Pub Date : 2025-12-03DOI: 10.1016/j.aop.2025.170292
S. Baid , A. Lahbas , M. Oulne
We extend our previously developed approach combining an energy-dependent Davidson potential with deformation-dependent mass formalism from -unstable to axially symmetric prolate-deformed nuclei within the Bohr Hamiltonian. The model is applied to analyze the collective properties of 62 nuclei (13 actinides and 49 rare earth nuclei). The theoretical framework employs four adjustable parameters that are optimized through least-squares fitting to experimental energy levels. Particular attention is given to the N = 90 isotones (150Nd, 152Sm, 154Gd, and 156Dy), which are considered the best candidates of X(5) critical point symmetry. Our results demonstrate significant improvements over previous approaches, particularly in addressing the overestimation of -band level spacings characteristic of the traditional Davidson potential. Analysis of effective potentials reveals distinctive signatures of criticality through deeper potential wells for 0 states and enhanced separation between the ground and band-head state minima. The model also provides satisfactory predictions for B(E2) transition ratios, though with a tendency to overestimate interband transitions. These results suggest that the combination of energy dependence and deformation-dependent mass offers a more comprehensive framework for describing nuclear collective properties in transitional regions.
{"title":"Vibrational and rotational excited states within a Bohr Hamiltonian with energy-dependent Davidson potential and deformation-dependent mass formalisms","authors":"S. Baid , A. Lahbas , M. Oulne","doi":"10.1016/j.aop.2025.170292","DOIUrl":"10.1016/j.aop.2025.170292","url":null,"abstract":"<div><div>We extend our previously developed approach combining an energy-dependent Davidson potential with deformation-dependent mass formalism from <span><math><mi>γ</mi></math></span>-unstable to axially symmetric prolate-deformed nuclei within the Bohr Hamiltonian. The model is applied to analyze the collective properties of 62 nuclei (13 actinides and 49 rare earth nuclei). The theoretical framework employs four adjustable parameters that are optimized through least-squares fitting to experimental energy levels. Particular attention is given to the N = 90 isotones (<sup>150</sup>Nd, <sup>152</sup>Sm, <sup>154</sup>Gd, and <sup>156</sup>Dy), which are considered the best candidates of X(5) critical point symmetry. Our results demonstrate significant improvements over previous approaches, particularly in addressing the overestimation of <span><math><mi>β</mi></math></span>-band level spacings characteristic of the traditional Davidson potential. Analysis of effective potentials reveals distinctive signatures of criticality through deeper potential wells for 0<span><math><msubsup><mrow></mrow><mrow><mi>β</mi></mrow><mrow><mo>+</mo></mrow></msubsup></math></span> states and enhanced separation between the ground and <span><math><mi>γ</mi></math></span> band-head state minima. The model also provides satisfactory predictions for B(E2) transition ratios, though with a tendency to overestimate interband transitions. These results suggest that the combination of energy dependence and deformation-dependent mass offers a more comprehensive framework for describing nuclear collective properties in transitional regions.</div></div>","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"485 ","pages":"Article 170292"},"PeriodicalIF":3.0,"publicationDate":"2025-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145691988","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}
We investigate the current–voltage characteristics of an extended Su–Schrieffer–Heeger (SSH) chain under irradiation by arbitrarily polarized light, demonstrating its potential as a light-controlled rectifier. Irradiation of light induces anisotropy in the system, enabling directional current flow and active control of rectification behavior. Our analysis demonstrates that, under optimized light parameters, the rectification efficiency can exceed 90%. Moreover, the direction of rectification – whether positive or negative – can be precisely controlled by varying the polarization of the light, highlighting the potential for external optical control of electronic behavior. The effect of light irradiation is incorporated using the Floquet–Bloch ansatz combined with the minimal coupling scheme, while charge transport is computed through the nonequilibrium Green’s function formalism within the Landauer–Büttiker framework.
