Charge delocalisation and hopping in an ultra-cold atomic lattice

Lead Research Organisation: Durham University
Department Name: Physics

Abstract

Using lasers, a cloud of atoms can be cooled to within a millionth of a degree above absolute zero. Atoms that are this cold hardly move at all, and they can be trapped using laser beams to make a crystal of regularly spaced atoms held in place by light, known as an optical lattice. The aim of this project is to study what happens when we excite the electrons in these atoms to high energies using a pulse of laser light. Normally the electrons in an atom orbit close tothe nucleus, but if we give the outermost electron more and more energy, its orbit gets larger and larger. Eventually the electron orbits of neighbouring atoms in the lattice begin to overlap, and the electrons no longer belong to a particular atom and can spread out along the lattice. This concept is important in many areas of physics, for example in explaining how the electrons in a metal free themselves to form an electrical current. The advantage of studying this with ultra-cold atoms trapped in an optical lattice is that the properties of each of the atoms in thelattice can be controlled extremely precisely. For example using a laser beam an electron can be removed from just one atom in the lattice, leaving behind a single positively charged ion. An electron from a neighbouring atom can then ``hop'' across to replace the lost electron, leaving behind an ion in its turn. Studying how electrons hop from atom to atom is one of the goals of this proposal.

Publications

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Bridge EM (2009) A vapor cell based on dispensers for laser spectroscopy. in The Review of scientific instruments

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Javaux C (2010) Modulation-free pump-probe spectroscopy of strontium atoms in The European Physical Journal D

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Mauger S (2007) Spectroscopy of strontium Rydberg states using electromagnetically induced transparency in Journal of Physics B: Atomic, Molecular and Optical Physics

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Millen J (2011) Spectroscopy of a cold strontium Rydberg gas in Journal of Physics B: Atomic, Molecular and Optical Physics

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Millen J (2010) Two-electron excitation of an interacting cold Rydberg gas. in Physical review letters

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Mukherjee R (2011) Many-body physics with alkaline-earth Rydberg lattices in Journal of Physics B: Atomic, Molecular and Optical Physics

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Vaillant C (2012) Long-range Rydberg-Rydberg interactions in calcium, strontium and ytterbium in Journal of Physics B: Atomic, Molecular and Optical Physics

 
Description We laser-cooled strontium atoms and created a Rydberg gas for the first time. We were the first to create a cold gas of doubly excited atoms. We also clauclated some of their properties.
Exploitation Route Underpin growing area of research on two-electron Rydberg atoms
Sectors Education,Other

URL https://www.jqc.org.uk/research/two-electron-rydberg-systems/
 
Description Used by other research groups to advance state of the art in the field
First Year Of Impact 2007
Sector Education,Other
Impact Types Cultural,Societal

 
Description EPSRC
Amount £596,000 (GBP)
Funding ID EP/J007021/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Academic/University
Country United Kingdom
Start 07/2012 
End 07/2016
 
Description Collaboration on two electron Rydberg atoms with MPIPKS Dresden (Pohl group) 
Organisation Max Planck Society
Department Max Planck Institute for the Physics of Complex Systems
Country Germany 
Sector Charity/Non Profit 
PI Contribution Start of a collaborative project on the theory of many-body physics with two-electron atoms
Start Year 2010