Non-invasive measurement of currents in analog quantum simulators

The scheme reveals persistent currents in optical lattices subject to synthetic magnetic fields.


Despite the pristine abilities of analog quantum simulators to study quantum dynamics, possibilities to detect currents are sparse. Here, we propose a flexible non-invasive technique to measure currents in quantum many-body systems by weakly coupling the system to an ancilla, followed by a measurement of the ancilla population. We numerically benchmark the scheme at the example of interacting bosons in a Harper–Hofstadter optical-lattice ladder, and discuss potential experimental error sources. The highly flexible protocol can be used with both hard-core and soft-core bosons as well as fermions, is easily extendable to more general observables like current–current correlations, and applies to other setups beyond cold atoms as we exemplify for the trapped-ion platform.

arXiv:2106.12599 [quant-ph]
Kevin T. Geier
PhD Student