CPM Seminar

Diagnosing quantum chaos using entanglement as a resource

Étienne Lantagne-Hurtubise

UBC

Classical chaotic systems exhibit exponentially diverging trajectories due to small differences in initial conditions. The analogous diagnostic in quantum systems is an exponential growth of out-of-time-ordered correlators (OTOCs). These quantities can be computed for various models, but their experimental study requires the ability to evolve quantum states backward in time. In this talk, I will discuss new protocols for measurements of OTOCs that evade the need for backward time evolution. Instead, they rely on the measurement of ordinary (time-ordered) correlators in the /thermofield double state/, an entangled state formed between two identical copies of the system under study. I will then use as an example the maximally-chaotic Sachdev-Ye-Kitaev model, believed to be holographically dual to a black hole, to illustrate the application of the protocols.