For systems of controllable qubits,we provide amethod for experimentally obtaining a useful 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 multiqubit out-of-time-order correlators using optimized control-Z or ZX-90 two-qubit gates common in superconducting transmon implementations.
J. Dressel, J. R. G. Alonso, M. Waegell, and N. Y. Halpern, Strengthening weak measurements of qubit out-of-time-order correlators, Phys. Rev. A 98, 012132 (2018).
American Physical Society