Long-Range Interactions for Hydrogen Atoms in Excited D States

Pressure shifts inside an atomic beam are among the more theoretically challenging effects in high-precision measurements of atomic transitions. A crucial element in their theoretical analysis is the understanding of long-range interatomic interactions inside the beam. For excited reference states, the presence of quasi-degenerate states leads to additional challenges, due to the necessity to diagonalize large matrices in the quasi-degenerate hyperfine manifolds. Here, we focus on the interactions of hydrogen atoms in reference states composed of an excited nD state (atom A), and in the metastable 2S state (atom B). We devote special attention to the cases n=3 and n=8. For n=3, the main effect is generated by quasi-degenerate virtual P states from both atoms A and B and leads to experimentally relevant second-order long-range (van-der-Waals) interactions proportional to the sixth inverse power of the interatomic distance. For n=8, in addition to virtual states with two states of P symmetry, one needs to take into account combined virtual P and F states from atoms A and B. The numerical value of the so-called C6 coefficients multiplying the interaction energy was found to grow with the principal quantum number of the reference D state; it was found to be of the order of 1011 in atomic units. The result allows for the calculation of the pressure shift inside atomic beams while driving transitions to nD states.

FCC-ee: physics motivations

Learning from the first twelve years of LHC running, this essay offers a brief journey through the FCC-ee physics programme from refined precision measurements to probes of new physics, highlighting some of the commentaries between the different runs of FCC-ee at various energies as well as the synergies between the two FCC-ee and FCC-hh collider stages.

Polariton Condensate and Landau-Zener-Stückelberg Interferometry Transition in Multilayer Transition Metal Dichalcogenides

This paper gives a detailed description of a high-performance polariton condensate for a quantum mechanical two-level system (TLS). We propose a transition metal dichalcogenides (TMDs) setup and theoretically carry out the spectroscopy of these polariton condensates. Through theoretical and numerical analysis, we obtain many features in two dimensional (2D) multilayer TMDs. We compute the energy of the system and the Landau-Zener-Stückelberg (LZS) quantum tunneling probability under the effect of a sequence of laser light. At certain critical 2D TMDs parameters, the system exhibits a multi-crossing scenario in a privileged position of 2D multilayer TMDs. We predict the consecutive modulations and highlight the conservation of the LZS interference patterns mapped from the 2D TMDs system. At weak coupling regime, a successful conversion of interferometry signals is identified for some values of laser frequency. We explain such a result as a valley sensitive cavity rate model due to coherent exchange and incoherent scattering, meaning that polariton condensate is formed in the valley around the Brillouin zone. The latter is used quantitatively and qualitatively to achieve high-precision measurements beyond that of its elementary constituents. The obtained results confirm that MoSe2 has the highest sensitivity to radiation field as compared to other 2D multilayer TMDs materials. Therefore, MoSe2 stands as an appropriate candidate among other 2D TMDs to form polariton condensates.

GEODESY, CARTOGRAPHY AND AERIAL PHOTOGRAPHY

The aim. The study of formulas determination of the point coordinates by the inverse linear-angular intersection method. Previously, we investigated the possibility of using electronic total stations to control the geometric parameters of industrial buildings. The applied application of electronic total stations for high-precision measurements has been investigated as well. [Vivat, 2018]. The formula for optimal use of the device with certain accuracy characteristics relative to the measured basis is analytically proved and derived [Litynskyi, 2014]. Measurements on the basis of the II category are performed and theoretical calculations are confirmed. The possibility of achieving high accuracy in determining the segment by the method of linear-angular measurements is shown [Litynsky, 2015]. The influence of the angle value on the accuracy of determining the coordinates by the sine theorem is investigated and the possibility of optimizing the determination of coordinates by the method of inverse linear-angular serif by the formulas of cosines and sines is investigated [Litynskyi, 2019]. Method. Establishing a mathematical interconnection between measured values (distances and angles) with the required (flat coordinates of a point), differentiation and finding the minima of functions. Results.There were five formulas selected, of which six combinations had been created to calculate the increments of coordinates and to estimate their accuracy. Numerical experiments show that neither method has a significant advantage, which is supported by the results presented in the graphs and tables. It is worth noting one feature of the second method - in which it is possible to determine the increments of coordinates with an accuracy that exceeds the accuracy of measuring the sides. The possibility of optimizing the coordinate increments determination due to the choice of calculation formulas is considered. The possibility of increasing the accuracy of determination of the coordinates increments using different calculation formulas is researched. Consequently, it is suggested to optimize the choice of calculation formulas depending on the position of the desired point. The results of these studies can be used to create electronic total station or laser tracker application software in order to improve the accuracy of coordinate determination.

Unleashing the full power of LHCb to probe Stealth New Physics

In this paper, we describe the potential of the LHCb experiment to detect Stealth physics. This refers to dynamics beyond the Standard Model that would elude searches that focus on energetic objects or precision measurements of known processes. Stealth signatures include long-lived particles and light resonances that are produced very rarely or together with overwhelming backgrounds. We will discuss why LHCb is equipped to discover this kind of physics at the Large Hadron Collider and provide examples of well-motivated theoretical models that can be probed with great detail at the experiment.

Controlling the dynamics of ultracold polar molecules in optical tweezers

Ultracold molecules trapped in optical tweezers show great promise for the implementation of quantum technologies and precision measurements. We study a prototypical scenario where two interacting polar molecules placed in separate traps are controlled using an external electric field. This, for instance, enables a quantum computing scheme in which the rotational structure is used to encode the qubit states. We estimate the typical operation timescales needed for state engineering to be in the range of few microseconds. We further underline the important role of the spatial structure of the two-body states, with the potential for significant gate speedup employing trap-induced resonances.