Quantum Mechanics is the most successful scientific theory in
history. Despite repeated experimental tests, it has never been
found to fail. And yet it poses deep problems of principle, when
extrapolated to the macroscopic scale. Apart from its inherently
probabilistic nature, and its predictions of macroscopic
superpositions and macroscopic entanglement, it also appears to be
incompatible at a rather fundamental level with General Relativity.
This is of course another very successful theory which has yet to
fail any experimental tests, but which also poses deep problems,
notably in its prediction of singularities in spacetime.
For a long time it seemed to be very difficult to examine these
questions in the lab. Macroscopic quantum states superpositions
seemed almost impossible to attain because of decoherence, and any
confrontation between quantum theory and General Relativity
apparently only existed in black holes or the early universe.
However, this situation has now changed. Key experiments have now
been done, looking at largescale superpositions in solid state and
quantumoptical systems, and at the decoherence mechanisms operating
therein. Experiments looking at possible lowenergy deviations from
quantum mechanics caused by gravitation (including possible
'gravitational decoherence' effects), are either planned or
underway. Many of these experiments are attempting to disentangle
conventional decoherence effects from possible 'intrinsic' effects,
which, if they exist, would indicate a breakdown of quantum
mechanics.
The purpose of this meeting is to bring together people from the
different fields connected to this enterprise, in order to foster
discussions and collaboration. The main topics to be addressed are:
(i) Our current understanding of 'conventional' decoherence
mechanisms, both qualitative and quantitative, and how far these
mechanisms can be tested in experiments. Theoretical ideas for
deviations from quantum mechanics in condensed matter and quantum
optical systems. The extent to which quantum mechanics has already
been tested at the mesoscopic or macroscopic scale in the lab, and
the status of current experiments in this area, testing for
macroscopic state superpositions, macoscopic coherence, and entanglement. Designs for future tests of macroscopic quantum
effects.
(ii) The theoretical clash between General Relativity and quantum
mechanics. The extent to which ideas in quantum gravity, or in string theory, resolve these problems. Intrinsic decoherence
mechanisms in quantum gravity, and ideas about gravitational
decoherence. Alternative theories which go beyond quantum mechanics,
in some cases incorporating a gravitational mechanism. Possible breakdowns of Lorentz invariance. Experimental tests of General
Relativity, and of theories which either confront General Relativity and quantum mechanics, or which go beyond either.
A key goal of this meeting will be to generate new ideas, and
suggest new experiments, on these different topics (as well as to
report on existing work).
