Sensitive radio-frequency read-out of quantum dots using an ultra-low-noise SQUID amplifier by Schupp, FJ, Vigneau, F, Wen, Y, Mavalankar, A, Griffiths, J, Jones, GAC, Farrer, I, Ritchie, DA, Smith, CG, Camenzind, LC, Yu, L, Zumbühl, DM, Briggs, GAD, Ares, N, Laird, EA