Assembling materials with distinct magnetic characteristics in antiferromagnetic/ferrimagnetic (AFM/FiM) heterostructures enables emergent magnetic functionalities. In this study, we elucidate the individual roles of the AFM and FiM layers in exchange-coupled NiO/ZnFe2O4 bilayers by varying the NiO thickness (150–750 nm) and reversing the stacking order. For NiO/ZnFe2O4 bilayers with a fixed ZnFe2O4 thickness, structural analysis shows mixed (111) and (100) textured growth of NiO accompanied by significant interfacial intermixing. In contrast, inverted ZnFe2O4/NiO bilayers exhibit a sharper interface and predominantly (100) textured NiO growth. These structural distinctions strongly influence the magnetic response: NiO/ZnFe2O4 bilayers display a larger exchange bias (HEB ≈ 1.2 kOe at 5 K) that increases exponentially with NiO thickness, whereas weaker biasing is observed in the inverted configuration. Coarse-grained micromagnetic simulations reproduce the hysteresis-loop shift and reveal interfacial exchange frustration. Overall, these results provide insights relevant to the design of oxide-based spintronic devices.
{"title":"Optimizing ZnFe2O4/NiO nanoheterostructures for exchange bias","authors":"Nitesh Singh , Moisés Gilberto Zarzoza Medina , Banasree Sadhukhan , Anil Annadi , Panagiotis Grammatikopoulos , Hsiung Chou , Murtaza Bohra","doi":"10.1016/j.physleta.2026.131353","DOIUrl":"10.1016/j.physleta.2026.131353","url":null,"abstract":"<div><div>Assembling materials with distinct magnetic characteristics in antiferromagnetic/ferrimagnetic (AFM/FiM) heterostructures enables emergent magnetic functionalities. In this study, we elucidate the individual roles of the AFM and FiM layers in exchange-coupled NiO/ZnFe<sub>2</sub>O<sub>4</sub> bilayers by varying the NiO thickness (150–750 nm) and reversing the stacking order. For NiO/ZnFe<sub>2</sub>O<sub>4</sub> bilayers with a fixed ZnFe<sub>2</sub>O<sub>4</sub> thickness, structural analysis shows mixed (111) and (100) textured growth of NiO accompanied by significant interfacial intermixing. In contrast, inverted ZnFe<sub>2</sub>O<sub>4</sub>/NiO bilayers exhibit a sharper interface and predominantly (100) textured NiO growth. These structural distinctions strongly influence the magnetic response: NiO/ZnFe<sub>2</sub>O<sub>4</sub> bilayers display a larger exchange bias (<em>H</em><sub>EB</sub> ≈ 1.2 kOe at 5 K) that increases exponentially with NiO thickness, whereas weaker biasing is observed in the inverted configuration. Coarse-grained micromagnetic simulations reproduce the hysteresis-loop shift and reveal interfacial exchange frustration. Overall, these results provide insights relevant to the design of oxide-based spintronic devices.</div></div>","PeriodicalId":20172,"journal":{"name":"Physics Letters A","volume":"573 ","pages":"Article 131353"},"PeriodicalIF":2.6,"publicationDate":"2026-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146039607","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Pub Date : 2026-01-09DOI: 10.1016/j.physleta.2026.131342
Sumaita Sultana, Golam Ali Sekh
We consider helicoidal spin-orbit coupled Bose-Einstein condensates in deep optical lattice and study the dynamics of Bloch oscillation. We show that the variation of helicoidal gauge potential with spin-orbit coupling is different in zero-momentum and plane-wave phases. The characteristics of Bloch oscillatio n are different in the two phases. In the zero-momentum phase, the Bloch oscillation is harmonic while it is anharmonic in the plane-wave phase. The amplitude of Bloch oscillation is found to be affected by the helicoidal gauge potential and spin-orbit coupling. We examine that the decay of Bloch oscillation caused by mean-field interaction can be managed by helicoidal spin-orbit coupling.