我们研究了任意偏振光照射下延伸的Su-Schrieffer-Heeger （SSH）链的电流-电压特性，证明了它作为光控整流器的潜力。光的照射引起系统的各向异性，使定向电流流动和整流行为的主动控制成为可能。我们的分析表明，在优化的光参数下，整流效率可以超过90%。此外，整流方向——无论是正的还是负的——可以通过改变光的偏振来精确控制，突出了外部光学控制电子行为的潜力。光照射的影响采用Floquet-Bloch ansatz结合最小耦合方案，而电荷输运则通过landauer - b ttiker框架内的非平衡格林函数形式计算。
{"title":"Photo-induced directional transport in extended SSH chains","authors":"Usham Harish Kumar Singha , Kallol Mondal , Sudin Ganguly , Santanu K. Maiti","doi":"10.1016/j.aop.2025.170317","DOIUrl":"10.1016/j.aop.2025.170317","url":null,"abstract":"<div><div>We investigate the current–voltage characteristics of an extended Su–Schrieffer–Heeger (SSH) chain under irradiation by arbitrarily polarized light, demonstrating its potential as a light-controlled rectifier. Irradiation of light induces anisotropy in the system, enabling directional current flow and active control of rectification behavior. Our analysis demonstrates that, under optimized light parameters, the rectification efficiency can exceed 90%. Moreover, the direction of rectification – whether positive or negative – can be precisely controlled by varying the polarization of the light, highlighting the potential for external optical control of electronic behavior. The effect of light irradiation is incorporated using the Floquet–Bloch ansatz combined with the minimal coupling scheme, while charge transport is computed through the nonequilibrium Green’s function formalism within the Landauer–Büttiker framework.</div></div>","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"485 ","pages":"Article 170317"},"PeriodicalIF":3.0,"publicationDate":"2025-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145691989","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}
We investigate the Galileon scalar field model by considering the lowest order Galileon term in the Lagrangian, through the introduction of a field potential. We explore the late-time cosmological development of light mass Galileon utilizing two different forms for , specifically the double exponential and Quintessence-Driven Slow-Contraction CDM potentials. We identify the critical points and assess their stability for these models. Our findings indicate that the light mass Galileon with double exponential potential facilitates the attainment of a stable attractor solution, while a stable solution is unattainable in the scenario of light mass Galileon with Quintessence-Driven Slow-Contraction CDM potential. Furthermore, in the former case, we derive a phase portrait in which all trajectories converge towards the stable attractor point.
{"title":"Light mass Galileon: Phase space analysis and its late time cosmic relevance","authors":"Yerlan Myrzakulov , Mohd Shahalam , Shynaray Myrzakul , Koblandy Yerzhanov","doi":"10.1016/j.aop.2025.170315","DOIUrl":"10.1016/j.aop.2025.170315","url":null,"abstract":"<div><div>We investigate the Galileon scalar field model by considering the lowest order Galileon term in the Lagrangian, <span><math><mrow><msup><mrow><mrow><mo>(</mo><msub><mrow><mi>∂</mi></mrow><mrow><mi>μ</mi></mrow></msub><mi>ϕ</mi><mo>)</mo></mrow></mrow><mrow><mn>2</mn></mrow></msup><mo>□</mo><mi>ϕ</mi></mrow></math></span> through the introduction of a field potential. We explore the late-time cosmological development of light mass Galileon utilizing two different forms for <span><math><mrow><mi>V</mi><mrow><mo>(</mo><mi>ϕ</mi><mo>)</mo></mrow></mrow></math></span>, specifically the double exponential and Quintessence-Driven Slow-Contraction CDM potentials. We identify the critical points and assess their stability for these models. Our findings indicate that the light mass Galileon with double exponential potential facilitates the attainment of a stable attractor solution, while a stable solution is unattainable in the scenario of light mass Galileon with Quintessence-Driven Slow-Contraction CDM potential. Furthermore, in the former case, we derive a phase portrait in which all trajectories converge towards the stable attractor point.</div></div>","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"485 ","pages":"Article 170315"},"PeriodicalIF":3.0,"publicationDate":"2025-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145692355","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 : 2025-12-01DOI: 10.1016/j.aop.2025.170303
Sergiu I. Vacaru
Modified gravity theories (MGTs) have long been studied as alternatives to general relativity (GR) and the standard CDM cosmological model. For example, exponential models often yield better fits to observational data, suggesting that CDM may be inadequate. In this work, we argue that the gravitational and accelerating cosmology paradigm can remain close to GR and CDM if one considers broader classes of off-diagonal cosmological solutions of the Einstein equations. These solutions are constructed using the anholonomic frame and connection deformation method (AFCDM), which enables the decoupling and integration of nonlinear systems in nonholonomic dyadic variables with connection distortions. The resulting off-diagonal Einstein manifolds and cosmological models are characterized by nonholonomic constraints, nonlinear symmetries, and effective cosmological constants. Such structures allow one to approximate cosmological effects, mimic features of MGTs, and describe gravitational polarization, local anisotropies, and dark energy and dark matter phenomena within GR. We further show that these models can be endowed with relativistic versions of Perelman’s thermodynamic variables for geometric flows, which we compute in general form for accelerating cosmology.
