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technical paper
Analog quantum control of magnonic cat states on a
We propose to directly and quantum-coherently couple a superconducting transmon qubit to magnons — the quanta of the collective spin excitations, in a nearby magnetic particle. The magnet’s stray field couples to the qubit via a superconducting interference device (SQUID) leading to strong and tunable interactions. More specifically, we predict a
resonant magnon-qubit exchange coupling, similar to the one studied in 3D cavity setups 1, and a novel magnon-qubit nonlinear interaction that is similar to the radiation-pressure
coupling in optomechanics 2. We show that the latter can be resonantly enhanced by dynamically driving the flux in the SQUID, and demonstrate a quantum control scheme to generate
magnon-qubit entanglement and magnonic Schrödinger cat states with high fidelity. Our results 3 enrich the quantum control toolbox in magnonic devices and open new possibilities for
constructing quantum magnonic networks on a chip.
References
1 Y. Tabuchi, S. Ishino, A. Noguchi, T. Ishikawa, R. Yamazaki, K. Usami, and Y. Nakamura, Science Vol. 349, p. 405 (2015).
2 M. Aspelmeyer, T. J. Kippenberg, and F. Marquardt, Rev. Mod. Phys. Vol. 86, p. 1391 (2014).
3 M. Kounalakis, G. E. W. Bauer, Y. M. Blanter, arXiv:2203.11893 (2022).
Fig. 1. Proposed circuit architecture.