Savely G. Karshenboim
A brief overview is given on precision determinations of values of the fundamental physical constants and the search for their variation with time by means of precision spectroscopy in the optical domain.
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Precision measurements comparing the fundamental properties of conjugate particles and antiparticles constitute stringent tests of CPT invariance. We review recent precision measurements of the BASE collaboration, which improved the uncertainty of the proton and antiproton magnetic moments and the comparison of the proton-to-antiproton charge-to-mass ratio. These measurements constitute the most stringent tests of CPT invariance with antiprotons. Further, we discuss the improved limit on the antiproton lifetime based on the storage of a cloud of antiprotons in the unique BASE reservoir trap. B…
In Penning traps electromagnetic forces are used to confine charged particles under well-controlled conditions for virtually unlimited time. Sensitive detection methods have been developed to allow observation of single stored ions. Various cooling methods can be employed to reduce the energy of the trapped particle to nearly at rest. In this review we summarize how highly charged ions offer unique possibilities for precision measurements in Penning traps. Precision atomic and nuclear masses as well as magnetic moments of bound electrons allow among others to determine fundamental constants li…
We consider an application of precision frequency measurements to searches for possible time variations of the fundamental physical constants. Current laboratory constraints on variations of the fine structure constant alpha and other fundamental constants are presented.
The quest for the value of the electron's atomic mass has been subject of continuing efforts over the last decades. Among the seemingly fundamental constants which parameterize the Standard Model (SM) of physics and which are thus responsible for its predictive power, the electron mass me plays a prominent role, as it is responsible for the structure and properties of atoms and molecules. This manifests in the close link with other fundamental constants, such as the Rydberg constant and the fine-structure constant α. However, the low mass of the electron considerably complicates its precise de…
Precision spectroscopy on cold molecules can potentially enable novel tests of fundamental laws of physics and alternative determination of some fundamental constants. Realizing this potential requires a thorough understanding of the systematic effects that shift the energy levels of molecules. We have performed a complete ab initio calculation of the magnetic field effects for a particular system, the heteronuclear molecular hydrogen ion HD+. Different spectroscopic schemes have been considered, and numerous transitions, all accessible by modern radiation sources and exhibiting well controlla…
Molecules and atomic highly charged ions provide powerful low-energy probes of the fundamental laws of physics: Polar molecules possess internal fields suitable to enhance fundamental symmetry violation by several orders of magnitudes, whereas atoms in high charge states can feature large relativistic effects and compressed level structures, ideally posed for high sensitivity to variations of fundamental constants. Polar, highly charged molecules could benefit from both: large internal fields and large relativistic effects. However, a high charge dramatically weakens chemical bonding and drive…
We briefly review recent experiments in atomic, molecular, and optical physics using precision measurements to search for physics beyond the Standard Model. We consider three main categories of experiments: searches for changes in fundamental constants, measurements of the anomalous magnetic moment of the electron, and searches for an electric dipole moment of the electron.
The CODATA recommended values of the fundamental constants are widely applied in particle, nuclear and atomic physics. They are a result of a complicated evaluation (adjustment) of numerous correlated data of different nature. Their application is often rather mechanical and as a result is not free of various confusions which are discussed in this note.
In 2003 we have measured the absolute frequency of the $(1S, F=1, m_F=\pm 1) \leftrightarrow (2S, F'=1, m_F'=\pm 1)$ two-photon transition in atomic hydrogen. We observed a variation of $(-29\pm 57)$ Hz over a 44 months interval separating this measurement from the previous one performed in 1999. We have combined this result with recently published results of optical transition frequency measurement in the $^{199}$Hg$^+$ ion and and comparison between clocks based on $^{87}$Rb and $^{133}$Cs. From this combination we deduce the stringent limits for fractional time variation of the fine structu…
Quantum logic control and precision measurements of molecular ions in a ring trap -- a new approach for testing fundamental symmetries
提出一种在分段环形离子阱中实现极性分子离子量子逻辑控制的新平台，通过分离静态框架中的态制备探测与旋转框架中的宇称选择性自旋进动，实现高保真度测量，用于搜寻电子电偶极矩和核磁四极矩。
A generally applicable approach for the calculation of relativistic one-electron properties with two-component wave functions is presented. The formalism is explicitly evaluated for the example of quasi-relativistic wavefunctions obtained within the zeroth order regular approximation (ZORA). The wide applicability of the scheme is demonstrated for the calculation of parity ($\mathcal{P}$) and time-reversal ($\mathcal{T}$) symmetry violating properties, which are important for searches of physics beyond the standard model of particle physics. The quality of the ZORA results is shown exemplarily…
The exceptional precision attainable using modern spectroscopic techniques provides a promising avenue to search for signatures of physics beyond the Standard Model in tiny shifts of the energy levels of atoms and molecules. We briefly review three categories of new-physics searches based in precision measurements: tests of QED using measurements of the anomalous magnetic moment of the electron and the value of the fine-structure constant, searches for time variation of the fundamental constants, and searches for a permanent electric dipole moment of an electron or atomic nucleus.
