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

ジョセフソン接合を含んだ超伝導量子ビットにおける半整数シャピロステップ

森 道康  ; 前川 禎通

Mori, Michiyasu; Maekawa, Sadamichi

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