DOE OSTI2011
Improved measurements of strongly correlated systems will enable the predicative design of the next generation of supermaterials. In this program, we are harnessing recent advances in the quantum manipulation of ultracold atomic gases to expand our ability to probe these technologically important materials in heretofore unexplored regions of temperature, resolution, and sensitivity parameter space. We are working to demonstrate the use of atom chips to enable single-shot, large area detection of magnetic flux at the 10 -7 flux quantum (Φ 0 ) level and below. By harnessing the extreme sensitivity of atomic clocks and Bose-Einstein condensates (BECs) to external perturbations, the cryogenic atom chip technology developed here will provide a magnetic flux detection capability that surpasses other techniques---such as scanning SQUIDs---by a factor of 10 1 --10 3 . We are testing the utility of this technique by using rubidium BECs to image the magnetic fields emanating from charge transport and magnetic domain percolation in strongly correlated materials as they undergo temperature-tuned metal--to--insulator phase transitions. Cryogenic atom chip microscopy introduces three very important features to the toolbox of high-resolution, strongly correlated material microscopy: simultaneous detection of magnetic and electric fields (down to the sub-single electron charge level); no invasive large magnetic fields or gradients; simultaneous micro- and macroscopic spatial resolution; freedom from 1/f flicker noise at low frequencies; and, perhaps most importantly, the complete decoupling of probe and sample temperatures. The first of these features will play an important role in studying the interplay between magnetic and electric domain structure. The last two are crucial for low frequency magnetic noise detection in, e.g., the cuprate pseudogap region and for precision measurements of transport in the high temperature, technologically relevant regime inaccessible to other techniques based on superconducting scanning probes. In periods 1--3 of this grant, which we now close at the University of Illinois at Urbana-Champaign and restart at Stanford University where our new lab is being built, we have demonstrated the ability to rapidly create Rb BECs and trap them within microns of a surface in a cryostat. Period 4 of this grant, to be performed at Stanford, will demonstrate the feasibility of using atom chips with a BEC to image transport features on a cryogenically cooled surface. Successful demonstration, in future funding cycles, will lead directly to the use of system for studies of transport in exotic and technologically relevant materials such as cuprate superconductors and topological insulators.
74 ATOMIC AND MOLECULAR PHYSICS↗