{"title":"Bloch oscillations of helicoidal spin-orbit coupled Bose-Einstein condensates in deep optical lattices","authors":"Sumaita Sultana, Golam Ali Sekh","doi":"10.1016/j.physleta.2026.131342","DOIUrl":"10.1016/j.physleta.2026.131342","url":null,"abstract":"<div><div>We consider helicoidal spin-orbit coupled Bose-Einstein condensates in deep optical lattice and study the dynamics of Bloch oscillation. We show that the variation of helicoidal gauge potential with spin-orbit coupling is different in zero-momentum and plane-wave phases. The characteristics of Bloch oscillatio n are different in the two phases. In the zero-momentum phase, the Bloch oscillation is harmonic while it is anharmonic in the plane-wave phase. The amplitude of Bloch oscillation is found to be affected by the helicoidal gauge potential and spin-orbit coupling. We examine that the decay of Bloch oscillation caused by mean-field interaction can be managed by helicoidal spin-orbit coupling.</div></div>","PeriodicalId":20172,"journal":{"name":"Physics Letters A","volume":"573 ","pages":"Article 131342"},"PeriodicalIF":2.6,"publicationDate":"2026-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145981953","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Pub Date : 2026-01-09DOI: 10.1016/j.physleta.2026.131352
Haosheng Xiao , Feng Ye , H.Y. Fu , Qian Li
Polarization splitter-rotators (PSRs) are key components for polarization management in high-speed modulators and polarization-division multiplexing systems on the lithium niobate-on-insulator (LNOI) platform. In this work, the particle swarm optimization (PSO) algorithm is introduced to overcome the large-footprint limitation of mode-evolution-based PSRs, demonstrating broadband and efficient PSRs on the LNOI platform. By combining the PSO algorithm, multi-segment design and width topology optimization are respectively implemented to enhance polarization mode conversion efficiency and broaden the bandwidth. Both optimized devices exhibit excellent performance, with insertion loss <0.27 dB, polarization extinction ratio >20 dB, and bandwidth >300 nm. The devices have a length of 300 μm and require only one single-step etching in fabrication. Further analysis confirms the devices exhibit definite fabrication tolerance for width, height, and sidewall angles. The demonstrated methodologies hold potential for extension to other mode-evolution-based integrated photonic devices, enabling the simultaneous achievement of broad bandwidth and compact footprint.
{"title":"Broadband and efficient polarization splitter-rotator based on adiabatic mode evolution on the lithium niobate-on-insulator platform","authors":"Haosheng Xiao , Feng Ye , H.Y. Fu , Qian Li","doi":"10.1016/j.physleta.2026.131352","DOIUrl":"10.1016/j.physleta.2026.131352","url":null,"abstract":"<div><div>Polarization splitter-rotators (PSRs) are key components for polarization management in high-speed modulators and polarization-division multiplexing systems on the lithium niobate-on-insulator (LNOI) platform. In this work, the particle swarm optimization (PSO) algorithm is introduced to overcome the large-footprint limitation of mode-evolution-based PSRs, demonstrating broadband and efficient PSRs on the LNOI platform. By combining the PSO algorithm, multi-segment design and width topology optimization are respectively implemented to enhance polarization mode conversion efficiency and broaden the bandwidth. Both optimized devices exhibit excellent performance, with insertion loss <0.27 dB, polarization extinction ratio >20 dB, and bandwidth >300 nm. The devices have a length of 300 μm and require only one single-step etching in fabrication. Further analysis confirms the devices exhibit definite fabrication tolerance for width, height, and sidewall angles. The demonstrated methodologies hold potential for extension to other mode-evolution-based integrated photonic devices, enabling the simultaneous achievement of broad bandwidth and compact footprint.</div></div>","PeriodicalId":20172,"journal":{"name":"Physics Letters A","volume":"572 ","pages":"Article 131352"},"PeriodicalIF":2.6,"publicationDate":"2026-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145980052","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Pub Date : 2026-01-09DOI: 10.1016/j.physleta.2026.131350
Asma Al-Qasimi
In an experiment involving multiple independent trials of a simple two-outcome random process, such as tossing a coin, it is well-known that the cumulative result is described by the binomial probability distribution. In a quantum mechanical version, in which the coins are replaced by identical independent qubits, the same distribution will describe the cumulative outcomes, and it is intuitive that quantum entanglement is not present, otherwise the outcomes of measurements on different qubits will be correlated, and the trials will no longer be independent. Here, we examine whether such assumptions are valid, and find that maximally entangled qubit states, symmetric under interchange of any pair of qubits (specifically, they are eigenvectors of the SWAP operator with eigenvalue ), can also give a binomially distributed outcome.
