Quantum Institute: Visitor Schedule

The Quantum Lunch is regularly held on Thursdays in the Theoretical Division Conference Room, TA-3, Building 123, Room 121.
For more information, contact Diego Dalvit.
To add your name to the Quantum Lunch email list, contact Charlotte Lehman

Thursday, September 2, 2010
12:30 PM - 2:00 PM

Speaker: Philip Johnson (American University)

Technical Host: Malcolm Boshier

TOPIC: Effective interactions, renormalization, and probing multi-body interactions with atom-number superposition states

Abstract
I will discuss our recent work on coherent, effective, multi-body interactions of ultracold atoms in optical lattices [Johnson et al 2009 New J. Phys. 11 093022 (2009)], whose predictions were recently observed in experiments on the collapse and revival of coherent atom states [Will et al, Nature 465, 197 (2010)]. To illustrate how superpositions of ultracold atom-number states can be used as interferometric probes of multi-body interactions, consider identical states |2> +|3> trapped in each well of an optical lattice. The time evolution of the relative phase between the two- and three-atom states |2> and |3> depends on the difference between two- and three-body effective Hamiltonians, allowing these to be sensitively compared by analyzing the visibility versus time of quantum interference fringes in the atom-density profile after the ensemble of superposition states is released from the lattice. Similarly, optimized superposition states can be created that probe four- and higher-body interactions. This new type of interferometry can be used to measure and distinguish between intrinsic and effective interactions (the later arising due to virtual excitation of atoms to higher vibrational states in a trap). I will also describe how optical lattices loaded with atom-number superposition states can be used to test the physics of renormalization and effective field theories.