Matthew Terraciano

A single-shot imaging magnetometer using cold atoms

We demonstrate a technique for imaging magnetic fields using velocity-selective two-photon resonances in a cold atom cloud. Freely expanding (85)Rb atoms released from a magneto-optical trap are exposed to a brief (approximately 1 ms), off-resonant, retro-reflected laser pulse in a lin-perp-lin configuration. Two-photon resonance between magnetic sublevels occurs only for atoms in narrow velocity classes dependent on the magnetic field strength. The momentum of resonant atoms is altered by the pulse, and this two-photon momentum change is easily visible after further ballistic expansion. When the momentum pulse is applied to an atom cloud with finite size, magnetic field variations across the sample result in position-dependent features in images of the expanded cloud. We demonstrate the technique by imaging magnetic field variations over approximately 5 mm with approximately 250 microm spatial resolution.

Magnetometry with High Sampling Rate Using Cold Atoms in a Movable Dark Optical Trap

We use Faraday spectroscopy of atoms confined to a crossed hollow beam trap to measure the magnetic field in a 200-micron-diameter spot with kilohertz sampling rate. Magnetic field maps are acquired by dynamic trap scanning.

Entanglement Measurement in a Cavity QED System

We measure an entanglement witness of a cavity QED system with the cross correlation of its orthogonal modes. The driven mode has information about the field, while the nondriven about the atom through spontaneous emission.

Cavity QED with an optical lattice; towards quantum feedback with atomic detuning

The incorporation of an optical lattice in a cavity QED system increases the number of parameters available for quantum feedback.