The European Physical Journal D最新文献

{"title":"Simulating coherent interaction of polarized laser light with multi-level atoms in one-dimensional birefringent media of high optical depth","authors":"Sergiy Stryzhenko,&nbsp;Leonid P. Yatsenko,&nbsp;Mark IJspeert","doi":"10.1140/epjd/s10053-026-01249-1","DOIUrl":"10.1140/epjd/s10053-026-01249-1","url":null,"abstract":"<p>We present a numerical approach to simulate the propagation of polarized light through a one-dimensional, optically dense, and strongly birefringent medium. The medium is modeled as a gas of atoms with a complex energy-level structure, exemplified by rubidium-87, confined within a birefringent, nonresonant waveguide such as a hollow fiber. The model is formulated within the rotating wave, slowly varying envelope, and Weisskopf–Wigner approximations and is optimized for computational efficiency through the extensive use of tensor operations. As applications, we reproduce key features of two previously reported experiments: biphoton generation via spontaneous four-wave mixing and Raman superfluorescence in an inhomogeneous medium. We further investigate the influence of Zeeman degeneracy and fiber birefringence on electromagnetically induced transparency (EIT) and show that these effects can significantly distort the extracted values of the ground-state dephasing rate.</p>","PeriodicalId":789,"journal":{"name":"The European Physical Journal D","volume":"80 9","pages":""},"PeriodicalIF":1.8,"publicationDate":"2026-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjd/s10053-026-01249-1.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148986330","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Linear gyrokinetic investigation of fast-ion temperature anisotropy in collisionless trapped electron mode instability","authors":"M. S. Hussain,&nbsp;Azhar Hussain,&nbsp;Tajammal H. Khokhar,&nbsp;A. A. Abid,&nbsp;M. N. S. Qureshi","doi":"10.1140/epjd/s10053-026-01250-8","DOIUrl":"10.1140/epjd/s10053-026-01250-8","url":null,"abstract":"<p>A linear gyrokinetic model is employed to investigate the influence of anisotropic fast ions on collisionless trapped electron modes (CTEMs) in deuterium-tritium tokamak plasmas. The analysis incorporates finite Larmor radius (FLR), magnetic drift, and anisotropic fast-ion dynamics through a modified dispersion relation containing both linear and quadratic frequency terms. The results show that fast ions do not directly drive the instability but significantly modify its dispersive properties through changes in the effective inertia and phase dynamics. At fixed parallel fast-ion temperature, increasing the anisotropy ratio <span>(xi =T_{perp f}/T_{parallel f})</span> generally reduces the mode frequency and enhances the growth rate through the combined influence of the anisotropic fast-ion response and the associated change in perpendicular energy and FLR effects. Systematic parameter scans further show that the magnitude of the fast-ion modification depends on the energetic-particle density, temperature, density gradient, and FLR strength. Overall, the results demonstrate that fast-ion temperature anisotropy plays an important role in regulating CTEM stability by modifying the balance between trapped-electron resonant drive and effective mode inertia. These findings provide qualitative insight into energetic particle–microinstability interactions in magnetized plasmas within a linear electrostatic framework, while electromagnetic effects are beyond the scope of the present study and may modify quantitative details in more complete models.</p><p>Schematic illustration of the regulation mechanism of fast-ion temperature anisotropy (xi = perpendicular temperature over parallel temperature) on collisionless trappedelectron mode (CTEM) instability. The anisotropic fast-ion population modifies the finite-Larmor-radius effect, magnetic-drift response, and effective mode inertia, leading to reduced real frequency and enhanced growth rate with increasing xi.</p>","PeriodicalId":789,"journal":{"name":"The European Physical Journal D","volume":"80 9","pages":""},"PeriodicalIF":1.8,"publicationDate":"2026-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148927181","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Photon-mediated thermodynamics and density fluctuations in an ensemble of laser-cooled cesium atoms","authors":"Arnab Ghosh,&nbsp;Inderpreet Kaur,&nbsp;Hemant Yadav,&nbsp;Shiva Kant Dwivedi,&nbsp;R. Shanmukesh,&nbsp;Mithun Thudiyangal,&nbsp;Matthew J. Davis,&nbsp;Bodhaditya Santra","doi":"10.1140/epjd/s10053-026-01247-3","DOIUrl":"10.1140/epjd/s10053-026-01247-3","url":null,"abstract":"<p>We present an experimental study of detuning-dependent properties of a laser-cooled cesium cloud in a magneto-optical trap. Fluorescence images are used to extract the cloud size, shot-to-shot width fluctuations, optical depth, density profiles, and spatial density fluctuation spectra as the trapping laser detuning is varied. Near resonance, the cloud exhibits larger spatial extent, increased width fluctuations, higher optical depth, and enhanced density fluctuation power, while larger detunings produce a more reproducible and spatially confined cloud. The measured density profiles are analyzed phenomenologically using a generalized Lane–Emden model with a polytropic equation of state, yielding detuning-dependent effective fit parameters in a weak interaction regime. Power spectrum and autocorrelation analyses reveal reproducible scale-dependent density correlations. The results provide a quantitative characterization of detuning-dependent radiative and collective effects in a cesium MOT and establish a basis for future measurements that can more directly test nonequilibrium transport and photon-mediated interaction models.