{"title":"Pascal’s triangle and quantum entanglement","authors":"Asma Al-Qasimi","doi":"10.1016/j.physleta.2026.131350","DOIUrl":"10.1016/j.physleta.2026.131350","url":null,"abstract":"<div><div>In an experiment involving multiple independent trials of a simple two-outcome random process, such as tossing a coin, it is well-known that the cumulative result is described by the binomial probability distribution. In a quantum mechanical version, in which the coins are replaced by identical independent qubits, the same distribution will describe the cumulative outcomes, and it is intuitive that quantum entanglement is not present, otherwise the outcomes of measurements on different qubits will be correlated, and the trials will no longer be independent. Here, we examine whether such assumptions are valid, and find that maximally entangled qubit states, symmetric under interchange of any pair of qubits (specifically, they are eigenvectors of the SWAP operator with eigenvalue <span><math><mrow><mo>+</mo><mn>1</mn></mrow></math></span>), can also give a binomially distributed outcome.</div></div>","PeriodicalId":20172,"journal":{"name":"Physics Letters A","volume":"573 ","pages":"Article 131350"},"PeriodicalIF":2.6,"publicationDate":"2026-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146039613","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Pub Date : 2026-01-08DOI: 10.1016/j.physleta.2026.131344
Ralph Adrian E. Farrales, Eric A. Galapon
A pair of Hermitian operators is canonical if they satisfy the commutator relation , where is the identity operator. However, the relation holds only in a proper subspace of the Hilbert space, referred to as the canonical domain. In infinite-dimensional Hilbert space, it was previously shown that canonical pairs exist in a canonical domain that is not necessarily dense. In finite-dimensional Hilbert space, we show in this work that canonical pairs exist in a closed proper subspace of the Hilbert space. We study the many possible canonical pairs and look into the uncertainty relation they satisfy. We apply our results by constructing time operators in finite-dimensional quantum mechanics. We show that the canonical domain determines the states in which measurement of these time operators yield parametric time.
{"title":"Canonical pairs in finite-dimensional Hilbert space","authors":"Ralph Adrian E. Farrales, Eric A. Galapon","doi":"10.1016/j.physleta.2026.131344","DOIUrl":"10.1016/j.physleta.2026.131344","url":null,"abstract":"<div><div>A pair of Hermitian operators <span><math><mrow><mo>(</mo><mi>A</mi><mo>,</mo><mi>B</mi><mo>)</mo></mrow></math></span> is canonical if they satisfy the commutator relation <span><math><mrow><mo>[</mo><mi>A</mi><mo>,</mo><mi>B</mi><mo>]</mo><mo>=</mo><mi>i</mi><mi>ℏ</mi><mi>I</mi></mrow></math></span>, where <span><math><mi>I</mi></math></span> is the identity operator. However, the relation holds only in a proper subspace of the Hilbert space, referred to as the canonical domain. In infinite-dimensional Hilbert space, it was previously shown that canonical pairs exist in a canonical domain that is not necessarily dense. In finite-dimensional Hilbert space, we show in this work that canonical pairs exist in a closed proper subspace of the Hilbert space. We study the many possible canonical pairs and look into the uncertainty relation they satisfy. We apply our results by constructing time operators in finite-dimensional quantum mechanics. We show that the canonical domain determines the states in which measurement of these time operators yield parametric time.</div></div>","PeriodicalId":20172,"journal":{"name":"Physics Letters A","volume":"572 ","pages":"Article 131344"},"PeriodicalIF":2.6,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145980051","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Pub Date : 2026-01-08DOI: 10.1016/j.physleta.2026.131348
R. Sufiani, Sajjad Saei
