Josephson Junctions and Single Electron Tunneling Physics


The PJVS system is based on ‘Quantum Phenomena’ (Josephson effect) given by the relation
2eVn = nhf
where n = 0, ± 1, 2 ±, ± 3, ---,       Vn= quantized voltage;            f = frequency of irradiation;                  h= Planck’s constant ;  e = electron charge
This forms the basis for standard of the unit of ‘Volt’ in India at par to the international level. The uncertainty in measurement of Zener Reference Standards is ± 350 nV at k=2 (inclusive of noise of Zener) at 10V level as per the ISO/IEC 17025:2005.
The salient features of the system are :
  • The non-hysteretic Josephson tunnel junctions made up of Nb electrodes and NbxSi1-x barriers.
  • The 10 V chip contains a total of 256,116 Josephson junctions organised in stacks of three junctions and distributed into 32 microwave coplanar waveguide lines.
  • The voltage steps are stable, have superior immunity to noise and have rapid settling time
10 V - PJVS at NPL-India, established in the collaboration with NIST, USA
The I-V curve of a single junction with the microwave power set to equalize the current range of each of the n = {−1, 0, and +1} steps
Photograph of a 10 V-PJVS chip (NIST,USA ) Operating frequency 18-22 GHz picture.2
(a). I-V curves for 23 subarrays
(b). Step flatness test at 18.645 GHz and 0.00 dBm. The array configuration is nnnnnnnnnnnnnnnpppppppp starting from subarray 1 and ending at subarray 23. “0” represents the zero step, “n” the negative step and “p” the positive step. The total array output is 0.000 231 331 5 V, measured by the system nanovoltmeter on 1 mV range.
Sub-Division Member:


Dr. V N Ojha


Mrs. Sandhya Malikaar Patel

Technical Assistant:

Shri Anish Mahaveer Bhargava

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