CCR scientists use gate set tomography to probe inner workings of quantum computers

Image of The January 20th, 2022 Nature cover shows an artist's impression of the three-qubit silicon device that was created by UNSW physicists, then measured and validated by Sandia quantum information scientists [Image credit: Tony Melov, UNSW].

Two papers published in the journal Nature — one coauthored by Sandia researchers — used a Sandia technique called gate set tomography (GST) to demonstrate logic operations exceeding the “fault tolerance threshold” of 99% fidelity in silicon quantum computing processors.  Spawned by a Sandia Early Career LDRD in 2012, GST has since been developed at Sandia’s ASCR-funded Quantum Performance Lab.  Sandia scientists collaborated with Australian researchers at the University of New South Wales in Sydney to publish one of the Nature papers, showcasing a three-qubit system comprising two atomic nuclei and one electron in a silicon chip.  In parallel, a group from Delft University of Technology in the Netherlands used Sandia’s pyGSTi software to demonstrate equally high-fidelity logic using electrons trapped in quantum dots.

For additional information, please see:

Madzik M.T., et al., Precision tomography of a three-qubit donor quantum processor in silicon.  Nature 601, 348-353 (2022).

Nature News & Views (Jan. 20, 2022), “Silicon qubits move a step closer to achieving error correction”.

YouTube video on Quantum operations with 99% fidelity – the key to practical quantum computers.

Sandia’s Quantum Performance Laboratory website

Robin J Blume-Kohout,

January 1, 2022