Compromise-Free Scaling of Qubit Speed and Coherence
Abstract
Across leading qubit platforms, a common trade-off persists: increasing coherence comes at the cost of operational speed, reflecting the notion that protecting a qubit from its noisy surroundings also limits control over it. This speed-coherence dilemma limits qubit performance across various technologies. Here, we demonstrate a hole spin qubit in a Ge/Si core/shell nanowire that triples its Rabi frequency while simultaneously quadrupling its Hahn-echo coherence time, boosting the Q-factor by over an order of magnitude. This is enabled by the direct Rashba spin-orbit interaction, emerging from heavy-hole-light-hole mixing through strong confinement in two dimensions. Tuning a gate voltage causes this interaction to peak, providing maximum drive speed and a point where the qubit is optimally protected from charge noise, allowing speed and coherence to scale together. Our proof-of-concept shows that careful dot design can overcome a long-standing limitation, offering a new approach towards building high-performance, fault-tolerant qubits.
Keywords
Cite
@article{arxiv.2402.07313,
title = {Compromise-Free Scaling of Qubit Speed and Coherence},
author = {Miguel J. Carballido and Simon Svab and Rafael S. Eggli and Taras Patlatiuk and Pierre Chevalier Kwon and Jonas Schuff and Rahel M. Kaiser and Leon C. Camenzind and Ang Li and Natalia Ares and Erik P. A. M Bakkers and Stefano Bosco and J. Carlos Egues and Daniel Loss and Dominik M. Zumbühl},
journal= {arXiv preprint arXiv:2402.07313},
year = {2025}
}
Comments
Main: 9 pages with 3 display items including references and methods; Supplementary: 17 pages with 10 display items including references