"Depletion" of Superfluid Density: Universal Low-temperature Thermodynamics of Superfluids

Fuente: arXiv
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Auteurs principaux: Berger, Viktor, Prokof'ev, Nikolay, Svistunov, Boris
Format: Preprint
Publié: 2025
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author Berger, Viktor
Prokof'ev, Nikolay
Svistunov, Boris
author_facet Berger, Viktor
Prokof'ev, Nikolay
Svistunov, Boris
contents In a Galilean superfluid, the depletion of superfluid density with rising temperature can be attributed to thermally excited non-interacting phonons. For systems without Galilean symmetry, it has been shown [1] that ``phonon wind" is no longer responsible for the depletion of superfluid density. In this work, we develop the theory of superfluid density at low temperature ($T$) and provide detailed derivations of all results announced in [1]. Using Popov's hydrodynamic action, we show that the theory of low-temperature depletion in a $d$-dimensional quantum superfluid maps onto the problem of finite-size ($L$) corrections in a $(d+1)$-dimensional anisotropic (pseudo-)classical-field system with U(1)-symmetric complex-valued action. In addition to generalizing Landau's (canonical) formula, we develop the grand canonical theory, which in a broader context reveals a universal scaling, $T^{d+1}$ and $1/L^{d+1}$, for finite-$T$ and finite-$L$ effects of many thermodynamic quantities. We validate our theory with numeric simulations of interacting lattice bosons and the J-current model.
format Preprint
id arxiv_https___arxiv_org_abs_2506_22683
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle "Depletion" of Superfluid Density: Universal Low-temperature Thermodynamics of Superfluids
Berger, Viktor
Prokof'ev, Nikolay
Svistunov, Boris
Quantum Gases
Statistical Mechanics
In a Galilean superfluid, the depletion of superfluid density with rising temperature can be attributed to thermally excited non-interacting phonons. For systems without Galilean symmetry, it has been shown [1] that ``phonon wind" is no longer responsible for the depletion of superfluid density. In this work, we develop the theory of superfluid density at low temperature ($T$) and provide detailed derivations of all results announced in [1]. Using Popov's hydrodynamic action, we show that the theory of low-temperature depletion in a $d$-dimensional quantum superfluid maps onto the problem of finite-size ($L$) corrections in a $(d+1)$-dimensional anisotropic (pseudo-)classical-field system with U(1)-symmetric complex-valued action. In addition to generalizing Landau's (canonical) formula, we develop the grand canonical theory, which in a broader context reveals a universal scaling, $T^{d+1}$ and $1/L^{d+1}$, for finite-$T$ and finite-$L$ effects of many thermodynamic quantities. We validate our theory with numeric simulations of interacting lattice bosons and the J-current model.
title "Depletion" of Superfluid Density: Universal Low-temperature Thermodynamics of Superfluids
topic Quantum Gases
Statistical Mechanics
url https://arxiv.org/abs/2506.22683