Realization of High-Fidelity CZ and ZZ -Free iSWAP Gates with a Tunable Coupler
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PhysRevX.11.021058.pdf
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Published version
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Author(s)
Sung, Youngkyu
Ding, Leon
Braumüller, Jochen
Vepsäläinen, Antti
Kannan, Bharath
Kjaergaard, Morten
Greene, Ami
Samach, Gabriel O
McNally, Chris
Kim, David
Date Issued
2021
Journal
Physical Review X
Publisher
American Physical Society (APS)
Citation
Sung, Youngkyu, Ding, Leon, Braumüller, Jochen, Vepsäläinen, Antti, Kannan, Bharath et al. 2021. "Realization of High-Fidelity CZ and ZZ -Free iSWAP Gates with a Tunable Coupler." Physical Review X, 11 (2).
Version
Final published version
Abstract
High-fidelity two-qubit gates at scale are a key requirement to realize the
full promise of quantum computation and simulation. The advent and use of
coupler elements to tunably control two-qubit interactions has improved
operational fidelity in many-qubit systems by reducing parasitic coupling and
frequency crowding issues. Nonetheless, two-qubit gate errors still limit the
capability of near-term quantum applications. The reason, in part, is the
existing framework for tunable couplers based on the dispersive approximation
does not fully incorporate three-body multi-level dynamics, which is essential
for addressing coherent leakage to the coupler and parasitic longitudinal
($ZZ$) interactions during two-qubit gates. Here, we present a systematic
approach that goes beyond the dispersive approximation to exploit the
engineered level structure of the coupler and optimize its control. Using this
approach, we experimentally demonstrate CZ and $ZZ$-free iSWAP gates with
two-qubit interaction fidelities of $99.76 \pm 0.07$% and $99.87 \pm 0.23$%,
respectively, which are close to their $T_1$ limits.
MIT Department
Massachusetts Institute of Technology. Research Laboratory of Electronics
Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science
Massachusetts Institute of Technology. Department of Physics
Lincoln Laboratory
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DOI of Published Version
https://doi.org/10.1103/PHYSREVX.11.021058
