Can a Rock be a Wave? From 100 years of De-Broglie's Wave-Particle Duality, to Quantum-Gravity
It is almost exactly 100 years since De-Broglie made public his outrageous hypothesis regarding
Wave-Particle Duality (WPD), where the latter plays a key role in interferometry. In parallel, the
Stern-Gerlach (SG) effect, found a century ago, has become a paradigm of quantum mechanics.
I will describe the realization of a half- [1-3] and full- [4-5] loop SG interferometer for single
atoms [6], and show how WPD, or complementarity, manifests itself. I will then use the
acquired understanding to show how this setup may be used to realize an interferometer for
macroscopic objects doped with a single spin [5], namely, to show that even rocks may reveal
themselves as waves. I emphasize decoherence channels which are unique to macroscopic
objects such as those relating to phonons [7,8] and rotation [9]. These must be addressed in
such a challenging experiment. The realization of such an experiment could open the door to a
new era of fundamental probes, including the realization of previously inaccessible tests of the
foundations of quantum theory and the interface of quantum mechanics and gravity, including
the probing of exotic theories such as the Diosi-Penrose gravitationally induced collapse. Time
permitting, and as an anecdote noting also De-Broglie's less popular assertion, namely, that the
standard description of QM is lacking, I will also present our recent work on Bohmian
mechanics, which is an extension of De-Broglie's ideas concerning the pilot wave [10].