Driving Quantum System into Decoherence-free Subspaces by Lyapunov Control

TL;DR

This paper proposes a Lyapunov control scheme to steer finite-dimensional quantum systems into decoherence-free subspaces, applicable to both closed and open systems, demonstrated through a four-level system example with successful numerical results.

Contribution

The paper introduces a novel Lyapunov control method for guiding quantum systems into decoherence-free subspaces, enhancing quantum coherence preservation techniques.

Findings

Control fields effectively drive systems into DFS

Scheme works for both closed and open quantum systems

Numerical simulations show good system dynamics control

Abstract

We present a scheme to drive a finite-dimensional quantum system into the decoherence-free subspaces(DFS) by Lyapunov control. Control fields are established by Lyapunov function. This proposal works well for both closed and open quantum systems, with replacing the DFS by desired subspaces for closed systems. An example which consists of a four-level system with three degenerate states driven by three lasers is presented to gain further insight of the scheme, numerical simulations for the dynamics of the system are performed and the results are good.