Ali Javadi, IBM

Abstract

Assertions are used extensively in classical programming to check for program bugs or runtime errors. In quantum computers, runtime error rates are typically many orders of magnitude higher than error rates in classical computing, making it critical to detect such errors. The problem is exacerbated due to several factors. The first is that we cannot observe quantum information without destroying it, and the second is that the process of detecting errors can itself introduce extra errors.

In this talk I will discuss error detection in quantum circuits dominated by Clifford gates, and show algorithms for finding good checks even in the presence of severe qubit connectivity constraints. The key idea is to use spacetime codes to probe for errors more efficiently. Such checks introduce little overhead and can in turn detect errors in a large region of the circuit. I will show the practicality of the approach by showing experimental results on IBM Quantum processors for circuits containing up to 50 logical qubits and close to 2,500 two-qubit gates. I will argue that such error detection methods form a viable bridge between near-term error mitigation and longer-term error correction in quantum computers.

Speaker bio: Ali Javadi-Abhari is a Principal Research Scientist at IBM Quantum. His research interests lie in quantum circuits and compilation. He was the architect of the Qiskit software framework for quantum information science, and led the software sub-thrust of the C2QA center of the National Quantum Initiative. He received his PhD from Princeton University in 2017.