Thermalization in circuit quantum thermodynamics

Thanks to advances in micro- and nano-fabrication techniques, microwave engineering and cryogenics, quantum technology is a fast-growing field of science and industry with great expectations for societal benefits.

A quantum bit, qubit, is one of the central elements in the present-day quantum science but most importantly in future quantum information processing.

Despite tremendous progress in improving the coherence of qubits, almost a million-fold improvement in 30-years in case of superconducting circuits, they still have to cope with different loss and decoherence mechanisms and they are vulnerable to influences from their environment, which can disrupt and destroy quantum information.

With the progress in ultrasensitive nanoscale bolometry in the field of circuit quantum thermodynamics (cQTD), and the intense studies of superconducting circuit quantum electrodynamics (cQED) as one of the leading technologies for the realization of a universal quantum computer, a combination of the two technologies provides a unique platform for studying thermalization and decoherence of e.g., a superconducting qubit in the presence of different environments.

On the fundamental side, the goals of the project are in understanding thermalization of open and closed quantum systems formed of superconducting qubits, Josephson junction arrays, and transmission lines, as opposed to true dissipative baths formed of on-chip resistors.

On the practical level mesoscopic heat baths in form of calorimeters will be developed by implementing cross-correlation thermometry towards wide-band detection of single microwave photons.

On the technological side I will advance my skills to advanced measurements of superconducting qubits and cross-correlation detection of temperature during the outgoing phase of the project in US (Chicago, Caltech, Seattle), and bring this expertise back to my host laboratory in Finland.