Cold Atom Quantum Simulation

posted on February 28, 2013 by

David Weld – UC Santa Barbara

Tuesday, March 5, 2013 4:30 p.m. Galileo- Pryne, Harvey Mudd College

Ultracold neutral atoms trapped in optical lattices represent a new frontier for the investigation of outstanding problems in many-body quantum mechanics.  These systems promise to bring the precision and control of atomic physics to bear on important problems in condensed matter physics, from nonequilibrium spin dynamics to d-wave superconductivity.   The ambit of this fast-growing field is expanding from measurement to control, and from statics to dynamics.  Breakthroughs in the ability to exert full spatiotemporal control over the evolution of cold atomic gases will enable a new generation of experiments at the boundary between condensed matter and atomic physics.

 At UCSB we are building two experimental platforms (based around ultracold lithium and strontium) which will enable the creation and study of new, highly tunable, and strongly correlated phases of matter.  Experimental goals of the lithium platform include quantum simulation of condensed matter Hamiltonians, the demonstration of effective time-reversal in a lattice-trapped gas, and the study of dynamical pseudospin ordering in higher-dimensional tilted lattices.  The rich electronic structure of strontium may enable the creation of chiral spin liquids and states exhibiting SU(10) magnetism, and the ultra-narrow intercombination transition along with the negligible scattering length of the heaviest stable strontium isotope are particularly appealing for quantum sensing experiments.

Molecular Motor Biophysics: Hardware Instrumentation and Nonlinear Physics

posted on February 18, 2013 by

Jing Xu – UC Merced

Tuesday, February 19, 2013 4:30 pm  Millikan Lab – Room 134

Experimental biophysicists build instruments to study nature’s nano-machines.  Molecular motors are nano-machines and are crucial for life: they transport materials in cells.  Motor-based transport is inherently a many body problem, and exhibits complex behavior yet to be understood.  An analytic model for multiple motor transport has been proposed, but has remained untested.  In this talk, I will discuss the construction of a single beam gradient optical trap in my laboratory. I will also discuss planned measurements using this optical trap, aimed at experimentally testing the current model and driving theory development.

“Heating” at the Nanoscale

posted on February 6, 2013 by

Prof. Douglas Natelson, Rice University

Monday, February 11, 2013 4:30 pm  Millikan Lab – Room 134

We are all familiar with the idea that driving current through a conductor generates heat. However, when we consider the flow of current at the nanometer scale, we see that the transport of electrons is, in general, a complicated quantum mechanical process, and ideas familiar from thermal equilibrium (e.g., “temperature”) become challenging to define. I will talk about my group’s recent experiments, where we combine clever nanofabrication with electronic and optical techniques to address this question. We use metal electrodes separated at the nanometer scale to push current through molecules. These electrodes act like optical antennas, allowing us to use optical spectroscopy to watch the vibrational modes of those molecules. We can see current-driven vibrational heating, giving us new information about the flow of energy at these scales.