QLCI: Hybrid Quantum Architectures and Networks (HQAN)

Quantum computing promises to transform the nation’s economy, security, and society by solving problems inaccessible to conventional supercomputers. Potential applications include catalyst design, optimizing fusion energy hardware, simulating and overcoming corrosion, and bio-marker discovery for predicting cancer treatment outcomes. Today’s state-of-the-art quantum computers are too small to fully realize this potential. The dominant approach around the world has been to increase the size of single quantum processing units (QPUs). This approach for scaling up quantum computer size has unsolved challenges, however. The NSF Quantum Leap Challenge Institute for Hybrid Quantum Architectures and Networks (HQAN) tackles the science and engineering needed to enable an alternative paradigm for scaling: distributed quantum computing. In this modular approach, which is analogous to how conventional supercomputers are constructed, multi-qubit nodes are linked by quantum interconnects. An advantage of this technique is that modules can be constructed using different qubit technologies that are optimized for distinct tasks, such as high-quality calculations or data storage. The HQAN research program is organized across three interdependent thrusts. The first focuses on advancing modular quantum computing on neutral atom and superconducting circuit platforms. These systems will be developed in a co-design framework that optimizes performance of key application kernels, including quantum state preparation, quantum phase estimation, and inter-module entanglement of logically encoded qubits. The second thrust will demonstrate quantum transduction solutions for fast and high-fidelity inter-module hybrid links and memory-enhanced quantum processing. The third will develop new materials, devices, and components to overcome scaling limitations of present-day technologies. Together, these activities will transform the nation's capabilities in quantum computing, both through high-impact demonstrations of modular quantum systems and through the development of breakthrough technologies to enable a leap over current, single-QPU approaches to a future of massively clustered QPUs. At the same time, HQAN will also expand the quantum workforce, which is critical to implementing quantum computing at scale, through a multi-faceted program spanning the general public, K–12 students, undergraduate and graduate trainees, and industry professionals. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.