Scientists clear hidden obstacle to scaling up silicon quantum computers
Pairwise calibration keeps five qubits on a shared control line accurate to about 99.9%
Researchers at the RIKEN Center for Emergent Matter Science and their collaborators have overcome a significant obstacle to building larger quantum computers, achieving highly accurate control of several silicon spin qubits operating at the same time. In a study published in the journal Nature Physics, the team traced a major source of simultaneous-operation errors to a microwave effect called the AC Stark shift and showed that a pairwise calibration technique, combined with an improved device design, kept five qubits on a shared control line accurate to about 99.9% even when all five ran at once.