State transfer in Open Quantum Systems

Shuang Cong, Long-Zhen HU, Fei Yang +1 more

Thibaut Lacroix

Shuang Cong, Jie Yang, Jianxiu Liu

To maintain state coherence in an open quantum systems, the decoherence-free subspace (DFS) is an effective method. The target state is usually needed to be in DFS. In the case the target state is not in DFS, we first design external control field I to construct a DFS included target state. Then another control field II is used to transfer the state of the system to be controlled to the expected target state. As is well known, invariant set contains all stable states of the system. Control Hamiltonian is designed to shrink invariant set and increase the transition probability from the system state to target state. In such a way, the state transfer and coherence maintain are completed. Numerical simulation is given for a four-level energy open quantum system to demonstrate the effectiveness of the control strategy proposed.

Gernot Schaller

Long-Zhen HU, Shuang Cong, Fei Yang +1 more

The weak-coupled two-level open quantum system described by non-Markovian time-convolution-less master equation is investigated in this paper. Based on the Lyapunov stability theorem, the system control laws used to transfer state are designed. The characteristics of the purity changes in the non-Markovian open quantum systems are studied. The effectiveness of the control system is ensured by adjusting the parameters of control laws. Three simulation experiments are implemented under the Matlab environment, they are the states transfer from the eigenstate to the superposition state, from the superposition state to the superposition state, and from the mixed state to the superposition state, respectively. Numerical experimental results show that the target state can be reached from different initial states under the action of the control laws designed, and demonstrate the effectiveness of quantum Lyapunov control method proposed.

Ángel S. Sanz, Salvador Miret-Artés