The paper highlights the importance of the time unit definition,by means of the atomic Cs frequency standard, in the definition of the base units of the International System of units (SI).
Masses of light nuclei provide a network of essential parameters used for the fundamental nature description. For example, the mass difference of tritium and helium-3 allows for an independent check of the limit on the electron-antineutrino mass.
The most precise mass measurements of the lightest nuclei, including helium-3, revealed considerable inconsistencies between the values reported by...
Phonons, quanta of Acoustic vibration, have much in common with photons, elementary excitation of Electro-Magnetic fields. Despite the fact that photonic devices have dominated physics and engineering for at least a century, and the acoustical systems have almost been forgotten. One of the main reasons for that is much lower energy losses exhibited by well designed photonic systems, e.g....
Over the past 20 years optical frequency combs [1], with atomic clocks [2], have been a powerful and enabling technology in the context of time and frequency measurement [1,2]. Impressively, optical atomic clocks have yielded an 8 order of magnitude improvement in accuracy in the past 30 years. These improvements are fueling a push toward redefinition of the SI second to optical atomic...
Optical atomic clocks are the most precise and accurate measurement devices ever constructed, reaching fractional systematic uncertainties below one part in $10^{-18}$ [1]. Their exceptional performance opens up a wide range of applications in fundamental science and technology. The extreme properties of highly charged ions (HCI) make them highly sensitive probes for tests of fundamental...
We discuss some of the many advantages that lutetium offers as an optical frequency reference. We illustrate the ease at which a comparison at the level of 1e-18 can be achieved and we show how the use of two available clock transitions can be used to verify clock performance between two systems.
Here our progress on the Ca+ ion optical clocks for the last few years will be reported, including both the laboratory clocks and the transportable clock.
First of all, the clock stability is greatly improved, with long term stability reaches the E-18 level; recently with a low E-16 level stability clock laser, the clock stability has been improved to ~ 1E-15/√τ, about another factor of 2...
We describe recent techniques, strategies, and efforts toward realizing next-generation optical clock uncertainty and stability with the NIST Yb optical lattice clock.
This talk will discuss a vibrational molecular lattice clock based on ultracold strontium dimers, its systematic evaluation at the 14th decimal digit, the current limitations, and paths forward.
We will present the progress of our Hg optical lattice clock. This work is motivated, in particular, by the low sensitivity of Hg to blackbody radiation and stray electric fields and by the possibility to use ratio between Hg and other optical transitions for fundamental physics and metrology. We re-port on our work done with the 199Hg fermionic isotope to improve uncertainty, stability and...
Precise quantum state engineering, many-body physics, and innovative laser technology are revolutionizing the performance of atomic clocks and metrology, providing opportunities to explore emerging phenomena and probe fundamental physics. A Wannier-Stark optical lattice configuration highlights such an example. Atom-light and atom-atom interactions in the shallow optical lattice are precisely...
We will present real-time optically steered timescales generated at the same time at OP and NPL. After a detailed description of the experimental chains, we will present the implemented algorithms for outlier filtering and frequency steering estimations. We will then analyse the performance of the experimental timescales based on local comparison against the local UTC(k) and remote comparisons...
Background ultralight scalar fields that are considered as a viable candidate for galactic dark matter may manifest themselves in apparent variation of fundamental constants, see, for example, [1,2].
In this talk, we will discuss some of the recent work of our group and collaborators, for example [3- 6], where we search for oscillating dark matter with Compton frequencies from near DC up to...
We report on results from long-term operation of the Yb1 ion optical clock of PTB, where we have obtained uptimes exceeding 80% over typical TAI reporting intervals of 30 days. Using these data and the special electronic structure of Yb+ allows us to improve searches for a coupling of ultra-light dark matter (UDM) to photons, temporal drifts of the fine structure constant and its potential...
