Graphene for Quantum metrology
In collaboration with METAS (Swiss Federal Institute of Metrology) we work on the development of new quantum standard of resistance based on Quantum Hall effect in graphene.
In electrical metrology, macroscopic quantum effects offer the possibility to realize primary standards with an unprecedented accuracy. The quantized Hall resistance (QHR) takes values only defined by the fundamental constants 'h' and 'e' and can be measured with an uncertainty on the order of 1 part per billion.
The larger energy level spacing observed between the first two Landau levels in graphene makes it an ideal candidate to realize a QHE standard operational under relaxed experimental conditions i.e. at higher temperatures and/or at lower magnetic field strengths.
At our lab, we are working towards the development of high accuracy of quantization of quantum Hall plateaus in CVD graphene films. Using a cryogenic current comparator, high precision measurements of the QHR on plateau i=2 reveal a quantization accuracy of within 30 ppb. This result shows that CVD graphene films can offer the quality required for metrological applications.
a) K. Thodkar, C. Nef, W. Fu, C. Schonenberger, M. Calame, F. Luond, F. Overney, and B. Jeanneret. CVD graphene for electrical quantum metrology. , Proceedings of the Conference on Precision Electromagnetic Measurements (CPEM 2014), August 24-29, 2014, pages 540-541, August 2014.
b) K. Thodkar, C. Schoenenberger, M. Calame, F. Luond, F. Overney, and B. Jeanneret. Characterization of HMDS treated CVD Graphene. , Proceedings of the Conference on Precision Electromagnetic Measurements (CPEM 2016), July 10-15, 2016, August 2016.\
c) High quality CVD graphene for quantum Hall resistance standards, to be submitted.