A Comparison of 2e/h Determinations at NSL Using Point-contact and Thin-film Josephson Junctions
Determinations of 2e/h by means of the a.c. Josephson frequency-voltage relationship have been reported by several groups of workers (1–7). Some of these determinations were carried out using thin-film Josephson junctions (1, 2, 6, 7) while others used point-contact junctions (4, 5, 7). Although no theoretical argument has been advanced to suggest that values of 2e/h obtained using different types of junction might differ, it is of interest to determine by experimental means whether any discrepancy exists at the present level of experimental precision. No such comparison has been reported since Parker et al. (7) indicated that there was no significant discrepancy at a precision of 0.9 p.p.m.
KeywordsVoltage Step Voltage Standard Divider Current Lead Film Mercury Cell
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