom detector, strongly coupled cavity QED system can help us to measure the temperature and the statistical properties of the cold atoms and the scheme has great potential in time-resolved atom-cavity microscopy and in tracking single atom trajectory.

Microtoroidal resonators based on chip is used to confine light in small volumes with extremely low losses. The resonator gives rise to extremely high quality factors and strong coupling between the resonator and atoms can thus be obtained. Very weak light on single photon level can demonstrate the manipulation of atomic states. We plan to couple the neutral Cesium atoms or quantum dots to the microtoroidal resonator and demonstrate quantum information processing based on the microtoroidal resonator system.

Thanks for our collaborators: Prof. Min Xiao’s research group in Nanjing University and Prof. Chenyang Xue’s research group in North University of China.