Scaling Superconducting Quantum Computers with Chiplet Architectures

TL;DR

This paper proposes a modular approach to scaling superconducting quantum computers by integrating smaller, high-yield chiplets within multi-chip modules, addressing fabrication variability and frequency collision issues.

Contribution

It introduces a chiplet-based architecture for quantum computers, demonstrating how modularity can overcome fabrication-induced defects and improve scalability.

Findings

Modular chiplet integration enhances quantum computer scalability.

Smaller chiplets have higher fabrication yields, reducing defects.

Analysis shows feasibility of scaling via quantum multi-chip modules.

Abstract

Fixed-frequency transmon quantum computers (QCs) have advanced in coherence times, addressability, and gate fidelities. Unfortunately, these devices are restricted by the number of on-chip qubits, capping processing power and slowing progress toward fault-tolerance. Although emerging transmon devices feature over 100 qubits, building QCs large enough for meaningful demonstrations of quantum advantage requires overcoming many design challenges. For example, today's transmon qubits suffer from significant variation due to limited precision in fabrication. As a result, barring significant improvements in current fabrication techniques, scaling QCs by building ever larger individual chips with more qubits is hampered by device variation. Severe device variation that degrades QC performance is referred to as a defect. Here, we focus on a specific defect known as a frequency collision. When transmon frequencies collide, their difference falls within a range that limits two-qubit gate fidelity. Frequency collisions occur with greater probability on larger QCs, causing collision-free yields to decline as the number of on-chip qubits increases. As a solution, we propose exploiting the higher yields associated with smaller QCs by integrating quantum chiplets within quantum multi-chip modules (MCMs). Yield, gate performance, and application-based analysis show the feasibility of QC scaling through modularity.