# Special CMT seminar Progress toward observation of quantum phase transitions in 2-d triangular ion arrays in the NIST 9Be+ Penning trap

Thursday, July 21, 2011 - 3:15pm - 4:30pm

Reiss 502

Joe Britton

NIST Boulder

Quantum spin models using pairwise Ising interactions are paradigms for modeling systems in condensed matter. Depending on the details of the interaction, these models can describe very different ground states, including paramagnetic, ferromagnetic or antiferromagnetic

order. Of particular interest are systems where the underlying lattice structure can frustrate long range order, resulting in spin-liquid and spin-glass behavior. A motivating example is high temperature superconducing materials which are thought to exhibit a spin-liquid phase.

Laser cooled, trapped atomic ions provide a good platform for modeling quantum magnetic systems. In this talk I will introduce the NIST Penning trap apparatus with emphasis on recent work with 2-d crystals of N=~200 9Be+ ions. Recent results in the context of quantum

simulation include demonstration of a uniform 2-d Ising interaction (Jz2). I will also discuss prospects for complicated Ising interactions.

Host: Jim Freericks