Quantum coherence in collectively decaying V-type qutrit ensembles exhibits long-lived plateaus at zero temperature due to symmetry-protected dark sectors. Using the analytically solved reduced dynamics of the symmetric single-excitation block as a fixed baseline, we develop a coherence-centric framework that evaluates the ℓ1 norm and relative-entropy coherence in closed form on the single-site marginal, surveys parameter dependence, and compares representative initial states. We then extend the baseline to finite temperature and non-Markovian environments using exponential-memory kernels via a pseudomode (Markovian) embedding and time-local TCL forms. In balanced-decay regimes these models display coherence revivals and late-time plateaus that exceed the Markovian zero-temperature value; BLP backflow and RHP CP-indivisibility diagnostics corroborate information return. Next, we introduce tunable protection by steering between bright and dark modes with weak, permutation-invariant controls, enabling rapid population transfer into a decoherence-free subspace (DFS). We further formalize uniformly decaying subspaces (UDS), propose a simple rate-balance indicator that predicts plateau robustness, and show how both DFS and UDS extend naturally to multibranch qudits (d > 3), where the protected sector grows and strengthens plateaus. Throughout, the coherence functionals remain unchanged while only the time laws of reduced coefficients are upgraded, yielding a compact, reproducible methodology for analyzing and designing noise-resilient multilevel platforms.
{"title":"Coherence freezing and tunable decoherence-free/uniformly-decaying subspaces in collectively decaying qutrits","authors":"R. Sufiani, Sajjad Saei","doi":"10.1016/j.physleta.2026.131348","DOIUrl":"10.1016/j.physleta.2026.131348","url":null,"abstract":"<div><div>Quantum coherence in collectively decaying V-type qutrit ensembles exhibits long-lived plateaus at zero temperature due to symmetry-protected dark sectors. Using the analytically solved reduced dynamics of the symmetric single-excitation block as a fixed baseline, we develop a coherence-centric framework that evaluates the ℓ<sub>1</sub> norm and relative-entropy coherence in closed form on the single-site marginal, surveys parameter dependence, and compares representative initial states. We then extend the baseline to finite temperature and non-Markovian environments using exponential-memory kernels via a pseudomode (Markovian) embedding and time-local TCL forms. In balanced-decay regimes these models display coherence revivals and late-time plateaus that exceed the Markovian zero-temperature value; BLP backflow and RHP CP-indivisibility diagnostics corroborate information return. Next, we introduce tunable protection by steering between bright and dark modes with weak, permutation-invariant controls, enabling rapid population transfer into a decoherence-free subspace (DFS). We further formalize uniformly decaying subspaces (UDS), propose a simple rate-balance indicator that predicts plateau robustness, and show how both DFS and UDS extend naturally to multibranch qudits (<em>d</em> > 3), where the protected sector grows and strengthens plateaus. Throughout, the coherence functionals remain unchanged while only the time laws of reduced coefficients are upgraded, yielding a compact, reproducible methodology for analyzing and designing noise-resilient multilevel platforms.</div></div>","PeriodicalId":20172,"journal":{"name":"Physics Letters A","volume":"574 ","pages":"Article 131348"},"PeriodicalIF":2.6,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146026057","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Pub Date : 2026-01-08DOI: 10.1016/j.physleta.2025.131318
Harjit Singh Ghotra
Theoretical investigation of direct laser acceleration (DLA) of electrons using a helical Laguerre-Gaussian (h-LG) beam is presented. The helical beam of a LG(p, m) beam has zero radial (p) and positively non-zero azimuthal (m) mode indices, which distinguishes it from a fundamental Gaussian beam with (). The electron laser interaction is found to be sensitive with the distinct (m) index for both linear and circular polarizations of the h-LG beam. It is possible to derive electron dynamics with a combination of electric and magnetic fields, electron phase velocity, electron trajectory, acceleration curve, and overall energy gain by the electron by varying the (m) index of the h-LG beam. The optimum values of beam waist at full width half maximum (FWHM), which contributes to the most energetic electrons in the GeV energy range, are provided for increasing laser power PW of h-LG beam. The findings shed new light on vacuum and plasma applications focused on multi-PW h-LG laser beams.
