Quantum Zeno Dynamics from General Quantum Operations

We consider the evolution of an arbitrary quantum dynamical semigroup of a finite-dimensional quantum system under frequent kicks, where each kick is a generic quantum operation. We develop a generalization of the Baker-Campbell-Hausdorff formula allowing to reformulate such pulsed dynamics as a continuous one. This reveals an adiabatic evolution. We obtain a general type of quantum Zeno dynamics, which unifies all known manifestations in the literature as well as describing new types.

Evanescent Wave Approximation for Non-Hermitian Hamiltonians

The counterpart of the rotating wave approximation for non-Hermitian Hamiltonians is considered, which allows for the derivation of a suitable effective Hamiltonian for systems with some states undergoing decay. In the limit of very high decay rates, on the basis of this effective description we can predict the occurrence of a quantum Zeno dynamics, which is interpreted as the removal of some coupling terms and the vanishing of an operatorial pseudo-Lamb shift.

Generation of W states via Lyapunov control by combination of quantum Zeno dynamics

We propose a scheme to create a 4-atom W state by Lyapunov control with the help of quantum Zeno effect. The effective Hamiltonian to describe quantum Zeno dynamics can be obtained in an invariant Zeno subspace and the 4-atom W state can be achieved through modulating the system parameters. Numerical simulation shows that the present scheme is robust against both cavity decay and the atom spontaneous emission. Furthermore, we present a proposal for W state conversion by the same principle, which provides theoretically a novel way for multi-qubits entanglement preparation.