Fast generation of multiparticle entangled state for flux qubits in a circle array of transmission line resonators with tunable coupling

TL;DR

This paper presents a rapid method to generate GHZ entangled states in superconducting flux qubits within circuit QED, achieving state creation in about 10 ns, much faster than qubit decoherence times.

Contribution

It introduces a one-step, fast GHZ state generation scheme using a tunable TLR circle array and a time-dependent microwave field to induce indirect qubit-qubit coupling.

Findings

GHZ states generated in ~10 ns

Method is faster than qubit coherence times

Potential for scaling to many qubits

Abstract

We study a one-step approach to the fast generation of Greenberger-Horne-Zeilinger (GHZ) states in a circuit QED system with superconducting flux qubits. The GHZ state can be generated in about 10 ns, which is much shorter than the coherence time of flux qubits and comparable with the time of single-qubit operation. In our proposal, a time-dependent microwave field is applied to a superconducting transmission line resonator (TLR) and displaces the resonator in a controlled manner, thus inducing indirect qubit-qubit coupling without residual entanglement between the qubits and the resonator. The design of a tunably coupled TLR circle array provides us with the potential for extending this one-step scheme to the case of many qubits coupled via several TLRs.