Half-integer Shapiro-steps in superconducting qubit with a $\pi$-Josephson junction

Abstract

A superconducting quantum interference device (SQUID) comprising 0- and $\pi$-Josephson junctions (JJs), called $\pi$-SQUID, is studied by the resistively shunted junction model. The $\pi$-SQUID shows half-integer Shapiro-steps (SS) under microwave irradiation at the voltage $V$ = $(\hslash /2e)\Omega (n/2)$, with angular frequency $\Omega$ and half-integer $n$/2 in addition to integer $n$. We show that the $\pi$-SQUID can be a $\pi$-qubit with spontaneous loop currents by which the half-integer SS are induced. Making the 0- and $\pi$-JJs equivalent is a key for the half-integer SS and realizing the $\pi$-qubit.

4 pages, 6figures

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• 0-pi Josephson tunnel junctions with ferromagnetic barrier
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Cited by in corpus (1)

• Vortex matter in a two-band SQUID-shaped superconducting film