It’s an open challenge to combine quantum coherence and controllability in an architecture that is scalable. We build planar superconducting qubits using standard methods and materials, but are also exploring unconventional approaches. Here, our focus lies on the qubit designs, the device architecture, and the materials. We aim to elucidate and push the limiting mechanisms for coherently operating our systems. Moreover, in building our devices we have unique opportunities to embed problem-specific interactions in the quantum hardware.

Running quantum algorithms is about coherently manipulating the state of many qubits, through the careful application of current and voltage pulses to the quantum circuit. A key element is using the native interactions present in the superconducting device to construct quantum logic gates, which in turn form the building blocks of large algorithms. An important part is quantifying the performance with trustworthy tools that can be applied to small- and large-scale systems. Developing such validation tools is intrinsically connected to algorithms, as problems in physics can be a source of inspiration.

We work with superconducting qubits that are cooled to a temperature of a mere 10 milliKelvin above absolute zero. Here, the quantum environment can be easily dominated by extrinsic and unforeseen intrinsic mechanisms, such as thermal radiation, stray magnetic fields, and other sources of noise. We also need to bring in high-frequency microwave and low frequency flux control signals from the outside.