Trapped ion

Using atomic ions, suspended in a vacuum by electric fields and manipulated with lasers, as qubits. Used by Quantinuum and others.

In 1995 Ignacio Cirac and Peter Zoller proposed performing two-qubit operations between cold ions lined up in a row, using their shared vibration as the go-between^[1]. An experimental demonstration followed the same year, making it the first concrete route to actually building a quantum computer.

Every ion of a given element is identical, so error rates are low and even distant ions can be linked directly. Operations are slower than in superconducting machines, though, and control becomes harder as the number of ions grows.