Search

Luminescent thermometers are highly effective in niche applications such as nanothermometry, in vivo imaging, and extreme conditions like high electromagnetic fields, radiation, and under mechanical or chemical stress. Advancing measurement precision, temperature resolution, and extending the temperature range are the main problems in this rapidly evolving research field, crucial in the work of R&D industry engineers and scientific researchers. Traditionally using single parameter for sensing leads to the sensor underperformance. Sensor fusion (SF), a well-established statistical tool used to enhance precision in autonomous vehicles, navigation systems, medical imaging, and wearable devices is here engineered for luminescent thermometry, by either fusing multiple sensor probes, or observing each temperature dependent feature as a separate sensor, resulting in always increased precision and extended usable temperature range. SF is a replacement and superior alternative to multiple linear regression models as it stands out for its versatility, enabling performance limits to be reached with any sensor probe material. It is compatible with both time-resolved and steady-state readouts, used independently or in combination, with single or multiple excitations. The benefits are illustrated using probes with Mn5+, Yb3+/Er3+/Ho3+, Sm2+, and Mn4+/Ho3+/Cr3+ activator ions., Comment: 18 pages, 9 figures

We formulate scalar electrodynamics in the braided $L_\infty$-algebra formalism and study its perturbative expansion in the algebraic framework of Batalin-Vilkovisky quantization. We confirm that UV/IR mixing is absent at one-loop order in this noncommutative field theory, and that the non-anomalous Ward-Takahashi identities for the braided gauge symmetry are satisfied., Comment: 48 pages; v2: minor changes

We formulate scalar field theories in a curved braided $L_\infty$-algebra formalism and analyse their correlation functions using Batalin-Vilkovisky quantization. We perform detailed calculations in cubic braided scalar field theory up to two-loop order and three-point multiplicity. The divergent tadpole contributions are eliminated by a suitable choice of central curvature for the $L_\infty$-structure, and we confirm the absence of UV/IR mixing. The calculations of higher loop and higher multiplicity correlators in homological perturbation theory are facilitated by the introduction of a novel diagrammatic calculus. We derive an algebraic version of the Schwinger-Dyson equations based on the homological perturbation lemma, and use them to prove the braided Wick theorem., Comment: 41 pages; v2: typos corrected; v3: minor changes and typos fixed; v4: Final version to be published in Fortschritte der Physik

Within the framework of noncommutative (NC) deformation of gauge field theory by twist, we first rederive the NC scalar and gauge field model from our previous papers and then generalize it to the second order in the Seiberg-Witten (SW) map. It turns out that SW expansion is finite and that it ceases at the second order in the deformation parameter, ultimately giving rise to the equation of motion for the scalar field that is nonperturbative and exact at the same order. As a further step, we show that the effective metric put forth and constructed in our previous work satisfies the equations of Einstein-Maxwell gravity, but only within the first order of deformation and when the gauge field is fixed by the Coulomb potential of the charged black hole. Thus obtained NC deformation of the Reissner--Nordstr\"om (RN) metric appears to have an additional off-diagonal element which scales linearly with a deformation parameter. We analyze various properties of this metric., Comment: 14 pages

In this paper we introduce a new type of approximate state reductions where the behaviors of the reduced and the original automaton do not have to be identical, but they must match on all words of length less than or equal to some given natural number. We provide four methods for performing such reductions., Comment: In Proceedings AFL 2023, arXiv:2309.01126

In this paper we deal with three models of weighted automata that take weights in the field of real numbers. The first of these models are classical weighted finite automata, the second one are crisp-deterministic weighted automata, and the third one are weighted automata over a vector space. We explore the interrelationships between weighted automata over a vector space and other two models., Comment: In Proceedings AFL 2023, arXiv:2309.01126

We study a noncommutative (NC) deformation of a charged scalar field, minimally coupled to a classical (commutative) Reissner Nordstrom like background. The deformation is performed via a particularly chosen Killing twist to ensure that the geometry remains undeformed (commutative). An action describing a NC scalar field minimally coupled to the RN geometry is manifestly invariant under the deformed U(1) gauge symmetry. We find the equation of motion and conclude that the same equation is obtained from the commutative theory in a modified geometrical background described by an effective metric. This correspondence we call duality between formal and effective approach. We also show that a NC deformation via semi Killing twist operator cannot be rewriten in terms of an effective metric. There is a dual description for those particular deformations., Comment: 11 pages, no figures. arXiv admin note: text overlap with arXiv:2208.06069

We address the problem of UV/IR mixing in noncommutative quantum field theories from the perspective of braided $L_\infty$-structures and the Batalin-Vilkovisky formalism. We describe the example of braided noncommutative scalar field theory and its quantization using braided homological perturbation theory. The formalism is illustrated through one-loop calculations of the two-point functions for $\phi^4$-theory in four dimensions and $\phi^3$-theory in six dimensions. In both cases we find that there are no non-planar diagrams and no UV/IR mixing., Comment: 22 pages, 4 figures; Contribution to the Proceedings of the Workshop on "Noncommutative and generalized geometry in string theory, gauge theory and related physical models", Corfu Summer Institute on Elementary Particle Physics and Gravity, 28 August-1 October 2022, Corfu, Greece. arXiv admin note: text overlap with arXiv:2302.10713

