@article{727dd0bc353b46e79860b6830024f433,
title = "Digital Coherent Control of a Superconducting Qubit",
abstract = "High-fidelity gate operations are essential to the realization of a fault-tolerant quantum computer. In addition, the physical resources required to implement gates must scale efficiently with system size. A longstanding goal of the superconducting qubit community is the tight integration of a superconducting quantum circuit with a proximal classical cryogenic control system. Here we implement coherent control of a superconducting transmon qubit using a single-flux quantum (SFQ) pulse driver cofabricated on the qubit chip. The pulse driver delivers trains of quantized flux pulses to the qubit through a weak capacitive coupling; coherent rotations of the qubit state are realized when the pulse-to-pulse timing is matched to a multiple of the qubit oscillation period. We measure the fidelity of SFQ-based gates to be approximately 95% using interleaved randomized benchmarking. Gate fidelities are limited by quasiparticle generation in the dissipative SFQ driver. We characterize the dissipative and dispersive contributions of the quasiparticle admittance and discuss mitigation strategies to suppress quasiparticle poisoning. These results open the door to integration of large-scale superconducting qubit arrays with SFQ control elements for low-latency feedback and stabilization.",
author = "E. Leonard and Beck, {M. A.} and J. Nelson and Christensen, {B. G.} and T. Thorbeck and C. Howington and A. Opremcak and Pechenezhskiy, {I. V.} and K. Dodge and Dupuis, {N. P.} and Hutchings, {M. D.} and J. Ku and F. Schlenker and J. Suttle and C. Wilen and S. Zhu and Vavilov, {M. G.} and Plourde, {B. L.T.} and R. McDermott",
note = "Funding Information: The authors thank O.A. Mukhanov, T.A. Ohki, M.J. Vinje, and F.K. Wilhelm for numerous stimulating discussions. This work is supported by the U.S. Government under Grant No. W911NF-15-1-0248; R.M. and B.L.T.P. acknowledge funding from the National Science Foundation under Grants No. QIS-1720304 and No. QIS-1720312, respectively. Portions of this work were performed at the Nanoscale Fabrication Center, a research core facility managed by the Wisconsin Centers for Nanoscale Technology and supported by the University of Wisconsin—Madison. Other portions were performed at the Cornell NanoScale Facility, a member of the National Nanotechnology Coordinated Infrastructure (NNCI), which is supported by the National Science Foundation under Grant No. NNCI-1542081. Microscopy and materials analysis infrastructure and instrumentation used for this work are supported by the National Science Foundation through the University of Wisconsin Nanoscale Imaging and Analysis Center (DMR-1720415). 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 U.S. Government. Publisher Copyright: {\textcopyright} 2019 American Physical Society.",
year = "2019",
month = jan,
day = "7",
doi = "10.1103/PhysRevApplied.11.014009",
language = "English (US)",
volume = "11",
journal = "Physical Review Applied",
issn = "2331-7019",
publisher = "American Physical Society",
number = "1",
}