SUPERFLUIDFERMIGAS 2 · Superfluidity in Fermi Gases
FP6 — Marie Curie Actions (Human Resources and Mobility)
- Duration
- 2004-02-15 → 2006-02-14
- EU contribution
- €153,072
- Participants
- 1
- Scheme
- EIF
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Results in brief
Final Activity Report Summary - SUPERFLUIDFERMIGAS 2 (Superfluidity in Fermi Gases)
The subject of our proposal was the study of superfluidity in an ultracold gas of fermionic atoms. Superfluidity is a quantum phenomenon closely related to superconductivity, in which a fluid flows without resistance. The most prominent example is liquid helium, but in recent years ultracold atomic gases have emerged as a new type of superfluid. Fermions are particles, such as electrons and some atoms, with half-integer spin and, during the last three to four years it became possible to form a superfluid in ultracold gases of interacting fermionic atoms. The most exciting links between these atomic gases and condensed matter physics are for fermions, since it is possible to create systems which correspond almost perfectly to important theoretical models. This could bring new understanding to areas such as high-temperature superconductivity, a phenomenon with enormous technological implications. During the time of the fellowship we used expansion measurements to investigate the properties and superfluid character of ultracold fermionic lithium. The gas was prepared in the strongly interacting regime with tuneable interactions, a unique and crucial feature of quantum gas experiments. Via releasing the gas from its trap under various conditions and analysing the dynamics of the expansion, we were able to test theoretical models describing this quantum many-body system. More specifically, we were able to characterise the momentum distribution of the gas in different regimes of atomic interactions and we saw evidence for a breakdown of superfluidity in the limit of weak attraction. We also undertook an upgrade of almost the entire experimental apparatus, enabling a whole series of new experiments in 2007 and beyond, including fermionic superfluidity in periodic potentials.
Data: CORDIS, © European Union
Project objective
Since the first observation of Bose-Einstein condensation (BEC) in a dilute atomic gas in 1995, the field of quantum degenerate gases has attracted a great deal of interest from the physics community.Research on ultra-cold Fermi gases has been developing at a very rapid pace since its inception in 1997, and is expected to lead to the next major breakthrough in atomic physics: the experimental realization of superfluidity in a quantum degenerate Fermi gas.Since the quantum statistics for fermions are the same as for electrons in solids, these experiments open up new opportunities for insights into condensed matter systems and the theories that describe them. The aim of the proposed research is to achieve superfluidity in a lithium-6 Fermi gas and study its properties in detail.The host institution, as well as three other groups worldwide, have just produced molecular condensates consisting of pairs of fermionic atoms by using a Feshbach resonance, which enables tunable interatomic interactions.In addition to enabling highly efficient production of cold molecules, this method will lead to the study of a new crossover regime between the superfluid phase of a molecular condensate and Bardeen-Cooper-Schrieffer (BCS) superfluidity for fermions with attractive interactions. The properties of the molecular condensate will be investigated and collective excitation modes will be employed to study the system in this crossover regime.Next, we will develop methods to investigate the superfluid character of the fermions and to measure the gap in the excitation spectrum. Another goal of our proposal is to load a Fermi gas into an optical lattice, in which investigations of the Fermi-Hubbard model will be performed.This research holds tremendous potential to push the boundaries of scientific knowledge on many-body physics, while also providing insights into technologically relevant areas such as superconductivity.
Original text from CORDIS.
Participants
- CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE · PARISCoordinatorFrance
Links
Data: CORDIS, © European Union