We use two-dimensional transverse laser cooling to produce an ultracold beam of YbF molecules. Through experiments and numerical simulations, we study how the cooling is influenced by the polarization configuration, laser intensity, laser detuning and applied magnetic field. The ultracold part of the beam contains more than $2 \times 10^5$ molecules per shot and has a temperature below 200 $μ$K, and the cooling yields a 300-fold increase in the brightness of the beam. The method can improve the precision of experiments that use molecules to test fundamental physics. In particular, the beam is …
This review article is devoted to application of precision molecular spectroscopy to studies of the possible spatial and temporal variations of the fundamental constants. Both astrophysical observations and laboratory experiments are discussed.
In the perspective of the outstanding developments of high-precision measurements of fundamental constants using polar molecules related to ultimate checks of fundamental theories, we investigate the possibly counterproductive role of black-body radiation on a series of diatomic molecules which would be trapped and observed for long durations. We show that the absorption of black-body radiation at room temperature may indeed limit the lifetime of trapped molecules prepared in a well-defined quantum state. Several examples are treated, corresponding to pure rotational absorption, pure vibration…
The paper discusses the line profile asymmetry of the photon scattering process that arises naturally in quantum electrodynamics (QED). Based on precision spectroscopic experiments conducted on hydrogen atoms, we focus our attention on the two-photon $1s-2s$ transition. As one of the most precisely determined transition frequencies, it is a key pillar of optical frequency standards and is used in determining fundamental physical constants, testing physical principles, and searching constraints on new fundamental interactions. The results obtained in this work show the need to take into account…
We consider fundamental physical constants which are among a few of the most important pieces of information we have learned about Nature after its intensive centuries-long studies. We discuss their multifunctional role in modern physics including problems related to the art of measurement, natural and practical units, origin of the constants, their possible calculability and variability etc.
Precision measurements in molecules have advanced rapidly in recent years through developments in techniques to cool, trap, and control. The complexity of molecules makes them a challenge to study, but also offers opportunities for enhanced sensitivity to many interesting effects. Polyatomic molecules offer additional complexity compared to diatomic molecules, yet are still "simple" enough to be laser-cooled and controlled. While laser cooling molecules is still a research frontier itself, there are many proposed and ongoing experiments seeking to combine the advanced control enabled by ultrac…
Precision measurements of the fundamental constants are tour de force of basic metrology, where the useful information is usually beyond the last digit of the measured value. They challenge theoretical models and measurement technologies and set a network of measurement equations on which a universal system of units can be built, which stems from the most basic concepts of physics. Because of their connection with the mass unit, the Avogadro and Planck constants are on the spotlight.
This report gives the 2014 self-consistent set of values of the constants and conversion factors of physics and chemistry recommended by the Committee on Data for Science and Technology (CODATA). These values are based on a least-squares adjustment that takes into account all data available up to 31 December 2014. The recommended values may also be found on the World Wide Web at physics.nist.gov/constants.
We present an optical-electronic approach to generating microwave signals with high spectral purity. By circumventing shot noise and operating near fundamental thermal limits, we demonstrate 10 GHz signals with an absolute timing jitter for a single hybrid oscillator of 420 attoseconds (1Hz - 5 GHz).
Advantages and disadvantages of fixation of fundamental physical constants' values for definition of SI units are considered. The case with a new definition of the mass unit on the base of a fixed value of the Avogadro constant is studied in detail. Criteria on choosing of a optimum FPC set with fixed values for the redefinition of the SI units are suggested. The minimal optimum FPC set that is consistent with the criteria is presented. The set comprises the speed of light, the constant of the ground state hyperfine transition of the caesium-133 atom, the Avogadro constant, the mass of the car…
The applications of spin-based quantum sensors to measurements probing fundamental physics are surveyed. Experimental methods and technologies developed for quantum information science have rapidly advanced in recent years, and these tools enable increasingly precise control and measurement of spin dynamics. Theories of beyond-the-Standard-Model physics predict, for example, symmetry violating electromagnetic moments aligned with particle spins, exotic spin-dependent forces, coupling of spins to ultralight bosonic dark matter fields, and changes to the local environment that affect spins. Spin…
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