A Direct Method For Analysis And Synthesis Of A Decoherence-Free Mode In Quantum Linear Systems

A decoherence-free mode lies at the heart of the preservation of quantum information against external noise. In this paper we propose a direct method for the analysis and synthesis of a decoherence-free mode in quantum linear systems. First, we derive a necessary condition for the existence of a decoherence-free mode. Then, the synthesis of the decoherence-free mode via Hamiltonian control is discussed.