International Journal of Theoretical Physics最新文献

Dispersionless models play a significant role in describing short-wave and ultrashort-pulse phenomena in nonlinear media, also in the geometric-optics limit of integrable systems. The nonlocal complex coupled dispersionless system in particular, offers a mathematically tractable setting for examining nonlinear interactions such as kinks, breathers, and mixed structures generated through binary Darboux transformations. We construct a binary Darboux transformation for the nonlocal complex coupled dispersionless system and obtain quasi-Grammian breather–kink interactions. These findings reveal the coexistence of symmetry-preserving and breaking solutions within complex coupled dispersionless systems. To further substantiate these theoretical results, the solution dynamics are illustrated through surface and contour plots, providing a visual representation of their behavior.

We investigate both photothermally induced transparency and optomechanically induced transparency within a hybrid optomechanical system. The left cavity of this system contains a Bose–Einstein condensate that is confined within and examined using pump and probe fields. The right cavity is linked to mechanical oscillation through the photothermal effect. We observe a transition from a single window to multiple windows by varying multiple coupling constants such as intercavity coupling, optomechanical coupling, and the strength of condensate-cavity coupling. The absorption and dispersion spectra for photothermally induced transparency and optomechanically induced transparency are discussed. Increasing coupling strength yields multiple transparency windows and modified slow-light behavior. Stronger optomechanical coupling induces extra window splitting and group delay enhancement. We show that the photothermal coefficient can be used to effectively tune the amplitude and window width of the transparency feature. Our results highlight the significance of using the effects of both photothermal and optomechanical interaction to engineer tunable transparency useful for photonic systems, signal control, and future technologies based on coherent light–matter interaction.

Short-time dynamics in the 2D Blume-Capel model, with a non-conserved order-parameter and short-ranged interactions, is analysed. For non-equilibrium dynamics, both at a critical point in the 2D Ising universality class and at the tricritical point, we reproduce the values (Theta =0.190({5})) and (Theta =-0.542({5})), respectively, of the critical initial slip exponent. These agree with more early estimates and with the Janssen-Schaub-Schmittmann scaling relation. In phase-ordering kinetics, after a quench into the ordered phase, we establish the validity of short-time dynamics. In the 2D Ising universality class, we find (Theta =0.39({1})) in agreement with the scaling relation (lambda =d-2Theta ).

We apply the methodology of our recent paper ‘The Dynamics of the Hubbard Model through Stochastic Calculus and Girsanov Transformation’ [1] to thermodynamic correlation functions in the Fermi-Hubbard model. They can be obtained from a stochastic differential equation (SDE) system. To this SDE system, a Girsanov transformation can be applied. This has the effect that the usual determinant or pfaffian which shows up in a pfaffian quantum Monte Carlo (PfQMC) representation [2] basically gets absorbed into the new integration variables and information from that pfaffian moves into the drift part of the transformed SDE system. While the PfQMC representation depends heavily on the choice of how the quartic interaction has been factorized into quadratic quantities in the beginning, the Girsanov transformed formula has the very remarkable property that it is nearly independent of that choice, the drift part of the transformed SDE system as well as a remaining exponential which has the obvious meaning of energy are always the same and do not depend on the Hubbard-Stratonovich details. The resulting formula may serve as a starting point for further theoretical or numerical investigations. Here we consider the spin-spin correlation at half-filling on a bipartite lattice and obtain an analytical proof that the signs of these correlations have to be of antiferromagnetic type, at arbitrary temperatures. Also, by checking against available benchmark data [3], we find that approximate ground state energies can be obtained from an ODE system. This may even hold for exact ground state energies, but future work would be required to prove or disprove this. As in [1], the methodology is generic and can be applied to arbitrary quantum many body or quantum field theoretical models.

Chiral symmetry restoration and deconfinement at larger numbers of light-quark flavors, (N_f), may impact the properties of light hadrons. In this work, we study several properties of the pion and kaon—such as their masses and other related quantities across a range of (N_f). We employ the symmetry-preserving, confining vector–vector flavor-dependent contact interaction (FCI) as an input to the Schwinger–Dyson equation (SDE) and the homogeneous Bethe–Salpeter equation (BSE). In the chiral limit ((m_f = 0)), increasing the number of flavors (N_f) leads to the restoration of chiral symmetry and deconfinement at a critical number of flavors, (N^{c}_{f} approx 8), where at above the dress quark mass (M_{0}) vanish. For (N_f < N_{f}^{c}), the Nambu-Goldstone boson mass (m^{0}_{GB}) remains unchanged, signalling the chiral symmetry broken. When (N_f > N_{f}^{c}), chiral symmetry is fully restored and (m^{0}_{GB}) rises rapidly, indicating a transition from a bound state to a resonant state. The bound-state dissociation occurs at a critical flavor number (N^{d}_{f}), which coincides with (N_{f}^c), providing a clear indicator of deconfinement as quarks and antiquarks detach from their bound states. On the other hand, when bare quark mass is considered ((m_f ne 0)), the chiral symmetry remains explicitly broken and is partially restored at and above (N^{c}_{f} approx 8.2). Pion and kaon masses (m_{(pi , K)}) rises rapidly and dissociate at (N^{d}_{f} =N^{d}_{(pi ,K)f} approx 8.2), which separates the bound states from their constituents, indicating a Mott-like dissociation of bound states into their constituents. We also verified the consistency of our findings across different flavors using the Gell-Mann-Oakes-Renner relation.

