We propose a Lyapunov-based control approach for state transfer based on the decoherence-free target state. The expected target state is constructed to be a decoherence-free state in a decoherence-free subspace （DFS...We propose a Lyapunov-based control approach for state transfer based on the decoherence-free target state. The expected target state is constructed to be a decoherence-free state in a decoherence-free subspace （DFS） by an external laser field I, so that the system state can be decoupled from the environment, and no more decoherence process will occur. With the decoherence-free target state, we design a Lyapunov-based control field II to steer the given initial state to the decoherence-free state of open quantum systems as completely as possible, and decouple the system state from the environment at the same time. In the end, it is verified that the state transfer control designed comes true on a A-type four-level atomic system, and the system can stay on the decoherence-free target state without coupling to environment.展开更多
The existence of decoherence-free subspace （DFS） has been discussed widely. In this paper, we propose an alternative scheme for generating the four-atom W states by manipulating DF qubits. The atoms are divided into...The existence of decoherence-free subspace （DFS） has been discussed widely. In this paper, we propose an alternative scheme for generating the four-atom W states by manipulating DF qubits. The atoms are divided into two pairs and trapped in two separate optical cavities. Manipulation of atoms within DFS may generate a two-atom maximally entangled state in an individual cavity, which is a stable state. After driving the system out of DFS, the atoms will interact resonantly with the cavity field. The photons leaking from the cavities interfere at the beamsplitter, which destroys which-path information, and are finally detected by one of the detectors, leading to the generation of a W state. In addition, the numerical simulation indicates that the fidelity of the prepared state can, for a very wide parameter regime, be very close to unity.展开更多
基金partly supported by the National Key Basic Research Program(No.2011CBA00200)the Natural Science Foundation of China(No. 61074050)the Doctoral Fund of Ministry of Education of China(No.20103402110044)
文摘We propose a Lyapunov-based control approach for state transfer based on the decoherence-free target state. The expected target state is constructed to be a decoherence-free state in a decoherence-free subspace （DFS） by an external laser field I, so that the system state can be decoupled from the environment, and no more decoherence process will occur. With the decoherence-free target state, we design a Lyapunov-based control field II to steer the given initial state to the decoherence-free state of open quantum systems as completely as possible, and decouple the system state from the environment at the same time. In the end, it is verified that the state transfer control designed comes true on a A-type four-level atomic system, and the system can stay on the decoherence-free target state without coupling to environment.
文摘The existence of decoherence-free subspace （DFS） has been discussed widely. In this paper, we propose an alternative scheme for generating the four-atom W states by manipulating DF qubits. The atoms are divided into two pairs and trapped in two separate optical cavities. Manipulation of atoms within DFS may generate a two-atom maximally entangled state in an individual cavity, which is a stable state. After driving the system out of DFS, the atoms will interact resonantly with the cavity field. The photons leaking from the cavities interfere at the beamsplitter, which destroys which-path information, and are finally detected by one of the detectors, leading to the generation of a W state. In addition, the numerical simulation indicates that the fidelity of the prepared state can, for a very wide parameter regime, be very close to unity.
基金supported by the NSFC under Grant(11074079)the Ph.D.Programs Foundation of Ministry of Education of China under Grant(20104407110009)Natural Science Foundation of Shanghai(15ZR1430600)
