Parity effect in superconducting aluminum single electron transistors with spatial gap profile controlled by film thickness

Yamamoto, T. and Nakamura, Y. and Pashkin, Yuri and Astafiev, Oleg V. and Tsai, Jaw-Shen (2006) Parity effect in superconducting aluminum single electron transistors with spatial gap profile controlled by film thickness. Applied Physics Letters, 88 (21): 212509. ISSN 0003-6951

Abstract

We propose a novel method for suppression of quasiparticle poisoning in Al Coulomb blockade devices. The method is based on creation of a proper energy gap profile along the device. In contrast to the previously used techniques, the energy gap is controlled by the film thickness. Our transport measurements confirm that the quasiparticle poisoning is suppressed and clear 2e periodicity is observed only when the island is made much thinner than the leads. This result is consistent with the existing model and provides a simple method to suppress quasiparticle poisoning.