Intertwined superfluid and density wave order in two-dimensional 4He. / Nyeki, Jan; Phillis, Anastasia; Ho, Andrew; Lee, Derek; Coleman, Piers; Cowan, Brian; Saunders, John.

In: Nature Physics, Vol. 13, 06.02.2017, p. 455-459.

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Intertwined superfluid and density wave order in two-dimensional 4He. / Nyeki, Jan; Phillis, Anastasia; Ho, Andrew; Lee, Derek; Coleman, Piers; Cowan, Brian; Saunders, John.

In: Nature Physics, Vol. 13, 06.02.2017, p. 455-459.

Research output: Contribution to journalLetter

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@article{2f528553f5364b59b671971d6029e3fb,
title = "Intertwined superfluid and density wave order in two-dimensional 4He",
abstract = "Superfluidity is a manifestation of the operation of the laws of quantum mechanics on a macroscopic scale. The conditions under which superfluidity becomes manifest have been extensively explored experimentally in both quantum liquids (liquid 4He being the canonical example) and ultracold atomic gases, including as a function of dimensionality. Of particular interest is the hitherto unresolved question of whether a solid can be superfluid. Here we report the identification of a new state of quantum matter with intertwined superfluid and density wave order in a system of two-dimensional bosons subject to a triangular lattice potential. Using a torsional oscillator we have measured the superfluid response of the second atomic layer of 4He adsorbed on the surface of graphite, over a wide temperature range down to 2 mK. Superfluidity is observed over a narrow range of film densities, emerging suddenly and subsequently collapsing towards a quantum critical point. The unusual temperature dependence of the superfluid density in the limit of zero temperature and the absence of a clear superfluid onset temperature are explained, self-consistently, by an ansatz for the excitation spectrum, reflecting density wave order, and a quasi-condensate wavefunction breaking both gauge and translational symmetry.",
keywords = "superfluidity, density wave, helium film , quantum critical point, supersolid, gauge symmetry, translational symmetry, torsional oscillator, atomic gas, 2D bosons, triangular lattice, condensate",
author = "Jan Nyeki and Anastasia Phillis and Andrew Ho and Derek Lee and Piers Coleman and Brian Cowan and John Saunders",
year = "2017",
month = "2",
day = "6",
doi = "10.1038/nphys4023",
language = "English",
volume = "13",
pages = "455--459",
journal = "Nature Physics",
issn = "1745-2473",
publisher = "Nature Publishing Group",

}

RIS

TY - JOUR

T1 - Intertwined superfluid and density wave order in two-dimensional 4He

AU - Nyeki, Jan

AU - Phillis, Anastasia

AU - Ho, Andrew

AU - Lee, Derek

AU - Coleman, Piers

AU - Cowan, Brian

AU - Saunders, John

PY - 2017/2/6

Y1 - 2017/2/6

N2 - Superfluidity is a manifestation of the operation of the laws of quantum mechanics on a macroscopic scale. The conditions under which superfluidity becomes manifest have been extensively explored experimentally in both quantum liquids (liquid 4He being the canonical example) and ultracold atomic gases, including as a function of dimensionality. Of particular interest is the hitherto unresolved question of whether a solid can be superfluid. Here we report the identification of a new state of quantum matter with intertwined superfluid and density wave order in a system of two-dimensional bosons subject to a triangular lattice potential. Using a torsional oscillator we have measured the superfluid response of the second atomic layer of 4He adsorbed on the surface of graphite, over a wide temperature range down to 2 mK. Superfluidity is observed over a narrow range of film densities, emerging suddenly and subsequently collapsing towards a quantum critical point. The unusual temperature dependence of the superfluid density in the limit of zero temperature and the absence of a clear superfluid onset temperature are explained, self-consistently, by an ansatz for the excitation spectrum, reflecting density wave order, and a quasi-condensate wavefunction breaking both gauge and translational symmetry.

AB - Superfluidity is a manifestation of the operation of the laws of quantum mechanics on a macroscopic scale. The conditions under which superfluidity becomes manifest have been extensively explored experimentally in both quantum liquids (liquid 4He being the canonical example) and ultracold atomic gases, including as a function of dimensionality. Of particular interest is the hitherto unresolved question of whether a solid can be superfluid. Here we report the identification of a new state of quantum matter with intertwined superfluid and density wave order in a system of two-dimensional bosons subject to a triangular lattice potential. Using a torsional oscillator we have measured the superfluid response of the second atomic layer of 4He adsorbed on the surface of graphite, over a wide temperature range down to 2 mK. Superfluidity is observed over a narrow range of film densities, emerging suddenly and subsequently collapsing towards a quantum critical point. The unusual temperature dependence of the superfluid density in the limit of zero temperature and the absence of a clear superfluid onset temperature are explained, self-consistently, by an ansatz for the excitation spectrum, reflecting density wave order, and a quasi-condensate wavefunction breaking both gauge and translational symmetry.

KW - superfluidity

KW - density wave

KW - helium film

KW - quantum critical point

KW - supersolid

KW - gauge symmetry

KW - translational symmetry

KW - torsional oscillator

KW - atomic gas

KW - 2D bosons

KW - triangular lattice

KW - condensate

UR - https://doi.org/10.6084/m9.figshare.4290752.v1

U2 - 10.1038/nphys4023

DO - 10.1038/nphys4023

M3 - Letter

VL - 13

SP - 455

EP - 459

JO - Nature Physics

JF - Nature Physics

SN - 1745-2473

ER -