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How Gate Set Tomography Diagnostic Validates Quantum Processors

Sandia researchers Andrew Baczewski and Erik Nielsen at a wall-mounted display screen

Sandia researchers Andrew Baczewski (left) and Erik Nielsen (right) are among the authors of newly published research on precision tomography.

Credit: Rebecca Gustaf / Sandia National Laboratories

A precision diagnostic developed at the U.S. Department of Energy's Sandia National Laboratories is emerging as a gold standard for detecting and describing problems inside quantum computing hardware.

Two papers published in the journal Nature describe how separate research teams — one including Sandia researchers — used a Sandia technique called gate set tomography to develop and validate highly reliable quantum processors.

Sandia scientists collaborated with researchers at the University of New South Wales on "Precision Tomography of a Three-Qubit Donor Quantum Processor in Silicon," Together, they used GST to show that a sophisticated, three-qubit system comprising two atomic nuclei and one electron in a silicon chip could be manipulated reliably with 99%-plus accuracy.

In "Quantum Logic with Spin Qubits Crossing the Surface Code Threshold," a group led by Professor Lieven Vandersypen at Delft University of Technology used gate set tomography to demonstrate the important milestone of 99%-plus accuracy but with a different approach, controlling electrons trapped within quantum dots instead of isolated atomic nuclei.

From Sandia National Laboratories
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