English

Fisher-symmetric informationally complete measurements for pure states

Quantum Physics 2016-05-11 v2

Abstract

We introduce a new kind of quantum measurement that is defined to be symmetric in the sense of uniform Fisher information across a set of parameters that injectively represent pure quantum states in the neighborhood of a fiducial pure state. The measurement is locally informationally complete---i.e., it uniquely determines these parameters, as opposed to distinguishing two arbitrary quantum states---and it is maximal in the sense of a multi-parameter quantum Cramer-Rao bound. For a dd-dimensional quantum system, requiring only local informational completeness allows us to reduce the number of outcomes of the measurement from a minimum close to but below 4d34d-3, for the usual notion of global pure-state informational completeness, to 2d12d-1.

Keywords

Cite

@article{arxiv.1507.06904,
  title  = {Fisher-symmetric informationally complete measurements for pure states},
  author = {Nan Li and Christopher Ferrie and Jonathan A. Gross and Amir Kalev and Carlton M. Caves},
  journal= {arXiv preprint arXiv:1507.06904},
  year   = {2016}
}

Comments

v2 has additional discussion of Fisher-symmetric measurements for mixed states and an additional example of a PFSIC that consists of coin flipping between two orthonormal bases. Two new authors. Additional minor changes throughout