Dirac mass induced by optical gain and loss
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arXiv
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| Format: | Preprint |
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2024
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| _version_ | 1866913313349173248 |
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| author | Yu, Letian Xue, Haoran Guo, Ruixiang Chan, Eng Aik Terh, Yun Yong Soci, Cesare Zhang, Baile Chong, Y. D. |
| author_facet | Yu, Letian Xue, Haoran Guo, Ruixiang Chan, Eng Aik Terh, Yun Yong Soci, Cesare Zhang, Baile Chong, Y. D. |
| contents | Mass is commonly regarded as an intrinsic property of matter, but modern physics reveals particle masses to have complex origins, such as the Higgs mechanism in high-energy physics. In crystal lattices such as graphene, relativistic Dirac particles can exist as low-energy quasiparticles with masses imparted by lattice symmetry-breaking perturbations. These mass-generating mechanisms all assume Hermiticity, or the conservation of energy in detail. Using a photonic synthetic lattice, we show experimentally that Dirac masses can be generated via non-Hermitian perturbations based on optical gain and loss. We then explore how the space-time engineering of the gain/loss-induced Dirac mass affects the quasiparticles. As we show, the quasiparticles undergo Klein tunnelling at spatial boundaries, but a local breaking of a non-Hermitian symmetry can produce a novel flux nonconservation effect at the domain walls. At a temporal boundary that abruptly flips the sign of the Dirac mass, we observe a variant of the time reflection phenomenon: in the nonrelativistic limit, the Dirac quasiparticle reverses its velocity, while in the relativistic limit the original velocity is retained. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2401_15528 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Dirac mass induced by optical gain and loss Yu, Letian Xue, Haoran Guo, Ruixiang Chan, Eng Aik Terh, Yun Yong Soci, Cesare Zhang, Baile Chong, Y. D. Mesoscale and Nanoscale Physics Mass is commonly regarded as an intrinsic property of matter, but modern physics reveals particle masses to have complex origins, such as the Higgs mechanism in high-energy physics. In crystal lattices such as graphene, relativistic Dirac particles can exist as low-energy quasiparticles with masses imparted by lattice symmetry-breaking perturbations. These mass-generating mechanisms all assume Hermiticity, or the conservation of energy in detail. Using a photonic synthetic lattice, we show experimentally that Dirac masses can be generated via non-Hermitian perturbations based on optical gain and loss. We then explore how the space-time engineering of the gain/loss-induced Dirac mass affects the quasiparticles. As we show, the quasiparticles undergo Klein tunnelling at spatial boundaries, but a local breaking of a non-Hermitian symmetry can produce a novel flux nonconservation effect at the domain walls. At a temporal boundary that abruptly flips the sign of the Dirac mass, we observe a variant of the time reflection phenomenon: in the nonrelativistic limit, the Dirac quasiparticle reverses its velocity, while in the relativistic limit the original velocity is retained. |
| title | Dirac mass induced by optical gain and loss |
| topic | Mesoscale and Nanoscale Physics |
| url | https://arxiv.org/abs/2401.15528 |