Aharonov-Casher effect in quantum ring ensembles

We study the transport of electrons through a single-mode quantum ring with electric-field induced Rashba spin-orbit interaction that is subject to an in-plane magnetic field and weakly coupled to electron reservoirs. Modeling a ring array by ensemble averaging over a Gaussian distribution of energy-level positions, we predict slow conductance oscillations as a function of the Rashba interaction and electron density due to spin-orbit interaction induced beating of the spacings between the levels crossed by the Fermi energy. Our results agree with experiments by Nitta c.s. [J. Nitta, J. Takagi, F. Nagasawa, and M. Kohda, J. Phys.: Conference Series1742-659610.1088/1742-6596/302/1/012002 302, 012002 (2011) and Nagasawa (unpublished)], thereby providing an interpretation that differs from the ordinary Aharonov-Casher effect in a single ring.