Tuning a quantum computer: what a violin teaches us about qubit calibration

Insider brief

• A new episode of The Quantum Kid’s Kai Asks series uses a violin to explain qubit calibration, featuring Kristina Callaghan, Quantum Education & Workforce Development Program Manager at Quantum Machines.
• Because of tiny fabrication differences, every superconducting qubit has its own resonant frequency, so researchers must find the right control settings for each one through steps such as spectroscopy and Rabi experiments, then re-tune them as they drift.
• As quantum computers scale and move into data centres, calibration becomes a growing workload, increasing demand for trained quantum technicians and engineers.

Before a violinist plays a note, they tune. Each string is tightened or loosened until it sounds exactly right, and even then, temperature and humidity will pull it out of tune again before long. Quantum computers have the same problem, only far more acute.

That was the starting point for the latest episode of Kai Asks, the short-form series from The Quantum Kid in which 10-year-old Kai puts his questions to one expert. Kai opened by playing his violin, then asked Kristina Callaghan, Quantum Education & Workforce Development Program Manager at Quantum Machines, how scientists tune the qubits inside a quantum computer.