Ground-state Hyperfine Transition Research Articles

CPT and Lorentz symmetry tests with hydrogen using a novel in-beam hyperfine spectroscopy method applicable to antihydrogen experiments

We present a Rabi-type measurement of two ground-state hydrogen hyperfine transitions performed in two opposite external magnetic field directions. This puts first constraints at the level of ▪ on a set of coefficients of the Standard Model Extension, which were not measured by previous experiments. Moreover, we introduce a novel method, applicable to antihydrogen hyperfine spectroscopy in a beam, that determines the zero-field hyperfine transition frequency from the two transitions measured at the same magnetic field. Our value, ▪, is in agreement with literature at a relative precision of 0.44 ppb. This is the highest precision achieved on hydrogen in a beam, improving over previous results by a factor of 6.

Questioning the Administrative Accountability of the ITU on the QUESS Oversight

In accordance with the SI unit of the unperturbed ground-state hyperfine transition frequency of the cesium 133 atom, Eutelsat has secured the safety procedures of telecommunication decays in the development of quantum communication technology. As observers of the International Atomic Energy Agency (IAEA), the International Telecommunication Union (ITU) is bound for intergovernmental observers with specialized agencies of the United Nations and IAEA based on reciprocity. The apparent overpowered photon beam of the Quantum Experiment at Space Scale (QUESS) military intelligence purposed telecommunication encryption designs launched around 2016, along with a German photon experiment directed at earth, were neither intervened by the ITU nor the IAEA. According to Article 10 63. 1. of the International Telecommunication Convention, the ITU is responsible with International Frequency Registration Board for the administrative accountability, however, Article 8 54. (3) gives rent to the administrative powers of the organization for agenda settings by the Secretary-General. The article analyzes and questions the administrative accountability of the ITU in the oversight of the high energy photon applications in the telecommunications and if the IAEA was informed by the International Frequency Registration Board on this matter. Correlated behaviors in the cyber-based criminology, with significant impact on public health and biological integrity from such operations, is supplemented for the alteration of financial & economic incentives in the democratic systems, which constituted the liberal International institutionalism. The research contends that criminal liabilities ought to be sought for in the criminological chain.

An electron turnstile for frequency-to-power conversion.

Single-electron transport relates an operation frequency f to the emitted current I through the electron charge e as I = ef (refs. 1-5). Similarly, direct frequency-to-power conversion (FPC) links both quantities through a known energy. FPC is a natural candidate for a power standard resorting to the most basic definition of the watt: energy emitted per unit of time. The energy is traceable to Planck's constant and the time is in turn traceable to the unperturbed ground state hyperfine transition frequency of the caesium 133 atom. Hence, FPC comprises a simple and elegant way to realize the watt6. In this spirit, single-photon emission7,8 and detection9 at known rates have been proposed as radiometric standards and experimentally realized10-14. However, power standards are so far only traceable to electrical units, that is, to the volt and the ohm6,15-17. In this Letter, we demonstrate an alternative proposal based on solid-state direct FPC using a hybrid single-electron transistor (SET). The SET injects n (integer) quasi-particles (QPs) per cycle into the two superconducting leads with discrete energies close to their superconducting gap Δ, even at zero source-drain voltage. Furthermore, the application of a bias voltage can vary the distribution of the power among the two leads, allowing for an almost equal power injection nΔf into the two. While in single-electron transport current is related to a fixed universal constant (e), in our approach Δ is a material-dependent quantity. We estimate that under optimized conditions errors can be well below 1%.

First international comparison of fountain primary frequency standards via a long distance optical fiber link

We report on the first comparison of distant caesium fountain primary frequency standards (PFSs) via an optical fiber link. The 1415 km long optical link connects two PFSs at LNE-SYRTE (Laboratoire National de métrologie et d’Essais—SYstème de Références Temps-Espace) in Paris (France) with two at PTB (Physikalisch-Technische Bundesanstalt) in Braunschweig (Germany). For a long time, these PFSs have been major contributors to accuracy of the International Atomic Time (TAI), with stated accuracies of around . They have also been the references for a number of absolute measurements of clock transition frequencies in various optical frequency standards in view of a future redefinition of the second. The phase coherent optical frequency transfer via a stabilized telecom fiber link enables far better resolution than any other means of frequency transfer based on satellite links. The agreement for each pair of distant fountains compared is well within the combined uncertainty of a few 10−16 for all the comparisons, which fully supports the stated PFSs’ uncertainties. The comparison also includes a rubidium fountain frequency standard participating in the steering of TAI and enables a new absolute determination of the 87Rb ground state hyperfine transition frequency with an uncertainty of .This paper is dedicated to the memory of André Clairon, who passed away on 24 December 2015, for his pioneering and long-lasting efforts in atomic fountains. He also pioneered optical links from as early as 1997.

