A Step Toward Simulating Spin Glasses
Atomic condensates in an optical cavity can potentially be used to simulate various quantum systems. One of these—an exotic magnet known as a spin glass—comprises a network of interacting particles, each of which can take one of two spin states. Now, researchers are a step closer to simulating these interactions. Yudan Guo at Stanford University, California, and colleagues have shown that two Bose-Einstein condensates (BECs) in a cavity can organize themselves into either of two possible states, which could stand in for the two spin states in a spin glass.
The team confined two BECs in a cavity and pumped them with a laser, causing the atoms in each BEC to scatter pump photons into the cavity. By exchanging momentum via these cavity photons, each BEC changed from having a simple density maximum at the atomic cloud’s center to having a density that oscillated in space in two perpendicular directions. These multiple density peaks formed a sort of “checkerboard” pattern. The relative positions of the BECs, which the researchers controlled with optical traps, determined whether the density-wave patterns in the two clouds had the same or opposite phase.
With control over the BEC-BEC interaction, Guo and colleagues say that researchers could simulate a frustrated system such as a spin glass by confining three or more BECs in the cavity. In this case, the phase of the density-wave pattern would emulate particle spin, with the system arranged so that no configuration could satisfy every condensate’s phase preference simultaneously.
Marric Stephens is a freelance science writer based in Bristol, UK.