Comparison of Coulomb Blockade Thermometers with the International Temperature Scale PLTS-2000

Abstract

The operation of the primary Coulomb blockade thermometer (CBT) is based on a measurement of bias voltage dependent conductance of arrays of tunnel junctions between normal metal electrodes. Here we report on a comparison of a CBT with a high accuracy realization of the PLTS-2000 temperature scale in the range from 0.008 K to 0.65 K. An overall agreement of about 1% was found for temperatures above 0.25 K. For lower temperatures increasing differences are caused by thermalization problems which are accounted for by numerical calculations based on electron-phonon decoupling.

Investigation of uncertainty components in Coulomb blockade thermometry

“…Normalizing the conductance means that the uncertainty in the conductance values is less important than the stability of the differential conductance measurement during the bias voltage sweep. In a recent work [15], the relative uncertainty in normalized conductance values was estimated to be about 4×10 -4 .…”

“…At present, the resulting uncertainty of CBT temperature measurements in the optimal temperature range is dominated by the measurement electronics at room temperature [15]. As stated in Equation 5, the temperature is directly deduced from the half width of the conductance dip V 1/2 and, therefore, the relative accuracy of the temperature measurement cannot be better than the relative accuracy of the bias voltage measurement.…”

Silver-epoxy microwave filters and thermalizers for millikelvin experiments

“…4) can serve as a primary thermometer. 46,47 Here, however, we use the conductance dip Dg=g as a secondary thermometer to avoid heating at finite bias. 27 At high temperatures, where the CBTs are in thermal equilibrium with the refrigerator, E C can be extracted from the temperature dependent Dg=g using the relation 45 Dg=g With E C obtained in this way, the measured Dg=g can be converted to the corresponding electron temperature T CBT in the full temperature range.…”

A robust platform cooled by superconducting electronic refrigerators

“…Throughout this work, bath temperatures of the cryostat are read with a ruthenium oxide resistor calibrated against a Coulomb blockade thermometer. 28 The bath temperature is not necessarily equal to the chip temperature (see Fig. 2, diamond symbols), as the latter can be significantly elevated due to the high input power of the cooler of about 100 nW.…”