Exchange-Only Spin-Orbit Qubits in Silicon and Germanium

TL;DR

This paper introduces a novel exchange-only spin-orbit qubit in silicon and germanium that simplifies multi-qubit operations, reduces leakage, and enhances scalability by leveraging spin-orbit interactions and a robust encoding.

Contribution

It proposes a new exchange-only spin-orbit qubit design that operates with two degenerate states, eliminating the need for fast clocks and enabling low-leakage two-qubit gates in a single step.

Findings

Enables all-electric microwave control of single spins in silicon and germanium.

Provides a robust encoding resilient to local variability in hole spin properties.

Facilitates low-leakage two-qubit gates with a single-step operation.

Abstract

The strong spin-orbit interaction in silicon and germanium hole quantum dots enables all-electric microwave control of single spins but is unsuited for multi-spin exchange-only qubits that rely on scalable discrete signals to suppress cross-talk and heating effects in large quantum processors. Here, we propose an exchange-only spin-orbit qubit that utilizes spin-orbit interactions to implement qubit gates and keeps the beneficial properties of the original encoding. Our encoding is robust to significant local variability in hole spin properties and, because it operates with two degenerate states, it eliminates the need for the rotating frame, avoiding the technologically demanding constraints of fast clocks and precise signal calibration. Unlike current exchange-only qubits, which require complex multi-step sequences prone to leakage, our qubit design enables low-leakage two-qubit gates in a single step, addressing critical challenges in scaling spin qubits.