Kerr non-linearity enhances the response of a graphene Josephson bolometer

Bolometers are radiation sensors that are central to wide areas such as dark matter search, radio astronomy, material science, and qubit readouts, among others. There have been different kinds of bolometer realizations in the recent past. The challenge is to have a single device that combines high sensitivity, broad bandwidth, and a fast readout scheme. Here we demonstrate the usage of Josephson parametric amplifiers (JPA) as highly sensitive bolometers. Our key finding is that the Kerr non-linearity of the JPA boosts the device's sensitivity. When the bolometer is biased in the non-linear regime, it enhances the up-converted signals (~100 times), resulting in an order of magnitude improvement in sensitivity compared to the linear regime. In the non-linear biasing, we achieve a NEP ~ 500 aW/ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msqrt><mml:mrow><mml:mi>Hz</mml:mi></mml:mrow> </mml:msqrt> </mml:math> . Our device offers a fast detection scheme with a thermal time constant of 4.26 μs and an intrinsic JPA time constant of 70 ns. Our work integrates a JPA into a bolometer, enabling a fast and sensitive operation compared to previously studied graphene-based bolometers. Our study demonstrates a way forward to improve the quantum sensors based on 2D materials by leveraging the inherent non-linear response.