In a superconducting circuit, conduction electrons condense into amacroscopic quantum state, such that currents and voltages behavequantum mechanically2,30. Our processor uses transmon qubits6, whichcan be thought of as nonlinear superconducting resonators at 5–7 GHz.The qubit is encoded as the two lowest quantum eigenstates of theresonant circuit. Each transmon has two controls: a microwave driveto excite the qubit, and a magnetic flux control to tune the frequency.Each qubit is connected to a linear resonator used to read out the qubitstate5. As shown in Fig. 1, each qubit is also connected to its neighbouringqubits using a new adjustable coupler31,32. Our coupler design allows usto quickly tune the qubit–qubit coupling from completely off to 40 MHz.One qubit did not function properly, so the device uses 53 qubits and86 couplers.