New Journal of Physics最新文献

{"title":"GCRL: a graph neural network framework for network connectivity robustness learning","authors":"Yu Zhang, Haowei Chen, Qiyu Chen, Jie Ding, Xiang Li","doi":"10.1088/1367-2630/ad6ead","DOIUrl":"https://doi.org/10.1088/1367-2630/ad6ead","url":null,"abstract":"The resilience and adaptability of complex networks is crucial in ensuring their functionality against disruptions. Particularly, maintaining network connectivity under various attack scenarios is a key aspect of such resilience. Network connectivity refers to the degree to which nodes within a network are interconnected and able to exchange information or resources. Its robustness reflects the ability of a network to maintain connectivity under various attacks. Such ability has profound physical significance, ensuring the stability and reliability of real-world systems. Currently, connectivity robustness assessments rely heavily on very time-consuming attack simulations. This paper introduces a graph neural network framework for network connectivity robustness learning (GCRL) to advance the study of network connectivity robustness. GCRL transforms initial degree distributions and network topology into informative embedding vectors, which are then processed by a robustness learning module mainly composed of multi-layer perceptron, achieving both high speed and precision. Our extensive experiments demonstrate the superior performance of GCRL obtained in less time compared to existing methods, especially in tough scenarios where test data distributions significantly differ from the training set. The framework also shows adaptability to networks of different sizes, making it a more generalized solution for complex network robustness learning.","PeriodicalId":19181,"journal":{"name":"New Journal of Physics","volume":"2 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142214493","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Spatial mode conversion of a reflected polarized beam from an isotropic medium at brewster angle","authors":"Hua-Jie Hu, He-He Li, Xin-Zhong Li","doi":"10.1088/1367-2630/ad50fe","DOIUrl":"https://doi.org/10.1088/1367-2630/ad50fe","url":null,"abstract":"In this study, the spatial mode evolution of a chiral polarized beam during reflection on an isotropic medium surface at Brewster angle is both theoretically and experimentally investigated. In this process, the topological charge of the reflection field’s horizontal component increases (decreases) by one, relative to the specific left (right) elliptical polarization incident beam. While incident <italic toggle=\"yes\">l</italic>_{<italic toggle=\"yes\">i</italic>}-order vortex beam is in a certain polarization state, the intensity distribution of the reflection field’s horizontal component appears as the interference pattern of the <inline-formula>\u0000<tex-math><?CDATA $l_{i}pm 1$?></tex-math><mml:math overflow=\"scroll\"><mml:mrow><mml:msub><mml:mi>l</mml:mi><mml:mrow><mml:mi>i</mml:mi></mml:mrow></mml:msub><mml:mo>±</mml:mo><mml:mn>1</mml:mn></mml:mrow></mml:math><inline-graphic xlink:href=\"njpad50feieqn1.gif\"></inline-graphic></inline-formula>-order output vortex beams. The conversion occurs between the spin and orbital angular momentum and does not violate the conservation of the total angular momentum. We explain the physical mechanism of this phenomenon using phase shift theorem, and analyze the effect of ellipticity and polarization angle on this physical phenomenon.","PeriodicalId":19181,"journal":{"name":"New Journal of Physics","volume":"6 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142214496","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Tighter upper bounds on the critical temperature of two-dimensional superfluids and superconductors from the BCS to the Bose regime","authors":"Tingting Shi, Wei Zhang, C A R Sá de Melo","doi":"10.1088/1367-2630/ad7281","DOIUrl":"https://doi.org/10.1088/1367-2630/ad7281","url":null,"abstract":"We discuss standard and tighter upper bounds on the critical temperature &lt;inline-formula&gt;\u0000&lt;tex-math&gt;&lt;?CDATA $T_textrm{c}$?&gt;&lt;/tex-math&gt;&lt;mml:math overflow=\"scroll\"&gt;&lt;mml:mrow&gt;&lt;mml:msub&gt;&lt;mml:mi&gt;T&lt;/mml:mi&gt;&lt;mml:mtext&gt;c&lt;/mml:mtext&gt;&lt;/mml:msub&gt;&lt;/mml:mrow&gt;&lt;/mml:math&gt;&lt;inline-graphic xlink:href=\"njpad7281ieqn1.gif\"&gt;&lt;/inline-graphic&gt;&lt;/inline-formula&gt; of two-dimensional superfluids and superconductors versus particle density &lt;italic toggle=\"yes\"&gt;n&lt;/italic&gt; or filling factor &lt;italic toggle=\"yes\"&gt;ν&lt;/italic&gt; for continuum and lattice systems from the Bardeen–Cooper–Schrieffer (BCS) to the Bose regime. We consider only one-band Hamiltonians, where the transition from the normal to the superfluid (superconducting) phase is governed by the Berezinskii–Kosterlitz–Thouless (BKT) mechanism of vortex-antivortex binding, such that a direct relation between the superfluid density tensor and &lt;inline-formula&gt;\u0000&lt;tex-math&gt;&lt;?CDATA $T_textrm{c}$?