Decoherence-free quantum information in Markovian systems

TL;DR

This paper investigates how system Hamiltonians cause decoherence in Markovian quantum systems and proposes conditions and methods to preserve quantum coherence by constructing robust subspaces.

Contribution

It provides necessary conditions on Hamiltonians for maintaining coherence and introduces a way to build decoherence-free subspaces in Markovian systems.

Findings

Quantum information decoheres due to system Hamiltonian effects.

Conditions for Hamiltonians that preserve coherence are established.

Robust subspaces for quantum information processing are constructed.

Abstract

Decoherence in Markovian systems can result indirectly from the action of a system Hamiltonian which is usually fixed and unavoidable. Here, we show that in general in Markovian systems, because of the system Hamiltonian, quantum information decoheres. We give conditions for the system Hamiltonian that must be satisfied if coherence is to be preserved. Finally, we show how to construct robust subspaces for quantum information processing.