No-Slip Boundary Conditions for Electron Hydrodynamics and the Thermal Casimir Pressure

2021

Universe

We consider axionlike particles as the most probable constituents of dark matter, the Yukawa-type corrections to Newton’s gravitational law and constraints on their parameters following from astrophysics and different laboratory experiments. After a brief discussion of the results by Prof. Yu. N. Gnedin in this field, we turn our attention to the recent experiment on measuring the differential Casimir force between Au-coated surfaces of a sphere and the top and bottom of rectangular trenches. In this experiment, the Casimir force was measured over an unusually wide separation region from 0.2 to 8μm and compared with the exact theory based on first principles of quantum electrodynamics at nonzero temperature. We use the measure of agreement between experiment and theory to obtain the constraints on the coupling constant of axionlike particles to nucleons and on the interaction strength of a Yukawa-type interaction. The constraints obtained on the axion-to-nucleon coupling constant and on the strength of a Yukawa interaction are stronger by factors of 4 and 24, respectively, than those found previously from gravitational experiments and measurements of the Casimir force but weaker than the constraints following from a differential measurement where the Casimir force was nullified. Some other already performed and planned experiments aimed at searching for axions and non-Newtonian gravity are discussed, and their prospects are evaluated.

Section: (T)supporting

confidence: 90%

Dark Matter Axions, Non-Newtonian Gravity and Constraints on Them from Recent Measurements of the Casimir Force in the Micrometer Separation Range

2021

Universe

“…According to our results, the suggested experiment will be capable to clearly discriminate between the magnetic fields computed using the Drude and plasma models but not between the fields computed using the plasma model and the spatially nonlocal permittivity of [58]. The latter, in any case, does not claim a complete description of the electromagnetic response of metals but can be considered as an example that through the spatial nonlocality in the framework of the Lifshitz theory it is possible to reach an agreement with the requirements of thermodynamics and the measurement data of high-precision experiments having regard to the relaxation properties of conduction electrons (see also [104] which considers other nonlocal permittivities with the same aim).…”

Section: Discussionmentioning

confidence: 99%

Experimentum crucis for Electromagnetic Response of Metals to Evanescent Waves and the Casimir Puzzle

Svetovoy

2022

Universe

It is well known that the Casimir force calculated at large separations using the Lifshitz theory differs by a factor of 2 for metals described by the Drude or plasma models. We argue that this difference is entirely determined by the contribution of transverse electric (s) evanescent waves. Taking into account that there is a lack of experimental information on the electromagnetic response of metals to low-frequency evanescent waves, we propose an experiment on measuring the magnetic field of an oscillating magnetic dipole spaced in a vacuum above a thick metallic plate. According to our results, the lateral components of this field are governed by the transverse electric evanescent waves and may vary by orders of magnitude depending on the model describing the permittivity of the plates used in calculations and the oscillation frequency of the magnetic dipole. Measuring the lateral component of the magnetic field for typical parameters of the magnetic dipole designed in the form of a 1-mm coil, one could either validate or disprove the applicability of the Drude model as a response function of metal in the range of low-frequency evanescent waves. This will elucidate the roots of the Casimir puzzle lying in the fact that the theoretical predictions of the Lifshitz theory using the Drude model are in contradiction with the high-precision measurements of the Casimir force at separations exceeding 150 nm. Possible implications of the suggested experiment for a wide range of topics in optics and condensed matter physics dealing with evanescent waves are discussed.

“…and ε(ω) is the frequencydependent dielectric permittivity of the plate metal. In this section, however, we do not use a specific form of the reflection coefficients making the results applicable to both the local and nonlocal response of the metal (note that the spatially nonlocal models are the subject of considerable discussion in relation to the problems of the Lifshitz theory mentioned above [42][43][44][45][46][47][48][49][50][51][52][53]). It has to be stressed also that in the configuration of fig.…”

mentioning

confidence: 99%

Probing the response of metals to low-frequency s-polarized evanescent fields

Svetovoy

2022

EPL

Experimental test for the response function of metals to the low-frequency s-polarized evanescent waves is proposed by measuring the lateral component of magnetic ﬁeld of an oscillating magnetic dipole spaced above a thick metallic plate. This suggestion is motivated by the fact that the Lifshitz theory using the Drude response function is in contradiction with high-precision measurements of the Casimir force performed at separations exceeding 150 nm. Analytic expressions for the lateral components of the magnetic ﬁeld, which are fully determined by the s-polarized evanescent waves, are reported in terms of the reﬂection coeﬃcients of the plate metal. Numerical computations are performed for the reasonable values of the experimental parameters for diﬀerent models of the dielectric response. The resulting ﬁelds diﬀer by the orders of magnitude depending on whether the Drude or plasma response function is used in computations. Thus, the measurement of the magnetic ﬁeld will allow to discriminate between these two options. Possible applications of the obtained results are discussed.