Heralding an Arbitrary Decoherence-Free Qubit State

TL;DR

This paper introduces an optical device that heralds the preparation of various decoherence-free subspace states, including basis states and arbitrary encodings, to protect quantum information against collective noise.

Contribution

It presents a novel optical heralding device capable of generating a range of DFS states and an interferometric method for characterizing arbitrary encodings.

Findings

Successfully heralds all three basis states of a DFS qutrit

Enables preparation of arbitrary DFS qubit states

Provides a technique for amplitude determination in arbitrary encodings

Abstract

We present an optical device which is capable of heralding a variety of DFS states which protect against collective noise. Specifically, it can prepare all three basis states which span a DFS qutrit as well as an arbitrarily encoded DFS qubit state. We also discuss an interferometric technique for determining the amplitudes associated with an arbitrary encoding. The heralded state may find use in coherent optical systems which exhibit collective correlations.