Observing the emergence of a quantum phase transition shell by shell
(2020) In Nature 587(7835). p.583-587- Abstract
Many-body physics describes phenomena that cannot be understood by looking only at the constituents of a system1. Striking examples are broken symmetry, phase transitions and collective excitations2. To understand how such collective behaviour emerges as a system is gradually assembled from individual particles has been a goal in atomic, nuclear and solid-state physics for decades3–6. Here we observe the few-body precursor of a quantum phase transition from a normal to a superfluid phase. The transition is signalled by the softening of the mode associated with amplitude vibrations of the order parameter, usually referred to as a Higgs mode7. We achieve fine control over ultracold fermions... (More)
Many-body physics describes phenomena that cannot be understood by looking only at the constituents of a system1. Striking examples are broken symmetry, phase transitions and collective excitations2. To understand how such collective behaviour emerges as a system is gradually assembled from individual particles has been a goal in atomic, nuclear and solid-state physics for decades3–6. Here we observe the few-body precursor of a quantum phase transition from a normal to a superfluid phase. The transition is signalled by the softening of the mode associated with amplitude vibrations of the order parameter, usually referred to as a Higgs mode7. We achieve fine control over ultracold fermions confined to two-dimensional harmonic potentials and prepare closed-shell configurations of 2, 6 and 12 fermionic atoms in the ground state with high fidelity. Spectroscopy is then performed on our mesoscopic system while tuning the pair energy from zero to a value larger than the shell spacing. Using full atom counting statistics, we find the lowest resonance to consist of coherently excited pairs only. The distinct non-monotonic interaction dependence of this many-body excitation, combined with comparison with numerical calculations allows us to identify it as the precursor of the Higgs mode. Our atomic simulator provides a way to study the emergence of collective phenomena and the thermodynamic limit, particle by particle.
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- author
- Bayha, Luca ; Holten, Marvin ; Klemt, Ralf ; Subramanian, Keerthan ; Bjerlin, Johannes LU ; Reimann, Stephanie M. LU ; Bruun, Georg M. LU ; Preiss, Philipp M. and Jochim, Selim
- organization
- publishing date
- 2020
- type
- Contribution to journal
- publication status
- published
- subject
- in
- Nature
- volume
- 587
- issue
- 7835
- pages
- 5 pages
- publisher
- Nature Publishing Group
- external identifiers
-
- pmid:33239796
- scopus:85096511149
- ISSN
- 0028-0836
- DOI
- 10.1038/s41586-020-2936-y
- language
- English
- LU publication?
- yes
- id
- 59b6d08a-200f-4271-a9d8-63d11cdefee4
- date added to LUP
- 2021-01-15 12:25:55
- date last changed
- 2025-07-11 18:40:51
@article{59b6d08a-200f-4271-a9d8-63d11cdefee4,
abstract = {{<p>Many-body physics describes phenomena that cannot be understood by looking only at the constituents of a system<sup>1</sup>. Striking examples are broken symmetry, phase transitions and collective excitations<sup>2</sup>. To understand how such collective behaviour emerges as a system is gradually assembled from individual particles has been a goal in atomic, nuclear and solid-state physics for decades<sup>3–6</sup>. Here we observe the few-body precursor of a quantum phase transition from a normal to a superfluid phase. The transition is signalled by the softening of the mode associated with amplitude vibrations of the order parameter, usually referred to as a Higgs mode<sup>7</sup>. We achieve fine control over ultracold fermions confined to two-dimensional harmonic potentials and prepare closed-shell configurations of 2, 6 and 12 fermionic atoms in the ground state with high fidelity. Spectroscopy is then performed on our mesoscopic system while tuning the pair energy from zero to a value larger than the shell spacing. Using full atom counting statistics, we find the lowest resonance to consist of coherently excited pairs only. The distinct non-monotonic interaction dependence of this many-body excitation, combined with comparison with numerical calculations allows us to identify it as the precursor of the Higgs mode. Our atomic simulator provides a way to study the emergence of collective phenomena and the thermodynamic limit, particle by particle.</p>}},
author = {{Bayha, Luca and Holten, Marvin and Klemt, Ralf and Subramanian, Keerthan and Bjerlin, Johannes and Reimann, Stephanie M. and Bruun, Georg M. and Preiss, Philipp M. and Jochim, Selim}},
issn = {{0028-0836}},
language = {{eng}},
number = {{7835}},
pages = {{583--587}},
publisher = {{Nature Publishing Group}},
series = {{Nature}},
title = {{Observing the emergence of a quantum phase transition shell by shell}},
url = {{http://dx.doi.org/10.1038/s41586-020-2936-y}},
doi = {{10.1038/s41586-020-2936-y}},
volume = {{587}},
year = {{2020}},
}