Fig. 2: Wavevector-selective parametric pumping and formation of an asymmetric magnon Bose–Einstein condensate (BEC).
From: Classical analog of qubit logic based on a magnon Bose–Einstein condensate
a Phased-array magnetic field excitation mechanism. The red bars represent microstrip antennas placed on the surface of an yttrium-iron-garnet (YIG) film. The wavevector \(+{q}_{{}_{{{{{{{{\rm{BEC}}}}}}}}}}\) of the BEC+ component of the double BEC is directed along the magnetization direction z. b Schematic view of wavevector-selective parametric pumping scheme using microwave photons of frequency ωp with large wavenumbers \({q}_{z}={q}_{{{{{{{{\rm{p}}}}}}}}}\gtrsim +2{q}_{{}_{{{{{{{{\rm{BEC}}}}}}}}}}\). The red dashed arrows illustrate the process of decaying the pump photon into two magnons with co-directional wavevectors. In this case, the density of magnon gas and the magnon condensate BEC+ in the area of positive wavenumbers qz (the green shaded area and large green dot, respectively) significantly exceeds the density of magnon gas and the magnon condensate BEC− in the area of negative wavenumbers qz (the blue shaded area and small blue dot, respectively). c Micromagnetic modeling of BEC formation using such wavevector-selective parametric pumping. The color code indicates the normalized magnon density.
