Lasing, quantum geometry and coherence in non-Hermitian flat bands

• URL: http://arxiv.org/abs/2308.08418v2
• Date: Fri, 18 Aug 2023 09:24:24 GMT
• Title: Lasing, quantum geometry and coherence in non-Hermitian flat bands
• Authors: Ivan Amelio, Nathan Goldman
• Abstract summary: We show that lasing in flat band lattices can be stabilized by means of the geometrical properties of the Bloch states. We analytically show that the phase dynamics display a surprising cancellation of the Kardar-Parisi-Zhang nonlinearity at the leading order.
• Score: 0.0
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: We show that lasing in flat band lattices can be stabilized by means of the geometrical properties of the Bloch states, in settings where the single-particle dispersion is flat in both its real and imaginary parts. We illustrate a general projection method and compute the collective excitations, which are shown to display a diffusive behavior ruled by quantum geometry through a peculiar coefficient involving gain, losses and interactions. Then, we analytically show that the phase dynamics display a surprising cancellation of the Kardar-Parisi-Zhang nonlinearity at the leading order. Because of the relevance of Kardar-Parisi-Zhang universality in one-dimensional geometries, we focus our study on the diamond chain and provide confirmation of these results through full numerical simulations.

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