The Future of Fault-Tolerant Quantum Computing

Yasunari Suzuki

Jangwoo Kim, Junpyo Kim, Junhyuk Choi +7 more

To run a practical size of quantum program, computer architects have been making tremendous efforts to realize fault-tolerant quantum computing (FTQC) which constructs a fault-tolerant logical qubit by correcting many erroneous physical qubits during runtime. However, it is extremely challenging to build a full-stack FTQC system consisting of heterogeneous stacks, where each stack incurs unique challenges regarding the fault tolerance and the interplay of the challenges incurs very complicated overall design choice problem. Therefore, computer architects must fully understand stack-specific optimizations and their system-level trade-offs, and resolve all the challenges together. In this article, we first introduce critical design challenges in architecting an FTQC system built on the superconducting technology, and then present our research outcomes to resolve the challenges to build an FTQC system realizing thousands of logical qubits. We also outline near-future directions to resolve the remaining challenges and provide insights toward realizing more scalable future FTQC systems.

Alexander M. Dalzell, Sam McArdle, Mario Berta +10 more

Daniel Gottesman

I discuss a variety of issues relating to near-future experiments demonstrating fault-tolerant quantum computation. I describe a family of fault-tolerant quantum circuits that can be performed with 5 qubits arranged on a ring with nearest-neighbor interactions. I also present a criterion whereby we can say that an experiment has succeeded in demonstrating fault tolerance. Finally, I discuss the possibility of using future fault-tolerant experiments to answer important questions about the interaction of fault-tolerant protocols with real experimental errors.

I. S. Osborne

Thierry Bonhomme, Catherine Lambert, Gérard Roucairol

Fault-tolerant quantum computing (FTQC) has the potential to reliably execute complex calculations by overcoming the problems raised from the errors and noise inherent in quantum systems. This paper builds upon a 2025 report issued by the National Academy of Technologies of France. After recalling the principles that underly the so-called "quantum advantage," the use of error-correcting codes in the design of fault-tolerant quantum computers is discussed. Also explored are the five most advanced physical technologies that can be used to build such computers and the challenges of scaling up to a sufficient size to run useful applications. After highlighting the limits of monolithic qubit integration, the focus turns to increasing the number of available physical qubits by interconnecting several quantum processing modules. The paper concludes with a discussion of technical and economic environments, their performance benchmarks, and their future coexistence with other computing technologies and with supercomputers.