Ion-number-density-dependent effects on hyperfine transition of trapped 199Hg+ ions in quadrupole linear ion traps

The ion-number-density-dependent frequency offsets and broadening of the ground state hyperfine transition spectra of trapped H199g+ ions were measured as a function of the end-cap voltage of the quadrupole linear ion trap. The number density of trapped H199g+ ions in the quadrupole linear trap was controlled by the end-cap voltage. The fractional frequency stability of H199g+ hyperfine transition to the 1 mV end-cap voltage variation was preliminary estimated to be less than 1×10−16. The causes of the ion-number-density-dependent frequency shift and spectrum broadening were analyzed theoretically and explained.

Antihydrogen synthesis in a double-CUSP trap towards test of the CPT-symmetry

The aim of the ASACUSA-CUSP experiment at CERN is to produce a cold, polarised antihydrogen beam and perform a high precision measurement of the ground-state hyperfine transition frequency of the antihydrogen atom and compare it with that of the hydrogen atom using the same spectroscopic beam line. Towards this goal a significant step was successfully accomplished: synthesised antihydrogen atoms have been produced in a CUSP magnetic configuration and detected at the end of our spectrometer beam line in 2012 [1]. During a long shut down at CERN the ASACUSA-CUSP experiment had been renewed by introducing a new double-CUSP magnetic configuration and a new semi-cylindrical tracking detector (AMT) [2], and by improving the transport feature of low energy antiproton beams. The new tracking detector monitors the antihydrogen synthesis during the mixing cycle of antiprotons and positrons. In this work the latest results and improvements of the antihydrogen synthesis will be presented including highlights from the last beam time.

Comparing a mercury optical lattice clock with microwave and optical frequency standards

In this paper we report the evaluation of an optical lattice clock based on neutral mercury with a relative uncertainty of . Comparing this characterized frequency standard to a 133Cs atomic fountain we determine the absolute frequency of the transition of 199Hg as (systematic), limited solely by the realization of the SI second. Furthermore, by comparing the mercury optical lattice clock to a 87Rb atomic fountain, we determine for the first time to our knowledge the ratio between the 199Hg clock transition and the 87Rb ground state hyperfine transition. Finally we present a direct optical to optical measurement of the 199Hg/87Sr frequency ratio. The obtained value of 2.629 314 209 898 909 15 with a fractional uncertainty of is in excellent agreement with a similar measurement obtained by Yamanaka et al (2015 Phys. Rev. Lett. 114 230801). This makes this frequency ratio one of the few physical quantities agreed upon by different laboratories to this level of uncertainty. Frequency ratio measurements of the kind reported in this paper have a strong impact for frequency metrology and fundamental physics as they can be used to monitor putative variations of fundamental constants.

Optimal Microwave Radiation Field Parameters for Mercury Ion Microwave Frequency Standards**Supported by the National Natural Science Foundation of China under Grant Nos 11074282 and 11474320.

We propose a method to determine the optimal power of the microwave resonance transition that simultaneously improves the signal-to-noise ratio and reduces line width based on saturation broadening theory and experiment. Saturation broadening spectra of the ground state hyperfine transition of trapped 199Hg+ ions are measured and analyzed. The value of the optimal microwave power is obtained by using the proposed method and is verified. Rabi oscillations decay spectra of trapped 199Hg+ ions are observed and the optimal microwave irradiation time for the maximum transition signal intensity is determined. This work will help to improve the short-term frequency stability of the mercury ion microwave frequency standard.

Measurement scheme and analysis for weak ground-state-hyperfine-transition moments through two-pathway coherent control

We report our detailed analysis of a table-top system for the measurement of the weak-force-induced electric dipole moment of a ground state hyperfine transition carried out in an atomic beam geometry. We describe an experimental configuration of conductors for application of orthogonal r.f. and static electric fields, with cavity enhancement of the r.f. field amplitude, that allows confinement of the r.f. field to a region in which the static fields are uniform and well-characterized. We carry out detailed numerical simulations of the field modes, and analyze the expected magnitude of statistical and systematic limits to the measurement of this transition amplitude in atomic cesium. The combination of an atomic beam with this configuration leads to strong suppression of magnetic dipole contributions to the atomic signal. The application of this technique to the measurement of extremely weak transition amplitudes in other atomic systems, especially alkali metals, seems very feasible.

Measuring Buffer-Gas Pressure in Sealed Glass Cells: An Assessment of the KSK Technique.