{"title":"Polarization and mode control in helical LG-beam-driven electron acceleration","authors":"Harjit Singh Ghotra","doi":"10.1016/j.physleta.2025.131318","DOIUrl":"10.1016/j.physleta.2025.131318","url":null,"abstract":"<div><div>Theoretical investigation of direct laser acceleration (DLA) of electrons using a helical Laguerre-Gaussian (h-LG) beam is presented. The helical beam of a LG(<em>p, m</em>) beam has zero radial (<em>p</em>) and positively non-zero azimuthal (<em>m</em>) mode indices, which distinguishes it from a fundamental Gaussian beam with (<span><math><mrow><mi>p</mi><mo>=</mo><mn>0</mn><mo>,</mo><mi>m</mi><mo>=</mo><mn>0</mn></mrow></math></span>). The electron laser interaction is found to be sensitive with the distinct (m) index for both linear and circular polarizations of the h-LG beam. It is possible to derive electron dynamics with a combination of electric and magnetic fields, electron phase velocity, electron trajectory, acceleration curve, and overall energy gain by the electron by varying the (m) index of the h-LG beam. The optimum values of beam waist at full width half maximum (FWHM), which contributes to the most energetic electrons in the GeV energy range, are provided for increasing laser power <span><math><mrow><msub><mi>P</mi><mn>0</mn></msub><mo>=</mo><mrow><mo>{</mo><mn>0.5</mn><mo>,</mo><mn>1</mn><mo>,</mo><mn>5</mn><mo>}</mo></mrow></mrow></math></span> PW of h-LG beam. The findings shed new light on vacuum and plasma applications focused on multi-PW h-LG laser beams.</div></div>","PeriodicalId":20172,"journal":{"name":"Physics Letters A","volume":"572 ","pages":"Article 131318"},"PeriodicalIF":2.6,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145979963","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Pub Date : 2026-01-08DOI: 10.1016/j.physleta.2026.131345
Adam Fredriksson, Erik Sjöqvist
Berry monopoles always cancel when summing over a complete set of energy eigenstates. We demonstrate that analogous sum rules exist for geometric phases and their underlying 2-forms in non-adiabatic evolution. Our result has implications for qudit computation as it limits the types of gates that can be implemented by purely geometric means.
{"title":"Sum rule for non-adiabatic geometric phases","authors":"Adam Fredriksson, Erik Sjöqvist","doi":"10.1016/j.physleta.2026.131345","DOIUrl":"10.1016/j.physleta.2026.131345","url":null,"abstract":"<div><div>Berry monopoles always cancel when summing over a complete set of energy eigenstates. We demonstrate that analogous sum rules exist for geometric phases and their underlying 2-forms in non-adiabatic evolution. Our result has implications for qudit computation as it limits the types of gates that can be implemented by purely geometric means.</div></div>","PeriodicalId":20172,"journal":{"name":"Physics Letters A","volume":"572 ","pages":"Article 131345"},"PeriodicalIF":2.6,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145980050","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Pub Date : 2026-01-08DOI: 10.1016/j.physleta.2026.131332
Alexander Felski , Andreas Fring , Bethan Turner
We present a detailed analysis of the sixth-order Pais-Uhlenbeck oscillator and construct three-dimensional ghost-free representations through a Tri-Hamiltonian framework. We identify a six-dimensional Abelian Lie algebra of the PU model’s dynamical flow and derive a hierarchy of conserved Hamiltonians governed by multiple compatible Poisson structures. These structures enable the realisation of a complete Tri-Hamiltonian formulation that generates identical dynamical flows. Positive-definite Hamiltonians are constructed, and their relation to the full Tri-Hamiltonian hierarchy is analysed. Furthermore, we develop a mapping between the PU model and a class of three-dimensional coupled second-order systems, revealing explicit conditions for ghost-free equivalence. We also explore the consequences of introducing interaction terms, showing that the multi-Hamiltonian structure is generally lost in such cases.
