Details of Grant 

EPSRC Reference:	EP/J016985/1
Title:	Collective strong coupling of light and matter with cold atoms in a ring resonator
Principal Investigator:	Goldwin, Dr J
Other Investigators:
Researcher Co-Investigators:
Project Partners:
Department:	School of Physics and Astronomy
Organisation:	University of Birmingham
Scheme:	First Grant - Revised 2009
Starts:	30 May 2012	Ends:	29 May 2014	Value (£):	89,063
EPSRC Research Topic Classifications:	Cold Atomic Species Light-Matter Interactions
EPSRC Industrial Sector Classifications:	No relevance to Underpinning Sectors
Related Grants:
Panel History:	Panel Date Panel Name Outcome 18 Apr 2012 EPSRC Physical Sciences Physics - April Announced
Summary on Grant Application Form
Optical cavities have played a central role in atomic, molecular, and optical physics since the development of the laser. Within such cavities, increased field intensity gives access to a variety of nonlinear optical phenomena, and increased interaction length allows detection of even trace amounts of gases. For large numbers of atoms in small enough cavities, the system enters a regime of collective strong coupling. In this case the atoms and cavity field behave cooperatively, giving rise to a rich nonlinear dynamics. The simplest resonator design comprises a pair of parallel mirrors, but ring geometries involving three or more mirrors are used in a number of important applications. Ring laser gyroscopes form the basis of rotation sensing in navigation systems, and passive ring resonators have been used to measure optical activity in chiral liquids. Here we propose experiments with ultracold gases in an optical ring cavity, operating in the regime of collective strong coupling of atoms and light. This system has applications to laser cooling of molecules, self-organisation, quantum simulation, and precision metrology. The first phase of the experiment aims to understand cavity-enhanced cooling as a way to generalise laser cooling for use with molecules. Preliminary work in this field suggests that spatial self-organisation of atoms plays a crucial role in enhancing the coherent scattering into the cavity mode. Although the majority of theoretical work on this topic has been carried out within the ring geometry, the few existing cavity cooling experiments have utilised standing wave resonators. We will therefore be perfectly placed to investigate proposed advantages of the ring geometry, related to translational invariance and the coherent exchange of momentum between degenerate cavity eigenmodes. In the second phase of the experiment we will perform direct quantum simulation of condensed matter systems. There has been phenomenal success using quantum gases in optical lattice potentials to mimic a variety of solid-state crystalline systems. However one ingredient missing in most of this work is any atomic backaction onto the lattice potential. In typical experiments, the underlying optical lattice is unaffected by the position or motion of the atoms, in contrast with solids and with optical lattices in resonators. Recent experiments with Bose-Einstein condensates in high-finesse cavities have begun to study cavity optomechanics, and a quantum phase transition to a supersolid has been demonstrated. We will exploit the ring geometry to study systems with moving lattices in a regime where atom density modifies the optical potential. This will provide a key testing ground for condensed matter systems where lattice excitations play an important role.
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Organisation Website:	http://www.bham.ac.uk