&gt;&lt;/tex-math&gt;&lt;mml:math overflow=\"scroll\"&gt;&lt;mml:mrow&gt;&lt;mml:msub&gt;&lt;mml:mi&gt;T&lt;/mml:mi&gt;&lt;mml:mtext&gt;c&lt;/mml:mtext&gt;&lt;/mml:msub&gt;&lt;/mml:mrow&gt;&lt;/mml:math&gt;&lt;inline-graphic xlink:href=\"njpad7281ieqn2.gif\"&gt;&lt;/inline-graphic&gt;&lt;/inline-formula&gt; exists. The standard critical temperature upper bound &lt;inline-formula&gt;\u0000&lt;tex-math&gt;&lt;?CDATA $T_textrm{c}^{mathrm{up1}}$?&gt;&lt;/tex-math&gt;&lt;mml:math overflow=\"scroll\"&gt;&lt;mml:mrow&gt;&lt;mml:msubsup&gt;&lt;mml:mi&gt;T&lt;/mml:mi&gt;&lt;mml:mtext&gt;c&lt;/mml:mtext&gt;&lt;mml:mrow&gt;&lt;mml:mrow&gt;&lt;mml:mi&gt;up&lt;/mml:mi&gt;&lt;mml:mn&gt;1&lt;/mml:mn&gt;&lt;/mml:mrow&gt;&lt;/mml:mrow&gt;&lt;/mml:msubsup&gt;&lt;/mml:mrow&gt;&lt;/mml:math&gt;&lt;inline-graphic xlink:href=\"njpad7281ieqn3.gif\"&gt;&lt;/inline-graphic&gt;&lt;/inline-formula&gt; is obtained from the Ferrell-Glover-Tinkham sum rule for the optical conductivity, which constrains the superfluid density tensor components. We demonstrate that it is imperative to consider at least the full effect of phase fluctuations of the order parameter for superfluidity (superconductivity) and use the renormalization group to obtain the phase-fluctuation critical temperature &lt;inline-formula&gt;\u0000&lt;tex-math&gt;&lt;?CDATA $T_textrm{c}^{,theta}$?&gt;&lt;/tex-math&gt;&lt;mml:math overflow=\"scroll\"&gt;&lt;mml:mrow&gt;&lt;mml:msubsup&gt;&lt;mml:mi&gt;T&lt;/mml:mi&gt;&lt;mml:mtext&gt;c&lt;/mml:mtext&gt;&lt;mml:mrow&gt;&lt;mml:mstyle scriptlevel=\"0\"&gt;&lt;/mml:mstyle&gt;&lt;mml:mi&gt;θ&lt;/mml:mi&gt;&lt;/mml:mrow&gt;&lt;/mml:msubsup&gt;&lt;/mml:mrow&gt;&lt;/mml:math&gt;&lt;inline-graphic xlink:href=\"njpad7281ieqn4.gif\"&gt;&lt;/inline-graphic&gt;&lt;/inline-formula&gt;, a much tighter bound to the critical temperature supremum than &lt;inline-formula&gt;\u0000&lt;tex-math&gt;&lt;?CDATA $T_textrm{c}^{mathrm{up1}}$?&gt;&lt;/tex-math&gt;&lt;mml:math overflow=\"scroll\"&gt;&lt;mml:mrow&gt;&lt;mml:msubsup&gt;&lt;mml:mi&gt;T&lt;/mml:mi&gt;&lt;mml:mtext&gt;c&lt;/mml:mtext&gt;&lt;mml:mrow&gt;&lt;mml:mrow&gt;&lt;mml:mi&gt;up&lt;/mml:mi&gt;&lt;mml:mn&gt;1&lt;/mml:mn&gt;&lt;/mml:mrow&gt;&lt;/mml:mrow&gt;&lt;/mml:msubsup&gt;&lt;/mml:mrow&gt;&lt;/mml:math&gt;&lt;inline-graphic xlink:href=\"njpad7281ieqn5.gif\"&gt;&lt;/inline-graphic&gt;&lt;/inline-formula&gt; over a wide range of densities or filling factors. We also discuss a fundamental difference between superfluids and superconductors in regards to the vortex core energy dependence on density. Going beyond phase fluctuations, we note that theories including ","PeriodicalId":19181,"journal":{"name":"New Journal of Physics","volume":"41 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142214498","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Disentangling different interfacial effects of reduced thin layer magnetizations","authors":"Sven Erik Ilse, René Nacke, Gisela Schütz, Eberhard Goering","doi":"10.1088/1367-2630/ad69b7","DOIUrl":"https://doi.org/10.1088/1367-2630/ad69b7","url":null,"abstract":"Thin buried magnetic layers ranging from thicknesses of a few atomic monolayers to several nanometers are omnipresent in the fields of magnetism and spintronics. For the functionality and fine tuning of devices build with such layers, exact knowledge of the depth dependent magnetic properties is essential. Especially the interfacial magnetic properties are important. Hence, understanding how magnetism is affected by structural variations, such as thickness or interface roughness, is mandatory. In this study, we use x-ray resonant magnetic reflectometry and magnetometry to study the high-resolution depth dependent magnetization profiles of thin magnetic transition metal layers sandwiched between an oxide and chromium layer. Compared to bulk materials, the room temperature saturation magnetization of these layers is reduced by up to 67%. These reductions are extremely sensitive to small structural variations. From the magnetic depth profiles, we disentangle different effects contributing to the magnetization reduction and the exact magnetic properties of the interface.","PeriodicalId":19181,"journal":{"name":"New Journal of Physics","volume":"8 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142214497","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Direct laser acceleration in varying plasma density profiles","authors":"R Babjak, B Martinez, M