Quantum many-body dynamics under continuous observation (Prof. M. Ueda)
Jan 23, 2018
14:30 - 15:30
Prof. Dr. Masahito Ueda
Department of Physics, University of Tokyo, Japan
New Lecture Hall, Room B 0.32
Quantum gas microscopy has revolutionalized our approach to quantum many-body systems where atoms trapped in an optical lattice can be observed in real time at the single-particle level.
At such extreme precision, the measurement backaction due
to Heisenberg’s uncertainty relation can no longer be ignored. One should
naturally be led to the question of whether or not many-body dynamics will be
modified and, if so, in what way. We will address this issue by focusing on
few-body dynamics and quantum critical phenomena. In the former, the
measurement distinguishablity of multiple particles leads to a complete
suppression of relative positional decoherence and quantum correlations persist
under continuous observation in a manner analogous to decoherence-free subspace
(PRA95, 022124 (2017)). In the
latter, the measurement backaction is shown to shift the quantum critical point
and yield a unique critical phase beyond the scope of the standard universality
class (PRA94, 053615 (2017); Nat.
Commun. 8, 15791 (2017)). We also
find that the propagation of correlations can exceed the Lieb-Robinson bound
under such continuous observation (arXiv:1709.03704). Continuous observation
also restricts the Hilbert space and the emergent nontrivial Berry phase yields
some startling effects such as the Zeno Hall effect and retroreflection (PRL118, 200401 (2017)).