In alkali rf-discharge lamps used for optical pumping in atomic clocks and magnetometers, a buffer-gas (Kr or Xe) allows electrons to extract energy from an rf-field, and these energized electrons eventually produce alkali resonant light. Contrary to naïve intuition, rf-discharge lamps can lose their noble-gas buffer over time. Recently, we began a long-term experimental program to better understand the mechanism of noble-gas loss in rf-discharge lamps, and needed a nondestructive means of measuring buffer-gas pressure changes in sealed glass cells. For this purpose, we settled on the Kazantsev, Smirnova, and Khutorshchikov (KSK) technique, which is based on inferring buffer-gas pressure from the collision shift of an alkali ground-state hyperfine transition frequency νhfs. Here, we discuss the basic KSK technique and two modifications that we have implemented for its improvement: use of a diode laser for optical pumping, and extrapolation of νhfs to zero magnetic field. Testing our system's long-term performance with a very low pressure reference cell (i.e., 3.3torr Xe), we find a reproducibility of 0.2% and an absolute accuracy of 5%. Further, our systematic drift is less than 1 mtorr/month.

Measurement of rubidium ground-state hyperfine transition frequency using atomic fountains

The results of precision measurements of the 87Rb ground-state hyperfine transition frequency, which were conducted at NPL from 2009 to 2013, are reported. The resulting frequency, measured using NPL’s Cs and Rb atomic frequency standards, demonstrates reasonable agreement with the most recent measurements reported by LNE-SYRTE.

The development of the superconducting double cusp magnet for intense antihydrogen beams

SynopsisWe have developed a superconducing double cusp magnet for the production of polarized intense antihydrogen atomic beams which are used to make microwave spectroscopy of a ground state hyperfine transition to test the CPT symmetry. The detail of specification and the focusing performance of the magnet will be presented.

Numerical simulations of hyperfine transitions of antihydrogen

One of the ASACUSA (Atomic Spectroscopy And Collisions Using Slow Antiprotons) collaboration’s goals is the measurement of the ground state hyperfine transition frequency in antihydrogen, the antimatter counterpart of one of the best known systems in physics. This high precision experiment yields a sensitive test of the fundamental symmetry of CPT. Numerical simulations of hyperfine transitions of antihydrogen atoms have been performed providing information on the required antihydrogen events and the achievable precision.

Laser spectroscopy of the ground-state hyperfine structure in H-like and Li-like bismuth

The LIBELLE experiment performed at the experimental storage ring (ESR) at the GSI Helmholtz Center in Darmstadt aims for the determination of the ground state hyperfine (HFS) transitions and lifetimes in hydrogen-like (209Bi82+) and lithium-like (209Bi80+) bismuth. The study of HFS transitions in highly charged ions enables precision tests of QED in extreme electric and magnetic fields otherwise not attainable in laboratory experiments. While the HFS transition in H-like bismuth was already observed in earlier experiments at the ESR, the LIBELLE experiment succeeded for the first time to measure the HFS transition in Li-like bismuth in a laser spectroscopy experiment.

Optically addressable nuclear spins in a solid with a six-hour coherence time

Space-like separation of entangled quantum states is a central concept in fundamental investigations of quantum mechanics and in quantum communication applications. Optical approaches are ubiquitous in the distribution of entanglement because entangled photons are easy to generate and transmit. However, extending this direct distribution beyond a range of a few hundred kilometres to a worldwide network is prohibited by losses associated with scattering, diffraction and absorption during transmission. A proposal to overcome this range limitation is the quantum repeater protocol, which involves the distribution of entangled pairs of optical modes among many quantum memories stationed along the transmission channel. To be effective, the memories must store the quantum information encoded on the optical modes for times that are long compared to the direct optical transmission time of the channel. Here we measure a decoherence rate of 8×10(-5)per second over 100milliseconds, which is the time required for light transmission on a global scale. The measurements were performed on a ground-state hyperfine transition of europium ion dopants in yttrium orthosilicate ((151)Eu(3+):Y2SiO5) using optically detected nuclear magnetic resonance techniques. The observed decoherence rate is at least an order of magnitude lower than that of any other system suitable for an optical quantum memory. Furthermore, by employing dynamic decoupling, a coherence time of 370±60minutes was achieved at 2kelvin. It has been almost universally assumed that light is the best long-distance carrier for quantum information. However, the coherence time observed here is long enough that nuclear spins travelling at 9kilometres per hour in a crystal would have a lower decoherence with distance than light in an optical fibre. This enables some very early approaches to entanglement distribution to be revisited, in particular those in which the spins are transported rather than the light.

