Strengthening weak measurements of qubit out-of-time-order correlatorsPhysical Review A 98(1)
For systems of controllable qubits, we provide a method for experimentally obtaining a use- ful class of multitime correlators using sequential generalized measurements of arbitrary strength. Specifically, if a correlator can be expressed as an average of nested (anti)commutators of operators that square to the identity, then that correlator can be determined exactly from the average of a measurement sequence.
As a relevant example, we provide quantum circuits for measuring multi- qubit out-of-time-order correlators using optimized control-Z or ZX -90 two-qubit gates common in superconducting transmon implementations.
The article was published in: Physical Review A 98(1): 012132.
This work was supported (in part) by the Fetzer Franklin Fund of the John E. Fetzer Memorial Trust.