Residual-<i>ZZ</i>-coupling suppression and fast two-qubit gate for Kerr-cat qubits based on level-degeneracy engineering
Abstract
Building large-scale quantum computers requires an interqubit-coupling scheme with a high on–off ratio to avoid unwanted crosstalk coming from residual coupling and to enable fast multi-qubit operations. We propose a ZZ-coupling scheme for two Kerr-cat qubits with a frequency-tunable coupler. By making four relevant states of the two Kerr-cat qubits quadruply degenerate, we can switch off the ZZ coupling. By partially lifting the level degeneracy, we can switch it on. We theoretically show that an experimentally feasible circuit model suppresses the residual ZZ coupling. Moreover, our circuit can realize RZZ(−π/2)-gate fidelity higher than 99.9% within 18 ns when decoherence is ignored. Our model includes the first-order terms in expansion beyond the rotating-wave approximation.
Article Details
Journal Info
Applied Physics Letters
American Institute of Physics
Authors (4)
Takaaki Aoki
Global Research and Development Center for Business by Quantum-AI Technology (G-QuAT), National Institute of Advanced Industrial Science and Technology (AIST) 1 , 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568,
Akiyoshi Tomonaga
Global Research and Development Center for Business by Quantum-AI Technology (G-QuAT), National Institute of Advanced Industrial Science and Technology (AIST) 1 , 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568,
Kosuke Mizuno
Global Research and Development Center for Business by Quantum-AI Technology (G-QuAT), National Institute of Advanced Industrial Science and Technology (AIST) 1 , 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568,
Shumpei Masuda
Global Research and Development Center for Business by Quantum-AI Technology (G-QuAT), National Institute of Advanced Industrial Science and Technology (AIST) 1 , 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568,