arXiv subjects

V. M. Mostepanenko

Publications and source records attributed to V. M. Mostepanenko.

At least 37 records · Page 2Linked to original sources

arXiv2023

How to strengthen constraints on non-Newtonian gravity from measuring the lateral Casimir force

It has been known that in the nanometer interaction range the available experimental data do not exclude the Yukawa-type corrections to Newton's gravitational law which exceed the Newtonian gravitational force by many orders of magnitude. The strongest constraints on the parameters of Yukawa-type interaction in this interaction range follow from the experiments on neutron scattering and from measurements of the lateral and normal Casimir forces between corrugated surfaces. In this work, we demonstrate that by optimizing the experimental configuration at the expense of the higher corrugation amplitudes and smaller periods of corrugations it is possible to considerably strengthen the currently available constraints within the wide interaction range from 4.5 to 37nm. We show that the maximum strengthening by more than a factor of 40 is reachable for the interaction range of 19nm.

quant-ph↗

arXiv2023

Comparison of the Lifshitz Theory Using the Nonconventional Fit of Response Functions with Precise Measurements of the Casimir Force

It has been known that the fundamental Lifshitz theory, which is based on first principles of thermal quantum field theory, experiences difficulties when compared with precise measurements of the Casimir force. We analyze the nonconventional fit of response functions of many materials along the imaginary frequency axis to the empirical model of "modified" oscillators which was recently proposed in the literature. According to our results, this model is unacceptable because at high frequencies it leads to the asymptotic behavior of response functions which is in contradiction with that following from the fundamental physical principles. We calculate the Casimir interaction in the configurations of several precise experiments using the Lifshitz theory and the response functions to quantized electromagnetic field expressed in terms of modified oscillators and demonstrate that the obtained results are excluded by the measurement data. This invalidates a claim made in the literature that the Casimir-van der Waals forces calculated using these response functions are in remarkable agreement with the experimental values. Possible reasons for a disagreement between experiment and theory are discussed, and the way to improve the situation is directed.

quant-ph↗

arXiv2022

Experimentum crucis for electromagnetic response of metals to evanescent waves and the Casimir puzzle

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 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 1-mm coil, one could either validate or disprove 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.

quant-ph↗

arXiv2022

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

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.

quant-ph↗

arXiv2022

The Casimir effect in graphene systems: Experiment and theory

The Casimir effect in graphene systems is reviewed with emphasis made on the large thermal correction to the Casimir force predicted at short separations between the test bodies. The computational results for the Casimir pressure and for the thermal correction are presented for both pristine graphene and real graphene sheets, which possess nonzero energy gap and chemical potential, obtained by means of exact polarization tensor. Two experiments on measuring the gradient of the Casimir force between an Au-coated sphere and graphene- coated substrates performed by using a modified atomic force microscope cantilever-based technique are described. It is shown that the measurement data of both experiments are in agreement with theoretical predictions of the Lifshitz theory using the polarization tensor. Additionally, several important improvements made in the second experiment, allowed to demonstrate the predicted large thermal effect in the Casimir interaction at short separations. Possible implications of this result to resolution of long-term problems of Casimir physics are discussed.

quant-ph↗

arXiv2022

Current status of the problem of thermal Casimir force

The problem of thermal Casimir force, which consists in disagreement of theoretical predictions of the fundamental Lifshitz theory with the measurement data of high precision experiments and some peculiar properties of the Casimir entropy, is reviewed. We discuss different approaches to the resolution of this problem proposed in the literature during the last twenty years. Particular attention is given to the role of the effects of spatial dispersion. The recently suggested nonlocal Drude-like permittivities which take proper account of the dissipation of conduction electrons and bring the predictions of the Lifshitz theory in agreement with experiment and requirements of thermodynamics are considered. The prospects of this approach in the ultimate resolution of the problem of thermal Casimir force are evaluated.

quant-ph↗

arXiv2022

Theory-experiment comparison for the Casimir force between metallic test bodies: A spatially nonlocal dielectric response

