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| Main Authors: | , , , , , , |
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| Format: | Preprint |
| Published: |
2022
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2203.05059 |
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| _version_ | 1866912000180748288 |
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| author | Saugmann, Pil Vargas, José Kiefer, Yann Hachman, Max Eichberger, Raphael Hemmerich, Andreas Larson, Jonas |
| author_facet | Saugmann, Pil Vargas, José Kiefer, Yann Hachman, Max Eichberger, Raphael Hemmerich, Andreas Larson, Jonas |
| contents | We propose and experimentally explore a method for realizing frustrated lattice models using a Bose-Einstein condensate held in an optical square lattice. A small lattice distortion opens up an energy gap such the lowest band splits into two. Along the edge of the first Brillouin zone for both bands a nearly flat energy-momentum dispersion is realized. For the excited band a highly degenerate energy minimum arises. By loading ultracold atoms into the excited band, a classically frustrated $XY$ model is formed, describing rotors on a square lattice with competing nearest and next nearest tunnelling couplings. Our experimental optical lattice provides a regime, where a fully coherent Bose-Einstein condensate is observed, and a regime where frustration is expected. If we adiabatically tune from the condensate regime to the regime of frustration, the momentum spectra shows a complete loss of coherence. Upon slowly tuning back to the condensate regime, coherence is largely restored. Good agreement with model calculations is obtained. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2203_05059 |
| institution | arXiv |
| publishDate | 2022 |
| record_format | arxiv |
| spellingShingle | Route towards classical frustration and band flattening via optical lattice distortion Saugmann, Pil Vargas, José Kiefer, Yann Hachman, Max Eichberger, Raphael Hemmerich, Andreas Larson, Jonas Quantum Gases Quantum Physics We propose and experimentally explore a method for realizing frustrated lattice models using a Bose-Einstein condensate held in an optical square lattice. A small lattice distortion opens up an energy gap such the lowest band splits into two. Along the edge of the first Brillouin zone for both bands a nearly flat energy-momentum dispersion is realized. For the excited band a highly degenerate energy minimum arises. By loading ultracold atoms into the excited band, a classically frustrated $XY$ model is formed, describing rotors on a square lattice with competing nearest and next nearest tunnelling couplings. Our experimental optical lattice provides a regime, where a fully coherent Bose-Einstein condensate is observed, and a regime where frustration is expected. If we adiabatically tune from the condensate regime to the regime of frustration, the momentum spectra shows a complete loss of coherence. Upon slowly tuning back to the condensate regime, coherence is largely restored. Good agreement with model calculations is obtained. |
| title | Route towards classical frustration and band flattening via optical lattice distortion |
| topic | Quantum Gases Quantum Physics |
| url | https://arxiv.org/abs/2203.05059 |