Matter Waves Research Articles

Dark sector tunneling field potentials for a dark big bang

All of the significant evidence for dark matter observed thus far has been through its gravitational interactions. After 40 years of direct detection experiments, the parameter space for weakly interacting massive particles (WIMPs) as dark matter candidates is rapidly approaching the neutrino floor. Moreover, there have been no signs of WIMPs in any particle production experiments so far. In this light, we consider a dark sector that is strongly decoupled from the visible sector, interacting exclusively through gravity. In this model, proposed by Freese and Winkler [Dark matter and gravitational waves from a dark big bang, ], dark matter can be produced through a first-order phase transition in the dark sector dubbed “the dark big bang.” We fully determine the allowed region of parameter space for the tunneling potential that leads to the realization of a dark big bang and is consistent with all experimental bounds available. Published by the American Physical Society 2024

Single Electron Self-coherence and Its Wave/Particle Duality in the Electron Microscope.

Intensities in high-resolution phase-contrast images from electron microscopes build up discretely in time by detecting single electrons. A wave description of pulse-like coherent-inelastic interaction of an electron with matter implies a time-dependent coexistence of coherent partial waves. Their superposition forms a wave package by phase decoherence of 0.5 - 1 radian with Heisenbergs energy uncertainty ΔEH = ħ/2 Δt-1 matching the energy loss ΔE of a coherent-inelastic interaction and sets the interaction time Δt. In these circumstances, the product of Planck's constant and the speed of light hc is given by the product of the expression for temporal coherence λ2/Δλ and the energy loss ΔE. Experimentally, the self-coherence length was measured by detecting the energy-dependent localization of scattered, plane matter waves in surface proximity exploiting the Goos-Hänchen shift. Chromatic-aberration Cc-corrected electron microscopy on boron nitride (BN) proves that the coherent crystal illumination and phase contrast are lost if the self-coherence length shrinks below the size of the crystal unit cell at ΔE > 200 eV. In perspective, the interaction time of any matter wave compares with the lifetime of a virtual particle of any elemental interaction, suggesting the present concept of coherent-inelastic interactions of matter waves might be generalizable.

Pattern formations and their active manipulation in a Rydberg noisy-dressed Bose-Einstein condensate.

We investigate the formation and manipulation of spatial patterns and their structural phase transitions by examining the effects of laser linewidth on the dynamics of Rydberg noise-dressed Bose-Einstein condensates (RnD BECs). We discover that the homogeneous matter wave can transition into various types of self-organized patterns, which are manipulated by tuning the laser linewidth, control field intensity, and atomic density. Remarkably, the system exhibits stable nonlocal matter-wave solitons, vortices, and soliton molecules under specific laser linewidths.

Effective spin dynamics of spin-orbit coupled matter-wave solitons in optical lattices

We consider matter–wave solitons in spin–orbit coupled Bose–Einstein condensates embedded in an optical lattice and study the dynamics of the soliton within the framework of Gross–Pitaevskii equations. We express spin components of the soliton pair in terms of nonlinear Bloch equations and investigate the effective spin dynamics. It is seen that the effective magnetic field that appears in the Bloch equation is affected by optical lattices, and thus the optical lattice influences the precessional frequency of the spin components. We make use of numerical approaches to investigate the dynamical behavior of density profiles and center-of-mass of the soliton pair in the presence of the optical lattice. It is shown that the spin density is periodically varying due to flipping of spinors between the two states. The amplitude of spin-flipping oscillation increases with lattice strength. We find that the system can also exhibit interesting nonlinear behavior for chosen values of parameters. We present a fixed point analysis to study the effects of optical lattices on the nonlinear dynamics of the spin components. It is seen that the optical lattice can act as a control parameter to change the dynamical behavior of the spin components from periodic to chaotic.

Irreducible cosmological backgrounds of a real scalar with a broken symmetry

We explore the irreducible cosmological implications of a singlet real scalar field. Our focus is on theories with an approximate and spontaneously broken Z2 symmetry where quasistable domain walls can form at early times. This seemingly simple framework bears a wealth of phenomenological implications that can be tackled by means of different cosmological and astrophysical probes. We elucidate the connection between domain wall dynamics and the production of dark matter and gravitational waves. In particular, we identify three main benchmark scenarios. The gravitational wave signal observed by pulsar timing arrays can be generated by the domain walls if the mass of the singlet is ms∼PeV. For lower masses, but with ms≳10 GeV, scalars produced in the annihilation of the domain walls can be dark matter with a distinctive feature in their power spectrum. Finally, the thermal bath provides an unavoidable source of unstable scalars via the freeze-in mechanism whose subsequent decays can be tested by their imprints on cosmological and terrestrial observables. Published by the American Physical Society 2024

