Observation of supersymmetric pseudo-Landau levels in strained microwave graphene

Abstract

Using an array of coupled microwave resonators arranged in a deformed honeycomb lattice, we experimentally observe the formation of pseudo-Landau levels in the whole crossover from vanishing to large pseudomagnetic field strength. This is achieved by utilizing an adaptable set-up in a geometry that is compatible with the pseudo-Landau levels at all field strengths. The adopted approach enables us to observe fully formed flat-band pseudo-Landau levels spectrally as sharp peaks in the photonic density of states, and image the associated wavefunctions spatially, where we provide clear evidence for a characteristic nodal structure reflecting the previously elusive supersymmetry in the underlying low-energy theory. In particular, we resolve the full sublattice polarization of the anomalous 0th pseudo-Landau level, which reveals a deep connection to zigzag edge states in the unstrained case.

Landau levels in strained two-dimensional photonic crystals

“…Strain-induced pseudomagnetic fields have been demonstrated experimentally in photonic systems of coupled waveguide arrays [13], exciton-polariton condensates based on coupled cavities [14,15], and microwave systems of coupled resonators [16]. Photonic Landau levels have also been discussed in the context of lasing models [17] and strain and related ideas have been explored as a means for producing pseudomagnetism in acoustic systems [18][19][20].…”