Cadmium is attractive for optical lattice clocks and for searches for Dark Matter and beyond-Standard-Model physics via isotope shift measurements. The cadmium clock transition has a small sensitivity to blackbody radiation and it has 8 stable isotopes, 6 spin 0 bosonic isotopes, and 2 spin ½ fermionic isotopes. Without using 229 nm light to drive the singlet transition, we capture thermal Cd...
The paper highlights the importance of the time unit definition,by means of the atomic Cs frequency standard, in the definition of the base units of the International System of units (SI).
Since August 2021, NICT has been generating UTC(NICT) with its scale interval calibrated by the intermittent operation of a Sr lattice clock . The improvement in the deviation of UTC-UTC(NICT) as well as the current limitation will be discussed.
In this paper, we discuss the possibility to redefine the SI second using the geometric mean of several optical clock transitions. This definition would allow to take advantage of the many high performance optical frequency standards currently available.
Here, we describe the fundamental properties of this definition and its practical implementation. Finally, we discuss its strengths and...
We describe our experiments towards the resonant laser excitation of the 8.3 eV nuclear transition in 229Th with the motivation to develop a highly accurate nuclear optical clock for metrology and tests of fundamental physics.
We show that low-phase noise and high-frequency stability can be simultaneously achieved in microwave sapphire oscillators. We describe the 9 GHz sapphire oscillator with interferometric signal processing, which was phase-locked to a stable RF reference by controlling microwave power dissipated in the sapphire resonator. The SSB phase noise of the oscillator was measured to be close to -170...
The Atomic Clock Ensemble in Space (ACES) mission is developing high performance clocks and links for space to test Einstein's theory of general relativity. From the International Space Station, the ACES payload will distribute a clock signal with fractional frequency instability and inaccuracy of $1\times10^{-16}$ establishing a worldwide network to compare clocks in space and on ground. ACES...
An “optical lattice clock” benefits from a low quantum-projection noise (QPN) by simultaneously interrogating many atoms trapped in an optical lattice [1]. The essence of the scheme is an engineered perturbation based on the “magic frequency” protocol, which has been proven successful up to 10-18 uncertainty [2-4]. About a thousand atoms enable such clocks to achieve 10-18 stability in a few...
We describe work at NIST to develop next-generation chip-scale atomic clocks based on optical transitions in vapor cells and thermal beams.
abstract attached below.
The precision of a quantum clock near zero temperature, depends on how it is driven and how it is measured. We investigate both limits to precision using quantum stochastic thermodynamics, and illustrate the results with examples (superconducting and nano mechanical). Of particular relevance is the nature of the measurement as the clock signal ultimately depends on estimating the fluctuations...
A nuclear-spin-based rotation sensor is implemented based on simultaneous measurements with two nitrogen isotopes intrinsic to nitrogen-vacancy centers in diamond, employing a microwave-free technique with optical addressing of nuclear spins. Differential measurements suppress systematics related to magnetic-field and temperature variations.
Networks of optical clocks find applications in precise navigation, in efforts to redefine the fundamental unit of the ‘second’ and in gravitational tests. As the frequency uncertainty and instability for state-of-the-art optical clocks has reached the 10^−19 level, the vision of a global-scale optical network that achieves comparable performances requires the dissemination of time and...
REFIMEVE is a national metrological network for time and frequency dissemination using the academic fiber network. It enables the coherent dissemination of time and/or frequency reference signals from LNE-SYRTE to around 15 labs and more than 30 in the future. We will show the latest extensions of the network in the Paris urban area and all over France, the architecture required for such a...
Frequency comparison using ultra-stable, free-space laser links between transportable optical atomic clocks will result in globally significant advancements in applications spanning from fundamental physics, to outputs with immediate societal impact. Here, we report on our work to demonstrate a low size, weight, and power, continuous-wave laser technology that is capable of free-space...
Applications of time and frequency signals on the fiber.
Research on room-temperature trapped ion atomic clocks at the Jet Propulsion Laboratory recently culminated in the launch of NASA's Deep Space Atomic Clock (DSAC) mission in 2019. Operating in space for 2 years, DSAC achieved a new level of performance among the most stable space clocks now in use and is expected to enable new space clock applications that require both high stability and...
