Annalen der Physik最新文献

In the present study, a trade off of sharing of entanglement between subsystems of a higher dimensional quantum state is derived. It is presented in terms of an inequality which is analogous to the Coffman–Kundu–Wootters inequality that succinctly describes monogamy of entanglement in $��C^2�\otimes �C^2�\otimes �C^2�$ dimensional pure state. To derive the monogamy inequality in $��C^d�\otimes �C^d�\otimes �C^d�$ dimension, G-concurrence measure of entanglement is considered as a measure of entanglement of maximal dimension. The approach of the present study incidentally points toward a rigorous framework which enables to obtain an upper bound of G-concurrence of a bipartite qudit mixed state. Obtained upper bound of G-concurrence is then shown to satisfy a monogamy relation.

A scheme is proposed for generating controllable quantum correlations in a cavity-magnomechanical system comprising a microwave cavity and two yttrium iron garnet (YIG) spheres. A single-mode squeezed vacuum field drives the cavity, while a red-detuned field excites the magnon modes within the YIG spheres. Activating the magnetostrictive effect in the spheres introduces phonon modes through geometric deformation. By linearizing the system dynamics and introducing slowly moving operators to neglect high-frequency oscillatory terms, the correlated noise from the single-mode squeezed vacuum field can be effectively transferred between the two magnon modes and the phonon modes. Control of the cavity-magnon coupling rate breaks the system's symmetry, enabling the generation of tunable quantum squeezing, entanglement, and one-way quantum steering. This tunability facilitates the development of quantum information processing platforms, offering a promising framework for advancing quantum information technologies.

The use of high-quality factor resonators is of undoubted interest for high-precision measurements and for applications in quantum technologies. Novel types of microwave sensors can be realized by coupling a first resonator acting as a stable frequency reference with a second resonator that is sensitive to a particular physical quantity. Here, a coupled cavity configuration is reported in which a high quality ($�Q$) factor elliptical TESLA-shaped superconducting cavity is coupled with a high permittivity ($�{\epsilon }_r$) $�{\mathrm{SrTiO}}_3$ puck, whose resonant frequency varies as a function of temperature due to the temperature dependence of the permittivity that reaches values higher than 30 000 below 1 K. Extensive electromagnetic simulations are used to test different coupling configurations, showing great versatility in tuning the coupling in the weak or strong regime, depending on the puck's position within the cavity. Moreover, for the coupled system, they allow investigation of the dependence of the zero transmission frequency (notch frequency) on changes in permittivity $�{\epsilon }_r$, obtaining a maximum value of 2.8 MHz per unit change of $�{\epsilon }_r$, for $��{\epsilon }_r�\approx �230�$. Finally, the use of the coupled system as a sensor that operates in different temperature ranges is discussed.

The statistics of sequential measurements of two non-commuting observables typically depends on the order in which they are measured. However, if a system evolves unitarily between sequential measurements of dichotomic observables (i.e., observables whose measurement outcomes are labeled by $��\pm �1�$), then the expectation value of the product of the sequential measurements is in fact independent of the order of the measurements, provided that one uses the inverse unitary for the opposite order. In this work, a quantum Bayes' rule is used to show that the aforementioned time symmetry for sequential measurements of dichotomic observables extends to open quantum systems that evolve according to a general quantum channel between measurements. Such results are quite striking in light of the standard view that open quantum systems—which may lose information to their environment—are not reversible in any operational sense. An example of such time-symmetric correlations is given for the amplitude-damping channel, where it is observed that the symmetry is realized by a reverse channel that is a combination of the Petz recovery map together with a dephasing channel.

Nanocones

Where the infinitesimal meets the infinite, nanocones of graphene and boron nitride arise as silent analogues of gravitation. Through the lens of the Teleparallel Equivalent of General Relativity, their torsional energies mirror the very fabric of spacetime, hinting that the smallest architectures of matter may unveil the hidden order of the cosmos. More details can be found in the Research Article by F. L. Carneiro and co-workers (DOI: 2400448).

In recent years, the exploration of topological phononic states in 2D materials has become a key research area. This study presents a systematic analysis of the distinctive topological characteristics in the monolayer binary compound InN₂. Within its phononic spectrum, prominent topological band crossings are observed in two optical branches, corresponding to two quadratic nodal points localized at the M and Γ points. A thorough examination of the underlying mechanisms governing band formation and dispersion conditions has been conducted. Notably, the edge states associated with these quadratic nodal points are clearly resolved. These states exhibit two critical properties: they are spatially well-separated from bulk band projections, and they display extensive spatial distributions—attributes that significantly enhance their experimental detectability and practical utility. To further advance the material's application potential, this work also characterizes its mechanical properties, revealing significant anisotropic behavior in key parameters. Collectively, the identification of these ideal topological quadratic nodal point states, combined with the material's inherent stability, provides a robust foundation for future experimental verification. This investigation is poised to accelerate progress in the rapidly developing field of 2D topological materials, offering new insights that may facilitate breakthroughs in phononic device design and topological quantum applications.

Lattice models that exhibit topological zero-energy boundary modes show a remarkable sensitivity to the system length and the applied boundary conditions. The exact solutions for the eigenenergies and band gap of the topological modes in a generalized two-band non-Hermitian model on a topolectrical circuit platform are presented, which show an extra-ordinary dependence on the system size. Additionally, it is shown that the introduction of non-Hermiticity results in the recovery of topological modes with the exact eigenenergy of zero at a certain critical system size. Such zero-admittance edge states are reflected in the large impedance peaks in the impedance spectrum. The results reveal that the boundary modes of a non-Hermitian lattice can be tuned via system size.