{"title":"Off-diagonal solutions in Einstein gravity modeling f(R) gravity and dynamical dark energy vs ΛCDM cosmology","authors":"Sergiu I. Vacaru","doi":"10.1016/j.aop.2025.170303","DOIUrl":"10.1016/j.aop.2025.170303","url":null,"abstract":"<div><div>Modified gravity theories (MGTs) have long been studied as alternatives to general relativity (GR) and the standard <span><math><mi>Λ</mi></math></span>CDM cosmological model. For example, exponential <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>R</mi><mo>)</mo></mrow></mrow></math></span> models often yield better fits to observational data, suggesting that <span><math><mi>Λ</mi></math></span>CDM may be inadequate. In this work, we argue that the gravitational and accelerating cosmology paradigm can remain close to GR and <span><math><mi>Λ</mi></math></span>CDM if one considers broader classes of off-diagonal cosmological solutions of the Einstein equations. These solutions are constructed using the anholonomic frame and connection deformation method (AFCDM), which enables the decoupling and integration of nonlinear systems in nonholonomic dyadic variables with connection distortions. The resulting off-diagonal Einstein manifolds and cosmological models are characterized by nonholonomic constraints, nonlinear symmetries, and effective cosmological constants. Such structures allow one to approximate cosmological effects, mimic features of MGTs, and describe gravitational polarization, local anisotropies, and dark energy and dark matter phenomena within GR. We further show that these models can be endowed with relativistic versions of Perelman’s thermodynamic variables for geometric flows, which we compute in general form for accelerating cosmology.</div></div>","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"485 ","pages":"Article 170303"},"PeriodicalIF":3.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145692356","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 : 2025-11-29DOI: 10.1016/j.aop.2025.170313
Farhang Loran , Ali Mostafazadeh
Stationary potential scattering admits a formulation in terms of the quantum dynamics generated by a non-Hermitian effective Hamiltonian. We use this formulation to give a proof of the reciprocity theorem in two and three dimensions that does not rely on the properties of the scattering operator, Green’s functions, or Green’s identities. In particular, we identify reciprocity with an operator identity satisfied by an integral operator , called the fundamental transfer matrix. This is a multi-dimensional generalization of the transfer matrix of potential scattering in one dimension that stores the information about the scattering amplitude of the potential. We use the property of that is responsible for reciprocity to identify the analog of the relation, , in two and three dimensions, and establish a generic anti-pseudo-Hermiticity of the scattering operator. Our results apply for both real and complex potentials.
{"title":"Reciprocity theorem and fundamental transfer matrix","authors":"Farhang Loran , Ali Mostafazadeh","doi":"10.1016/j.aop.2025.170313","DOIUrl":"10.1016/j.aop.2025.170313","url":null,"abstract":"<div><div>Stationary potential scattering admits a formulation in terms of the quantum dynamics generated by a non-Hermitian effective Hamiltonian. We use this formulation to give a proof of the reciprocity theorem in two and three dimensions that does not rely on the properties of the scattering operator, Green’s functions, or Green’s identities. In particular, we identify reciprocity with an operator identity satisfied by an integral operator <span><math><mover><mrow><mi>M</mi></mrow><mrow><mo>̂</mo></mrow></mover></math></span>, called the fundamental transfer matrix. This is a multi-dimensional generalization of the transfer matrix <span><math><mi>M</mi></math></span> of potential scattering in one dimension that stores the information about the scattering amplitude of the potential. We use the property of <span><math><mover><mrow><mi>M</mi></mrow><mrow><mo>̂</mo></mrow></mover></math></span> that is responsible for reciprocity to identify the analog of the relation, <span><math><mrow><mo>det</mo><mi>M</mi><mo>=</mo><mn>1</mn></mrow></math></span>, in two and three dimensions, and establish a generic anti-pseudo-Hermiticity of the scattering operator. Our results apply for both real and complex potentials.</div></div>","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"485 ","pages":"Article 170313"},"PeriodicalIF":3.0,"publicationDate":"2025-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145691987","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 : 2025-11-28DOI: 10.1016/j.aop.2025.170301
Rui Zhu