\u0000</p>","PeriodicalId":789,"journal":{"name":"The European Physical Journal D","volume":"80 9","pages":""},"PeriodicalIF":1.8,"publicationDate":"2026-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148927242","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Associative ionization in S-wave collisions between muonic hydrogen and hydrogen atoms","authors":"Arata Neki,&nbsp;Takuma Yamashita,&nbsp;Yasushi Kino","doi":"10.1140/epjd/s10053-026-01248-2","DOIUrl":"10.1140/epjd/s10053-026-01248-2","url":null,"abstract":"<p>We report a four-body calculation of associative ionization cross sections in S-wave collisions between a muonic hydrogen atom and an ordinary hydrogen atom, <span>(textrm{p}upmu (textrm{1s}))</span> + <span>(textrm{H}(textrm{1s}))</span>. Because the energy released during the formation of the muonic molecular ion (<span>(textrm{pp}upmu )</span>) exceeds 100 eV, the associative ionization in this system is exothermic, producing <span>(textrm{pp}upmu )</span> and a free electron. We performed scattering calculations with two open channels for the spin-singlet and triplet states of two protons. At collision energies below 0.5 eV, the formation cross sections for the excited state of <span>(textrm{pp}upmu )</span> follow Wigner’s threshold law at collision energies below 0.5 eV. The calculated <span>(textrm{pp}upmu )</span> formation rate is consistent with, though slightly lower than, the experimental value measured in hydrogen gas [V. A. Andreev et al., Phys. Rev. C 91, 055502 (2015)].</p>","PeriodicalId":789,"journal":{"name":"The European Physical Journal D","volume":"80 9","pages":""},"PeriodicalIF":1.8,"publicationDate":"2026-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjd/s10053-026-01248-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148926778","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of storage on plasma-activated water generated by a plasma jet","authors":"Maryam G. Jasim,&nbsp;Hammad R. Humud","doi":"10.1140/epjd/s10053-026-01243-7","DOIUrl":"10.1140/epjd/s10053-026-01243-7","url":null,"abstract":"<div><p>Plasma-activated water (PAW) was generated using an atmospheric pressure plasma jet and investigated in terms of its physicochemical properties and storage stability. Optical emission spectroscopy indicated the presence of reactive species such as OH radicals and atomic oxygen, indicating oxygen-dominated plasma chemistry. Hydrogen peroxide increased to 240 mg/L, while nitrate and nitrite reached 100 mg/L and 11 mg/L, respectively, at 20 min of treatment. These changes were accompanied by a decrease in pH to 3.04, an increase in ORP to 510 mV, and an increase in conductivity from 15.4 to 28 mS·cm⁻¹, indicating the formation of a highly oxidative liquid. During four weeks of storage, hydrogen peroxide and nitrite decreased, whereas nitrate remained relatively stable. In parallel, pH increased, while ORP and conductivity decreased, reflecting reduced reactivity. These results suggest that PAW is a dynamically evolving system, in which oxygen-containing plasma chemistry may contribute to the formation and long-term stability of reactive species.</p><h3>Graphical Abstract</h3><div><figure><div><div><picture><source><img></source></picture></div><div><p>Graphical abstract illustrating the generation of plasma-activated water using an Ar + O₂ atmospheric-pressure plasma jet and the evolution of reactive species and physicochemical properties during four weeks of storage at 4 °C</p></div></div></figure></div></div>","PeriodicalId":789,"journal":{"name":"The European Physical Journal D","volume":"80 9","pages":""},"PeriodicalIF":1.8,"publicationDate":"2026-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148926604","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Scaling dependencies in irradiation-driven molecular dynamics simulations: case study of W(CO)(_6) fragmentation","authors":"Soumyo Kheto,&nbsp;Alexey Verkhovtsev,&nbsp;Bobby Antony,&nbsp;Andrey V. Solov’yov","doi":"10.1140/epjd/s10053-026-01244-6","DOIUrl":"10.1140/epjd/s10053-026-01244-6","url":null,"abstract":"<p>Irradiation-driven fragmentation and chemistry of organometallic molecules are central to nanofabrication techniques based on the use of focused charged-particle beams. In this paper, the electron irradiation-induced fragmentation of W(CO)<span>(_6)</span>, a commonly used precursor for focused electron beam-induced deposition (FEBID), is investigated computationally using the irradiation-driven molecular dynamics (IDMD) method. Simulations are performed on gas-phase molecular ensembles with different densities and under different irradiation conditions. The results reveal progressive fragmentation of W(CO)<span>(_6)</span> molecules into W(CO)<span>(_n)</span> (<span>(n=0)</span>–5) species, accompanied by the formation of W-rich molecular clusters. The evolution of fragment abundances is strongly dependent on both precursor density and electron fluence. Higher densities and larger fluences result in more extensive fragmentation and promote the aggregation of tungsten atoms into small metal clusters. Under certain irradiation conditions, the studied molecular systems evolve towards a quasi-steady fragment distribution characterised by slightly varying fragment abundances. The obtained scaling relations between irradiation parameters and fragment distributions provide guidance on the efficient choice of IDMD simulation parameters for studying radiation-induced precursor fragmentation, thus supporting a quantitative description of precursor fragmentation dynamics. The implications of this work for IDMD simulations of the FEBID process are also discussed.