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As the base unit of time interval, the second holds a place of preeminence in the world of metrology. Time interval, and its reciprocal, frequency, can be measured with more resolution and less uncertainty than any of the other physical quantities. The precise realization of the second was made possible by the development of frequency standards bas...
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... it provided a glimpse of what the future would bring, and was widely pub- licized. Lyons was given a five-minute interview by Edward R. Murrow over the CBS Network on January 14, 1949 [27] and features also appeared in Time, Newsweek, Business Week, and else- where. [24] Lyons was even mentioned in a popular cartoon feature a few years later (Fig. 6), although the drawing was not of the ammonia device, but rather of the cesium standard that would later become known as NBS-1 (see Section ...
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Frequency is the rate of occurrence of a repetitive event. If T is the period of a repetitive event, then the frequency f = 1/ T. The International System of Units (SI) states that the period should always be expressed in units of seconds (s), and the frequency should always be expressed in hertz (Hz). The frequency of electric signals often is mea...
Citations
... Laser-cooling technology underpins the most advanced atomic clocks 6 , and while recent efforts in photonic integration 7,8 and vacuum technology [9][10][11] have advanced the state of the art, significant hurdles to miniaturization and lowpower operation remain 12 . Atomic beams have played a significant role throughout the history of frequency metrology, serving as commercial frequency standards since the 1960s and as national frequency standards for realization of the SI second 13,14 . Miniaturized atomic beams [15][16][17][18][19] offer a path for exceeding the long-term stability of existing chip-scale devices while circumventing the complexity and power needs of more advanced laser-cooled schemes. ...
Atomic beams are a longstanding technology for atom-based sensors and clocks with widespread use in commercial frequency standards. Here, we report the demonstration of a chip-scale microwave atomic beam clock using coherent population trapping (CPT) interrogation in a passively pumped atomic beam device. The beam device consists of a hermetically sealed vacuum cell fabricated from an anodically bonded stack of glass and Si wafers in which lithographically defined capillaries produce Rb atomic beams and passive pumps maintain the vacuum environment. A prototype chip-scale clock is realized using Ramsey CPT spectroscopy of the atomic beam over a 10 mm distance and demonstrates a fractional frequency stability of ≈1.2 × 10⁻⁹/τ\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\sqrt{\tau }$$\end{document} for integration times, τ, from 1 s to 250 s, limited by detection noise. Optimized atomic beam clocks based on this approach may exceed the long-term stability of existing chip-scale clocks, and leading long-term systematics are predicted to limit the ultimate fractional frequency stability below 10⁻¹².
... Next, we apply the gravitational decrease of periodic time: At each circumferential radius r, the time interval d t(r) of an atomic clock is equal to the periodic time T (r) of a photon [67,68]. Thus, the measured time d t(r) exhibits the following decrease of periodic time, see Eq. (63): ...
In general relativity, space exhibits curvature: Local curvature can be described by the Schwarzschild metric, SM. A global curvature that can take any value is inherent to the Friedmann Lemaître equation, FLE. However, observations show that the global curvature is zero. That shortcoming of the FLE has been named flatness problem. In this paper, we unify the local SM and the global FLE, and thereby we solve the flatness problem. Moreover, applications of that solution are outlined.
... The resonant frequency of the transition between cesium atom ground states is used to define the second [1]. From the early laboratory beam clocks made by NBS [2], PTB [3] and so on, to the various compact beam clocks that are penetrating into different fields of scientific research and practical use, beam clocks have been kept in a state of development. Compact clocks will still be of great importance for a long time because of the simple construction, the portability as well as the good long-term stability. ...
... For rubidium clocks, as an example, laser provides higher signal-to-noise ratio than traditional lamp [5]. In fountain clocks like NIST-F1/F2 [2], PTB-CSF1/CSF2 [6], SYRTE's FO2-Cs [7] and a variety of cold atomic optical clocks, laser is also the basis of atomic cooling. ...
Light detection is widely used in atomic clocks. The simple detecting structure induces the light shift which influences the clock’s long-term stability. We introduce a new method to suppress light shift by using pulsed light instead of continuous light to detect atomic states. Under a suitable pulsed sequence, the part of the atoms which do not simultaneously interact with light and microwave field are detected. We demonstrate the validity of our approach in a magnetic-state-selected cesium beam clock. Using a well-tuned sequence, the light shift coefficient is reduced by a factor of about 10, in comparison with the continuous light detection scheme. In a clock stability test with extra light power noise, the result shows good immunity of the method to laser power fluctuations. We also analyze the sources of the clock short-term stability degradation, including the Dick effect and the fact that a reduced number of atoms is detected in the pulsed detection case.
... The coupling of the quantum cavity modes with the system modes gives rise to hybridization modes known as polaritons. An extensive amount of literature (both theoretical or experimental) focuses on studying the energy splitting between such polaritons [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25]. ...
