The realization about ten years ago, in laboratory experiments, of Bose-Einstein condensates (BEC) and degenerate Fermi gases (DFG) has been a major achievement in the field of atomic physics. Loading ultra-cold degenerate gases, be it fermions, bosons, fermion-boson or fermion-fermion mixtures into optical lattices has opened fascinating new perspectives. Indeed the high degree of control and precision achieved in these experiments (the optical potentials can be tailored almost at will, spurious dephasing processes can be circumvented, etc) has allowed systematic studies of physical phenomena mostly observed until now in condensed-matter systems and has even opened a window on completely new phenomena.
This convergence has favoured the cross-fertilization of two communities as evidenced by the experimental observation, with degenerate quantum gases, of the superfluid to Mott insulator transition, the Berezinskii-Kosterlitz-Thouless transition, the Abrikhosov vortex lattice to name a few examples. One of the great assets of ultra-cold atoms is the fine tuning of inter-particle interactions through the use of the so-called Feshbach resonances as evidenced by the recent clear-cut evidence of the BEC-BCS crossover in the cold fermion community, or by the track of the Fulde–Ferrell–Larkin–Ovchinnikov (FFLO) state when the spin populations are unbalanced.
The recent interplay between disorder or frustration and interactions paves now the way to the observation of new quantum phases such as Bose, Fermi glasses, spin glasses or spin ices, etc. Directions with perspectives in quantum information and computation are also explored making a bridge with another vast community. One has the feeling that the gold mine is far from being exhausted, with much many predicted phenomena still to be observed (or understood) than what the current experimental resources can work out. With about 80 BEC and about 15 DFG experiments all over the world and 10 years of constant progress, it seems to us that it is time to have a survey of the achievements and perspectives in the field.
The objectives of the « quantum transport » part of this proposed Les Houches School session in Singapore will be to initiate the young participants to this very active field of research, to offer them an overview of its last developments, to make them share with the lecturers, who are major actors in the field, the excitements and challenges of the community and to promote discussions and links in view of future collaborations (internships, PhD, post-docs, etc).
Quantum information is the field of research studying information processing within the realm of quantum mechanics by incorporating two key features, the superposition principle and entanglement. This subject pools a vast international community with people having very different backgrounds (informatics, mathematics, atomic physics, optics, condensed matter, etc).
The two main parts of the field are quantum cryptography, which allows to dramatically increase the security of key distribution over a public channel, and quantum computation, which develops algorithms able to decrease dramatically the time needed to solve complex problems like factoring integers into products of primes. The elementary component of this new informatics is the quantum bit (qubit) and by combining different qubits one can build up elementary quantum gates. An interesting feature is that a finite number of quantum gates, thus coined universal, are enough to implement any quantum computation once appropriately connected.
The physical realisation of these universal quantum gates would yield a quantum computer, the Grail in the field. However the practical difficulties are huge because full quantum operation of the computer requests to protect qubits from decoherence due to coupling to the surrounding environment. Many experimental systems are currently under investigation (trapped ions, trapped neutral atoms, nano-junctions, quantum dots, RMN, quantum electrodynamics in micro-wave and optical cavities) and radical and innovative solutions are actively looked for. The stakes of quantum information are thus covering many different aspects, from fundamental and applied science to cutting-edge technology, economy (e.g. through encryption of secured communications of any kind) and above all to the development of a society being increasingly dependent of information technologies.
The objectives of the « quantum information » part of this proposed Les Houches School session in Singapore will be to initiate the young participants to this very active field of research, to offer them an overview of the last developments, to make them share with the lecturers, which are leaders in quantum information, the excitements and challenges of the field and to promote discussions and links in view of future collaborations (internships, PhD, post-docs, etc).