Quantum Coherent Tunable Coupling of Superconducting Qubits
A. O. Niskanen, K. Harrabi, Fumiki Yoshihara, Yasunobu Nakamura, Seth Lloyd, Jaw-Shen Tsai · Science · 2007
To do large-scale quantum information processing, it is necessary to control the interactions between individual qubits while retaining quantum coherence. To this end, superconducting circuits allow for a high degree of flexibility. We report on the time-domain tunable coupling of optimally biased superconducting flux qubits. By modulating the nonlinear inductance of an additional coupling element, we parametrically induced a two-qubit transition that was otherwise forbidden. We observed an on/off coupling ratio of 19 and were able to demonstrate a simple quantum protocol.