Half-integer Shapiro-steps in superconducting qubit with a π-Josephson junction
Michiyasu Mori, Sadamichi Maekawa · Applied Physics Express · 2021
Abstract A superconducting quantum interference device (SQUID) comprising 0- and π-Josephson junctions (JJs), called π-SQUID, is studied by the resistively shunted junction model. The π-SQUID shows half-integer Shapiro-steps (SS) under microwave irradiation at the voltage V = ( ℏ / 2 e ) Ω ( n / 2 ) , with angular frequency Ω and half-integer n/2 in addition to integer n. We show that the π-SQUID can be a π-qubit with spontaneous loop currents by which the half-integer SS are induced. Making the 0- and π-JJs equivalent is a key for the half-integer SS and realizing the π-qubit.