</p><p>Molecular ensemble of W(CO)₆ precursors before and after electron irradiation. (a, left) Initial configuration of W(CO)₆ molecules within the simulation box in the gas phase. (b, right) Post-irradiation configuration showing extensive molecular fragmentation and the formation of metal-containing nanostructures.</p>","PeriodicalId":789,"journal":{"name":"The European Physical Journal D","volume":"80 9","pages":""},"PeriodicalIF":1.8,"publicationDate":"2026-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148871704","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unpassivated edges as gateways to collision-driven topological transformations in finite graphene nanoflakes","authors":"Klaudia Cielinska,&nbsp;Alexey V. Verkhovtsev,&nbsp;Cauê P. Souza,&nbsp;Matthew D. Dickers,&nbsp;Andrey V. Solov’yov,&nbsp;Nigel J. Mason,&nbsp;Felipe Fantuzzi","doi":"10.1140/epjd/s10053-026-01242-8","DOIUrl":"10.1140/epjd/s10053-026-01242-8","url":null,"abstract":"<p>Finite graphene nanoflakes occupy a unique position in the carbon allotrope landscape. Near equilibrium, these systems exhibit pronounced structural robustness, indicating that large-scale allotropic transformations require strongly non-equilibrium energy deposition. In this work, we investigate how unpassivated graphene edges act as chemically active gateways for collision-driven topological transformations in finite graphene systems. Using reactive molecular dynamics simulations, we model energetic collisions involving a C<span>(_{60})</span> fullerene projectile and a finite C<span>(_{296})</span> graphene nanoflake across a broad parameter space of collision energies, incidence angles, and edge orientations. The structural response is analysed through statistical transformation maps that quantify the probability of nanoflake bending, edge stitching, and the formation of nanotube-like structures. We identify a regime of collision energies and oblique incidence angles under which localised energy deposition at unpassivated edges promotes bond rearrangement, cooperative bending, and covalent stitching between opposing edges. Furthermore, we find that armchair-directed impacts align opposing zigzag edges and promote efficient edge-to-edge stitching over a broader parameter range. In contrast, zigzag-directed impacts are associated with a higher probability for atom ejection and bring opposing armchair edges into contact, which is less favourable for seam propagation, resulting in a narrower parameter window for nanotube-like structure formation. These results establish a non-equilibrium framework linking local edge chemistry and collision-induced energy deposition to topological evolution in finite graphene systems. The results demonstrate collision-driven self-organisation as a viable pathway for the emergence of tubular nanostructures without reliance on catalytic surfaces or sustained thermal annealing.</p>","PeriodicalId":789,"journal":{"name":"The European Physical Journal D","volume":"80 9","pages":""},"PeriodicalIF":1.8,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjd/s10053-026-01242-8.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148871656","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fragmentation of uridine monophosphate induced by MeV carbon cluster irradiation: role of spatial energy concentration","authors":"Naruki Uno,&nbsp;Ayana Tachibana,&nbsp;Tetsuro Ohta,&nbsp;Takuya Majima,&nbsp;Manabu Saito,&nbsp;Hidetsugu Tsuchida","doi":"10.1140/epjd/s10053-026-01233-9","DOIUrl":"10.1140/epjd/s10053-026-01233-9","url":null,"abstract":"<div><p>The fragmentation of uridine 5′-monophosphate (UMP) induced by MeV carbon cluster ions C_<i>n</i>⁺ (<i>n</i> = 1–4) was investigated using time-of-flight secondary-ion mass spectrometry. This process is directly correlated with three-dimensional ionization density rather than linear energy transfer (LET). By varying the cluster size at a fixed projectile velocity, the spatial proximity of ionization events was systematically controlled while maintaining comparable atomic velocities. A clear shift in fragmentation patterns was observed: the relative yield of base-derived fragments increased with cluster size, whereas contributions from the ribose- and phosphate-related fragments decreased. The magnitude of the linear electronic stopping power alone does not fully account for this trend. Comparison with monoatomic ions of comparable stopping power reveals a cluster-specific enhancement of base-related fragmentation. When the data are analyzed using a modified stopping parameter that incorporates geometrical ion-track overlap, consistent scaling behavior is observed across both monoatomic and cluster projectiles. These results indicate that molecular fragmentation is more closely correlated with the spatial concentration of deposited electronic energy rather than with one-dimensional energy loss alone. The findings suggest that controlled cluster irradiation provides a useful approach for probing molecular processes under spatially concentrated ionization conditions.