We have developed several sub-10 mL vacuum-gap Fabry-Perot cavities that provide ~$10^{-14}$ factional frequency stability and ultralow phase noise, using scalable lithographic techniques to fabricate million-finesse mirrors.
Mode-locked Kerr frequency combs generated in nonlinear resonators pumped with coherent monochromatic light have attracted significant attention because of their practical importance associated with their applications in optical and microwave frequency generation, signal synthesis, clocks and others. Dichromatic resonant continuous wave pumping of a nonlinear optical resonator can result in...
We have demonstrated a chip-scale atomic beam clock based on a new chip-scale atomic beam platform. The chip-scale beam clock presents a pathway for exceeding the long-term stability of existing chip-scale atomic clocks while maintaining compact and low-power operation.
A sample of laser cooled atoms are created inside an additively manufactured loop-gap microwave cavity using a grating magneto-optic trap. Using a Ramsey excitation scheme with free evolution times of up to 10 ms and based on the 87Rb ground-state clock transition we demonstrate this setup as a viable route forward for a miniaturised atomic clock.
We introduce a compact atomic clock based on laser-cooled atoms trapped inside a loop-gap microwave cavity. The cavity occupies a volume eight times smaller than conventional cylindrical cavities with ten apertures required for optical manipulation of cold atoms. The measured linewidth of the central Ramsey spectrum was 19.6 Hz. The corresponding frequency instability was $4.5×10^{−13}...
We have recently demonstrated a laser-cooled optical beam clock based on the 10mHz-wide 1S0-3P0 transition in neutral ytterbium. Our goal is to combine the robust architecture of a beam clock with the improved performance offered by optical transitions to produce a device that can provide high-performance timing capabilities outside of the lab.
A Resilient Enhanced Time Scale Infrastructure (RETSI) is being built by the National Physical Laboratory (NPL) as part of the UK National Timing Centre programme. RETSI will comprise four geographically distributed time scale laboratories at sites located across the UK, which will support the generation of the national time scale, UTC(NPL). The purpose of RETSI is to improve the resilience of...
Precise measurements of weak laser power are necessary, while few methods can meet this requirement. To realize the measurement of weak laser power down to microwatt and nanowatt, we adopt an atomic clock to measure the laser power, which is traceable to the output frequency of the atomic clock. A 795 nm semiconductor laser and a Rb atomic clock are utilized. The laser is incident into the...
We present a scheme based on the temporal control of single-photon sources and single-photon detectors to learn the parameters of an optical cavity with a nonlinear response. The scheme works by learning the temporal shape of a single-photon pulse reflected from the cavity. This can be achieved using a Raman single-photon detector, a simple quantum memory, with a controllable read-pulse to...
We describe a passive, fibre-optic frequency reference with a state-of-the-art short-timescale stability of 0.1 Hz/$\sqrt{\text{Hz}}$. We model and compute limiting noise sources, including Double Rayleigh scattering and intrinsic fibre thermal noise.
We demonstrate the absolute frequency calibration of a laser against a GPS disciplined OCXO using a free spectral range cavity readout designed for next generation geodesy missions.
The concept of the active optical clock (AOC) [1] was proposed seventeen years ago by prof. Jingbiao Chen. After early calculations and experiments that demonstrated the advantages of “cavity-pulling suppression” and “narrower linewidth”, the development of AOCs soon became an active competition involving many research groups that proposed schemes based on different atomic gain mediums, and...
We describe a novel method to search for ultra-light, wave-like dark matter by sensing ultra-weak electric fields using trapped ions. We present technical advancement in our system for near-ground state laser cooling and laser beam delievery to increase our spin-motion and spin-spin entanglement.
Our work [Dailey et al., Nature Astronomy 5, 150 (2021)] extends the gravitational and electromag-netic modalities of multi-messenger astronomy to exotic (beyond the Standard Model of elementary particles) fields. We are interested in a direct detection of exotic fields emitted by the powerful astrophysical events such as binary black hole mergers. While the progenitors can be located in...
