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Strong-coupling ansatz for the one-dimensional Fermi gas in a harmonic potential

Levinsen, J; Massignan, P; Bruun, GM; Parish, MM; (2014) Strong-coupling ansatz for the one-dimensional Fermi gas in a harmonic potential. Science Advances , 1 (6) , Article e1500197. 10.1126/sciadv.1500197. Green open access

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Abstract

A major challenge in modern physics is to accurately describe strongly interacting quantum many-body systems. One-dimensional systems provide fundamental insights since they are often amenable to exact methods. However, no exact solution is known for the experimentally relevant case of external confinement. Here, we propose a powerful ansatz for the one-dimensional Fermi gas in a harmonic potential near the limit of infinite short-range repulsion. For the case of a single impurity in a Fermi sea, we show that our ansatz is indistinguishable from numerically exact results in both the few- and many-body limits. We furthermore derive an effective Heisenberg spin-chain model corresponding to our ansatz, valid for any spin-mixture, within which we obtain the impurity eigenstates analytically. In particular, the classical Pascal's triangle emerges in the expression for the ground-state wavefunction. As well as providing an important benchmark for strongly correlated physics, our results are relevant for emerging quantum technologies, where a precise knowledge of one-dimensional quantum states is paramount.

Type: Article
Title: Strong-coupling ansatz for the one-dimensional Fermi gas in a harmonic potential
Open access status: An open access version is available from UCL Discovery
DOI: 10.1126/sciadv.1500197
Publisher version: http://dx.doi.org/10.1126/sciadv.1500197
Language: English
Additional information: Copyright © 2015, The Authors This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Keywords: cond-mat.quant-gas, cond-mat.quant-gas, cond-mat.str-el, quant-ph
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
URI: https://discovery.ucl.ac.uk/id/eprint/1471745
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