... The Hamiltonian formula given in equation (1) is obtained straightforwardly from the standard MG (minimum coupling) Hamiltonian available in any textbook (such as [26]) in two steps: (a) by considering just a single field mode of a cavity inside which the considered atomic/molecular system is placed, and neglecting all the other cavity modes, see references [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25]; (b) by incorporating the already mentioned dipole approximation [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26]. Note that equation (1) contains the physical mass m. ...
... The Hamiltonian formula given in equation (1) is obtained straightforwardly from the standard MG (minimum coupling) Hamiltonian available in any textbook (such as [26]) in two steps: (a) by considering just a single field mode of a cavity inside which the considered atomic/molecular system is placed, and neglecting all the other cavity modes, see references [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25]; (b) by incorporating the already mentioned dipole approximation [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26]. Note that equation (1) contains the physical mass m. ...
We show that the correspondence between quantum and classical mechanics can be tuned by varying the coupling strength between an atom or a molecule and the modes of a cavity. In the acceleration gauge (AG) representation, the cavity-matter system is described by an effective Hamiltonian, with a non-trivial coupling appearing in the potential, and with renormalized masses. Importantly, and counterintuitively, the AG coupling changes non-monotonically with the strength of the cavity-matter interaction. As a result, one obtains an effective (approximately decoupled) cavity-matter dynamics both for the case of weak and strong interactions. In the weak coupling regime, the effective mass parameters essentially coincide with their standard interaction free counterparts. In contrast, the renormalized atomic/molecular mass increases as the cavity-matter inter-action is increased. This results in AG dynamics of matter governed by a conventionally looking atomic/molecular Hamiltonian, whose effective Planck constant is reduced when the cavity-matter interaction is increased.
... Gravitational time dilation: The periodic time T (r) of photons is used for time measurement, e.g. in atomic clocks (Bundesanstalt (2007), Lombardi et al. (2007)). Accordingly, the periodic time changes the time interval dt(r) by the same factor: ...
Since Planck discovered quantization in 1900, the nature of quanta was a mystery. That problem is solved in this book.
We derive the postulates of quantum physics from the equivalence principles, gravity and relativity, by analyzing the vacuum.
We clarify various conundrums of quanta:
- We derive nonlocality.
- We find the origin of the Schrödinger equation.
- We find the origin of the probabilities of quanta.
- We find the basis of the Planck constant h.
- We find a generalized Schrödinger equation.
- We find the origin of quantum gravity.
- We discover how quanta, vacuum and curved space are related.
Using the concepts of space, time, gravity and vacuum, we discover how vacuum propagates at the velocity of light. We realize how that propagation causes quantization. We apply that propagation to the calculation of the density parameter ΩΛ of the vacuum of the universe. Our result is in precise accordance with observation, whereby we do not apply any fit.
Invited to discover the nature of quanta are classes from grade 10 or higher, courses, research clubs, enthusiasts, observers, experimentalists, mathematicians, natural scientists, researchers …
... Gravitational time dilation: The periodic time T (r) of photons is used for time measurement, e.g. in atomic clocks (Bundesanstalt (2007), Lombardi et al. (2007)). Accordingly, the periodic time changes the time interval dt(r) by the same factor: ...
Universe: Unified from Microcosm to Macrocosm: Series
Volume 4
ISSN: 2629-1525
ISBN: 978-3-96831-008-4
Modern physics is based on two great concepts: general relativity theory, GRT and quantum theory, QT. However, effects faster than light are called nonlocal, and they seem to be impossible in nature and in GRT, while they occur in QT, this contrast is called EPR paradox. We solve it as follows: The curved spacetime in GRT corresponds to additionally forming vacuum. We calculate its volume, and we discover: It explains curvature of space as well as the expansion since the Big Bang. One half of that volume forms in a nonlocal manner: Thus nature and GRT are nonlocal and so no paradox remains. The formation of spacetime, however, is local. With it we combine GRT and QT: We derive the field theory, the quadrupole or spin 2 symmetry, the waves and the quanta of spacetime. These provide precise accordance to observation without any fit parameter, of course. The quanta of spacetime include the propagation and formation of vacuum. So they explain the dark energy and the time evolution of dark energy and structure, which in turn explains the discrepancy inherent to observed values of the Hubble constant H0 and of matter fluctuations sigma8. The quanta of spacetime include the quanta of gravitational interaction. So they explain the graviton by its symmetry, propagation, quantization and mechanism of interaction: Quanta of spacetime form, the resulting heterogeneity generates curvature, and this causes gravitational force. So the graviton is now understood in exceptionally deep detail! The quanta of spacetime in the visible universe are traced back to one single quantum at the Big Bang. At its space, there immediately formed many quanta of zero-point energies of radiation. Altogether the complete energy and mass of the visible universe is traced back to the Big Bang. The quanta of spacetime are invariant at Lorentz transformations and at all other linear transformations. These quanta solve many fundamental problems and explain various interesting systems, including black holes. We derive all results with a smooth progression, and we summarize our findings in 15 propositions and 34 theorems.
... The initial uncertainty of this atomic clock was 10 −10 when invented. During the last 50 years, the level of uncertainty has been improved significantly, decreasing by roughly one order of magnitude every ten years to reach a current value of ∼ 2×10 −16 [26][27][28]. ...