A cesium atomic fountain clock KRISS-F1 and an optical lattice clock KRISS-Yb1 share their duty of steering a hydrogen maser that generates local time scale in Korea. In order to secure the redundancy of primary frequency standards, we plan to build another fountain clock named KRISS-F2. Since the performance of a fountain clock depends largely on the microwave cavity, we make efforts on the...
Cesium atomic fountain primary frequency standards(PFS) and Rubidium fountain clocks are building to produce more accurate and stable local atomic time UTC(NTSC). The abstract presents 2 Cesium fountain PFS and 2 Rubidium at National Time Service Center, Chinese Academy of Sciences (NTSC).
In the experiment of a 10MHz low phase noise crystal oscillator, a collapse phenomenon was ob-served in the phase noise curve when testing with Agilent E5052B. It was believed that this was caused by the instrument's background noise. The numerical relationship of this phenomenon was estimated, and a solution was proposed.
Downsizing and improving robustness of the laser system was performed to realize an transportable optical lattice clock with a volume of 250 L.
Our efforts with the optical lattice clock NICT-Sr1 are now focused on contribution to both the international and the local timescale. Since 2018, NICT-Sr1 has been recognized as a secondary frequency standard and contributed to TAI calibration. Since August 2021 it serves as a reference for the generation of UTC(NICT), which now deviates from UTC by only few nanoseconds.
By measuring the frequencies emitted as atoms transition between energy levels, atomic frequency standards are among the most advanced devices available for keeping time. Here, we report our recent progress in developing an optical frequency standard based on a single $^{171}$Yb$^+$. With the laser Doppler cooling, a single ytterbium ion is cooled to crystallization and the temperature of the...
Despite the abundance of experimental searches for dark matter (DM), there is no confirmed detection to date. However, we can utilise the precision that atomic physics allows to search for interactions between DM and atomic systems. In this work, I will discuss the prospect for DM detection with atomic systems, the tools needed to accurately assess the possibility, and potential implications...
With the development of quantum frequency standard at optical frequency [1], the robust and portable optical beam clocks have attracted a lot of attention [2,3]. The calcium atomic beam clock is one promising scheme due to its relatively simple interrogating and detecting schemes, which can be used for time-keeping, satellite navigation and space exploration [4].
Here we demonstrate an...
We present an optical atomic clock based on spectroscopy of the relatively narrow $^1S_0 ↔ ^3P_1$ intercombination line in neutral ytterbium. We show that this system is not only able to achieve short- and medium-term frequency instability better than 10-14 but is also compact and robust. We demonstrate the potential of this system by performing extensive field testing of the clock with an...
We will present our latest results towards implementing a free-space optical quantum time transfer system. We compare experiments using correlated photon pairs over a 100 m free-space link with a theoretical model we have developed to determine the fundamental limits of our system.
Ultra-stable Fabry-Pérot cavities are ideal tools for ultra-light dark matter detection, since the fluctuations of length of the cavity can be detected on the frequency of the laser stabilized on the cavity. At FEMTO-ST, we dispose of an ultra-stable silicon cavity suitable for a test of detection of ultra-light dark matter in an energy range close to $10^{-10}$ eV.c$^{-2}$. We present the...
We introduce a novel molecular sensor designed for the study of fundamental interactions, focusing on clock transitions within a Hg-Hg system. Our project implements optical Feshbach resonances in systems involving Hg$_2$ or Hg-alkali systems, with the ultimate goal of constructing a Hg$_2$ optical molecular clock. This tool has the potential to push limits for fundamental research by...
While Cs fountain clocks have achieved a typical Type B uncertainties of a few parts in E16, and are employed as the primary frequency standards to realize the definition of the second, Rb fountain clock has also been studied. Due to its low collisional shift and more robust cooling lasers, a Rb fountain clock is easier to operate and more suitable be to a commercial clock. A new Rb fountain...
