Few Electron Transfer using Helium-Channel CCDs

Electrons floating on liquid helium have been proposed as a promising candidate for quantum computing due to their predicted long spin coherence times [1] and high mobilities [2]. In addition, the exceptionally small spin-orbit coupling allows mobile electrons to retain their long spin coherence, enabling fast and coherent qubit transport. Charge-coupled devices (CCDs) have been shown to enable efficient clocked electron transport along gate-defined channels across the surface of superfluid helium [3]. Here, we demonstrate transfer of as few as 2 electrons across 6 gate-defined helium-filled channels using a 3-phase CCD. An electron sensitivity of 2 was achieved at a time constant of 1 second using a home-built cryogenic cascode amplifier circuit. The CCDs were fabricated using a complementary metal-oxide-semiconductor (CMOS) back end of line (BEOL) metallization process at the Sandia National Laboratories MESA fab.

[1] S. A. Lyon, Phys. Rev. A 74, 052338 (2006)

[2] Shirahama et al., J. Low Temp. Phys. 101, 439-444 (1995)

[3] Bradbury et al., Phys. Rev. Lett. 107, 266803 (2011)