Greenberger-Horne-Zeilinger state protocols for fully connected qubit networks

Abstract

We generalize the recently proposed Greenberger-Horne-Zeilinger (GHZ) tripartite protocol [A. Galiautdinov, J. M. Martinis, Phys. Rev. A 78, 010305(R) (2008)] to fully connected networks of weakly coupled qubits interacting by way of anisotropic Heisenberg exchange g(XX+YY)+g1*ZZ. Our model adopted here differs from the more familiar Ising-Heisenberg chain in that here every qubit interacts with every other qubit in the circuit. The assumption of identical couplings on all qubit pairs allows an elegant proof of the protocol for arbitrary N. In order to further make contact with experiment, we study fidelity degradation due to coupling imperfections by numerically simulating the N=3 and N=4 cases. Our simulations indicate that the best fidelity at unequal couplings is achieved when (a) the system is initially prepared in the uniform superposition state (similarly to how it is done in the ideal case), and (b) the entangling time and the final rotations on each of the qubits are appropriately adjusted.

11 pages, 1 figure

References in corpus (5)

• Proposal for generating and detecting multi-qubit GHZ states in circuit QED
• Fully-connected network of superconducting qubits in a cavity
• Maximally entangling tripartite protocols for Josephson phase qubits
• Production of multipartite entanglement for electron spins in quantum dots
• Entanglement generation via a completely mixed nuclear spin bath

Cited by in corpus (5)

• One-step multi-qubit GHZ state generation in a circuit QED system
• Greenberger-Horne-Zeilinger generation protocol for N superconducting transmon qubits capacitively coupled to a quantum bus
• Controllable anisotropic exchange coupling between spin qubits in quantum dots
• Efficient creation of multipartite entanglement in flux qubits
• Simulating GHZ Correlations Relaxing Physical Constraints