It has been known that the Lifshitz theory of the Casimir force comes into conflict with the measurement data if the response of conduction electrons in metals to electromagnetic fluctuations is described by the well tested dissipative Drude model. The same theory is in a very good agreement with measurements of the Casimir force from graphene whose spatially nonlocal electromagnetic response is derived from the first principles of quantum electrodynamics. Here, we propose the spatially nonlocal phenomenological dielectric functions of metals which lead to nearly the same response, as the standard Drude model, to the propagating waves, but to a different response in the case of evanescent waves. Unlike some previous suggestions of this type, the response functions considered here depend on all components of the wave vector as is most natural in the formalism of specular reflection used. It is shown that these response functions satisfy the Kramers-Kronig relations. We derive respective expressions for the surface impedances and reflection coefficients. The obtained results are used to compute the effective Casimir pressure between two parallel plates, the Casimir force between a sphere and a plate, and its gradient in configurations of the most precise experiments performed with both nonmagnetic (Au) and magnetic (Ni) test bodies. It is shown that in all cases (Au-Au, Au-Ni, and Ni-Ni test bodies) the predictions of the Lifshitz theory found by using the dissipative nonlocal response functions are in as good agreement with the measurement data, as was reached previously with the dissipationless plasma model. Possible developments and applications of these results are discussed.

quant-ph↗

arXiv2021

Casimir effect for magnetic media: Spatially nonlocal response to the off-shell quantum fluctuation

We extend the Lifshitz theory of the Casimir force to the case of two parallel magnetic metal plates possessing a spatially nonlocal dielectric response. By solving Maxwell equations in the configuration of an electromagnetic wave incident on the boundary plane of a magnetic metal semispace, the exact surface impedances are expressed in terms of its magnetic permeability and longitudinal and transverse dielectric functions. This allows application of the Lifshitz theory with reflection coefficients written via the surface impedances for calculation of the Casimir pressure between magnetic metal (Ni) plates whose dielectric responses are described by the alternative nonlocal response functions introduced for the case of nonmagnetic media. It is shown that at separations from 100 to 800~nm the Casimir pressures computed using the alternative nonlocal and local plasma response functions differ by less than 1\%. At separations of a few micrometers, the predictions of these two approaches differ between themselves and between that one obtained using the Drude function by several tens of percent. We also compute the gradient of the Casimir force between Ni-coated surfaces of a sphere and a plate using the alternative nonlocal response functions and find a very good agreement with the measurement data. Implications of the obtained results determined by the off-shell quantum fluctuations to a resolution of long-standing problems in the Casimir physics are discussed.

quant-ph↗

arXiv2021

Experimental and theoretical investigation of the thermal effect in the Casimir interaction from graphene

We present the results of an experiment on measuring the gradient of the Casimir force between an Au-coated hollow glass microsphere and graphene-coated fused silica plate by means of a modified atomic force microscope cantilever based technique operated in the dynamic regime. These measurements were performed in high vacuum at room temperature. The energy gap and the concentration of impurities in the graphene sample used have been measured utilizing scanning tunnelling spectroscopy and Raman spectroscopy, respectively. The measurement results for the gradients of the Casimir force are found to be in a very good agreement with theory using the polarization tensor of graphene at nonzero temperature depending on the energy gap and chemical potential with no fitting parameters. The theoretical predictions of the same theory at zero temperature are experimentally excluded over the measurement region from 250 to 517 nm. We have also investigated a dependence of the thermal correction to the Casimir force gradient on the values of the energy gap, chemical potential, and on the presence of a substrate supporting the graphene sheet. It is shown that the observed thermal effect is consistent in size with that arising for pristine graphene sheets if the impact of real conditions such as nonzero values of the energy gap, chemical potential, and the presence of a substrate is included. Implications of the obtained results to the resolution of the long-standing problems in Casimir physics are discussed. In addition to the paper published previously [M. Liu {\it et al}., Phys. Rev. Lett. {\bf 126}, 206802 (2021)], we present measurement results for the energy gap of the graphene sample, double the experimental data for the Casimir force, and perform a more complete theoretical analysis.

quant-ph↗

arXiv2021

Casimir pressure in peptide films on metallic substrates: Change of sign via graphene coating