The homotopy algebraic formalism of braided noncommutative field theory is used to define the explicit example of braided electrodynamics, that is, $\mathsf{U}(1)$ gauge theory minimally coupled to a Dirac fermion. We construct the braided $L_\infty$-algebra of this field theory and obtain the braided equations of motion, action functional and conserved matter current. The modifications of the electric charge conservation law due to the braided noncommutative deformation are described. We develop a braided generalization of Wick's theorem, and use it to compute correlation functions of the braided quantum field theory using homological perturbation theory. Our putative calculations indicate that the braided theory does not contain the non-planar Feynman diagrams of conventional noncommutative quantum field theory, and that correlators do not exhibit UV/IR mixing., Comment: 48 pages, 6 figures; v2: typos fixed, sign rules corrected, references added; v3: major change of conclusions - the corrected calculation of the vertex in braided QED renders all two-point correlators free from UV/IR mixing

Quantum Hamiltonians containing nonseparable products of non-commuting operators, such as $\hat{\bf x}^m \hat{\bf p}^n$, are problematic for numerical studies using split-operator techniques since such products cannot be represented as a sum of separable terms, such as $T(\hat{\bf p}) + V(\hat{\bf x})$. In the case of classical physics, Chin [Phys. Rev. E $\bf 80$, 037701 (2009)] developed a procedure to approximately represent nonseparable terms in terms of separable ones. We extend Chin's idea to quantum systems. We demonstrate our findings by numerically evolving the Wigner distribution of a Kerr-type oscillator whose Hamiltonian contains the nonseparable term $\hat{\bf x}^2 \hat{\bf p}^2 + \hat{\bf p}^2 \hat{\bf x}^2$. The general applicability of Chin's approach to any Hamiltonian of polynomial form is proven., Comment: Fixed typos and extended discussion (6 pages, 1 figure)

Some noncommutative (NC) theories posses a certain type of dualities that are implicitly built within their structure. In this paper we establish still another example of this kind. More precisely, we show that the noncommutative U(1) gauge theory coupled to a NC scalar field and to a classical geometry of the Reissner Nordstrom (RN) type is completely equivalent at the level of equations of motion to the commutative U(1) gauge theory coupled to a commutative scalar field and to a classical geometry background, different from the starting RN background. The new (effective) metric is obtained from the RN metric by switching on an additional nonvanishing r-phi component. Using this duality between two theories and physical systems they describe, we formulate an effective approach to studying a dynamics of spin 1/2 fields on the curved background of RN type with an abiding noncommutative structure. As opposed to that, we also study the dynamics of spin 1/2 fields in a more formal way, by studying the semiclassical theory which describes the NC U(1) gauge field coupled with NC spin 1/2 field and also with gravity which is however treated classically. Upon utilising the Seiberg Witten map in order to write the NC spinor and NC gauge fields in terms of their corresponding commutative degrees of freedom, we find that the equation of motion for the fermion field obtained within the formal approach exactly coincides with the equation of motion obtained within the effective approach that utilises noncommutative duality. We then use these results to analyze the problem of stability of solutions of the equations of motion and the associated issue of superradiance, as related to fermions in RN spacetime with an allpervasive noncommutative structure., Comment: 19 pages, no figures; revtex4; references and appendix added, version to appear in EPJC

Topological gravity (in the sense that it is metric-independent) in a $2n$-dimensional spacetime can be formulated as a gauge field theory for the AdS gauge group $SO(2,2n-1)$ by adding a multiplet of scalar fields. These scalars can break the gauge invariance of the topological gravity action, thus making a connection with Einstein's gravity. This review is about a noncommutative (NC) star-product deformation of the four-dimensional AdS gauge theory of gravity, including Dirac spinors and the Yang-Mills field. In general, NC actions can be expanded in powers of the canonical noncommutativity parameter $\theta$ using the Seiberg-Witten map. The leading-order term of the expansion is the classical action, while the higher-order $\theta$-dependent terms are interpreted as new types of coupling between classical fields due to spacetime noncommutativity. We study how these perturbative NC corrections affect the field equations of motion and derive some phenomenological consequences, such as NC-deformed Landau levels of an electron. Finally, we discuss how topological gravity in four dimensions (both classical and noncommutative) appears as a low-energy sector of five-dimensional Chern-Simons gauge theory in the sense of Kaluza-Klein reduction., Comment: 18 pages; Contribution to the special issue of the European Physical Journal on "Noncommutativity and Physics"; v2: published version

