n -qubit-controlled phase gate with superconducting quantum-interference devices coupled to a resonator
Chui‐Ping Yang, Siyuan Han · Physical Review A · 2005
We present a way to realize an $n$-qubit controlled phase gate with superconducting quantum-interference devices (SQUIDs) by coupling them to a superconducting resonator. In this proposal, the two logical states of a qubit are represented by the two lowest levels of a SQUID. An intermediate level of each SQUID is utilized to facilitate coherent control and manipulation of quantum states of the qubits. It is interesting to note that an $n$-qubit controlled phase gate can be achieved with $n$ SQUIDs by successively applying a $\ensuremath{\pi}∕2$ Jaynes-Cummings pulse to each of the $n\ensuremath{-}1$ control SQUIDs before and after a $\ensuremath{\pi}$ Jaynes-Cummings pulse on the target SQUID.