The gravitational redshift effect of quantum matter waves passing a binary black hole

The gravitational redshift effect of quantum matter waves passing a binary black hole

The Entropy of Mixing in Self-Assembly and the Role of Surface Tension in Modeling the Critical Micelle Concentration

A theory for the micelle formation of nonionic head-tail amphiphiles (detergents) in aqueous solutions is derived based on the traditional molecular thermodynamic modeling approach and a variant of the Flory–Huggins theory that goes beyond lattice models. The theory is used to analyze experimental values for the critical micelle concentration of n-alkyl-ß-D-maltosides within a mass action model. To correlate those parts of the micellization free energy, which depend on the transfer of hydrophobic molecule parts into the aqueous phase, with molecular surfaces, known data for the solubility of alkanes in water are reanalyzed. The correct surface tension to be used in connection with the solvent-excluded surface of the alky tail is ~30 mN/m. This value is smaller than the measured surface tension of a macroscopic alkane–water interface, because the transfer free energy contains a contribution from the incorporation of the alkane or alkyl chain into water, representing the change in free volume in the aqueous phase. The Flory–Huggins theory works well, if one takes into account the difference in liberation free energy between micelles and monomers, which can be described in terms of the aggregation number as well as the thermal de Broglie wavelength and the free volume of the detergent monomer.

Spatial adiabatic passage of ultracold atoms in optical tweezers.

Coherent manipulation of matter waves, a distinctive hallmark of quantum mechanics, is fundamental to modern quantum technologies. Spatial adiabatic passage (SAP) is a prime example of this phenomenon, where a wave packet is transferred between two uncoupled localized modes by adjusting the tunneling coupling to an intermediate third mode in a counterintuitive sequence. Although this concept was introduced over two decades ago, its observation was previously limited to electromagnetic waves. In this study, we demonstrate this quantum interference effect using massive particles that tunnel between three micro-optical traps ("optical tweezers"). We begin by preparing ultracold fermionic atoms in low vibrational eigenstates of one trap, followed by manipulating the distance between the traps to execute the SAP protocol. We observe a smooth and high-efficiency transfer of atoms between the two outer traps, with a very low population remaining in the central trap. These findings open possibilities for advanced control schemes in optical tweezer array platforms.

Entangled matter waves for quantum enhanced sensing

Entangled matter waves for quantum enhanced sensing

Sensing Aharonov-Bohm Phase Using a Multiply-Orbiting-Ion Interferometer.

Interferometers, which are built using spatially propagating light or matter waves, are commonly used to measure physical quantities. These measurements are made possible by exploiting the interference between waves traveling along different paths. This study introduces a novel approach to sensing of the Aharonov-Bohm phase, an ion matter-wave interferometer operating within a two-dimensional rotational trajectory in a trap potential. The ion orbitals in the nearly circular potential change rotation direction with time. This reversal of rotation direction results in a corresponding change in the interference phase. Our study is the first attempt to utilize propagating matter waves of an ion in constructing a two-dimensional interferometer for the measurement of physical quantities. Given that the scale factor of the interferometer to the cyclotron motion and the rotation of the system is common, the sensitivity to the Aharonov-Bohm phase in this study corresponds to a rotation sensitivity of approximately 300 rad/s. Besides advancing interferometry, our work also lays the foundation for future research into the use of ion matter waves in gyroscopic applications.

Physicochemical properties of the confined hydrogen atom under dense semiclassical hydrogen plasma

Some fundamental quantities governing the physicochemical properties of the spherically confined (contained in a spherical box) hydrogen atom embedded in dense semiclassical hydrogen plasma have been investigated. These quantities specifically include the energy levels, wavefunctions, 2k-pole oscillator strength, 2k-pole polarizability, hyperfine spitting, effective pressure on the boundary of the confining surface. The effect of plasma is described by a pseudopotential which takes care of the collective effect and the quantum mechanical effects at short distances of the plasma particles by means of two adjustable parameters, namely, the screening parameter and the de Broglie wavelength. Energy eigenvalues of the atom for various box sizes and for different values of the plasma parameters are computed accurately within a variational framework by employing a large wavefunction which automatically takes care of the requisite boundary conditions. Convergence of the computed results is corroborated by increasing the number of terms in the wavefunction. Particular attention is paid on determining the critical size box for which all the bound states of the atom cease to exist. Based on the computed energies and the corresponding eigenfunctions, mean values of various powers of the radial coordinate, oscillator strengths, polarizability of various order, hyperfine splitting, and the effective pressure on the boundary have been evaluated. A comprehensive study is made on the changes of those quantities for varying box size and plasma parameters. Efforts are made to distinguish the changes arising out of the spatial confinement and the plasma confinement.

