Transport and Phonon Damping in $$^{4}$$He

Beauvois, K.; Godfrin, H.; Krotscheck, E.; Zillich, Robert E.

doi:10.1007/s10909-019-02219-1

Cited by 5 publications

(31 citation statements)

References 27 publications

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“…20. The same observation applies to the polynomial fits of the dispersion curve made in different ranges (0.015<k<0.5, 0.015<k<0.6, and 0.18<k<0.6 Å−1 ) with the Jastrow-Feenberg Euler-Lagrange microscopic theory 34,35 . The resulting sound velocities display a small dependence on the selected k-range, not visible at the scale of Fig.…”

Section: A Phononsmentioning

confidence: 62%

“…Non-linear ultrasound data 36,37 (available only between 0 and 15 bar), interpolated to P=0, 2, 5, 10 bar, and extrapolated to large wave-vectors: thick dash-dotted lines. Theory: DMBT 34,35 curves are shown by thin lines for several atomic densities (see graph legend and Table II).…”

Section: A Phononsmentioning

confidence: 99%

“…Sound velocities from ultrasound 45,46 , heat capacity 48,50 , our analysis of compressibility 47 data, and the present neutron scattering measurements, as a function of density (see Table II). Red line: Jastrow-Feenberg Euler-Lagrange calculation 34,35 . Short-dash line: Quantum Monte-Carlo calculation 17 with Aziz II potential.…”

Section: A Phononsmentioning

confidence: 99%

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The dispersion relation of Landau elementary excitations and the thermodynamic properties of superfluid $^4$He

Godfrin,

Beauvois,

Sultan

et al. 2020

Preprint

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The dispersion relation ǫ(k) of the elementary excitations of superfluid 4 He has been measured at very low temperatures, from saturated vapor pressure up to solidification, using a high flux time-offlight neutron scattering spectrometer equipped with a high spatial resolution detector (10 5 'pixels'). A complete determination of ǫ(k) is achieved, from very low wave-vectors up to the end of Pitaeskii's plateau. The results compare favorably in the whole the wave-vector range with the predictions of the dynamic many-body theory (DMBT). At low wave-vectors, bridging the gap between ultrasonic data and former neutron measurements, the evolution with the pressure from anomalous to normal dispersion, as well as the peculiar wave-vector dependence of the phase and group velocities, are accurately characterized. The thermodynamic properties have been calculated analytically, developing Landau's model, using the measured dispersion curve. A good agreement is found below 0.85 K between direct heat capacity measurements and the calculated specific heat, if thermodynamically consistent power series expansions are used. The thermodynamic properties have also been calculated numerically; in this case, the results are applicable with excellent accuracy up to 1.3 K, a temperature above which the dispersion relation itself becomes temperature dependent.

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Section: A Phononsmentioning

confidence: 62%

Section: A Phononsmentioning

confidence: 99%

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The dispersion relation of Landau elementary excitations and the thermodynamic properties of superfluid $^4$He

Godfrin,

Beauvois,

Sultan

et al. 2020

Preprint

Self Cite

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“…Hence, we observe that at low pressure and at the typical base temperature of a dilution refrigerator (T ∼ 10 mK), the quality factor is independent of frequency up to a cut-off frequency of the order of 1 GHz, above which the quality factor decreases following a 1/Ω 4 q frequency dependence. Recent high-precision neutron measurements from Beauvois et al [54] compared to theory [74] confirm that the dispersion coefficient, negative at low pressure (γ < 0), changes sign and becomes positive (γ > 0) at a pressure P 20 bar (ρ 0 = 169 kg/m 3 ). This indicates a concave dispersion relation at high pressure and low wave numbers.…”

Section: Phonon -Phonon Interactionmentioning

confidence: 94%

Superfluid Optomechanics With Phononic Nanostructures

et al. 2021

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In quantum optomechanics, finding materials and strategies to limit losses has been crucial to the progress of the field. Recently, superfluid 4 He was proposed as a promising mechanical element for quantum optomechanics. This quantum fluid shows highly desirable properties (e.g. extremely low acoustic loss) for a quantum optomechanical system. In current implementations, superfluid optomechanical systems suffer from external sources of loss, which spoils the quality factor of resonators. In this work, we propose a new implementation, exploiting nanofluidic confinement. Our approach, based on acoustic resonators formed within phononic nanostructures, aims at limiting radiation losses to preserve the intrinsic properties of superfluid 4 He. In this work, we estimate the optomechanical system parameters. Using recent theory, we derive the expected quality factors for acoustic resonators in different thermodynamic conditions. We calculate the sources of loss induced by the phononic nanostructures with numerical simulations. Our results indicate the feasibility of the proposed approach in a broad range of parameters, which opens new prospects for more complex geometries.

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“…More recently, approximations to the excitation spectrum that also contain even powers of q have been made (see, e.g., Ref. [55]). The addition of such terms to the dispersion relation is not expected to alter the basic picture we develop, so to simplify the discussion we do not take them into account explicitly.…”

Section: B Helium Excitationsmentioning

confidence: 99%

Searching for low mass dark matter via phonon creation in superfluid He4

et al. 2020

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We consider the scattering of dark matter particles from superfluid liquid 4 He, which has been proposed as a target for their direct detection. Focusing on dark matter masses below ∼1 MeV, we demonstrate from sum-rule arguments the importance of the production of single phonons with energies ω ≲ 1 meV. We show further that the anomalous dispersion of phonons in liquid 4 He at low pressures [i.e., d 2 ωðqÞ=dq 2 > 0, where q and ωðqÞ are the phonon momentum and energy] has the important consequence that a single phonon will decay over a relatively short distance into a shower of lower-energy phonons centered on the direction of the original phonon. Thus, the experimental challenge in this regime is to detect a shower of low-energy phonons, not just a single phonon. Additional information from the distribution of phonons in such a shower could enhance the determination of the dark matter mass.

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Transport and Phonon Damping in $$^{4}$$He

Cited by 5 publications

References 27 publications

The dispersion relation of Landau elementary excitations and the thermodynamic properties of superfluid $^4$He

The dispersion relation of Landau elementary excitations and the thermodynamic properties of superfluid $^4$He

Superfluid Optomechanics With Phononic Nanostructures

Searching for low mass dark matter via phonon creation in superfluid He4

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