The quantum Hall effect (QHE) provides a stable standard of electrical resistance, based on fundamental physical constants. However, the Gallium Arsenide QHE devices used in metrology labs have to be cooled to temperatures of 0.3 Kelvin, which limits their range of application.

In a joint project with QinetiQ, NPL is developing QHE devices based on the low effective-mass semiconductor Indium Antimonide. We show that these devices work at temperatures as "high" as 4.2 Kelvin, requiring much less sophisticated refrigeration.

Stephen Giblin graduated from Bristol University in 1997, with a PhD in magnetic properties of high-temperature superconductors. He joined NPL in May 1997 to work on electrical current standards based on single-electron transport in nano-scale devices. Stephen has also worked on many aspects of primary electrical metrology, including quantum Hall effect resistance standards, cryogenic current comparators, and ac bridges for precise impedance measurement.