14_density
Measuring the Quantum State of a Large Angular Momentum
G. Klose, G. Smith, and Poul S. Jessen
Optical Sciences Center, University of Arizona, Tucson, AZ 85721
We demonstrate a general method to measure the quantum state of an angular momentum of arbitrary magnitude. The (2F+1) x (2F+1) density matrix is completely determined from a set of Stern-Gerlach measurements with (4F+1) different orientations of the quantization axis. We implement the protocol for laser cooled Cesium atoms in the 6 S1/2 (F=4) hyperfine ground state and apply it to a variety of test states prepared by optical pumping and Larmor precession. A comparison of input and measured states shows typical reconstruction fidelities greater than about 0.95.