Controlled Quantum Open Systems

Ming Zhang, Wei Kang Zhu, Dewen Hu

This paper demonstrates that the decoherence-free subsystem of open quantum dynamical system is open-loop controllable if the suitable coherent controls are permitted. This result is in marked contrast to the fact that open quantum dynamical systems are not open-loop controllable. In other words, combining the decoherence-free subsystem condition with coherent control on the open quantum dynamical systems will enhance the ability to suppress the decoherence and to manipulate open quantum dynamical systems.

Christian Arenz

Ming Zhang, Hong‐Yi Dai, Gong Er-Ling +2 more

This paper discusses the concept of controllable subspace for open quantum dynamical systems.It is constructively demonstrated that combining structural features of decoherence-free subspaces with the ability to perform open-loop coherent control on open quantum systems will allow decoherence-free subspaces to be controllable.This is in contrast to the observation that open quantum dynamical systems are not open-loop controllable.To a certain extent, this paper gives an alternative control theoretical interpretation on why decoherence-free subspaces can be useful for quantum computation.

H. J. Carmichael

Mingyi Zhang, Hui Dai, G.-H. Dong +2 more

This paper proposes the concept of subsystem controllability for both closed and open quantum dynamical systems, and the existence conditions of controllable subsystems are derived accordingly. It is demonstrated that a controllable subsystem may exist for a closed quantum dynamical system even if the overall system is not controllable. Furthermore, we also demonstrate that, for a class of decoherence-free subsystems of Markovian open quantum dynamical systems, the subsystems are controllable under open-loop coherent control if the initial states of the open systems are factorized. To a certain extent, this paper gives an alternative control theoretical interpretation on why decoherence-free subsystems are useful for quantum computation.

Daniel A. Lidar, Paolo Zanardi A, Lorenzo Campos Venuti