Superconducting grid-bus surface code architecture for hole-spin qubits

TL;DR

This paper proposes a scalable 2D surface code architecture using superconducting resonators and hole-spin qubits in nanowires, enabling high-fidelity entangling gates suitable for quantum error correction.

Contribution

It introduces a hybrid superconducting-resonator and hole-spin qubit architecture with tunable interactions for scalable quantum computing.

Findings

Gate fidelities approach 99% with current coherence times.

Entangling gates are realized via a third-order virtual photon process.

The architecture supports fault-tolerant quantum error correction.

Abstract

We present a scalable hybrid architecture for the 2D surface code combining superconducting resonators and hole-spin qubits in nanowires with tunable direct Rashba spin-orbit coupling. The back-bone of this architecture is a square lattice of capacitively coupled coplanar waveguide resonators each of which hosts a nanowire hole-spin qubit. Both the frequency of the qubits and their coupling to the microwave field are tunable by a static electric field applied via the resonator center pin. In the dispersive regime, an entangling two-qubit gate can be realized via a third order process, whereby a virtual photon in one resonator is created by a first qubit, coherently transferred to a neighboring resonator, and absorbed by a second qubit in that resonator. Numerical simulations with state-of-the-art coherence times yield gate fidelities approaching the $99\%$ fault tolerance threshold.