Strengthening weak measurements for qubit multitime correlators
We re-examine the measurement strength needed to determine multitime correlators for qubits. We show a method that uses sequential generalized measurements. 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 of arbitrary strength. We show that both two-point and four-point (out-of-time-ordered) correlators belong to this useful class of qubit correlators.