Direct Characterization of Quantum Measurements using Weak Values
arXiv:2005.10423 · doi:10.1103/PhysRevLett.127.180401
Abstract
The time-symmetric formalism endows the weak measurement and its outcome, the weak value,many unique features. In particular, it allows a direct tomography of quantum states without resort to complicated reconstruction algorithms and provides an operational meaning to wave functions and density matrices. Here, we propose and experimentally demonstrate the direct tomography of a measurement apparatus by taking the backward direction of weak measurement formalism. Our protocol works rigorously with the arbitrary measurement strength, which offers an improved accuracy and precision. The precision can be further improved by taking into account the completeness condition of the measurement operators, which also ensures the feasibility of our protocol for the characterization of the arbitrary quantum measurement. Our work provides new insight on the symmetry between quantum states and measurements, as well as an efficient method to characterize a measurement apparatus.
6 pages, 3 figures
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- Resource-efficient Direct Characterization of General Density Matrix
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- State distinguishability under weak measurement and post-selection: A unified system and device perspective
- Characterizing entangled state update in different reference frames with weak measurements