What will future quantum computers look like?

Quantum computing promises to solve classically intractable problems, but building useful systems requires a fault-tolerant logical architecture for protecting and processing quantum information. After decades of progress, the field has largely converged on the surface-code architecture, which nevertheless appears fundamentally difficult to scale, with practical applications likely requiring millions of physical qubits. Rather than racing toward ever-larger devices, this talk asks whether we should instead rethink fault-tolerant architectures from first principles, challenging many of the assumptions behind today’s dominant paradigm.

I will introduce a new class of high-rate architectures that aim to rebuild the core components of a quantum computer. These architectures combine high-rate quantum codes, which dramatically increase information storage density, with high-rate logical operations that allow many logical gates to be executed in parallel. When co-designed with hardware controls, compilation strategies, and algorithmic structure, this approach enables large-scale, fault-tolerant algorithms with massive parallelism and low overhead. Together, this full-stack design offers a path toward reducing hardware requirements from millions of physical qubits to on the order of ten thousand or fewer, bringing fault-tolerant quantum computers with unprecedented capabilities within reach of near-term and possibly even existing devices.

Speaker: Qian Xu, Caltech