Operating semiconductor qubits without individual barrier gates

TL;DR

This paper introduces a novel spin qubit architecture that eliminates the need for individual barrier gates, simplifying fabrication and control while enabling tunable two-qubit interactions through plunger gate voltages.

Contribution

The authors propose and experimentally validate a method to control two-qubit interactions without individual barrier gates, reducing fabrication complexity in semiconductor spin qubits.

Findings

Exchange energy $J$ can be tuned from 100 kHz to 60 MHz by adjusting plunger gates.

Two-qubit operations are possible without changing barrier gate voltages.

The new architecture simplifies fabrication while maintaining universal quantum control.

Abstract

Semiconductor spin qubits have emerged as a promising platform for quantum computing, following a significant improvement in their control fidelities over recent years. Increasing the qubit count remains challenging, beginning with the fabrication of small features and complex fanouts. A particular challenge has been formed by the need for individual barrier gates to control the exchange interaction between adjacent spin qubits. Here, we propose a method to vary two-qubit interactions without applying pulses on individual barrier gates while also remaining insensitive to detuning noise in first order. Experimentally we find that changing plunger gate voltages over 300 mV can tune the exchange energy $J$ from 100 kHz to 60 MHz. This allows us to perform two-qubit operations without changing the barrier gate voltage. Based on these findings we conceptualize a spin qubit architecture without individual barrier gates, simplifying the fabrication while maintaining the control necessary for universal quantum computation.