We developed our 2nd generation transportable optical lattice clock. Clock operation of this system was demonstrated. Its performance was evaluated by synchronous frequency comparison to our 1st generation transportable system.
In this work, we demonstrated a dual-atom-interferometric gyroscope based on two contin-uous cold 87Rb beams, which can decouple the rotation rate and acceleration from interference phase shifts.
In this paper, we propose a scheme utilizing dual-species atoms that integrates atomic interferomet-ric inertial sensors and the atomic clock into a unified system. The preliminary experimental results have confirmed the system's capability to perform subsequent inertial measurements, thus establishing a foundation for further experiments.
Design and construction of an in-vacuum cryogenic radiation shield that enables controlling the BBR shift uncertainty below the $10^{-19}$ level
Novel scheme that enables loading arbitrary atomic sample distributions over more than 5 mm in 1D optical lattices
A novel version of the electric Aharonov-Bohm effect is proposed where the quantum system which picks up the Aharonov-Bohm phase is confined to a Faraday cage with a time-varying, spatially uniform scalar potential. The electric and magnetic fields in this region are effectively zero for the entire period of the experiment. The observable consequence of this version of the electric...
The physics and parts of the design of a 2-colour rubidium optical clock for application in space is presented. The design targets a size weight and power of 20 L, 20 kg and 100 W. The clock aims to meet performance requirements necessary for operation in global navigation satellite systems.
We present a new way to excite a sapphire-loaded cavity resonator based on a balanced microwave dipole probe in a Mach Zehnder interferometric configuration. The probe is constructed from two separate coaxial electric field probes inserted into a cylindrical cavity resonator from opposite sides with a small gap between them, so they act as an active wire dipole antenna. The power into the...
T-REFIMEVE is a new project funding the infrastructure REFIMEVE, in which one of the objectives is the deployment of a White Rabbit network at the French national scale. Here we report on our current status of the deployment of a White Rabbit network disseminating UTC(OP) to five academic users over a maximum distance of 40 km. We report loop-back measurements and compare results obtained with...
In this work, we present a novel optical setup for interferometric fiber links with an inherently very low temperature sensitivity, based on standard fiber and components, in a topology free of uncompensated optical paths. The terminals are designed to be deployed outside of well-controlled labs, for example for chronometric levelling with transportable optical clocks. We setup two terminals...
We present the portable saturable absorber-based fibre combs made for the 88Sr+ single ion clock measurement campaign against NRC-FCs2 Caesium fountain clock. We also present the setup that we intend to use for this clock comparison.
Up to now, the mechanism and light shift in CPT-Ramsey have not yet been clarified theoretically. Using the time evolution of the Bloch vector after the steady-state condition is achieved at the first excitation pulse, we derived an expression of CPT-Ramsey fringes and formulized the light shift in CPT-Ramsey connecting to the ordinal light shift due to Rabi-pulling, which are suitable to...
The FOCOS mission will perform precise time and frequency comparisons between a high-stability optical clock in an elliptical orbit and ground optical clocks via a high-performance free-space optical link. The high frequency stability of an orbiting clock allows an improved measurement of the gravitational redshift by a factor of 30,000, precise worldwide time transfer, and searches for dark...
The original proposal for the Aharonov-Bohm (AB) effect [1] focused on the scalar and vector potentials of the electromagnetic interaction. In particular, the seminal paper of Aharonov and Bohm [1] focused mostly on the AB effect connected with the vector potential and magnetic field (vector-magnetic AB effect) rather than the scalar potential and electric field (scalar-electric AB effect)....
We trace the evolution of laser metrology from the first laser rangefinders built in 1961 to spectacularly successful science applications: the LIGO gravitational wave detector and the Laser Ranging Interferometer of the Earth-orbiting GRACE Follow-On mission. Methods for reducing imperfections in the apparatus and the effect of fundamental noise sources are described, including laser...
