Fig. 1: Immersion of a superconducting quantum circuit in liquid 3He.
From: Quantum bath suppression in a superconducting circuit by immersion cooling
a In vacuum the environment of the quantum circuit is poorly thermalised to the cold plate of the refrigerator. b When immersed in liquid 3He, the cooling of the environment is significantly improved by 3He acting as a heat sink. c A superconducting resonator, used in our measurements, taking the temperature of the decohering environment of quantum circuits. d Experimental setup: The immersion cell containing the sample is thermally anchored to an adiabatic nuclear demagnetisation stage that reaches T = 400 μK. The nuclear stage is mounted to the mixing chamber plate of a dry dilution refrigerator. e Energy relaxation pathway from the TLS bath to the cold plate via 3He and silver sinter. The link between TLS medium and liquid 3He is the bottleneck for further quantum bath suppression.