The pseudospin-3/2 Dirac–Weyl system is the kind of system bearing the quasiparticle band structure of two cones with different apex angles and their reversed replica touching at the apex, whose properties can be described by the pseudospin-3/2 Dirac equation. In this work, we analytically solved the pseudospin-3/2 Dirac equation and investigated the electronic transport properties in the double-barrier modulated two-dimensional system. The probability current density operator is explicitly derived from the time-dependent pseudospin-3/2 Dirac equation, which paves way for investigation of the electronic transport properties of general pseudospin- Dirac–Weyl systems with an integer or half integer larger than 1. As a result of the double-cone band structure, the pseudospin-3/2 system has two incident channels for a single incident energy and incident angle pair. Similar to its counterparts of pseudospin-1/2 and pseudospin-1 Dirac–Weyl systems, the Klein tunneling and resonant tunneling effects in the transmission probability are numerically observed for incidence coming from both Dirac cones in the double-barrier-modulated pseudospin-3/2 system. In contrast to its pseudospin-1/2 and -1 counterparts, the Klein tunneling and resonant tunneling effects are differentiated into double-channel and single-channel incidences, corresponding to different regimes in the - dispersion plane. Without a flat band, the super Klein tunneling effect of the pseudospin-1 Dirac–Weyl system does not occur in the pseudospin-3/2 system. Using the numerically obtained probability current density, the zero-temperature conductivity, shot noise, and Fano factor are calculated. As a combined result of double-channel incidence, Klein tunneling, and resonant tunneling, in comparison with its pseudospin-1/2 (graphene) and pseudospin-1 counterparts, the conductivity and shot noise in the pseudospin-3/2 double-barrier structure is enhanced. A Fano factor between 0.4 and 0.5 close to the Dirac point is observed.
{"title":"Transport properties of the pseudospin-3/2 Dirac–Weyl fermions in the double-barrier-modulated two-dimensional system","authors":"Rui Zhu","doi":"10.1016/j.aop.2025.170301","DOIUrl":"10.1016/j.aop.2025.170301","url":null,"abstract":"<div><div>The pseudospin-3/2 Dirac–Weyl system is the kind of system bearing the quasiparticle band structure of two cones with different apex angles and their reversed replica touching at the apex, whose properties can be described by the pseudospin-3/2 Dirac equation. In this work, we analytically solved the pseudospin-3/2 Dirac equation and investigated the electronic transport properties in the double-barrier modulated two-dimensional system. The probability current density operator is explicitly derived from the time-dependent pseudospin-3/2 Dirac equation, which paves way for investigation of the electronic transport properties of general pseudospin-<span><math><mi>s</mi></math></span> Dirac–Weyl systems with <span><math><mi>s</mi></math></span> an integer or half integer larger than 1. As a result of the double-cone band structure, the pseudospin-3/2 system has two incident channels for a single incident energy and incident angle pair. Similar to its counterparts of pseudospin-1/2 and pseudospin-1 Dirac–Weyl systems, the Klein tunneling and resonant tunneling effects in the transmission probability are numerically observed for incidence coming from both Dirac cones in the double-barrier-modulated pseudospin-3/2 system. In contrast to its pseudospin-1/2 and -1 counterparts, the Klein tunneling and resonant tunneling effects are differentiated into double-channel and single-channel incidences, corresponding to different regimes in the <span><math><mi>E</mi></math></span>-<span><math><msub><mrow><mi>k</mi></mrow><mrow><mi>y</mi></mrow></msub></math></span> dispersion plane. Without a flat band, the super Klein tunneling effect of the pseudospin-1 Dirac–Weyl system does not occur in the pseudospin-3/2 system. Using the numerically obtained probability current density, the zero-temperature conductivity, shot noise, and Fano factor are calculated. As a combined result of double-channel incidence, Klein tunneling, and resonant tunneling, in comparison with its pseudospin-1/2 (graphene) and pseudospin-1 counterparts, the conductivity and shot noise in the pseudospin-3/2 double-barrier structure is enhanced. A Fano factor between 0.4 and 0.5 close to the Dirac point <span><math><mrow><msub><mrow><mi>E</mi></mrow><mrow><mi>F</mi></mrow></msub><mo>=</mo><msub><mrow><mi>V</mi></mrow><mrow><mn>0</mn></mrow></msub></mrow></math></span> is observed.</div></div>","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"485 ","pages":"Article 170301"},"PeriodicalIF":3.0,"publicationDate":"2025-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145692411","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 : 2025-11-27DOI: 10.1016/j.aop.2025.170300
G. Abellán , N. Bolívar , I. Vasilev
We construct and analyse a class of static spherically symmetric spacetimes in general relativity sourced exclusively by classical electrostatic configurations. Using a spherically symmetric Painlevé–Gullstrand-like metric with unit lapse and a radial shift function, we develop piecewise-defined solutions where the interior geometry is flat and the exterior is supported by several sources inspired by electromagnetic distributions. These include point-charge-like fields, Yukawa-screened electric fields, dielectric layers, and Hulthén-type field. The Einstein equations naturally impose a relation between the energy density and radial pressure, while the tangential pressure is derived from the metric. We systematically evaluate the classical energy conditions in each model and study the appearance of singular behaviour using Israel junction conditions. This framework offers an analytically tractable setting to explore the gravitational effects of physically simple, well-understood sources without resorting to exotic matter.
