Recently, I gave a couple of perspective talks on quantum advantage, one at the annual retreat of the CIQC and one at a recent KITP programme. I started off by polling the audience on who believed quantum advantage had been achieved. Just this one, simple question. The audience was mostly experimental and theoretical physicists with…

Quantum Frontiers is a platform dedicated to exploring the frontiers of quantum science and technology. Readers can find articles, interviews, and discussions on topics such as quantum physics, quantum computing, and quantum information theory. Additionally, they can learn about quantum experiments, quantum communication, and interdisciplinary research in quantum science.

Quantum Frontiers

Quantum advantage refers to quantum computers solving tasks that classical computers cannot, with exponential scaling differences. Recent experiments by Google, USTC, and Quantinuum have demonstrated random circuit sampling on 53-83 qubits with statistically significant cross-entropy benchmark scores, though only the 2019 Google experiment has been classically simulated. These demonstrations use random quantum circuits as the computational task, achieving XEB scores between 0.05-0.2% that indicate nontrivial quantum behavior. However, verifying these results requires proxies and extrapolation from classically tractable regimes, making the advantage claims indirect. Despite solving useless tasks, these experiments show quantum devices can perform computations beyond classical supercomputers' reach.

Has quantum advantage been achieved?

Part 1: What is quantum advantage and what has been done?