Spectroscopy and coherence lifetime extension of hyperfine transitions in151Eu3+:Y2SiO5

We report a low-temperature spectroscopic characterization of the ground-state hyperfine transitions in ${}^{151}\mathrm{Eu}{}^{3+}{\mathrm{:Y}}_{2}{\mathrm{SiO}}_{5}$ via coherent Raman scattering. Inhomogeneous linewidths of 21 and 38 kHz were measured for the ${I}_{z}=\ifmmode\pm\else\textpm\fi{}\frac{1}{2}$ $\ensuremath{\leftrightarrow}$ $\ifmmode\pm\else\textpm\fi{}\frac{3}{2}$ and the $\ifmmode\pm\else\textpm\fi{}\frac{3}{2}$ $\ensuremath{\leftrightarrow}$ $\ifmmode\pm\else\textpm\fi{}\frac{5}{2}$ ground-state transitions, respectively. Spin-echo decays were recorded for the ${I}_{z}=\ifmmode\pm\else\textpm\fi{}\frac{1}{2}$ $\ensuremath{\leftrightarrow}$ $\ifmmode\pm\else\textpm\fi{}\frac{3}{2}$ transition at zero field and for a small static magnetic field. In the latter case, analysis by a simple model gave an amplitude of 284 Hz and a correlation time of 3.5 ms for the transition frequency fluctuations. Application of a dynamical decoupling sequence resulted in coherence lifetimes up to 474 ms, an 18-fold increase compared to the spin intrinsic phase memory time of 26 ms.

Laser spectroscopy methods for probing highly charged ions at GSI

We describe two opposite and partly complementary experimental approaches for performing high-precision laser spectroscopy of dipole-forbidden transitions in highly charged ions. We report on the wavelength determination of the ground state hyperfine transitions in hydrogen-like and lithium-like bismuth ions confined in the experimental storage ring at GSI. Direct comparison of the experimental results with theoretical predictions reveals an agreement of the specific hyperfine-structure splitting difference $\Delta ^{\prime }E$ within the 1- σ confidence interval of the experimental value. Additionally, we discuss an experimental strategy based on ion manipulation and cooling in a cylindrical open-endcap Penning trap to further increase the precision of the previous measurement. Trapping and laser cooling of external produced singly charged magnesium ions is demonstrated. This represents a first step towards sympathetic cooling of simultaneously confined ion species in order to perform laser spectroscopy measurements on highly charged ions nearly at rest. These measurements will offer new prospects in the field of laser-based tests of quantum electrodynamics in strong electric and magnetic fields.

High-Accuracy Measurement of the Blackbody Radiation Frequency Shift of the Ground-State Hyperfine Transition inCs133

We report a high-accuracy direct measurement of the blackbody radiation shift of the 133Cs ground-state hyperfine transition. This frequency shift is one of the largest systematic frequency biases encountered in realizing the current definition of the International System of Units (SI) second. Uncertainty in the blackbody radiation frequency shift correction has led to its being the focus of intense theoretical effort by a variety of research groups. Our experimental measurement of the shift used three primary frequency standards operating at different temperatures. We achieved an uncertainty a factor of five smaller than the previous best direct measurement. These results tend to validate the claimed accuracy of the recently calculated values.

Contributing to TAI with a secondary representation of the SI second

We report the first contribution to international atomic time (TAI) based on a secondary representation of the SI second. This work is done with the LNE-SYRTE FO2-Rb fountain frequency standard using the 87Rb ground-state hyperfine transition. We describe FO2-Rb and how it is connected to local and international time scales. We report on local measurements of this frequency standard in the SI system, i.e. against primary frequency standards (PFSs), down to a fractional uncertainty of 4.4 × 10−16, and on the establishment of the recommended value for the 87Rb hyperfine transition by the CIPM. We also report on the process that led to the participation of the FO2-Rb frequency standard in Circular T and to the elaboration of TAI. This participation enables us to demonstrate absolute frequency measurement directly in terms of the SI second realized by the TAI ensemble with a statistical uncertainty of 1.1 × 10−16, therefore at the limit allowed by the accuracy of PFSs. This work constitutes a demonstration of how other secondary representations, based on optical transitions, could also be used for TAI, and an investigation of a number of issues relevant to a future redefinition of the SI second.

A Low Noise and Computer Controllable Oscillator for CPT Atomic Clock

This paper presents an digital microwave oscillator which employs a phase lock loop (PLL) chip and a direct digital synthesizer (DDS) chips to realize a pure frequency at 3.417GHz (half of the 87Rb atom ground-state hyperfine transition frequency) for the coherent population trapping (CPT) atomic clock application. And at this frequency, the oscillator demonstrates low noise (lower than-50dBc/Hz@100Hz and lower than-55dBc/Hz@1kHz) and purity. Moreover, based on the communication between a computer and the MCU, this oscillator could be completely controlled by self-developed user interface.