An expectation value expansion of Hermitian operators in a discrete Hilbert space
Abstract
We discuss a real-valued expansion of any Hermitian operator defined in a Hilbert space of finite dimension N, where N is a prime number, or an integer power of a prime. The expansion has a direct interpretation in terms of the operator expectation values for a set of complementary bases. The expansion can be said to be the complement of the discrete Wigner function. We expect the expansion to be of use in quantum information applications since qubits typically are represented by a discrete, and finite-dimensional physical system of dimension N=2^p, where p is the number of qubits involved. As a particular example we use the expansion to prove that an intermediate measurement basis (a Breidbart basis) cannot be found if the Hilbert space dimension is 3 or 4.
Keywords
Cite
@article{arxiv.quant-ph/0011037,
title = {An expectation value expansion of Hermitian operators in a discrete Hilbert space},
author = {Roberth Asplund and Gunnar Bjork and Mohamed Bourenanne},
journal= {arXiv preprint arXiv:quant-ph/0011037},
year = {2019}
}
Comments
A mild update. In particular, I. D. Ivanovic's earlier derivation of the expansion is properly acknowledged. 16 pages, one PS figure, 1 table, written in RevTeX