Cold Atom Physics

Light can be guided in optical fibres from one place to the next nearly without loss. If the diameter of the fibre is smaller than the wavelength of the light a large fraction of the light intensity is found outside the fibre. The extent of the light outside the fibre is also small; the transverse size of the fibre photon is about the size of the cross section of an atom interacting with the photon. If an atom is placed near the thin fibre there is a high probability that the atom interacts with the photon.

In Stefan Eriksson’s Cold Matter Research Laboratory investigations are underway on quantum interfaces between atoms and photons in sub-wavelength diameter optical fibres, which are drawn by stretching an ordinary optical fibre under intense heat. Stefan and team will use the unparalleled control of the state of the atom provided by laser cooling and trapping to manipulate atoms near the fibre. Their plan is to first understand the atom-fibre photon infarction in this highly controlled environment with possible future applications in quantum enhanced sensing and information processing.

The team is highly skilled in quantum optics and atomic physics. Past experience includes atom interferometry with Bose-Einstein condensates on atom chips and laser physics. The labotatory has a fully operational laser cooling and trapping apparatus in which fibres and other chip scale devices can be mounted. The team has built a fibre pulling apparatus that allows the fabrication of fibres with diameters that taper down from the standard 125 microns to a few hundred nano-metres and back again over a few millimetres long segment of the fibre. The team has single photon sensitive detection capabilities.

Saijun Wu’s laboratory has an ultra-high-vacuum laser cooling apparatus capable of slowing and cooling neutral rubidium atoms (with a capacity to slow and cool lithium atoms under development). A high sensitivity holographic microscope for imaging neutral atoms under laser cooling has been developed. Saijun has a Dell workstation with Graphic Processing Unit (GPU) for scientific computing, in particular, for holographic reconstruction of cold atom images at the shot noise limit, and for simulating light-atom interaction dynamics in novel laser cooling schemes. He has active links with a number of prominent groups in the field of cold atoms, notably: the group of Trey Porto at the University of Maryland’s Joint Quantum Institute; the team under Christophe Salomon and Frederic Chevy the LKB, Paris and Stefan Kuhr’s group at the University of Strathclyde.