
This PITP/Les Houches summer school was an experiment in several ways,
and it would be very useful to us at PITP if you could answer several questions.
The questionnaire can be
filled out by anyone who attended the school  this includes students,
lecturers, and invited guests/companions.
Please fill out this form if you are intending to submit
anything to be published in the proceedings of the school, as we need
to know in advance, as accurately as possible, who will be contributing, and what is the expected size
of their contribution.
The school will cover the following main themes:
(1) MAGNETISM at the MICROSCOPIC SCALE: The microscopic
basis of
magnetic phenomena, hierarchies of effective Hamiltonians in
stronglycorrelated systems, including wellknown models like the
Anderson and Kondo Hamiltonians (and lattice versions of these), the
Hubbard Hamiltonian, and refinements of these like the ZSA model.
There will be some emphasis on the chemistry of interesting magnetic
systems, including magnetic molecules, and on new 'quantum
materials' showing magnetic properties. The physics of
stronglycorrelated systems requires both analytic and powerful
numerical methods, and the results of some of these latter methods
will be discussed in some detail, notably density functional,
dynamical cluster, and dynamical mean field theories, and also
Quantum Monte Carlo methods.
(2) EXOTIC ORDER in QUANTUM MAGNETS: The standard
classical magnetic
ordering theory fails to describe ordering in genuine quantum
magnets. This is particularly clear in lower dimensions, where one
can get many exotic kinds of ordering, both local and nonlocal.
This even happens in 3 dimensions, with systems of particular
interest being He3 (solid and superfluid) and quantum spin glasses like the LiHoYF
system. A key feature of many of the novel magnetic
states is their nontrivial topological properties. New kinds of
quantum liquids range from simple spin liquids to more exotic systems
like the Quantum Hall ferromagnets or spin BoseEinstein
condensates of key interest are spin and charge fractionalisation,
and exotic quasiparticle statistics. Some of the most interesting
states occur in 1dimensional spin systems, which are also of great
current interest in the context of quantum computation.
(3) DISORDERED MAGNETS: Many remarkable critical
phenomena
(including the clearest examples of quantum critical phenomena)
occur in disordered magnetic systems. In recent years novel features
of these have been discovered in the lowT quantum regime of these
systems, including quantum spin glass phases, as well as novel
ordering in systems having random fields and/or positional disorder.
There
are also very interesting connections to phenomena in other systems,
such
as dipolar glasses at very low T.
(4) QUANTUM NANOMAGNETISM: At very small scales, or near
surfaces,
magnetic systems can behave very differently from at macroscopic
scales. Three are of particular interest, viz., (i) Magnetic
molecules, which show a variety of quantum tunneling phenomena, and
which have been the object of many studies in a search for coherent
tunneling in the search for spin qubit systems; (ii) mesoscopic and
nanoscopic conductors, which not only show interesting classical
'spintronic' phenomena, but also are predicted to show a variety of
interesting quantum effects, including 'spin Hall' effects, which
often depend on interesting topological properties of the underlying
quantum states; and (iii) spins on metallic surfaces, which show
fascinating manybody effects, and which can can be investigated
directly using STM imaging techniques.

We thank our
generous sponsors:



(5) LARGESCALE QUANTUM PHENOMENA IN MAGNETS: Tunneling
of
largespin molecules and of magnetic solitons has been seen already
at the nanoscopic and mesoscopic scale, and further more exotic
phenomena of this kind are predicted. Perhaps the most dramatic part
of this field is the search for largescale entanglement, and the
application of this to quantum computation. The key problem here, as
in other kinds of quantum computation, is the understanding of both
the mechanisms of decoherence, how to suppress decoherence, and how
to understand its dynamics. Magnetic systems are offering a rather
unique window on these very general questions. One exciting new
possibility has appeared in the idea of topological quantum
computation, where the computation is embodied in the topological
properties of a spin wavefunction, and is almost immune to
decoherence.

