IBM Breakthrough: Ballistic Electron Transport in InAs Nanowire Cross‑Junctions

Published today in the peer‑reviewed journal Nano Letters, IBM scientists have successfully guided an electron through an InAs III‑V semiconductor nanowire integrated on silicon, achieving ballistic transport for the first time. This milestone lays the groundwork for next‑generation quantum wire devices that could be incorporated into future high‑performance computing systems.

Dr. Johannes Gooth, lead author and IBM scientist, explains the significance of this work in a detailed Q&A.

Q: The paper’s title is “Ballistic one‑dimensional InAs nanowire cross‑junction interconnects.” What challenges does this nanoscale ballistic transport present?

JG: It’s akin to shooting a missile, but on the atomic scale. Electrons travel from one contact to the opposite one without scattering, preserving their full quantum state—energy, momentum, and spin. The challenge is to fabricate nanowires that are geometrically precise and free of internal scatterers. The template‑assisted selective epitaxy (TASE) process developed at IBM Zürich provides that level of control for the first time.

Q: How does this research compare to other quantum technologies?

JG: Unlike optical or superconducting platforms, our technique is scalable and fully compatible with standard CMOS processes, making it attractive for industrial deployment.

Q: What role does quantum transport play in building a universal quantum computer?

JG: Ballistic connections dramatically expand the computational state space compared to classically connected systems. Coupling our nanowires with superconductors enables topologically protected, fault‑tolerant quantum computing—an essential advantage for a universal quantum computer.

Q: Can this be manufactured with existing processes, and what are the next steps?

JG: Yes, our devices integrate seamlessly into existing CMOS workflows. The next phase involves functionalizing the cross‑junctions—adding superconducting hybrids for Majorana braiding and quantum dots—to build fully operational quantum circuits.

Ballistic one‑dimensional InAs nanowire cross‑junction interconnects, Johannes Gooth, Mattias Borg, Heinz Schmid, Vanessa Schaller, Stephan Wirths, Kirsten E Moselund, Mathieu Luisier, Siegfried Karg, and Heike Riel, Nano Letters, DOI: 10.1021/acs.nanolett.7b00400, Publication Date (Web): March 23, 2017