O. N. Prudnikov, V. I. Yudin, R. Ya. Ilenkov
et al.
We consider a laser cooling and trapping of alkaline-earth and similar atoms in a bichromatic field resonant to a closed optical transition $^1S_0 \to \, ^1P_1$ or $^1S_0 \to \, ^3P_1$. It is shown that new kinetic effects emerge compared to monochromatic fields, enabling the formation of a deep macroscopic trap capable of capturing and cooling neutral atoms to sub-Doppler temperatures. Such a purely optical macroscopic trap can serve as an alternative to the well-known magneto-optical trap and can be used in applications requiring minimization of the magnetic field in the cold atom cloud region. The obtained results are of interest for the new generation of quantum sensors and optical frequency standards.
Lothar Maisenbacher, Vitaly Wirthl, Arthur Matveev
et al.
Quantum electrodynamics (QED), the first relativistic quantum field theory, describes light-matter interactions at a fundamental level and is one of the pillars of the Standard Model (SM). Through the extraordinary precision of QED, the SM predicts the energy levels of simple systems such as the hydrogen atom with up to 13 significant digits, making hydrogen spectroscopy an ideal test bed. The consistency of physical constants extracted from different transitions in hydrogen using QED, such as the proton charge radius $r_\mathrm{p}$, constitutes a test of the theory. However, values of $r_\mathrm{p}$ from recent measurements of atomic hydrogen are partly discrepant with each other and with a more precise value from spectroscopy of muonic hydrogen. This prevents a test of QED at the level of experimental uncertainties. Here we present a measurement of the 2S-6P transition in atomic hydrogen with sufficient precision to distinguish between the discrepant values of $r_\mathrm{p}$ and enable rigorous testing of QED and the SM overall. Our result $ν^{}_{\text{2S-6P}}$ = 730,690,248,610.79(48) kHz gives a value of $r_\mathrm{p}$ = 0.8406(15) fm at least 2.5-fold more precise than from other atomic hydrogen determinations and in excellent agreement with the muonic value. The SM prediction of the transition frequency (730,690,248,610.79(23) kHz) is in excellent agreement with our result, testing the SM to 0.7 parts per trillion (ppt) and, specifically, bound-state QED corrections to 0.5 parts per million (ppm), their most precise test so far.
Ultralight bosonic dark matter with masses in the meV range, corresponding to terahertz (THz) Compton frequencies, remains largely unexplored due to the difficulty of achieving both efficient signal conversion and single-photon-sensitive detection at THz frequencies. We propose a hybrid detection architecture that integrates a dielectric haloscope, Rydberg-atom transducer, and superconducting nanowire single-photon detection within a unified cryogenic platform operating at $\lesssim 1\,\text{K}$. The dielectric haloscope converts dark matter into THz photons via phase-matched resonant enhancement, achieving form factors $C \sim 0.4$ and loaded quality factors $Q_L \sim 10^4$. A cold $^{87}$Rb ensemble then coherently up-converts the THz signal to the optical domain through six-wave mixing among Rydberg states. The intrinsic directionality and narrow bandwidth ($Δν_{\mathrm{atomic}} \sim 1\,\text{MHz}$) of this process provide extra suppression of isotropic thermal backgrounds. With 10 days of integration at $0.3\,\text{K}$, we project sensitivity to the axion-photon coupling $g_{aγγ} \sim 10^{-13}\,\mathrm{GeV}^{-1}$ at $m_a \sim 0.4\,\text{meV}$, reaching the QCD axion band and opening the THz window for searches of both axion and dark photon dark matter.
Expressibility is a crucial factor of a parameterized quantum circuit (PQC). In the context of variational-quantum-algorithm-based quantum machine learning (QML), a QML model composed of a highly expressible PQC and a sufficient number of qubits is theoretically capable of approximating any arbitrary continuous function. While much research has explored the relationship between expressibility and learning performance, as well as the number of layers in PQCs, the connection between expressibility and PQC structure has received comparatively less attention. In this article, we analyze the connection between expressibility and the types of quantum gates within PQCs using a gradient boosting tree model and Shapley additive explanations values. Our analysis is performed on 1615 instances of PQC derived from 19 PQC topologies, each with 2–18 qubits and 1–5 layers. The findings of our analysis provide guidance for designing highly expressible PQCs, suggesting the integration of more X-rotation or Y-rotation gates while maintaining a careful balance with the number of <sc>cnot</sc> gates . Furthermore, our evaluation offers an additional evidence of expressibility saturation, as observed by previous studies.
Atomic physics. Constitution and properties of matter, Materials of engineering and construction. Mechanics of materials
І. М. Karnaukhov, V. І. Slisenko, B. V. Borts
et al.
