Feasibility of Coulomb blockade thermometry in metrology

Coulomb blockade thermometer (CBT) is a simple, magnetic-field-independent primary thermometer for everyday use at cryogenic temperatures. Its propert ies are well understood by now. The absolute accuracy at present is about /- 0.5%. Recently, we have started studying the possibility of using CBT in metrological applications. We have especially in mind the future extension of the international temperature scale below 0.65 K, which is the lower en d of ITS-90. Experiments with arrays containing more than 100 tunnel juncti ons in series are in progress in order to decrease the effects of electroma gnetic environment and of co-tunnelling even below the present level. (C) 2 000 Elsevier Science B.V. All rights reserved.