Quantum Accelerometry Based on a Geometric Phase

A conceptual model of a promising quantum accelerometer based on a two-mode atomic Bose–Einstein condensate has been proposed. Acceleration generates a specific difference in geometric phases between the condensate modes, which shifts the interference pattern of matter waves. The modes have ring configurations, in the plane of which the measured acceleration vector lies. The homogeneity of the potentials of the ring configurations is interrupted by additional localized potentials generated by defects. Under the variation of the parameters of appropriately located defects with a certain structure, the wavefunctions of the condensate modes acquire geometric phases that differ in the presence of acceleration. Calculations performed for ring configurations of the condensate of 87Rb atoms with a radius of 0.25 mm has showed that the proposed scheme can detect a microgravity of ~10–6–10–7g.

Role of meteorology and air pollution on fog conditions over Delhi during the peak winter 2024

Severe air pollution and foggy conditions during winter are persistent challenges, pose significant health hazards, and disrupt daily routines worldwide. In this study, we have investigated the conditions favoring the prolonged fog events in Delhi during January 2024 using observations, back trajectories, and reanalysis datasets. Analysis of visibility observations reveals that foggy (54, 121, 139, and 372 half-hours of very dense, dense, moderate, and shallow fog, respectively) conditions persisted in Delhi for 46 % of the time during the study period. The existence of 3–4 days of cold wave to severe cold wave conditions and the lack of passage of strong western disturbances across north and northwest India have also favored the prolonged fog formation. In addition, high relative humidity (>80 %), shallow boundary layer (216 m), stable weather conditions such as the absence of significant surface winds, the existence of cold wave to severe cold wave, temperature inversion (up to 4 °C), poor ventilation, and presence of high particulate matter (PM10: 298 μg/m3 and PM2.5: 182 μg/m3) facilitated the fog formation. Further, analyses reveal a spurt in daily particulate matter (PM10: 603 μg/m3 and PM2.5: 420 μg/m3; 13.4 and 28 times, respectively, exceeded the WHO air quality guideline levels) along with 4.5 h of zero visibility on 14th January. The analysis of particulate matter reveals the dominance of fine particles from nearby regions, which could have originated from the large-scale anthropogenic open biomass burning used for heating activities. The results derived from this study indicate the need for an accurate representation of the local anthropogenic emissions in the atmospheric models to improve the predictability of air quality and fog and provide insights into the need for their control, particularly during such extreme events.

Theory of Electron Transport in Two-Barrier Five-Layer Semiconductor Structures

The dependence of the transparency coefficient of a five-layer two-barrier structure on the electron energy and the ratio of the widths of two neighboring potential barriers is calculated. It is shown that the extremum of the transparency coefficient significantly depends on the geometric dimensions of the structure layers. In a symmetric five-layer two-barrier semiconductor structure, the condition for the occurrence of "resonant" electron transitions is defined. It is demonstrated that the mechanism of such (resonant) transitions is explained by the interference of de Broglie waves of electrons in the potential well, where the phases of de Broglie waves are determined by the geometric dimensions of the structure, and their amplitudes - by the ratio of the carrier energy to the height of the potential barrier. It has been established that with an increase in the effective mass of charge carriers, the number of intersections of the quantities fR (ξ) and ((1-2ξ))/(√(ξ-ξ2) increases. These intersections determine the dimensionally-quantized levels where electrons are localized.

Effects of combined exposure to fine particulate matter and cold waves and on IHD hospitalizations at low and high altitudes

Climate change and air pollution are major challenges facing the world today. Cold waves and air pollution significantly impact ischemic heart disease (IHD), but the extent of these effects at different altitudes remains unclear, especially their interactions. We collected daily meteorological, pollutant, and IHD hospitalization data from Xining and Xinxiang from 2016 to 2021. Using a time-stratified case-crossover approach, we fitted conditional Poisson regression models to assess the association between cold waves, PM2.5, and IHD hospitalizations and quantified their interactions. Additionally, we calculated the attributable fraction (AF) and attributable number (AN) of hospitalizations due to exposure to cold waves and medium to high-level PM2.5. We also performed stratified analyses by altitude, gender, and age. Both cold waves and PM2.5 were positively associated with IHD hospitalization rates in Xining and Xinxiang, but the differences between the two regions were not significant. The relative risk of cold waves was 1.15 (1.07, 1.24) in Xining and 1.16 (1.11, 1.21) in Xinxiang. In Xining, there was an interaction between cold waves and different levels of PM2.5. We estimated the attributable fraction due to the joint exposure of cold waves and PM2.5 to be 0.14–0.49 in Xining and 0.26–0.36 in Xinxiang. Older adults and males faced higher risks. This study highlights the importance of reducing PM2.5 exposure and optimizing extreme weather warning systems and suggests further exploration of the impacts of individual behaviors and regional characteristics on IHD.

