Asymmetric Fermi Superfluids and Engineered Quantum Systems

Asymmetric Fermi Superfluids: electrons come in two types - called spinup and spin down . In superconductors each spin up electron joins a spindown electron to form what is called a Cooper pair. These are responsiblefor conducting electric current without dissipation. The question arises -what happens when there are more spin up than spin down electrons? What isthe best way to accomodate the extra spin up ones? It turns out that thisis an extremely difficult and still open problem after more than fortyyears. Recently we have a new experimental system - cold gases of atoms (instead ofelectrons) which exhibit the same physics as superconductors and theexperiments are much easier to perform and interpret than with electronsso we have a real opportunity to solve this puzzle. We can also ask whatwould happen if instead of playing with different spins we paired atomswith different masses - a question which cannot be easily asked withelectrons. My research will help to interpret experiments in the search for new phases of matter which are expected to appear in these systems. Further, I hope to be able to provide a unified theoretical framework at the end when the problem is solved.Engineered Quantum Systems: 1) nonequilibrium physics - cold atoms arevery slow and we can change the conditions they experience in the labfaster than the time it takes them to react! We can also photograph themin action. This allows us to study the complicated motions that theyundergo as they rearrange themselves in response tosomething that we did (like compressing them, suddenly giving them moreenergy, etc). This is a new field since other systems (such as electronsin metals) usually move too fast for us to see what they are doing. It is also a new way of exploring so-called many-body quantum mechanics - what happens when there are many atoms in a time-dependent situation. 2) interfaces for quantum information - recent progress in quantum computing has proposed the idea of hybrid quantum computing. Some systems (liketrapped ions) are very good memories for qubits. Others (like solid statenanostructures) work very well as CPUs. How do we transfer qubits betweenthem and which systems couple best? I propose to study a variety ofatom-solid state systems in search of the best interface technology inwhat promises to become a vital area of research in the near future.