Z -Gate Operation on a Superconducting Flux Qubit via its Readout SQUID
Xueying Jin, Simon Gustavsson, Jonas Bylander, Fei Yan, Fumiki Yoshihara, Yasunobu Nakamura, Terry P. Orlando, William D. Oliver · Physical Review Applied · 2015
In quantum information processing, fast qubit gates rely on strong coupling to control fields, but unfortunately a qubit generally cannot distinguish actual control fields from environmental noise. One of the desired logic elements, the so-called $Z$-gate, switches the sign of a ``1'' but leaves a ``0'' unchanged. This study presents a $Z$-gate with a tunable coupling element that is strong only when needed, which keeps noise low yet speed high.