Quantized thermal conductance: measurements in nanostructures

We are performing experiments to probe directly the thermal conductance of suspended nanostructures with lateral dimensions approximate to 100 nm. It has been recently predicted that at low temperatures, thermal conductance i n such a structure approaches a universal value of pi(2)k(B)(2)T/3h for eac h massless, ballistic phonon channel, independent of material characteristi cs. We have developed ultra-sensitive, low dissipation DC-SQUID-based noise thermometry, and extreme isolation from the electronic environment in orde r to perform this measurement at temperatures below 70 mK, (C) 2000 Elsevie r Science B.V. All rights reserved.