Mapping the functional connectome has the potential to uncover key insights into brain organisation. However, existing workflows for functional connectomics are limited in their adaptability to new data, and principled workflow design is a challenging combinatorial problem. We introduce a new analytic paradigm and software toolbox that implements common operations used in functional connectomics as fully differentiable processing blocks. Under this paradigm, workflow configurations exist as reparameterisations of a differentiable functional that interpolates them. The differentiable program that we envision occupies a niche midway between traditional pipelines and end-to-end neural networks, combining the glass-box tractability and domain knowledge of the former with the amenability to optimisation of the latter. In this preliminary work, we provide a proof of concept for differentiable connectomics, demonstrating the capacity of our processing blocks both to recapitulate canonical knowledge in neuroscience and to make new discoveries in an unsupervised setting. Our differentiable modules are competitive with state-of-the-art methods in problem domains including functional parcellation, denoising, and covariance modelling. Taken together, our results and software demonstrate the promise of differentiable programming for functional connectomics., Comment: 12 pages, 6 figures (Supplement: 10 pages, 3 figures). For associated code, see https://github.com/rciric/hypercoil

Using the recently developed formalism of braided noncommutative field theory, we construct an explicit example of braided electrodynamics, that is, a noncommutative $U(1)$ gauge theory coupled to a Dirac fermion. We construct the braided $L_\infty$-algebra of this field theory and apply the formalism to obtain the braided equations of motion, action functional and conserved matter current. The braided deformation leads to a modification of the charge conservation. Finally, the Feynman integral appearing in the one-loop contribution to the vacuum polarization diagram is calculated. There are no non-planar diagrams, but the UV/IR mixing appears nevertheless. We comment on this unexpected result., Comment: 16 pages; Contribution to the Proceedings of the Workshop on "New Developments in Quantum Gravity and String Theory", Corfu Summer Institute on Elementary Particle Physics and Gravity, 29 August-9 October 2021, Corfu, Greece

The air quality in classrooms across all types of schools in Lower Saxony in the north of Germany has been monitored during June to December 2021 in a large study. Novel sensor instruments for air quality monitoring were wall mounted in 329 rooms in 50 schools and day nurseries. Each sensor instrument records data for carbon dioxide CO$_2$, sound level, temperature, and humidity. All collected data are transmitted for monitoring and further statistical evaluation by WiFi connection to the database. This study provides for the first time a detailed survey of the air quality situation and handling in schools during more than six months. The situation can be characterized by large variety in classroom area and volume combined with very diverse air ventilation possibilities. To control virus transmission via aerosol in classrooms an individual monitoring of air quality combined with high compliance for ventilation according to the signaled recommendation is urgently required.

Organic-inorganic metal halide perovskites have recently attracted increasing attention as highly efficient light harvesting materials for photovoltaic applications. However, the precise control of crystallization and morphology of organometallic perovskites deposited from solution, considered crucial for enhancing the final photovoltaic performance, remains challenging. In this context, here, we report on growing microcrystalline deposits of CH3NH3PbI3 (MAPbI3), by one-step solution casting on cylinde-shaped quartz substrates (rods). We show that the substrate curvature has a strong influence on morphology of the obtained polycrystalline deposits of MAPbI3. Although the crystalline width and length markedly decreased for substrates with higher curvatures, the photoluminescence (PL) spectral peak positions did not significantly evolve for MAPbI3 deposits on substrates with different diameters. The crystalline size reduction and denser coverage of microcrystalline MAPbI3 deposits on cylinder-shaped substrates with higher curvatures were attributed to two major contributions, both related to the annealing step of the MAPbI3 deposits. In particular, the diameter-dependent variability of the heat capacities and the substrate curvature-enhanced solvent evaporation rate seemed to contribute the most to the crystallization process and the resulting morphology changes of MAPbI3 deposits on cylinder-shaped quartz substrates with various diameters. The longitudinal geometry of cylinder-shaped substrates provided also a facile solution for checking the PL response of the deposits of MAPbI3 exposed to the flow of various gaseous media, such as oxygen, nitrogen and argon. Overall, the approach reported herein inspires novel, cylinder-shaped geometries of MAPbI3 deposits, which can find applications in low-cost photo-optical devices, including gas sensors.

We define a new homotopy algebraic structure, that we call a braided $L_\infty$-algebra, and use it to systematically construct a new class of noncommutative field theories, that we call braided field theories. Braided field theories have gauge symmetries which realize a braided Lie algebra, whose Noether identities are inhomogeneous extensions of the classical identities, and which do not act on the solutions of the field equations. We use Drinfel'd twist deformation quantization techniques to generate new noncommutative deformations of classical field theories with braided gauge symmetries, which we compare to the more conventional theories with star-gauge symmetries. We apply our formalism to introduce a braided version of general relativity without matter fields in the Einstein-Cartan-Palatini formalism. In the limit of vanishing deformation parameter, the braided theory of noncommutative gravity reduces to classical gravity without any extensions., Comment: 68 pages; v2: presentation improved, references added; Final version to be published in Letters in Mathematical Physics