{"title":"Gravitational effects of sources inspired by ideal electromagnetic fields in spherical Painlevé–Gullstrand coordinates","authors":"G. Abellán , N. Bolívar , I. Vasilev","doi":"10.1016/j.aop.2025.170300","DOIUrl":"10.1016/j.aop.2025.170300","url":null,"abstract":"<div><div>We construct and analyse a class of static spherically symmetric spacetimes in general relativity sourced exclusively by classical electrostatic configurations. Using a spherically symmetric Painlevé–Gullstrand-like metric with unit lapse and a radial shift function, we develop piecewise-defined solutions where the interior geometry is flat and the exterior is supported by several sources inspired by electromagnetic distributions. These include point-charge-like fields, Yukawa-screened electric fields, dielectric layers, and Hulthén-type field. The Einstein equations naturally impose a relation between the energy density and radial pressure, while the tangential pressure is derived from the metric. We systematically evaluate the classical energy conditions in each model and study the appearance of singular behaviour using Israel junction conditions. This framework offers an analytically tractable setting to explore the gravitational effects of physically simple, well-understood sources without resorting to exotic matter.</div></div>","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"485 ","pages":"Article 170300"},"PeriodicalIF":3.0,"publicationDate":"2025-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145622793","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 : 2025-11-25DOI: 10.1016/j.aop.2025.170306
Radouan Hab arrih , Ayoub Ghaba , Pablo Díaz , David Laroze , Ahmed Jellal
We study quantum steering and entanglement in two coupled harmonic oscillators using Wigner function techniques in phase space. We derive expressions for purity and quantum steering in the - and -directions. Our results extend previous studies from the weak coupling regime to the ultra-strong coupling regime, revealing significant deviations in behavior. In particular, we show that quantum steering between excited oscillators is completely absent even in the ultra-strong coupling regime. Similarly, resonant oscillators show no steering, and ground states cannot steer any receiver state. We find that quantum steering increases as the system approaches resonance and in certain ultra-strong coupling regimes. This behavior shows a clear asymmetry, with steering occurring in only one direction. It highlights the delicate balance of interaction strengths that shapes quantum correlations. These results improve our understanding of how excitation levels and coupling strengths affect quantum steering and entanglement in coupled harmonic oscillators.
{"title":"Quantum steering and entanglement in two coupled harmonic oscillators","authors":"Radouan Hab arrih , Ayoub Ghaba , Pablo Díaz , David Laroze , Ahmed Jellal","doi":"10.1016/j.aop.2025.170306","DOIUrl":"10.1016/j.aop.2025.170306","url":null,"abstract":"<div><div>We study quantum steering and entanglement in two coupled harmonic oscillators using Wigner function techniques in phase space. We derive expressions for purity and quantum steering in the <span><math><mi>x</mi></math></span>- and <span><math><mi>y</mi></math></span>-directions. Our results extend previous studies from the weak coupling regime to the ultra-strong coupling regime, revealing significant deviations in behavior. In particular, we show that quantum steering between excited oscillators is completely absent even in the ultra-strong coupling regime. Similarly, resonant oscillators show no steering, and ground states cannot steer any receiver state. We find that quantum steering increases as the system approaches resonance and in certain ultra-strong coupling regimes. This behavior shows a clear asymmetry, with steering occurring in only one direction. It highlights the delicate balance of interaction strengths that shapes quantum correlations. These results improve our understanding of how excitation levels and coupling strengths affect quantum steering and entanglement in coupled harmonic oscillators.</div></div>","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"484 ","pages":"Article 170306"},"PeriodicalIF":3.0,"publicationDate":"2025-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145621589","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 : 2025-11-25DOI: 10.1016/j.aop.2025.170304
Himanshu Badhani , C.M. Chandrashekar
Evolutions under non-Hermitian Hamiltonians with unbroken symmetry can be considered unitary under appropriate choices of inner products, facilitated by the so-called metric operator. While it is understood that the choice of the metric operator has no bearing on the description of the system, in this work, we show that this choice does dictate the entanglement structure of the system. We show that the partial trace of the Hermitized density matrix gives the correct representation of the reduced subsystem, and based on such operations, we elucidate the metric dependency of the reduced dynamics and consequently the observable dependence of the subsystem decomposition. We use a non-Hermitian -symmetric quantum walk as a toy model to study this metric dependency, where we use the internal (coin state) as the subsystem of interest and study the coin-position entanglement and non-Markovianity of the coin dynamics.