Laser linewidth narrowing is critical to advances in frequency standards and metrology, including optical clocks, trapped ion qubit manipulation, gravity wave detection, and quantum sensing. Common feedback actuator mechanisms include piezoelectric transducers and laser diode injection current, but non-linear crystal electro-optic modulators (EOMs) are preferred for their higher bandwidth and...
We present high performance, transportable, dual-axis optical frequency references based upon NPL's patented cubic cavity design. These cavities have demonstrated leading insensitivity to micro-vibrational perturbations and are pushing fractional frequency instability performance beyond the mid 10-15 level at 1 s. These characteristics led themselves to many applications including spaced-based...
We present the development of alkali-alloy-based vapor cells for operating Chip-Scale Atomic Clocks (CSAC) at ambient temperatures up to 105 °C. Potassium is chosen for a better miscibility as compared with gold for the designed operating temperature. The caesium vapor density is reduced as predicted by the Raoult's law through mixing a controlled amount of potassium metal in the vapor cell....
Recent advances in atomic spectroscopy techniques have created a new era of unprecedented precision in the study of atomic phenomena. Atomic physics plays an ever-growing role in fundamental physics studies, including through atomic parity violation and searches for permanent electric dipole moments, as well as for tests of the CPT theorem and Lorentz symmetry, searches for variation of...
Hydrogen masers remain the best available option for a flywheel oscillator that can bridge both accidental and intentional gaps in the operation of an optical frequency standard. Our poster will show applications and statistical evaluation of such measurements spanning optical and radio-frequency domains.
This work discusses how a traditional focus on physical signals in clock composition and time scale generation can limit the potential benefits of digital electronics. The paper presents a digital approach that emphasizes the information carried by sinusoids, rather than the sinusoids themselves, to enable numerical implementation of clock composition functionalities. The work compares an...
The Wide-Band Josephson Parametric Amplifier (JPA) by Raytheon BBN is used in the characterisation experiment for its implementation in the ORGAN Q experiment. The JPA was set in a 3-wave mixing configuration: a DC current source provided a tunable resonant frequency while a pump modulator was used to provide parametric amplification of an input signal. Results show that input frequency ranges...
We describe an agile microwave synthesis system devised of an ultra-low phase-noise cryogenic sapphire oscillator (CSO) that serves as a master clock for a ytterbium ion (Yb+) qubit. We report a 10X improvement of qubit coherence time from 0.9 to 8.7 seconds and single-qubit quantum gates with errors of 1.6e-6 achieved with the synthesis system. Using a filter function approach [1], we find...
Since the advent of gravitational wave (GW) detection in 2015 [1], many such further events have been recorded by the current generation of laser interferometric GW detectors. While highly successful; such detectors possess a limitation in that they are insensitive to potential GWs in the high frequency bands of several hundreds of kHz and above. This has motivated the emergence of a new wave...
Silicon is a common material used in the make up of hybrid quantum systems and semiconductor devices, and is often implemented at low temperatures for quantum technologies, in particular in the isotopically pure form of Si-28. The absence of nuclear spins in such a sample make it an ideal system to realise a multitude of solid state devices based off implanted impurities, including clocks....
We demonstrate a method for suppression of the light shift in rubidium two-photon spectroscopy based on digital signal processing of the fluorescence signal to generate an error signal with lock point independent of probe power.
Bulk Acoustic Wave (BAW) resonators utilize the piezoelectric effect in materials like quartz or lithium niobate to generate and detect acoustic waves within a solid medium [1,2]. These devices find applications in filtering and stabilizing radio frequency (RF) signals in communication systems [3,4]. The objective of this research project is to investigate the properties of LiNbO3-BAW...
Single crystal calcium tungstate (CaWO_4) is an important crystal for WIMP dark matter searches and more recently has become an interesting material for microwave quantum electrodynamic experiments that investigate spins in solids. We construct a dielectrically loaded microwave cavity resonator from a cylindrical single crystal of CaWO_4 and perform whispering gallery multi-mode spectroscopy...