... The adhesive layer is a square cylindrical lattice consisting of 18 dipoles wrapped around the DN 25CF tube.The three fins were arranged symmetrically around the longitudinal magnetic axis to generate the required magnetic field. Each fin had five layers: the first, second, third, and fourth layers had two rows of26,23,19, and 15 dipoles in each; whereas the fifth layer has one row of 8 dipoles. This arrangement generates a better magnetic field profile according to the simulation, seeFig. ...
Optical atomic clocks have proven to be the most stable clocks with the lowest systematic uncertainty which has now reached a record level of (9 � 4 � 1019). Thus
optical clocks now surpass the best fountain Cs atomic clocks by three orders of magnitude which opens the prospect of using optical clocks as frequency standards for
timekeeping in the near future.
This thesis describes the progress that has been made towards a stationary optical
lattice clock based on strontium atoms and reports the results of an ongoing
characterization.
An experimental apparatus was designed and built to efficiently slow, cool, and
trap the strontium atoms which represent the heart of the strontium optical lattice
clock discussed in this thesis. The novel aspects of the experimental development
described in the thesis comprise a frequency doubling cavity for producing 461 nm
laser light employed for cooling and trapping the strontium atoms in the �first stage
cooling. This cavity provided sufficient power for cooling and trapping the strontium
atoms for up to 300 mW of 461 nm laser light. Furthermore, a new design of Zeeman
slower based on spherical permanent magnets was produced, built and characterized.
The slower is compact, tunable, easy to assemble and maintain, and cost-effective
as the permanent magnets do not require any power supply or water cooling. It is
suggested that this kind of Zeeman slower constitutes an ideal solution for portable
optical clock systems. A blue magneto-optical trap was realized for the �first time with
such a Zeeman slower. With about 30 mW of a 461 nm laser, up to 6�108 atoms
were captured.
... This approach gave birth to the atomic clock. The interested reader is directed to a review of the roles atomic transitions in alkali vapours (fundamental components of OPMs) have had in the definition of time (Lombardi et al., 2007). ...
Optically Pumped Magnetometers (OPMs) have emerged as a viable and wearable alternative to cryogenic, superconducting MEG systems. This new generation of sensors has the advantage of not requiring cryogenic cooling and as a result can be flexibly placed on any part of the body. The purpose of this review is to provide a neuroscience audience with the theoretical background needed to understand the physical basis for the signal observed by OPMs. Those already familiar with the physics of MRI and NMR should note that OPMs share much of the same theory as the operation of OPMs rely on magnetic resonance. This review establishes the physical basis for the signal equation for OPMs. We re-derive the equations defining the bounds on OPM performance and highlight the important trade-offs between quantities such as bandwidth, sensor size and sensitivity. These equations lead to a direct upper bound on the gain change due to cross-talk for a multi-channel OPM system.
... Ultra-cold quantum gases can be utilized for quantum simulations that are both extremely clean and controllable, as well as for precision measurements. Examples therein include optical lattice-based Bose/Fermi-Hubbard models 1-6 , artificial gauge fields [7][8][9] , Feshbach resonances [10][11][12] , and optical clocks 13,14 . However, the environmental noise that occurs in ultra-cold atoms will cause decoherence in systems, presenting a particular drawback when utilizing such ideal experimental platforms. ...
Ultra-low noise magnetic field is essential for many branches of scientific research. Examplesinclude experiments conducted on ultra-cold atoms, quantum simulations, as well as precisionmeasurements. In ultra-cold atom experiments specifically, a bias magnetic field will be oftenserved as a quantization axis and be applied for Zeeman splitting. As atomic states areusually sensitive to magnetic fields, a magnetic field characterized by ultra-low noise as wellas high stability is typically required for experimentation. For this study, a bias magneticfield is successfully stabilized at 14.5G, with the root mean square (RMS) value of the noisereduced to 18.5{\mu}G (1.28ppm) by placing{\mu}-metal magnetic shields together with a dynamicalfeedback circuit. Long-time instability is also regulated consistently below 7{\mu}G. The level ofnoise exhibited in the bias magnetic field is further confirmed by evaluating the coherencetime of a Bose-Einstein condensate characterized by Rabi oscillation. It is concluded thatthis approach can be applied to other physical systems as well.
... Atomic time and frequency standards based on the absorption of microwaves by Cs/Rb vapors were discovered in the 1950s [1,2]. They soon became the most accurate frequency references for time and frequency measurements, playing a very important role in today's technology [3][4][5]. ...
This paper is a review that surveys work on the fabrication of miniature alkali vapor cells for miniature and chip-scale atomic clocks. Technology on microelectromechanical systems (MEMS) cells from the literature is described in detail. Special attention is paid to alkali atom introduction methods and sealing of the MEMS structure. Characteristics of each technology are collated and compared. The article’s rhetoric is guided by the proposed classification of MEMS cell fabrication methods and contains a historical outline of MEMS cell technology development.