{"title":"Three-dimensional ghost-free representations of the Pais-Uhlenbeck model from Tri-Hamiltonians","authors":"Alexander Felski , Andreas Fring , Bethan Turner","doi":"10.1016/j.physleta.2026.131332","DOIUrl":"10.1016/j.physleta.2026.131332","url":null,"abstract":"<div><div>We present a detailed analysis of the sixth-order Pais-Uhlenbeck oscillator and construct three-dimensional ghost-free representations through a Tri-Hamiltonian framework. We identify a six-dimensional Abelian Lie algebra of the PU model’s dynamical flow and derive a hierarchy of conserved Hamiltonians governed by multiple compatible Poisson structures. These structures enable the realisation of a complete Tri-Hamiltonian formulation that generates identical dynamical flows. Positive-definite Hamiltonians are constructed, and their relation to the full Tri-Hamiltonian hierarchy is analysed. Furthermore, we develop a mapping between the PU model and a class of three-dimensional coupled second-order systems, revealing explicit conditions for ghost-free equivalence. We also explore the consequences of introducing interaction terms, showing that the multi-Hamiltonian structure is generally lost in such cases.</div></div>","PeriodicalId":20172,"journal":{"name":"Physics Letters A","volume":"572 ","pages":"Article 131332"},"PeriodicalIF":2.6,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145980047","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Pub Date : 2026-01-07DOI: 10.1016/j.physleta.2025.131316
Yin-Da Guo , Kai-Dong Zhou , Shou-Shan Bao , Hong Zhang
Superradiance enables scalar fields to extract energy and angular momentum from a rotating black hole (BH), leading to the formation of a BH-condensate system. Previous studies mainly focus on the phase velocity, which propagates in the azimuthal direction. In this work, we show that the superradiant scalar condensate presents a nontrivial group velocity distribution. In the region sufficiently far from the BH, the condensate exhibits a radial velocity magnitude that approaches , while the polar and azimuthal velocity magnitudes asymptotically decline as ∝1/r.
{"title":"Local group velocity distribution inside superradiant condensates","authors":"Yin-Da Guo , Kai-Dong Zhou , Shou-Shan Bao , Hong Zhang","doi":"10.1016/j.physleta.2025.131316","DOIUrl":"10.1016/j.physleta.2025.131316","url":null,"abstract":"<div><div>Superradiance enables scalar fields to extract energy and angular momentum from a rotating black hole (BH), leading to the formation of a BH-condensate system. Previous studies mainly focus on the phase velocity, which propagates in the azimuthal direction. In this work, we show that the superradiant scalar condensate presents a nontrivial group velocity distribution. In the region sufficiently far from the BH, the condensate exhibits a radial velocity magnitude that approaches <span><math><mrow><mrow><mo>(</mo><msub><mi>r</mi><mi>g</mi></msub><mi>μ</mi><mo>/</mo><mn>2</mn><mo>)</mo></mrow><mi>sin</mi><mrow><mo>(</mo><mn>2</mn><mi>ω</mi><mi>t</mi><mo>−</mo><mn>2</mn><mi>φ</mi><mo>)</mo></mrow></mrow></math></span>, while the polar and azimuthal velocity magnitudes asymptotically decline as ∝1/<em>r</em>.</div></div>","PeriodicalId":20172,"journal":{"name":"Physics Letters A","volume":"572 ","pages":"Article 131316"},"PeriodicalIF":2.6,"publicationDate":"2026-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145904020","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
扫码关注我们
求助内容：
应助结果提醒方式：
京公网安备 11010802042870号