Permutationally invariant quantum tomography

TL;DR

This paper introduces a scalable quantum tomography method focusing on permutationally invariant states, reducing experimental effort and uncertainties, demonstrated on a four-qubit photonic Dicke state.

Contribution

It proposes a new measurement strategy for efficiently reconstructing permutationally invariant quantum states in large multiqubit systems.

Findings

Efficient tomography of a four-qubit symmetric Dicke state.

Minimized measurement effort and uncertainties in state reconstruction.

Applicable to large multiqubit quantum registers.

Abstract

We present a scalable method for the tomography of large multiqubit quantum registers. It acquires information about the permutationally invariant part of the density operator, which is a good approximation to the true state in many, relevant cases. Our method gives the best measurement strategy to minimize the experimental effort as well as the uncertainties of the reconstructed density matrix. We apply our method to the experimental tomography of a photonic four-qubit symmetric Dicke state.