Southwest Quantum Information and Technology

Fourteenth Annual Meeting, February 16-19, 2012
Albuquerque, New Mexico

Full Program | Thursday | Friday | Saturday | Sunday | All Sessions

SESSION 12: Atom-Light Interface - Franciscan Room
Session Chair:
8:30am-9:15am	James Thompson, JILA (invited)
	Ensemble Cavity QED & Precision Metrology
	Abstract. I will discuss quantum metrology experiments using large ensembles of cold, trapped atoms and cavity QED. The first portion of the talk will describe conditional spin squeezing of the clock transition of a million Rb atoms, achieved by utilizing the vacuum Rabi splitting as a collective QND meter. The second portion of the talk will describe a Raman laser that operates deep into the superradiant or bad-cavity regime. The system is demonstrated to operate with <1 intracavity photon and with an effective excited state decay linewidth <1 Hz. This model system demonstrates key physics for future active optical clocks that may achieve frequency linewidths approaching 1 mHz due to reduced sensitivity to thermal mirror noise.
9:15am-9:45am	Morgan Mitchell, ICFO - Institute of Photonic Sciences
	Quantum Technologies for Light-Matter Interaction
	Abstract. We describe experiments with highly non-classical states (heralded single photons and NooN states) in interaction with atomic ensembles. Our approach uses ultra-bright cavity-enhanced down-conversion and ultra-narrowband ``interaction-free measurement'' filters. With these we demonstrate heralded single photons that are at least 94 % atom-resonant, with multi-photon contamination below 4%. Also 90% fidelity NooN states, and sensitivity beyond the standard quantum limit in a near-resonant Faraday rotation magnetometer. The potential for highly multi-partite, atom-resonant entanglement using these techniques will also be discussed.
9:45am-10:15am	Leigh Norris, University of New Mexico
	Enhanced Spin Squeezing Through Quantum Control of Qudits
	Abstract. Spin squeezed states have applications in metrology and quantum information processing. While there has been significant progress in producing spin squeezed states and understanding their properties, most spin squeezing research to date has focused on ensembles of qubit spins. We explore squeezed state production in an ensemble of spin f>1/2 alkali atoms (qudits). Collective interactions are achieved through coherent quantum feedback of a laser probe, interacting with the ensemble through the Faraday interaction. This process can be enhanced through further control of the atomic qudits. We control the internal atomic state both before and after the collective interaction. Initial preparation increases the collective squeezing parameter through enhancement of resolvable quantum fluctuations. Qudit control can then be used to map entanglement created by the collective interaction to different pseudo-spin subspaces where they are metrologically useful, e.g., the clock transition or the stretched state for magnetometry. In the latter case, additional internal control can be used to squeeze the individual atoms, further enhancing the total squeezing in a multiplicative manner. The actual squeezing will depend on a balance between the enhanced coupling and decoherence. These considerations highlight the unique capabilities of our platform: we are able to transfer coherences and correlations between subspaces and integrate control tools to explore a wider variety of nonclassical states, with ultimate application in sensors or other quantum information processors.