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An improved electronic determination of the Boltzmann constant by Johnson noise thermometry

机译：约翰逊噪声测温法改进玻尔兹曼常数的电子测定

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Recent measurements using acoustic gas thermometry have determined the value of the Boltzmann constant, k, with a relative uncertainty less than 1 × 10−6. These results have been supported by a measurement with a relative uncertainty of 1.9 × 10−6 made with dielectric-constant gas thermometry. Together, the measurements meet the requirements of the International Committee for Weights and Measures and enable them to proceed with the redefinition of the kelvin in 2018. In further support, we provide a new determination of k using a purely electronic approach, Johnson noise thermometry, in which the thermal noise power generated by a sensing resistor immersed in a triple-point-of-water cell is compared to the noise power of a quantum-accurate pseudo-random noise waveform of nominally equal noise power. The experimental setup differs from that of the 2015 determination in several respects: a 100 Ω resistor is used as the thermal noise source, identical thin coaxial cables made of solid beryllium–copper conductors and foam dielectrics are used to connect the thermal and quantum-accurate noise sources to the correlator so as to minimize the temperature and frequency sensitivity of the impedances in the connecting leads, and no trimming capacitors or inductors are inserted into the connecting leads. The combination of reduced uncertainty due to spectral mismatches in the connecting leads and reduced statistical uncertainty due to a longer integration period of 100 d results in an improved determination of k = 1.380 649 7(37) × 10−23 J K−1 with a relative standard uncertainty of 2.7 × 10−6 and a relative offset of 0.89 × 10−6 from the CODATA 2014 recommended value. The most significant terms in the uncertainty budget, the statistical uncertainty and the spectral-mismatch uncertainty, are uncorrelated with the corresponding uncertainties in the 2015 measurements.
机译：最近使用声学气体测温法进行的测量已经确定了玻尔兹曼常数k的值，相对不确定度小于1×10 -6 。这些结果得到了用介电常数气体测温法进行的相对不确定度为1.9×10 -6 的测量的支持。这些测量结果一起满足国际度量衡委员会的要求，并使它们能够在2018年重新定义开尔文。在进一步的支持下，我们使用纯电子方法（约翰逊噪声测温法）提供了一种新的k测定方法，其中，将浸没在三点水单元中的传感电阻器产生的热噪声功率与名义上等于噪声功率的量子精确伪随机噪声波形的噪声功率进行比较。实验设置与2015年确定的设置在几个方面有所不同：一个100Ω电阻器用作热噪声源，相同的由实心铍铜导体和泡沫电介质制成的细同轴电缆用于连接热和量子精度噪声源提供给相关器，以最小化连接导线中阻抗的温度和频率敏感性，并且没有微调电容器或电感器插入连接导线中。由于连接引线中的光谱不匹配而导致的不确定性降低，以及由于100 d较长的积分时间导致的统计不确定性降低，从而提高了k = 1.380 649 7（37）×10 −23 JK −1 ，相对标准不确定度为2.7×10 -6 ，相对于CODATA 2014的相对偏移为0.89×10 -6 推荐值。不确定性预算中最重要的术语，统计不确定性和频谱不匹配不确定性与2015年测量中的相应不确定性无关。

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