@article{642d8b0932ab41a1b0c7e17c0d45e285,
title = "Universal Stabilization of a Parametrically Coupled Qubit",
abstract = "We autonomously stabilize arbitrary states of a qubit through parametric modulation of the coupling between a fixed frequency qubit and resonator. The coupling modulation is achieved with a tunable coupling design, in which the qubit and the resonator are connected in parallel to a superconducting quantum interference device. This allows for quasistatic tuning of the qubit-cavity coupling strength from 12 MHz to more than 300 MHz. Additionally, the coupling can be dynamically modulated, allowing for single-photon exchange in 6 ns. Qubit coherence times exceeding 20 μs are maintained over the majority of the range of tuning, limited primarily by the Purcell effect. The parametric stabilization technique realized using the tunable coupler involves engineering the qubit bath through a combination of photon nonconserving sideband interactions realized by flux modulation, and direct qubit Rabi driving. We demonstrate that the qubit can be stabilized to arbitrary states on the Bloch sphere with a worst-case fidelity exceeding 80%.",
author = "Yao Lu and S. Chakram and N. Leung and N. Earnest and Naik, {R. K.} and Ziwen Huang and Peter Groszkowski and Eliot Kapit and Jens Koch and Schuster, {David I.}",
note = "Funding Information: We thank M. W. Wei, Andy C. Y. Li, D. C. Mckay, and J. Lawrence for helpful discussions. Research was sponsored by the Army Research Laboratory and was accomplished under Cooperative Grant No. W911NF-15-2-0058. The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the official policies, either expressed or implied, of the Army Research Laboratory or the U.S. Government. The U.S. Government is authorized to reproduce and distribute reprints for government purposes notwithstanding any copyright notation herein. Research was also supported by the U.S. Department of Defense (DOD) under DOD Contract No. H98230-15-C0453. Use of the Center for Nanoscale Materials, an Office of Science user facility, was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Award No. DE-AC02-06CH11357. This work made use of the Pritzker Nanofabrication Facility of the Institute for Molecular Engineering at the University of Chicago, which receives support from SHyNE, a node of the National Science Foundation{\textquoteright}s National Nanotechnology Coordinated Infrastructure (Grant No. NSF NNCI-1542205). E. K. was supported by the Louisiana Board of Regents Grant No. LEQSF(2016-19)-RD-A-19 and by the National Science Foundation Grant No. PHY-1653820. We gratefully acknowledge support from the David and Lucile Packard Foundation. Publisher Copyright: {\textcopyright} 2017 American Physical Society.",
year = "2017",
month = oct,
day = "13",
doi = "https://doi.org/10.1103/PhysRevLett.119.150502",
language = "American English",
volume = "119",
journal = "Physical review letters",
issn = "0031-9007",
publisher = "American Physical Society",
number = "15",
}