Trapping single electrons on liquid helium
ABSTRACT Surface-state electrons on liquid helium, localised in quantum dots, have been proposed as condensed matter qubits. We now demonstrate experimentally that small numbers of electrons, including a single isolated electron, can be held in a novel electrostatic trap above the surface of superfluid helium. A potential well is created using microfabricated electrodes in a 5 μm diameter pool of helium. Electrons are injected into the trap from an electron reservoir on a helium microchannel. They are individually detected using a superconducting single-electron transistor (SET) as an electrometer. A Coulomb staircase is observed as electrons leave the trap one-by-one until the trap is empty. A design for a prototype quantum information processor using an array of electron traps on liquid helium is presented.
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ABSTRACT: We investigate the structure of one-component and multicomponent planar Coulomb crystals in RF traps. Due to the RF confinement particular features emerge, especially in the case of multicomponent crystals. After briefly discussing one-component planar crystals, we consider the case of multicomponent crystals and, in particular, planar bicrystals. We show that in the multicomponent case, the spatial separation among components depends on the strength of axial confinement which also imposes a limit on the number of ions that can exist in the innermost shell. These theoretical results are confirmed by molecular dynamics simulations. Finally, we discuss some experimental issues.Journal of Physics B Atomic Molecular and Optical Physics 07/2009; 42(15):154004. DOI:10.1088/0953-4075/42/15/154004 · 1.92 Impact Factor
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ABSTRACT: We present here an experimental study of Wigner islands formed by electrons floating over helium. Electrons are trapped electrostatically in a mesoscopic structure covered with a helium film, behaving as a quantum dot in the near-classical limit. By removing electrons one by one, we are able to find the addition spectrum, i.e., the energy required to add (or extract) one electron from the trap with occupation number N . Experimental addition spectra are compared with Monte Carlo simulations for the actual trap geometry, confirming the ordered state of electrons over helium in the island.Physical review. B, Condensed matter 01/2009; 79(4):45406-. DOI:10.1103/PhysRevB.79.045406 · 3.66 Impact Factor
Article: Planar Coulomb bicrystals[Show abstract] [Hide abstract]
ABSTRACT: We numerically studied two-component planar Coulomb crystals (planar bicrystals) in rf traps. The number of ions in the inner shell was found to be limited by the mass difference between the two components and we calculated the maximum possible number of ions in the inner shells for various mass ratios. When large axial potentials are applied the spatial separation between components depends on the trapping parameters as well as on the ion masses and charges. We derived the spatial separation both theoretically and numerically and discussed its effect on the efficiency of sympathetic cooling and on rf heating. We suggest using planar bicrystals for implementing quantum simulation and computation.Physical Review A 10/2008; 78(4). DOI:10.1103/PhysRevA.78.042340 · 2.99 Impact Factor