Sensitive and fast bolometer integrable with superconducting qubit readout

Traditionally, bolometers have been too slow and inaccurate to operate in quantum sensing applications in the microwave regime. Thus their benefits such as simple setup, broad input band, absence of quantum noise, and energy-resolving calorimetry has not been harnessed in microwave quantum sensing. We report on a new type of a bolometer that simultaneously reaches the lowest noise reported for any bolometer, 20 zW/Hz^0.5 [1], and is roughly three orders of magnitude faster than the previous ultralow-noise bolometers. The thermal time constant, measured at the 100-ns range, corresponds to the typical speed of state-of-the-art high-fidelity qubit readout schemes [2]. The extracted energy resolution of this bolometer being in the 10-GHz range it manifests as a potentially important future tool in reading out superconducting qubits [3] or in quantum sensing applications in the microwave regime [4].

[1] R. Kokkoniemi et al., Commun. Phys. 2, 124 (2019).
[2] J. Heinsoo et al., Phys. Rev. Applied 10, 034040 (2018).
[3] Opremcak, A. et al., Science 361, 1239 (2018).
[4] S. Pogorzalek et al, Nat. Commun. 10, 2604 (2019).