Speaker
Description
Solid-state qubit systems such as T centres and donor spin qubits in silicon are atomic architectures of increasing interest as promising routes toward scalable quantum technologies. These systems can exploit nuclear and electronic degrees of freedom, are optically addressable, can operate at room temperature [1,2] , and naturally exhibit sought-after quantum behaviour such as long spin coherence times [1]. These architectures are compatible with solid-state optical and electronic devices, which connects them to the vast capabilities and commercial importance of the semiconductor industry, yet challenges in their fabrication persist [2]. Most notably, there exists a capability gap in reliably positioning target atoms or few-atom functional groups with atomic-scale precision.
Here, we apply Inverted-Mode Scanning Tunneling Microscopy (IM-STM) [3], an approach which has the potential to address fabrication limitations by enabling deterministic placement of covalently-bound atoms within crystalline hosts: atomically-precise mechanosynthesis. IM-STM reverses the traditional roles of probe and sample, using flat, crystalline Si(100) mesas as probes and customized 3D molecules deposited on a Si substrate as local STM imagers. These 3D molecules enable atomically precise modification of the “probe”, including donation and abstraction of atoms to and from the surface. We demonstrate these capabilities through the orientated placement of C2H moieties on Si(100) probes into two stable surface configurations. C2H moieties play a key role in quantum applications, serving as the main constituent of T centres. Structures containing up to eight C2H units are presented, substantiating the ability to construct complex, tailored atomic structures using IM-STM. Mechanically controlled chemical reactions such as these offer a new fabrication technique to support the needs of the solid-state qubit community, where coherence, readout fidelity, and interqubit coupling strengths are strongly dependent on placement accuracy and local electronic environment.
[1] Zhang, G., Cheng, Y., Chou, J.-P. & Gali, A. Material platforms for defect qubits and single-photon emitters. Appl. Phys. Rev. 7, 031308 (2020).
[2] Chatterjee, A. et al. Semiconductor qubits in practice. Nat. Rev. Phys. 3, 157–177 (2021).
[3] Barrera, E. et al. Inverted-Mode Scanning Tunneling Microscopy for Atomically Precise Fabrication. arXiv (2025) doi:10.48550/arxiv.2512.24431.
| Keyword-1 | scanning tunneling microscopy |
|---|---|
| Keyword-2 | atomically precise fabrication |
| Keyword-3 | t centres |