</p><h3>Graphical abstract</h3><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":789,"journal":{"name":"The European Physical Journal D","volume":"80 8","pages":""},"PeriodicalIF":1.8,"publicationDate":"2026-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148928105","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of Landau-quantized trapped electrons on linear and nonlinear ion-acoustic wave propagation in degenerate plasma","authors":"Mansoor Ahmad,&nbsp;Muhammad Adnan,&nbsp;Anisa Qamar","doi":"10.1140/epjd/s10053-026-01240-w","DOIUrl":"10.1140/epjd/s10053-026-01240-w","url":null,"abstract":"<p>The present work investigates the effects of Landau-quantized trapped electrons, obliqueness of propagation, and external magnetic-field strength on the linear and nonlinear propagation of ion-acoustic waves in fully and partially degenerate plasmas. The linear analysis yields a modified dispersion relation supporting slow and fast ion-acoustic modes. It is found that the fast mode is more strongly influenced by the quantized magnetic-field parameter than the slow mode, with the effect becoming more pronounced in partially degenerate plasma. To describe the weakly nonlinear regime, a rotation-modified Korteweg–de Vries (rmKdV) equation is derived by employing the reductive perturbation technique. Because the Lorentz-force contribution renders the rmKdV equation non-integrable for finite ion gyrofrequency and oblique propagation, the nonlinear evolution is examined numerically through the fourth-order Runge–Kutta time-stepping modified exponential time-differencing (METDRK4) scheme. The numerical results reveal the formation of both compressive and rarefactive solitary structures, depending on the quantized magnetic-field parameter. For small values of this parameter, the nonlinear response remains qualitatively similar in fully and partially degenerate plasmas, whereas for larger values, substantial differences emerge, especially in the partially degenerate case. It is further shown that increasing the ion gyrofrequency or the obliqueness strengthens rotational dispersion, accelerates the decay of solitary structures, and leads to the development of non-stationary radiative wave patterns. The solitary waves lose energy continuously to oscillatory tails, undergo steepening, and generate secondary localized structures during their evolution. These results show that Landau quantization, trapped-electron effects, and rotational dispersion jointly govern the linear dispersion and nonlinear dynamics of ion-acoustic waves in dense magnetized degenerate plasma environments.</p>","PeriodicalId":789,"journal":{"name":"The European Physical Journal D","volume":"80 8","pages":""},"PeriodicalIF":1.8,"publicationDate":"2026-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148837534","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Resource reduction for variational quantum algorithms by non-demolition measurements","authors":"D. Melegari,&nbsp;R. Abdul Razaq,&nbsp;G. Minuto,&nbsp;P. Solinas","doi":"10.1140/epjd/s10053-026-01197-w","DOIUrl":"10.1140/epjd/s10053-026-01197-w","url":null,"abstract":"<p>We present a comparative study of two implementations of a variational quantum algorithm aimed at minimizing the energy of a complex quantum system. In one implementation, we extract the information of the energy gradient by projective measurements. In the second implementation, called the non-demolition approach, the gradient information is stored in a quantum detector, which is eventually measured. As prototypical examples, we study the energy minimization of the lithium-based molecules and then extend the analysis systems with increased complexity. We find that while both approaches are able to identify the energy minimum, the non-demolition approach has a clear advantage in terms of the overall computational resources needed. This advantage increases linearly with the complexity of the quantum system, making the non-demolition approach the ideal candidate to implement such variational quantum algorithms.</p><p>Schematic representation of the energy minimization process for the H2 and LiH molecules using direct measurement (DM) and quantum non-demolition measurement (QNDM) approaches. Both methods converge to the minimum energy with similar accuracy, but the QNDM approach requires significantly fewer quantum resources (up to  79% reduction in gate count for LiH), highlighting its efficiency for variational quantum algorithms</p>","PeriodicalId":789,"journal":{"name":"The European Physical Journal D","volume":"80 8","pages":""},"PeriodicalIF":1.8,"publicationDate":"2026-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjd/s10053-026-01197-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148837533","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}