We will outline a new approach to mitigating fundamental Brownian coating thermal noise in optical cavities using multiple higher order TEM gaussian modes [4]. By blending the readout signals of mul-tiple higher order modes, the effective sampling area of mirrors increases. This improves the averag-ing of thermal motion, thereby lowering the overall length noise. Reducing or mitigating this...
With outstanding systematic uncertainties at the $10^{-18}$ level or below optical atomic clocks surpass the best cesium clocks that currently define the time unit. With the related impact on various applications, a growing number of laboratories around the world are developing transportable optical clocks. We are developing a single-ion optical clock targeting a total volume well below 500 L....
We introduce our research in developing a miniaturized optical clock at KRISS using 87Rb two-photon 5S1/2 to 5D5/2 transition in a chip-scale vapor cell. This transition provides a narrow spectral linewidth with potential applications in deployable optical clocks. We obtain a resonance spectrum of the two-photon transition with a chip-scale rubidium vapor cell with a size of 4×7×2.6 mm. The...
Optical atomic clocks have become essential for exploring fundamental physics, providing valuable data for analysis. Our research focuses on using this data to search for variations in fundamental constants. We aim to understand the sensitivity differences between active and passive optical atomic clocks when detecting transient effects. Additionally, we propose using a cryogenic ultra-stable...
Precise frequency synchronization between distant points is essential for a huge range of scientific measurements. Frequency synchronization to moving targets, such as a satellite in orbit, will provide tests of fundamental physics [1]. Frequency synchronization has been improved with the use of free space optical technology. However, robust optical control systems must be designed to measure...
Optical Raman excitation is used to investigate the ground-state clock transition in laser cooled Rb atoms. The initial state preparation in a Ramsey-type scheme is achieved by coherent population trapping whereas the second pulse is a Raman π/2 pulse allowing the evolution of the coherence to be mapped back onto the bare atomic states. This allows for a significant increase in detected signal...
Free-space, optical frequency laser links offer high-speed communications between ground and space on the order of terabits per second. However, the atmosphere is a difficult medium for laser propagation. Turbulence causes a beam to deflect and distort as it travels, and also generates large power losses. Additionally, laser links are highly directional and therefore have stringent pointing...
We present the industrial mass manufacturing processes that has enabled us to develop the Frequency Distribution System for the mid-frequency Square Kilometre Array radio telescope. The system performs microwave frequency dissemination across an optical fibre network, encompassing 197 modular receive-transmit nodes and a total fibre link of > 3000 km, with individual segments up to 173 km in...
Laser phase-noise (PM) to detected intensity-noise (AM) conversion is fundamental to the field/matter interaction: it cannot be avoided, only mitigated. It occurs when laser light passes through a resonant atomic vapor in atomic clocks, magnetometers, and rf-sensors, and it occurs when laser-induced-fluorescence is detected from an atomic or molecular beam. More specifically, it is a...
Singly ionized lutetium (176Lu+) is both attractive for high accuracy clock applications [3,4] and well suited for integrated photonics. With the exception of one repump laser at 350-nm, all other laser wavelengths are within the transparency window of silicon nitride (SiN). Leveraging commercially available SiN microfabrication processes, we have designed and fabricated an ion trap with...
We report progress on the development and out-of-lab demonstrations of a next-generation optical timing reference based on the dual-wavelength excitation of the $5S_{1/2}\rightarrow5D_{5/2}$ two-photon transition of rubidium-87.
We make use of the robustness of mature laser telecommunications technologies, FPGA-based control systems and automation, and a compact optical frequency comb to...
Precision atomic metrology gives us an extraordinary probe of physics beyond the Standard Model, but also necessitates accurate calculations of these systems for planning and supporting experiments, as well as to interpret the results as limits on new physics. Calculations in open-shell systems currently used or proposed for these experiments pose a challenge for atomic structure theory. I...