Krus, M Vranic","doi":"10.1088/1367-2630/ad7280","DOIUrl":"https://doi.org/10.1088/1367-2630/ad7280","url":null,"abstract":"Direct laser acceleration has proven to be an efficient source of high-charge electron bunches and high brilliance x-rays. However, an analytical description of the acceleration in the interaction with varying plasma density targets is still missing. Here, we provide an analytical estimate of the maximum energies that electrons can achieve in such a case. We demonstrate that the maximum energy depends on the local electron properties at the moment when the electron fulfills the resonant condition at the beginning of the acceleration. This knowledge enables density shaping for various purposes. One application is to decrease the required acceleration distance needed to achieve the maximum electron energy. Another use for density tailoring is to achieve acceleration beyond the radiation reaction limit. We derive the energy scaling law that is valid for arbitrary density profile that varies slowly compared with the betatron period. Our results can be applied to electron heating in exponential preplasma of thin foils, ablating plasma plumes, or gas jets with long-scale ramp-up.","PeriodicalId":19181,"journal":{"name":"New Journal of Physics","volume":"16 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142214499","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Trade-off relations between Bell nonlocality and local Kochen–Specker contextuality in generalized Bell scenarios","authors":"Lucas E A Porto, Gabriel Ruffolo, Rafael Rabelo, Marcelo Terra Cunha, Paweł Kurzyński","doi":"10.1088/1367-2630/ad7167","DOIUrl":"https://doi.org/10.1088/1367-2630/ad7167","url":null,"abstract":"The relations between Bell nonlocality and Kochen–Specker contextuality have been subject of research from many different perspectives in the last decades. Recently, some interesting results on these relations have been explored in the so-called generalized Bell scenarios, that is, scenarios where Bell spatial separation (or agency independence) coexist with (at least one of the) parties’ ability to perform compatible measurements at each round of the experiment. When this party has an <italic toggle=\"yes\">n</italic>-cycle compatiblity setup, it was first claimed that Bell nonlocality could not be concomitantly observed with contextuality at this party’s local experiment. However, by a more natural reading of the definition of locality, it turns out that both Bell nonlocality and local contextuality can, in fact, be jointly present. In spite of it, in this work we prove that in the simplest of those scenarios there cannot be arbitrary amounts of both of these two resources together. That is, in these cases we show that the violation of any Bell inequality limits the possible violations of any local noncontextuality inequality. We also explore this trade-off relation using quantifiers of nonlocality and contextuality, discussing how such a relation can be understood in terms of a ‘global’ notion of contextuality, and we study possible extensions of this result to other scenarios.","PeriodicalId":19181,"journal":{"name":"New Journal of Physics","volume":"72 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142214500","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"TNSA based proton acceleration by two oblique laser pulses in the presence of an axial magnetic field","authors":"Imran Khan, Vikrant Saxena","doi":"10.1088/1367-2630/ad7052","DOIUrl":"https://doi.org/10.1088/1367-2630/ad7052","url":null,"abstract":"We employ two-dimensional particle-in-cell simulations to examine, in detail, the effect of a kilo-Tesla magnetic field applied along the normal of a flat TNSA target on the cutoff energy of protons/ions. The two cases of (i) normally incident single laser pulse, and (ii) two obliquely incident laser pulses are thoroughly examined. It is shown that the two-oblique-pulse configuration combined with an external magnetic field results in a stronger enhancement (56 MeV–75 MeV) in the protons’ cutoff energies than the normally incident single laser pulse with an external magnetic field (19 MeV–24 MeV). This combination of two-oblique laser pulses along with a kilo-Tesla level external magnetic field is therefore found to be highly effective in accelerating protons/ions in the TNSA regime.","PeriodicalId":19181,"journal":{"name":"New Journal of Physics","volume":"6 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142214502","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Topology-optimized photonic topological crystalline insulators with multiband helical edge states","authors":"Yafeng Chen, Zhihao Lan, Hai-Xiao Wang, Liang An, Zhongqing