Observation of a single electron trapped over surface of 4 He.
Emmanuel Rousseau, Dmitri Ponarine, and Yury Mukharsky
CEA-Saclay/DSM/DRECAM/SPEC, 91191 Gif sur Yvette, Cedex, France
We are reporting trapping of electrons in a microfabricated ring filled with a film of liquid 4 He. The
electrons float over the surface of helium. They are detected by a Single Electron Transistor (SET)
located at the bottom of the ring. The SET also serves to regulate the depth of the potential well were
the electrons are localized. We can feed electrons in and out from the ring by applying potentials to
nearby electrodes. As an electron leaves the ring, the SET signal changes by 0.4 electron charge. As
many as several tens of electrons leaving the ring can be easily identified. The conditions at which an
electron leaves the ring are quite repeatable and the results of the measurements will be compared with
numerical and analytical predictions for charging a quantum dot.
This experiment aims at using an electron suspended over helium as a qubit. Good stability of the
threshold voltages indicates that the fluctuations caused by the substrate are weak. In addition, ability
to populate a pool of electrons with pre-defined number of them opens route for new studies, such as
phase transitions of an electron island in a quantum dot.
Sorting category: Da Conducting electrons in condensed matter
Keywords: qubit,electron,surface,helium
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