Pairwise balancing of forces in traveling granular waves

A survey is given of the forces at work inside traveling roll waves and monoclinal flood waves in dry granular matter. By numerically solving the generalized Saint-Venant equations for shallow granular flow, we find a hierarchy of pairwise near-balancing forces, which together are responsible for sustaining the shape of the nonlinear waves in question. The leading force pair is gravity vs. friction, followed by inertia vs. pressure, while the minor imbalance left by the aforementioned pairs is settled by a (small though essential) diffusive force.

Detecting single gravitons with quantum sensing

The quantization of gravity is widely believed to result in gravitons – particles of discrete energy that form gravitational waves. But their detection has so far been considered impossible. Here we show that signatures of single graviton exchange can be observed in laboratory experiments. We show that stimulated and spontaneous single-graviton processes can become relevant for massive quantum acoustic resonators and that stimulated absorption can be resolved through continuous sensing of quantum jumps. We analyze the feasibility of observing the exchange of single energy quanta between matter and gravitational waves. Our results show that single graviton signatures are within reach of experiments. In analogy to the discovery of the photo-electric effect for photons, such signatures can provide the first experimental clue of the quantization of gravity.

Topological structures, dark matter and gravitational waves in E6

We discuss the appearance of topological structures from the spontaneous breaking of E6 to the Standard Model via its maximal subgroup SO(10) × U(1)ψ. They include dumbbells, metastable strings, as well as domain walls bounded by necklaces. We provide a novel scenario for producing metastable strings based on the symmetry breaking U(1)ψ ⟶ ℤ8 ⟶ ℤ4. The metastable string arises from the merger of ℤ8 strings that bound a domain wall. An unbroken gauge ℤ2 symmetry from SO(10) breaking yields viable stable dark matter candidates as well as topologically stable strings. We discuss the gravitational wave emission from two varieties of cosmic strings, namely the superheavy metastable ones and the intermediate scale topologically stable cosmic strings.

Multilevel dynamics of matter waves scattering in finite potential wells

We explore the dynamics of matter wave scattering in finite potential wells using analytical solutions of the Schrödinger equation within the framework of a quantum shutter model. We find that the incident wave interferes with the bound states of the quantum well, resulting in time-domain oscillations. These oscillations exhibit Rabi-type frequencies, characterised by the energy differences between the incident wave and the bound states of the quantum well. We show that in systems with double-bound states, the interference pattern is characterised by quantum beats in the time-dependent probability density. The period of these beatings depends on the energy difference between the bound states, which can be tuned by controlling the potential parameters. In the general case where bound, anti-bound, and resonant states coexist in the system spectrum, complex oscillations in the probability density arise from the interactions of the incident wave with different quantum states. We demonstrate that the bound states sector can effectively describe this complex behaviour, providing a simple and reliable analytical expression for the probability density in multilevel systems. This formula highlights the significant role of bound states, whose interaction with the incident wave dominates the transient probability density. This contrasts with conventional systems with potential barriers and wells, where resonances govern the wave dynamics.

String theory and the first half of the universe

We perform a detailed study of stringy moduli-driven cosmologies between the end of inflation and the commencement of the Hot Big Bang, including both the background and cosmological perturbations: a period that can cover half the lifetime of the universe on a logarithmic scale. Compared to the standard cosmology, stringy cosmologies with vacua that address the hierarchy problem motivate extended kination, tracker and moduli-dominated epochs involving significantly trans-Planckian field excursions.We analyse the cosmology within the framework of the Large Volume Scenario but explain how analogous cosmological features are expected in other string theory models characterized by final vacua located in the asymptotic regions of moduli space.Conventional effective field theory is unable to control Planck-suppressed operators and so such epochs require a stringy completion for a consistent analysis. Perturbation growth in these stringy cosmologies is substantially enhanced compared to conventional cosmological histories. The transPlanckian field evolution results in radical changes to Standard Model couplings during this history and we outline potential applications to baryogenesis, dark matter and gravitational wave production.