We find that the Casimir pressure in peptide films deposited on metallic substrates is always repulsive which makes these films less stable. It is shown that by adding a graphene sheet on top of peptide film one can change the sign of the Casimir pressure by making it attractive. For this purpose, the formalism of the Lifshitz theory is extended to the case when the film and substrate materials are described by the frequency-dependent dielectric permittivities, whereas the response of graphene to the electromagnetic field is governed by the polarization tensor in (2+1)-dimensional space-time found in the framework of the Dirac model. Both pristine and gapped and doped graphene sheets are considered possessing some nonzero energy gap and chemical potential. According to our results, in all cases the presence of graphene sheet makes the Casimir pressure in peptide film deposited on a metallic substrate attractive starting from some minimum film thickness. The value of this minimum thickness becomes smaller with increasing chemical potential and larger with increasing energy gap and the fraction of water in peptide film. The physical explanation for these results is provided, and their possible applications in organic electronics are discussed.

cond-mat.mes-hall↗

arXiv2021

Casimir entropy and nonlocal response functions to the off-shell quantum fluctuations

The nonlocal response functions to quantum fluctuations are used to find asymptotic expressions for the Casimir free energy and entropy at arbitrarily low temperature in the configuration of two parallel metallic plates. It is shown that by introducing an alternative nonlocal response to the off-the-mass-shell fluctuations the Lifshitz theory is brought into agreement with the requirements of thermodynamics. According to our results, the Casimir entropy calculated using the nonlocal response functions, which take into account dissipation of conduction electrons, remains positive and monotonously goes to zero with vanishing temperature, i.e., satisfies the Nernst heat theorem. This is true for both plates with perfect crystal lattices and for lattices with defects of structure. The obtained results are discussed in the context of the Casimir puzzle.

quant-ph↗

arXiv2021

Demonstration of an Unusual Thermal Effect in the Casimir Force from Graphene

We report precision measurements of the gradient of the Casimir force between an Au-coated sphere and graphene sheet deposited on a silica plate. The measurement data are compared with exact theory using the polarization tensor found in the framework of the Dirac model including effects of the nonzero chemical potential and energy gap of the graphene sample with no fitting parameters. The very good agreement between experiment and theory demonstrates the unusually big thermal effect at separations below 1 mum which has never been observed for conventional 3D materials. Thus, it is confirmed experimentally that for graphene the effective temperature is determined by the Fermi velocity rather than by the speed of light.

quant-ph↗

arXiv2021

Casimir Puzzle and Casimir Conundrum: Discovery and Search for Resolution

We review complicated problems in the Lifshitz theory describing the Casimir force between real material plates made of metals and dielectrics including different approaches to their resolution. It has been shown that both for metallic plates with perfect crystal lattices and for any dielectric plates the Casimir entropy calculated in the framework of the Lifshitz theory violates the Nernst heat theorem when the well approved dielectric functions are used in computations. The respective theoretical Casimir forces are excluded by the measurement data of numerous precision experiments. In the literature this situation received the names of the Casimir puzzle and the Casimir conundrum for the cases of metallic and dielectric plates, respectively. The review presents a summary of the main facts on this subject on both theoretical and experimental sides. Next, we discuss the main approaches proposed in the literature in order to bring the Lifshitz theory in agreement with the measurement data and with the laws of thermodynamics. Special attention is paid to the recently suggested spatially nonlocal Drude-like response functions which take into account the relaxation properties of conduction electrons, as does the standard Drude model, but lead to the theoretical results in agreement with both thermodynamics and the measurement data through the alternative response to quantum fluctuations off the mass shell. Further advances and trends in this field of research are discussed.

quant-ph↗

arXiv2021

Casimir-Polder Interaction of an Atom with a Cavity Wall Made of Phase-Change Material out of Thermal Equilibrium

We consider the out-of-thermal-equilibrium Casimir-Polder interaction between atoms of He$^*$, Na, Cs, and Rb and a cavity wall made of sapphire coated with a vanadium dioxide film which undergoes the dielectric-to-metal phase transition with increasing wall temperature. Numerical computations of the Casimir-Polder force and its gradient as the functions of atom-wall separation and wall temperature are made when the latter exceeds the temperature of the environment. The obtained results are compared with those in experiment on measuring the gradient of the Casimir-Polder force between $^{87}$Rb atoms and a silica glass wall out of thermal equilibrium. It is shown that the use of phase-change wall material increases significantly the force magnitude and especially the force gradient, as opposed to the case of dielectric wall.

quant-ph↗

arXiv2020

Effect of increased stability of peptide-based coatings in the Casimir regime via nanoparticle doping

