Superconducting quantum bits, or qubits, use circuits made from superconducting materials to harness quantum mechanical states. These devices contain many atoms, but can behave as simple, controllable qubits. We are building technologies for the control and measurement of superconducting qubits to enable the first demonstration of an extensible, medium-scale quantum processor. Our approach includes the development of multilayer architectures where qubit and wiring circuitry are fabricated on different chips that are bonded together by means of thermocompression bonding technologies. This will make it possible to address qubits on a two-dimensional lattice on the order of 100 qubits. Implementing a two-dimensional array of superconducting qubits will allow for the realization of quantum-error correction, a critical step on the way to a fully scalable architecture. Through this work we also hope to study the loss mechanisms that limit the coherence time of superconducting qubits.
Figure 1. Two chips bonded with indium forming a tunnel for superconducting qubits (credit C.R.H. McRae and M. Mariantoni 2017).