Abstract
The strong spin-orbit coupling in hole spin qubits enables fast and electrically tunable gates, but at the same time enhances the susceptibility of the qubit to charge noise. Suppressing this noise is a significant challenge in semiconductor quantum computing. Here, we show theoretically that hole fin field-effect transistors (FinFETs) are not only very compatible with modern CMOS technology, but they present operational sweet spots where the charge noise is completely removed. The presence of these sweet spots is a result of the interplay between the anisotropy of the material and the triangular shape of the FinFET cross section, and it does not require an extreme fine-tuning of the electrostatics of the device. We present how the sweet spots appear in FinFETs grown along different crystallographic axes and we study in detail how the behavior of these devices changes when the cross-section area and aspect ratio are varied. We identify designs that maximize the qubit performance and could pave the way towards a scalable spin-based quantum computer.
- Received 18 November 2020
- Revised 8 February 2021
- Accepted 2 March 2021
DOI:https://doi.org/10.1103/PRXQuantum.2.010348
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.
Published by the American Physical Society
Physics Subject Headings (PhySH)
Popular Summary
Building a universal quantum computer is a formidably difficult task. In most semiconductor architectures, quantum information is stored in the spin of confined particles. A scalable way to manipulate these quantum bits relies on the presence of spin-orbit coupling, which enables fast and fully electrical gates. At the same time, however, this coupling renders the spins susceptible to the charge noise caused by random fluctuations of the electric field, reducing their lifetime. Suppressing this noise is a significant challenge to scale up quantum processors. Here, we propose a device with a fully tunable spin-orbit coupling that can operate in a regime where the charge noise is completely removed.
Our proposal is based on silicon technology, which is used for everyday computers, and comprises a fin field-effect transistor, where the charge carriers are holes rather than electrons. These devices are attractive because of their large spin-orbit coupling. We show that, depending on the design of the fin, this coupling can be switched on and off on demand, yielding convenient operational working points where the qubit is immune to charge noise and the quantum information can be reliably stored when the qubit is idle. When the qubit is operational, large spin-orbit coupling can be restored by changing the gate potential and fast qubit gates are possible.
In this work, we propose realistic designs that can be used to define charge noise-free qubits and can provide building blocks for the realization of a scalable semiconductor quantum computer.