{"title":"Reduced dynamics in quasi-Hermitian systems","authors":"Himanshu Badhani , C.M. Chandrashekar","doi":"10.1016/j.aop.2025.170304","DOIUrl":"10.1016/j.aop.2025.170304","url":null,"abstract":"<div><div>Evolutions under non-Hermitian Hamiltonians with unbroken <span><math><mrow><mi>P</mi><mi>T</mi></mrow></math></span> symmetry can be considered unitary under appropriate choices of inner products, facilitated by the so-called metric operator. While it is understood that the choice of the metric operator has no bearing on the description of the system, in this work, we show that this choice does dictate the entanglement structure of the system. We show that the partial trace of the Hermitized density matrix gives the correct representation of the reduced subsystem, and based on such operations, we elucidate the metric dependency of the reduced dynamics and consequently the observable dependence of the subsystem decomposition. We use a non-Hermitian <span><math><mi>PT</mi></math></span>-symmetric quantum walk as a toy model to study this metric dependency, where we use the internal (coin state) as the subsystem of interest and study the coin-position entanglement and non-Markovianity of the coin dynamics.</div></div>","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"484 ","pages":"Article 170304"},"PeriodicalIF":3.0,"publicationDate":"2025-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145621591","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 : 2025-11-25DOI: 10.1016/j.aop.2025.170305
Sara Giordano , Miguel A. Martin-Delgado
Testing graph completeness is a critical problem in computer science and network theory. Leveraging quantum computation, we present an efficient algorithm using the Szegedy quantum walk and quantum phase estimation (QPE). Our algorithm, which takes the number of nodes and the adjacency matrix as input, constructs a quantum walk operator and applies QPE to estimate its eigenvalues. These eigenvalues reveal the graph’s structural properties, enabling us to determine its completeness. We establish a relationship between the number of nodes in a complete graph and the number of marked nodes, optimizing the success probability and running time. The time complexity of our algorithm is , where is the number of nodes of the graph. offering a clear quantum advantage over classical methods. This approach is useful in network structure analysis, evaluating classical routing algorithms, and assessing systems based on pairwise comparisons.
{"title":"Quantum algorithm for testing graph completeness","authors":"Sara Giordano , Miguel A. Martin-Delgado","doi":"10.1016/j.aop.2025.170305","DOIUrl":"10.1016/j.aop.2025.170305","url":null,"abstract":"<div><div>Testing graph completeness is a critical problem in computer science and network theory. Leveraging quantum computation, we present an efficient algorithm using the Szegedy quantum walk and quantum phase estimation (QPE). Our algorithm, which takes the number of nodes and the adjacency matrix as input, constructs a quantum walk operator and applies QPE to estimate its eigenvalues. These eigenvalues reveal the graph’s structural properties, enabling us to determine its completeness. We establish a relationship between the number of nodes in a complete graph and the number of marked nodes, optimizing the success probability and running time. The time complexity of our algorithm is <span><math><mrow><mi>O</mi><mrow><mo>(</mo><msup><mrow><mo>log</mo></mrow><mrow><mn>2</mn></mrow></msup><mi>n</mi><mo>)</mo></mrow></mrow></math></span>, where <span><math><mi>n</mi></math></span> is the number of nodes of the graph. offering a clear quantum advantage over classical methods. This approach is useful in network structure analysis, evaluating classical routing algorithms, and assessing systems based on pairwise comparisons.</div></div>","PeriodicalId":8249,"journal":{"name":"Annals of Physics","volume":"484 ","pages":"Article 170305"},"PeriodicalIF":3.0,"publicationDate":"2025-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145621638","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}
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