Google Research Blog March 5, 2018
The guiding design principle for this device is to preserve the underlying physics of our previous 9-qubit linear array technology, which demonstrated low error rates for readout (1%), single-qubit gates (0.1%) and most importantly two-qubit gates (0.6%) as their best result. This device uses the same scheme for coupling, control, and readout, but is scaled to a square array of 72 qubits. They chose a device of this size to be able to demonstrate quantum supremacy in the future, investigate first and second order error-correction using the surface code, and to facilitate quantum algorithm development on actual hardware… read more.
2D conceptual chart showing the relationship between error rate and number of qubits. The intended research direction of the Quantum AI Lab is shown in red.