September 16, 20224:00 pm – 5:00 pm (CDT)

## Spin-wave analogue of a qubit controlled by AC magnonic crystal

Speaker:

Ankang Liu (TAMU)

Host:

A. Finkelstein

Location:

We study an analogue of a quantum bit (qubit) which can be tuned by a magnonic crystal with an alternating current (AC) modulation. Generally, the magnonic crystal, which has a spatial modulation described by the wave vector $q$, couples the spin wave with the wave vector $k$ to the one with wave vector $k-q$. For a conventional magnonic crystal with direct current (DC) supply, a band gap is opened at $k=\pm q/2$. If instead of the DC current the magnonic crystal is supplied with an AC modulation, then the band gap is shifted to $k$ satisfying $|\omega_{s}(k)-\omega_{s}(k-q)|=\omega_{ac}$; here $\omega_{s}(k)$ is the dispersion of the spin wave, while $\omega_{ac}$ is the frequency of the AC modulation. This provides a possibility of controlling the propagation of the spin waves with wave vectors differ from $k=q/2$. The time evolution of such a qubit can be controlled by properly suited pulses generated by the magnonic crystal. The dynamic of the system can be interpreted in terms of the motion on a Bloch sphere. The tunable qubit opens a perspective to use the AC magnonic crystal for the wave computing.