The overall aim of this proposal is to use the powerful techniques developed for manipulating ground-state atoms, such as optical lattices, to study ultra-cold Rydberg gases and plasmas. More specifically, this proposal uses strontium atoms in a lattice t o look at two different electron transport effects.
The first is delocalisation of electrons along the lattice. A Rydberg atom with principal quantum number n=60 has an orbital radius of 280 nm. In an optical lattice, this orbital radius can exceed the distance between atoms in neighbouring sites, and the electronic wavefunctions of atoms trapped at different sites will begin to overlap.
It has been suggested that under these circumstances the Rydberg gas may undergo a Mott-type transition to a state where the electrons become delocalised. Ionizing a single site of the optical lattice provides an ideal way to study a second kind of charge transport that is predicted to occur in ultra-cold mixtures of atoms and ions. At such low temperatures, the cross-section for charge-transfer collisions can be high, and the thermal de Broglie wavelength of the atoms and ions, approaches the inter-particle spacing in the gas.
Under these conditions, an electron can "hop" from a neutral atom onto an ion, and charge transport occurs via the movement of positively charged "holes". This part of the proposal relies on the unique electronic structure of strontium atoms. In combination with techniques developed in quantum information research, this will allow us to control t he electronic state of the gas at the level of a single particle.
Fields of science
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