We find that thin peptide films and coatings doped with metallic nanoparticles are more stable due to the role of electromagnetic fluctuations. It is shown that for the doped freestanding in vacuum peptide film the Casimir attraction becomes larger in magnitude. For dielectric substrates coated with peptide films, the nanoparticle doping leads to a wider range of film thicknesses where the Casimir pressure is attractive and to larger pressure magnitudes at the points of extremum. The doping of peptide coatings with magnetic nanoparticles preserves all the advantages of nonmagnetic ones and simultaneously imparts superparamagnetic properties to the coating which could extend significantly the application areas of bioelectronics.

cond-mat.mes-hall↗

arXiv2020

An alternative response to the off-shell quantum fluctuations: A step forward in resolution of the Casimir puzzle

The spatially nonlocal response functions are proposed which nearly coincide with the commonly used local response for electromagnetic fields and fluctuations on the mass shell, but differ significantly for the off-shell fluctuating field. It is shown that the fundamental Lifshitz theory using the suggested response functions comes to an agreement with the measurement data for the Casimir force without neglecting the dissipation of free electrons. We demonstrate that reflectances of the on-shell electromagnetic waves calculated using the nonlocal and commonly employed local responses differ only slightly. The Kramers-Kronig relations for nonlocal response functions possessing the first- and second-order poles at zero frequency are derived, i.e., the proposed response satisfies the principle of causality. An application of these results to resolution of the Casimir puzzle, which lies in the fact that the Lifshitz theory is experimentally consistent only with discarded dissipation, is discussed.

quant-ph↗

arXiv2020

Casimir and Casimir-Polder Forces in Graphene Systems: Quantum Field Theoretical Description and Thermodynamics

We review recent results on the low-temperature behaviors of the Casimir-Polder and Casimir free energy an entropy for a polarizable atom interacting with a graphene sheet and for two graphene sheets, respectively. These results are discussed in the wide context of problems arising in the Lifshitz theory of van der Waals and Casimir forces when it is applied to metallic and dielectric bodies. After a brief treatment of different approaches to theoretical description of the electromagnetic response of graphene, we concentrate on the derivation of response function in the framework of thermal quantum field theory in the Matsubara formulation using the polarization tensor in (2+1)-dimensional space-time. The asymptotic expressions for the Casimir-Polder and Casimir free energy and entropy at low temperature, obtained with the polarization tensor, are presented for a pristine graphene as well as for graphene sheets possessing some nonzero energy gap $Δ$ and chemical potential $μ$ under different relationships between the values of $Δ$ and $μ$. Along with reviewing the results obtained in the literature, we present some new findings concerning the case of zero gap and nonzero chemical potential. The conclusion is made that the Lifshitz theory of the Casimir and Casimir-Polder forces in graphene systems using the quantum field theoretical description of a pristine graphene, as well as real graphene sheets with $Δ>2μ$ or $Δ<2μ$, is consistent with the requirements of thermodynamics. The case of graphene with $Δ=2μ\neq 0$ leads to an entropic anomaly, but is argued to be physically unrealistic. The way to a resolution of thermodynamic problems in the Lifshitz theory based on the results obtained for graphene is discussed.

quant-ph↗

arXiv2020

The State of the Art in Constraining Axion-to-Nucleon Coupling and Non-Newtonian Gravity from Laboratory Experiments

Constraints on the Yukawa-type corrections to Newton's gravitational law and on the coupling constant of axionlike particles to nucleons obtained from different laboratory experiments are reviewed and compared. The constraints on non-Newtonian gravity under discussion cover the wide interaction range from nanometers to millimeters and follow from the experiments on neutron scattering, measuring the Casimir force and Cavendish-type experiments. The constraints on the axion-to-nucleon coupling constant following from the magnetometer measurements, Cavendish-type experiments, Casimir physics, and experiments with beams of molecular hydrogen are considered which refer to the region of axion masses from $10^{-10}$ eV to 200 eV. Particular attention is given to the recent constraints obtained from measuring the Casimir force at nanometer separation distance between the test bodies. Several proposed experiments focused on constraining the non-Newtonian gravity, axionlike particles and other hypothetical weakly interacting particles, such as chameleons and symmetrons, are discussed.

hep-ph↗