We reconsider velocity addition/subtraction in Special Relativity (SR) and re-derive its well-known non-commutative and non-associative algebraic properties in a self contained way, including various explicit expressions for the Thomas angle, the derivation of which will be seen to be not as challenging as often suggested. All this is based on the polar-decomposition theorem in the traditional component language, in which Lorentz transformations are ordinary matrices. In the second part of this paper we offer a less familiar alternative geometric view, that leads to an invariant definition of the concept of relative velocity between two states of motion, which is based on the boost-link-theorem, of which we also offer an elementary proof that does not seem to be widely known in the relativity literature. Finally we compare this to the corresponding geometric definitions in Galilei-Newton spacetime, emphasising similarities and differences. Regarding the presentation of the material we will pursue an uncompromising pedagogical strategy, willingly accepting repetitions and occasional redundancies if deemed beneficial for clarity and the avoidance of anticipated misunderstandings. An appendix with four sections includes some mathematical details on results needed in the main text, as well some recollections on notions like semi-direct products of groups and affine spaces.

We reply to the comment by Lambare who criticizes our interpretation of the linear Sagnac effect. To remove the discontinuity appearing with the use of the Lorentz transformations in the interpretation of the effect, Lambare introduces an ad hoc time interval ((T)_{E}) different from the one observed. By invalidating Lambare’s arguments, we claim that a consistent interpretation requires ((T)_{E}) to be the same as the one experimentally observed.

The realization of nonlocality in Heisenberg XYZ states through Bell–Clauser–Horne–Shimony–Holt and Einstein–Podolsky–Rosen steering inequalities has recently been formalized as a fundamental quantum information resource. This framework elucidates the hierarchical relation among entanglement, steerability, and Bell-CHSH nonlocality, and supports advancements in quantum computing and quantum communication. Therefore, this work investigates the dynamics of steerability, Bell nonlocality, and entanglement in two-qubit Heisenberg XYZ states within the framework of Milburn’s intrinsic decoherence model, focusing on the influence of increasing the couplings of symmetric helical exchange spin-orbit interactions, spin-spin interactions, and the presence of an externally applied inhomogeneous magnetic field. The results show that the ability of spin-spin interactions to generate two-qubit Bell nonlocality, quantum steerability, and entanglement, and its robustness against the decoherence effect depend on the antiferromagnetic/ferromagnetic Heisenberg XYZ, symmetric helical exchange (x, y, z)-interactions, and magnetic field in the x-direction. It is found that an increase in the couplings of (x, y, z)-interactions, and magnetic field strength strongly support the amplifications of two-qubit nonlocality’s generations. Conversely, an increase in these parameters accelerates the decoherence-induced degradation of the amplified nonlocality generations.

We investigate a wide class of quasi-twisted codes of index 2, determining the generators of their Symplectic duals. Sufficient conditions ensuring self-orthogonality with respect to the Symplectic inner product are derived. Through Symplectic construction, we obtain a class of high-performance ternary quantum stabilizer codes, including six record-breaking ternary quantum stabilizer codes.

This comment re-examines the scheme proposed by Kazemikhah et al. [Int. J. Theor. Phys. 60, 378–386 (2021)] for bidirectional quantum teleportation of arbitrary n-qubit states using a four-qubit cluster state. Our analysis reveals that the protocol does not fully realize the intended n-qubit bidirectional teleportation. Specifically, the state-reduction and state-reconstruction procedures operate correctly only for particular two-, three-, or four-qubit states of the form ((alpha _0| 00.. rangle + alpha _1| 11.. rangle )). Therefore, the protocol can bidirectionally teleport only such specific states rather than an arbitrary n-qubit state. Additionally, we also show that the entangled channel employed in the protocol does not correspond to a true four-qubit cluster state. Nonetheless, the work of Kazemikhah et al. provides an important conceptual foundation for reduction–reconstruction strategies, which has subsequently motivated related research, including the N-qubit GHZ-like state teleportation scheme proposed in 10.1063/5.0179501.