Su","doi":"10.1088/1367-2630/ad6fc5","DOIUrl":"https://doi.org/10.1088/1367-2630/ad6fc5","url":null,"abstract":"Photonic topological crystalline insulators (PTCIs) with helical edge states provide an alternative way to achieve robust electromagnetic wave transport and processing. However, most existing PTCIs only involve a single topological bandgap, and generally support a pair of gapped helical edge states, restricting the scope of applications in various fields such as multiband waveguides, filters, and communication systems. Here, we design dual-band PTCIs, in which multiple helical edge modes appear within two distinct bulk gaps, for transverse electric (TE) and transverse magnetic (TM) modes, respectively, by introducing the topology optimization method into the photonic crystals with glide symmetry. For PTCIs with TE modes, the mismatched frequency ranges of edge modes hosted by two orthometric boundaries offer an opportunity to realize a photonic demultiplexer. For PTCIs with TM modes, we show the enhanced second harmonic (SH) generation through the coupling of multiband edge modes by matching the frequency ranges of edge modes within the first and second bandgaps to fundamental and SH waves, respectively. This work provides a new way for designing multiband PTCIs with helical edge states, having promising potentials in developing multiband topological photonic devices for both linear and nonlinear applications.","PeriodicalId":19181,"journal":{"name":"New Journal of Physics","volume":"21 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142214503","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Impact of torque on active Brownian particle: exact moments in two and three dimensions","authors":"Anweshika Pattanayak, Amir Shee, Debasish Chaudhuri, Abhishek Chaudhuri","doi":"10.1088/1367-2630/ad6a32","DOIUrl":"https://doi.org/10.1088/1367-2630/ad6a32","url":null,"abstract":"In this work, we investigate the effects of torque, accounting for translational diffusion, on active Brownian particles (ABPs) in two (2d) and three (3d) dimensions. The torque is equivalent to chirality in 2d, well known as chiral active Brownian particles (cABPs), whereas in 3d, this is introduced as an external torque on the ABPs. Despite the inherent complexity in solving the Fokker–Planck equation, we demonstrate a Laplace transform method to precisely calculate the temporal evolution of various dynamic moments. Our analysis yields explicit expressions for multiple moments, such as the second and fourth moments of displacement, revealing the impact of persistence and chirality/torque. These moments exhibit oscillatory behavior, and excess kurtosis indicates deviations from the Gaussian distribution during intermediate time intervals.","PeriodicalId":19181,"journal":{"name":"New Journal of Physics","volume":"118 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142214504","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Reducing the number of qubits in quantum simulations of one dimensional many-body Hamiltonians","authors":"Somayeh Mehrabankar, Miguel Ángel García-March, Carmen G Almudéver, Armando Pérez","doi":"10.1088/1367-2630/ad6d84","DOIUrl":"https://doi.org/10.1088/1367-2630/ad6d84","url":null,"abstract":"We investigate the Ising and Heisenberg models using the block renormalization group method (BRGM), focusing on its behavior across different system sizes. The BRGM reduces the number of spins by a factor of 1/2 (1/3) for the Ising (Heisenberg) model, effectively preserving essential physical features of the model while using only a fraction of the spins. Through a comparative analysis, we demonstrate that as the system size increases, there is an exponential convergence between results obtained from the original and renormalized Ising Hamiltonians, provided the coupling constants are redefined accordingly. Remarkably, for a spin chain with 24 spins, all physical features, including magnetization, correlation function, and entanglement entropy, exhibit an exact correspondence with the results from the original Hamiltonian. The study of the Heisenberg model also shows this tendency, although complete convergence may appear for a size much larger than 24 spins, and is therefore beyond our computational capabilities. The success of BRGM in accurately characterizing the Ising model, even with a relatively small number of spins, underscores its robustness and utility in studying complex physical systems, and facilitates its simulation on current NISQ computers, where the available number of qubits is largely constrained.","PeriodicalId":19181,"journal":{"name":"New Journal of Physics","volume":"96 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142214525","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}