Characterization and Control of Measurement-Induced Dephasing on Superconducting Flux Qubit with a Josephson Bifurcation Amplifier
Kosuke Kakuyanagi, Yuichiro Matsuzaki, Tatsuya Baba, Hayato Nakano, Shiro Saito, Kouichi Semba · Journal of the Physical Society of Japan · 2016
Quantum measurements play a central role in quantum information processing. Understanding the mechanism of the quantum measurements is essential to both improve the visibility of the readout and decrease the projection error during measurement. Here, we describe and demonstrate an experimental protocol for quantifying a measurement backaction when we readout a superconducting flux qubit using a Josephson bifurcation amplifier. The coupling with the Josephson bifurcation amplifier induces a dephasing on the flux qubit during the readout. We have succeeded in estimating and controlling the strength of such a measurement-induced dephasing by changing the pulse height of the microwave driving. Our results are crucial for designing a suitable quantum readout technique for the realization of practical quantum devices.