6. Conclusion and outlook

Throughout history, the determination of constants has always benefited from advances in instrumentation. Modern metrology is increasingly benefiting from the implementation of quantum phenomena. The current trend is to develop instrumentation capable of generating or measuring a single quantum: a photon, an electron, a spin, and so on. In this context, the use of single-electron nanodevices offers an interesting prospect for the development of fast, quantized current sources. These nanodevices, capable of supplying a current proportional to the elementary charge, would enable a new experiment to be set up for measuring e with an uncertainty on the expected value of the order of 10 ^-8 . Such devices are therefore being considered for the evaluation of elemental charge, and will probably play a part in the next CODATA adjustment.