The e-SI-Amp sample package

Exchangeable electron pump sample holder

Working with the manufacturer of bespoke cryogenic components Aivon, we have developed a sample enclosure for electron pump samples compatible with cryostats at VTT, NPL and Aalto.

This can be used to test the universality of different electron pump architectures and the robustness of electron pump performance when the same device is exchanged between labs.

It uses three high bandwidth SMP connectors (which are very compact), parallel multi-pin DC omnetics connectors to enable all device terminals to be grounded when the device is being transported/handled. This sample holder is available commercially from Aivon.

How do you know if a quantum standard is working?

The quantum hall effect provides a robust resistance standard that is identical in all systems measured.

An interesting question surrounding the development of quantum electrical standards is whether they ever need to be ‘validated’ or checked against other standards, either locally within a lab or across different labs.

If all of the implementation-dependent details drop out, and you are left with a physical effect that only depends up on fundamental constants, do you still need to check that you have the correct answer?

Metrologists have tested Josephson voltage and quantum hall resistance standards, in similar or dissimilar combinations, showing that the quantised voltages and resistance are universal at an accuracy much better than the part per billion resolution used in top level electrical metrology. Devices are also routinely fabricated and tested in one country and sent to another with the expectation that a quantum standard will behave in exactly the same way in another lab.

Confidence can be further boosted by various in situ tests that can be performed to indicate that a measurement is valid (e.g. zero voltage drops the edge of a quantum hall sample and exact ratios of the hall resistance on different plateau)

Testing universality and robustness of electron pumps as a quantum standard

Universality and robustness testing of electron pumps

For electron pumps, this question of universality, and the robustness of devices when transported between labs is less well explored.  While multiple pumps have been tested to the part per million level against other standards, this is often within one lab, and might be of pumps of essentially the same design and in the same material systems. Comparisons of pumps of different types, and tests of the robustness of these devices when measured in different location are required.

The e-SI-Amp project is addressing this by developing ‘electron pump exchange’ procedures. This will enable labs to test each other’s electron pumps in a way that has not been possible in the past.

Although this might sound simple, there are several difficulties in performing these kind pump comparison and exchange experiments.

  • Expertise on how to operate a particular pump implementation may be required.
  • Expertise in how NOT to handle a pump may be required to not destroy it!
  • Samples may be mounted in non-universal sample packages that are not compatible with different fridges.
  • Duplicate equipment (cryostats, signal generators) may be required to compare two pumps.

The e-SI-amp project are obviously exchanging information about device operation and best practice among the electron pump research community to help with problems of device operation. Our new sample holder includes all of the features required to operate an electron pump in a form factor compatible with the measurement system of several partner labs. This will enable the same electron pump to be measured in multiple locations, testing the robustness of device operations.



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