On-chip Thermometry for Scaling Quantum Hardware

As superconducting qubit systems scale up, the increased complexity of packaging and interconnects introduces more interfaces between the coldest plate in the dilution refrigerator (MXC) and the qubit chip. This can lead to thermalization issues, where the qubits operate at a higher temperature than what is indicated by the oxide-based thermometers on the MXC.

While qubits can, in principle, be used to gauge their own temperature by measuring thermal population or coherence, these measurements are influenced by factors such as design and materials. Furthermore, qubit characterizations necessitate a complex measurement system, which is not suitable for the rapid hardware testing required in R&D.

Our solution involves on-chip thermometers based on Dayem bridges. This concept, previously demonstrated at 1K, has been further developed at Rigetti to function within the relevant temperature ranges for superconducting qubits. This talk will detail Rigetti's ongoing research and development of on-chip thermometry, emphasizing its advantages for hardware development.