Cavity-mediated entanglement of parametrically driven spin qubits via sidebands

TL;DR

This paper presents a method for entangling spin qubits in quantum dots via cavity sidebands driven by external fields, enabling tunable entanglement without tuning qubit and cavity frequencies into resonance.

Contribution

It introduces a model for entanglement using parametric drives and sidebands, applicable to various spin qubit types, enhancing scalability and control in quantum information processing.

Findings

Sideband resonance enables tunable entanglement with ac control.

High nonlinearity of spin qubits facilitates drive-activated entanglement.

Parameter regimes identified for robust entangling gates with low photon sensitivity.

Abstract

We consider a pair of quantum dot-based spin qubits that interact via microwave photons in a superconducting cavity, and that are also parametrically driven by separate external electric fields. For this system, we formulate a model for spin qubit entanglement in the presence of mutually off-resonant qubit and cavity frequencies. We show that the sidebands generated via the driving fields enable highly tunable qubit-qubit entanglement using only ac control and without requiring the qubit and cavity frequencies to be tuned into simultaneous resonance. The model we derive can be mapped to a variety of qubit types, including detuning-driven one-electron spin qubits in double quantum dots and three-electron resonant exchange qubits in triple quantum dots. The high degree of nonlinearity inherent in spin qubits renders these systems particularly favorable for parametric drive-activated entanglement. We determine multiple common resonance conditions for the two driven qubits and the cavity and identify experimentally relevant parameter regimes that enable the implementation of entangling gates with suppressed sensitivity to cavity photon occupation and decay. The parametrically driven sideband resonance approach we describe provides a promising route toward scalability and modularity in spin-based quantum information processing through drive-enabled tunability that can also be implemented in micromagnet-free electron and hole systems for spin-photon coupling.