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Strengthening weak measurements of qubit out-of-time-order correlators

Physical Review A 98(1)
Dressel, J. Alonso, J.R.G.Waegell, M.Halpern, N.Y. Institute for Quantum Studies,
Chapman University,
Orange, CA, USA

Schmid College of Science and Technology,
Chapman University,
Orange, CA, USA

Institute for Quantum Information and Matter,
Pasadena, CA, USA
2018 Physics

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.

Full article

This work was supported (in part) by the Fetzer Franklin Fund of the John E. Fetzer Memorial Trust.