High bandwith high sensitivity electronic thermometry in SiMOS transistors*

In the worldwide efforts to build the first useful quantum processor, semiconductor quantum dots are attracting increasing interest owing to their scalability prospects. In this approach, the qubits can be encoded in the spin degree of freedom of individual electronic charges localized in gate-defined potential wells. Recent work indicates that the heat generated by the manipulation and read-out of qubits constitutes a bottleneck for the efficient operation of large-scale quantum processors.

In this work we use radio-frequency reflectometery to probe the interdot transitions between two adjacent gate-tunable islands inside a silicon nanowire with multiple gates. The temperature dependence of the transition resonance between two islands is described by two different models, depending on the island sizes. We then use the quantum dot reflectometry signal as a tool for fast and local temperature measurements, which we can operate with MHz bandwidth and state-of-the-art sensitivity. Following the application of a microwave pulse, we  measure a microsecond-scale thermal relaxation in the local electronic temperature. This result marks an important step towards understanding dissipation in silicon spin qubit devices.