Qdev seminar by Robin Harper, University of Sydney

Characterising and modelling the noise in quantum devices running error correcting circuits

In this talk I will discuss two noise characterisation protocols.

The first allows the scalable extraction of a 2^n parameter locally averaged Pauli channel from current devices (arXiv:1907.13022). This protocol can be applied to extract the noise channel from devices running error correcting circuits. As the number of data qubits in such devices exceed 30 or so, such channels can no longer be fully represented. I will use data from a 38-qubit (20 data qubit) device to show how to build Markov graph models from the data extracted and provide evidence that such models appear to capture the elements of the noise that will be essential in allowing bespoke error correction decoders to be written.

The second protocol allows the simultaneous characterization of the Pauli eigenvalues of all the gates used in the error correcting circuits (arXiv:2108.05803). Importantly each gate is characterised in the environment in which it being used, giving a wealth of diagnostic information.

Bio:

Robin Harper received his PhD (machine learning) from University of New South Wales 2009 and a PhD (Physics) from the University of Sydney in 2018. He is a Sydney Quantum Academy fellow, based at the University of Sydney. He specializes in tomography, benchmarking, and noise characterization, including the implementation of rigorously proven protocols on noisy multi-qubit devices.