In this paper, we propose a protocol to realize the conversions between Greenberger-Horne-Zeilinger (GHZ) states and
W states of spin qubits. By analyzing and simplifying the dynamics of the system, the control fields are designed via the inverse Hamiltonian engineering based on the Lie transforms. Moreover, the states' conversions between multitype GHZ states and
W states can be executed deterministically and reversibly, which makes the protocol resource saving and flexible. We show in numerical simulations that the state conversions are robust against the systematic errors, random noise, and frequency mismatching of the control fields. Therefore, the protocol may provide some useful prospectives to the research of quantum mechanics and applications of quantum information processing based on GHZ states and
W states.
Abstract A protocol to realize complete and nondestructive atomic Greenberger–Horne–Zeilinger (GHZ)‐state analysis in cavity quantum electrodynamics (QED) systems is presented. In this protocol, the three information‐carrier atoms and the three auxiliary atoms are trapped in six separated cavities, respectively. After ten‐step operations, the information for distinguishing the eight different GHZ states of the three information‐carrier atoms is encoded on the auxiliary atoms. Thus, by means of detecting the auxiliary atoms, complete and nondestructive GHZ‐state analysis with high success probability is realized. Moreover, the driving pluses of operations are designed as a simple superposition of Gaussian or trigonometric functions by using the invariant‐based inverse engineering. Therefore, the protocol can be realized experimentally and applied in some quantum information tasks based on complete GHZ‐state analysis with less physical entanglement resource.
Abstract Schemes for converting photonic polarized‐entangled Knill–Laflamme–Milburn (KLM) states to Greenberger–Horne–Zeilinger (GHZ) states are proposed using weak cross‐Kerr nonlinearity and X‐quadrature homodyne measurement. Analyses show that the two‐qubit (Bell state) and three‐qubit conversion cases have very high fidelities and close‐to‐unity probabilities. The conversion processes are robust against photon loss. The schemes linking these two entangled states may be helpful to the study of quantum information processing based on them.