A Novel Tip-Based Approach to Atomically Precise Energy Efficient Spin Qubit Quantum Devices

Tiptek, LLC will meet a critical national need by developing improved methods to fabricate quantum computers, as part of the EES2 goal of increasing microelectronics energy efficiency one-thousand-fold in the next 20 years. The goal of this work is to solve a major problem in qubit device fabrication: How to place phosphorus dopants in silicon with atomic precision and then prevent them from subsequently moving. We will employ nanoprobe-based hydrogen depassivation lithography (HDL) to position the phosphorus atom dopants in an atomically precise way, and then carry out subsequent silicon overgrowth to generate a defect-free epitaxial layer with no movement of the phosphorus atoms from their original placement. Our approach to achieve the perfect qubit addresses the dopant diffusion process through two innova- tions: (1) We will develop a new and much improved nanoprobe, which will enable and significantly enhance the ability to position dopants precisely in silicon, and (2) we will develop a new process to carry out the silicon encapsulation step that prevents dopant atom movement. This collaborative project will combine experts from Tiptek, LLC (the sole US manufacturer of nanoprobes), the University of Illinois at Urbana-Champaign (home of Prof. Joe Lyding, the inventor of HDL and co-PI on this project), and Sandia National Laboratories (a world leader in quantum computing). The potential commercial applications of quantum computers lie in several technology sectors, including cybersecurity, materials and pharmaceuticals, banking and finance, and advanced manufacturing. In particular, three principal applications of quantum computing are especially promising: Improved encryption and de-encryption methods, faster and more accurate methods to discover advanced materials and drugs, and faster solutions of large-scale combinatorics problems such as scheduling, planning, or logistics to make businesses more efficient or detecting deepfakes. Summary for Members of Congress: Quantum computers carry out calculations with quantum bits (called qubits) that can exist in multiple states simultaneously, in contrast to conventional computers which employ bits that exist in only two states. If quantum computers can be successfully developed, they will be far faster and more powerful than even the fastest computers today; this proposal will overcome one of the key hurdles of how to make such quantum computers reliably and reproducibly.