The Measurement of Photon Number States Using Cavity QED

S. Brattke, Gerhard R. Guthöhrlein, Matthias Keller +3 more

J. M. Geremia

An experimentally viable approach for preparing arbitrary photon number states of a cavity mode using continuous measurement and real-time quantum feedback is presented. The procedure passively monitors the number state actually achieved in each feedback-stabilized measurement trajectory, thus providing nondestructively verifiable photon generation. The feasibility of a possible cavity QED implementation in the many-atom, good-cavity-coupling regime is analyzed.

R. M. S. Knops, Wolfgang P. Schleich, Herman C. W. Beijerinck +1 more

Huai‐Zhi Wu, Zhen‐Biao Yang, Shi‐Biao Zheng

We propose a scheme for the direct measurement of Wigner function in two-mode cavity QED. The atoms are sent to resonantly interact with two orthogonally polarized cavity modes in the presence of strong classical field. The probability of measuring the atom in the ground state directly gives the useful information of the cavity field. This method can be used for quantum non-demolition measurement of the photon number.

Hans Martens, Willem M. de Muynck

Moonjoo Lee, Wontaek Seo, Hyun-Gue Hong +2 more

We report the measurement of the population and coherence of identically prepared two-level atoms with the cavity-QED microlaser. The atomic superposition state after coherent interaction with a pump field is directly mapped to the intra-cavity photon number and frequency shift of the microlaser. Our scheme is applicable to quantum information as a tool for analyzing a two-level atomic qubit.