Time-domain Coherent Magnon Interference with On-chip Superconducting Hybrid Magnonic Circuits*

Hybrid magnonic systems have recently emerged as a new promising direction that exploits the advantages of magnon excitations for processing quantum information [1]. Here, we develop a superconducting circuit platform, incorporating chip-mounted single-crystal YIG spheres that are mounted in lithographically defined holes on silicon substrates with superconducting resonators, for implementing microwave-mediated distant magnon-magnon interactions [2]. In particular, we use the two-YIG-sphere-one-superconducting-resonator system to demonstrate time-domain coherent magnon interference [3]. By sending a microwave pulse to one sphere and measuring the time trace of microwave output from the other antenna, we can measure the Rabi-like oscillation of magnon excitations between the two remote YIG spheres that are strongly coupled from their dispersive coupling to the superconducting resonator bus. In addition, we show that by sending two microwave pulses with a certainly time delay, their interactions to the YIG sphere lead to coherent interference, i.e. constructive or destructive interference depending on the relative phase delay of the two pulses. This allow us to program the magnon-magnon hybrid states by changing the frequency of the pulse microwave and the time delay. Our results provide a high-performance, circuit integrated cavity magnonic system for building coherent magnon networks and processing hybrid magnon excitations in the time domain.