This paper presents the results of the first testing of technological equipment to produce radiopharmaceuticals "Sodium pertechnetate (99mTc), extraction, solution for injection" with technological equipment located in the laboratory of radioisotope production at NSC "Kharkiv Institute of Physics and Technology" (KIPT). The "hot" cells and technological equipment mounted inside the cells meet the requirements of the European standard and guarantee the safety of operators during the production process. The technology for producing radiopharmaceuticals is based on the extraction of 99mTc with methyl ethyl ketone from alkaline solutions of 99Mo. 99mTc is obtained as a daughter product of 99Mo radioactive decay, which is formed as a result of the 98Mo(n, γ)99Mo radiation capture reaction during irradiation of natural molybdenum oxide powder MoO3 (98Mo 24.13 %) with neutrons inside the core of a nuclear facility. Since the NSC KIPT Subcritical Assembly "Neutron Source" is at the stage of physical start-up, the ampoules with MoO3 powder were irradiated in the core of the WWR-M research nuclear reactor of the Institute for Nuclear Research of the National Academy of Sciences of Ukraine. The results of gamma spectrometric studies of the initial solution containing radioisotopes 99Mo + 99mTc and the finished solution with radioisotope 99mTc showed the absence of radionuclide impurities.
Atomic physics. Constitution and properties of matter
Fernando Arias-Aragón, Giovanni Grilli di Cortona, Enrico Nardi
et al.
Due to Heisenberg's uncertainty principle, atomic electrons localized around the nucleus exhibit a characteristic momentum distribution that, in elements with high atomic number, remains significant up to relativistic values. Consequently, in fixed-target experiments, atoms can effectively act as electron accelerators, increasing the centre-of-mass energy in collisions with beam particles. In this work, we leverage this effect to explore its potential for new physics searches. We consider positrons from beams of various energies annihilating with atomic electrons in a $^{74}$W fixed target. We compute the production rates of new vector bosons and pseudoscalar particles as functions of their couplings and masses. We show that the electron-at-rest approximation significantly underestimates the mass reach for producing these new states compared to the results obtained by properly accounting for atomic electron momenta. In particular, we estimate the sensitivity for detecting these new particles using the positron beam at the Beam Test Facility linac at the Laboratori Nazionali di Frascati, the H4 beamline in the CERN North Area, and the proposed Continuous Electron Beam Accelerator Facility of Jefferson Laboratory.
Zoltán Kovács-Krausz, Dániel Nagy, Albin Márffy
et al.
Abstract The layered van der Waals material ZrTe5 is known as a candidate topological insulator (TI), however its topological phase and the relation with other properties such as an apparent Dirac semimetallic state is still a subject of debate. We employ a semiclassical multicarrier transport (MCT) model to analyze the magnetotransport of ZrTe5 nanodevices at hydrostatic pressures up to 2 GPa. The temperature dependence of the MCT results between 10 and 300 K is assessed in the context of thermal activation, and we obtain the positions of conduction and valence band edges in the vicinity of the chemical potential. We find evidence of the closing and re-opening of the band gap with increasing pressure, which is consistent with a phase transition from weak to strong TI. This matches expectations from ab initio band structure calculations, as well as previous observations that CVT-grown ZrTe5 is a weak TI in ambient conditions.
Materials of engineering and construction. Mechanics of materials, Atomic physics. Constitution and properties of matter
Imaging with undetected photons (IUP) enables the possibility of sensing changes in the phase and the transmission of a beam of light that need never be detected. This has led to the possibility of infrared sensing with visible silicon camera technology, for example. Relying on the interference of two identical pairs of photons, IUP was initially achieved using unidirectional paths through two nonlinear crystal pair sources. More recently, folded arrangements using bidirectional paths through a single-crystal have become common for their simplicity. Here, we theoretically model and experimentally implement a novel setup involving three interference paths through a single nonlinear crystal. This establishes two independent IUP sensing modes in addition to a third linear interference mode. We achieve this using a polarization state quantum eraser approach, with excellent agreement between experiment and theory. This system provides a new route to control and optimize IUP interference in a single-crystal folded arrangement by using controllable quantum erasure to balance the interferometer, opening the door to new implementations and applications for IUP.
