Weak Measurement of Superconducting Qubit Reconciles Incompatible Operators

• URL: http://arxiv.org/abs/2008.09131v3
• Date: Thu, 11 Mar 2021 19:04:20 GMT
• Title: Weak Measurement of Superconducting Qubit Reconciles Incompatible Operators
• Authors: Jonathan T. Monroe, Nicole Yunger Halpern, Taeho Lee, Kater W. Murch
• Abstract summary: Weak measurements are shown to obey an uncertainty relation cast in terms of entropies. A weak measurement can reconcile two strong measurements' incompatibility, via backaction on the state. We provide experimental support for the physical interpretation of the weak value as a determinant of a weak measurement's ability to reconcile operations.
• Score: 1.651690213572386
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: Traditional uncertainty relations dictate a minimal amount of noise in incompatible projective quantum measurements. However, not all measurements are projective. Weak measurements are minimally invasive methods for obtaining partial state information without projection. Recently, weak measurements were shown to obey an uncertainty relation cast in terms of entropies. We experimentally test this entropic uncertainty relation with strong and weak measurements of a superconducting transmon qubit. A weak measurement, we find, can reconcile two strong measurements' incompatibility, via backaction on the state. Mathematically, a weak value -- a preselected and postselected expectation value -- lowers the uncertainty bound. Hence we provide experimental support for the physical interpretation of the weak value as a determinant of a weak measurement's ability to reconcile incompatible operations.

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