Atomic physics. Constitution and properties of matter
In a recent advance, Nb3Cl8 two-dimensional crystals with a kagome lattice and electronic topological flat bands has been experimentally fabricated (Nano Lett. 2022, 22, 4596). In this work motivated by the aforementioned progress, we conduct first-principles calculations to explore the structural, phonon dispersion relations, single-layer exfoliation energies and mechanical features of the Nb3X8 (X=Cl, Br, I) nanosheets. Acquired phonon dispersion relations reveal the dynamical stability of the Nb3X8 (X=Cl, Br, I) monolayers. In order to isolate single-layer crystals from bulk counterparts, we predicted exfoliation energies of 0.24, 0.27 and 0.28 J/m2, for the Nb3Cl8, Nb3Br8 and Nb3I8 monolayers, respectively, which are noticeably lower than that of the graphene. We found that the Nb3X8 monolayers are relatively strong nanosheets with isotropic elasticity and anisotropic tensile strength. It is moreover shown that by increasing the atomic weight of halogen atoms in the Nb3X8 nanosheets, mechanical characteristics decline. Presented results provide a useful vision about the key physical properties of novel 2D systems of Nb3X8 (X=Cl, Br, I).
Studies of the effects of the weak interaction in atomic systems provide tests of the Standard Model of particle physics, and explore physics scenarios beyond the Standard Model. In addition, these studies can offer valuable insights into low-energy nuclear physics. We provide an overview of the field of atomic parity violation, and discuss implications to nuclear and particle physics, and ongoing experimental efforts. Furthermore, we present our plans for precision measurements of the signatures of the weak interaction in atomic ytterbium.
This work presents a stable and reliable turnkey continuous-wave laser system for a Yb/Ba multispecies trapped-ion quantum computer. The compact and rack-mountable optics system exhibits high robustness, operating over a year without realignment, regardless of temperature changes in the laboratory. The overall optical system is divided into a few isolated modules interconnected by optical fibers for easy maintenance. The light sources are frequency-stabilized by comparing their frequencies with two complementary references: 1) a commercial Fizeau wavelength meter and 2) a high-finesse optical cavity. This scheme enables automatic frequency stabilization for days with a sub-MHz precision.
Atomic physics. Constitution and properties of matter, Materials of engineering and construction. Mechanics of materials
High-precision hydrogen spectroscopy is an active field which helps to determine the Rydberg constant and proton charge radius, tests bound-state QED, and can search for Beyond Standard Model (BSM) Physics. Additionally, with recent demonstrations of anti-hydrogen trapping and spectroscopy, a new line of investigation is possible whereby hydrogen can be compared to its antimatter counterpart. The next generation of precision hydrogen spectroscopy will likely require additional motional control of the atomic sample - similar to what is possible with heavier elements. Unfortunately, laser cooling - one of the cornerstones of modern precision atomic physics - is difficult in hydrogen due to the vacuum ultraviolet radiation required. Here, we sidestep the challenges inherent in laser cooling and demonstrate a technique whereby we load metastable atoms from a cryogenic beam into a moving optical lattice, decelerate the lattice, and observe a commensurate deceleration of the atoms. Since the optical lattice is governed by standard optoelectronics, this technique represents a robust platform for the motional control of hydrogen. Our technique could enable greater precision in hydrogen spectroscopy and be transferred to exotic simple atoms such as antihydrogen.
S. N. Sytova, A. P. Dunets, A. N. Kavalenka
et al.
A review of the information system for nuclear material accounting and control at the level of the Belarusian regulatory body in the field of nuclear and radiation safety is presented. This system is developed in accordance with International Atomic Energy Agency (IAEA) requirements depicted in Code 10 of the State subsidiary arrangements. The system provides automatic generation of the following accounting reports: physical inventory listing, inventory change report, material balance report, and textual report for each material balance area as well as the corresponding General Ledger. It provides all necessary calculations and pre-calculations, based on input data, to produce accurate accounting reports. The system implements the import/export of data to/from the system using Code 10 (labelled and fixed formats), as well as making adjustments to accounting documents in accordance with IAEA rules. There are two possibilities of nuclear material accounting in the system. The first consists of importing into the system of all reporting documents from the material balance areas of facilities and the subsequent possibility of checking the received data using an independent recalculation tool in the system. The second one includes the registration of all necessary information on nuclear material batches at locations outside facilities and their movement in the material balance area and then automatic generation of all required reports and General Ledger.
Atomic physics. Constitution and properties of matter
We evaluate the rate of the absorption of an optical nanofiber mode by a Cs atom in an electric quadrupole transition. With the Cs atom localized near the outer surface of the optical nano-fiber, an interaction occurs between the atomic quadrupole tensor components and the gradients of the vector components of the electric field of a hybrid fiber mode. The absorption rate is evaluated as a function of the radial position of the atom from the fiber axis, assuming a specific value of the laser power and we use experimentally accessible parameters. We find that the absorption of the hybrid modes by the Cs atom decreases as the atom recedes away from the fiber axis and formally vanishes at sufficiently large radial distances. Close to the fiber, however, the absorption rate for the input power chosen can be two orders of magnitude larger than the quadrupole de-excitation rate despite the moderate power used.