Optical frequency standards have achieved fractional stabilities of a few parts in 1E19 [1], with accuracies approaching and soon reaching the same level [2]. Furthermore, extraordinary progresses have been made on rendering these complex apparatuses transportable [3,4], such to enable their use as quantum sensors for testing fundamental physics and General Relativity [5].
In order to...
The ASACUSA collaboration at CERN aims to measure the antiproton-to-electron mass ratio with high precision using sub Doppler two-photon laser spectroscopy of metastable antiprotonic helium. Any deviation from the proton value would indicate a broken fundamental symmetry of nature. The new ELENA storage ring is used to synthesize samples of antiprotonic helium and the experiment relies on...
Contribution of primary and secondary frequency standards to UTC and the support from BIPM to the redefintion of the second and accurate time and frequency metrology
At 3x10^(-13)/t^(1/2) and a stability floor at 10^(-15) level, JPL’s Deep Space Atomic Clock (DSAC) is the state-of-the-art (SOA) microwave clock of its size, close to the size constraints in deep space applications [1]. To reach frequency stability beyond that of DSAC in a similar size, one will have to take the new approach of the optical clock where the clock ticking rate is at hundreds of...
The laser-cooled cadmium-ion microwave frequency standard has been developed at Tsinghua University for thirteen years. Recently, the ground-state hyperfine splitting frequency of $^{113}\mathrm{Cd}^{+}$ was determined to be 15199862855.02799(27) Hz, and the fractional frequency instability was measured to be $4.2\times10^{-13}/\sqrt{\tau}$. The result was consistent with previously reported...
We present efforts at the US Naval Observatory to integrate optical-clock technology into our clock ensemble. Emphasis will be on our use of an optical local oscillator disciplined to an atomic fountain, measured directly in the clock measurement, as well as on our calcium-beam clock development.
We present the recent progress on the optically detected magnetic-state-selected cesium beam clock (OMCC). The stability of the compact prototype reaches 4.0E-13@100s, 4.5E-14@10000s and 2.2E-14@1d. We use beam optics to increase SNR to obtain better short-term stability. We propose detuned light detection method and pulsed light detection method to suppress the light shift. To further...
Due to the gravitational redshift, clocks can be utilized for height determination in geodesy. To become geodetically relevant, fractional clock frequency differences of about $1\times10^{-18}$ need to be resolvable. Our second-generation transportable strontium lattice clock represents our recent efforts in reaching the required level of accuracy with an in-field deployable device. These...
We explore applicability of several variations of pure frequency-based spectroscopic techniques to molecular systems and their metrology. In these techniques we take advantage from linear phenom-enon well-known as mode pushing in an optical cavity with an absorbing medium and intrinsic physical connection between absorption and dispersion. It was demonstrated that mode frequency shifts...
We report on the first detailed study of the interplay between QED and many-body effects in heavy atoms for E1 transition amplitudes. We use the radiative potential method and check its validity by comparing against the results of rigorous QED. We study the effects of core relaxation, polarization of the core by the E1 field, and valence-core correlations for the heavy alkali-metal atoms Rb,...
We theoretically and experimentally study the precision of a quantum clock near zero temperature, explicitly accounting for the effect of continuous measurement. We theoretically find the precision of the clock in each regime, which reveals that in the coherent regime reveals that the precision can in principle, be arbitrarily large in spite of the presence of measurement backaction. We also...
The Biological and Physical Science (BPS) division is the newest addition to the NASA Science Mission Directorate (SMD). The BPS mission is to “enable exploration by expanding the frontiers of knowledge, capability, and opportunity in space, and pioneer scientific discovery in and beyond Low Earth Orbit to drive advances in science, technology, and space exploration to enhance knowledge,...
At the National Research Council Canada, we are re-evaluating the NRC-FCs2 caesium fountain clock. The systematic uncertainty has been dominated by four contributions: cold collisions, the distributed cavity phase (DCP) shift, microwave leakage, and synchronous phase transients. We have significantly reduced all but the DCP shift, which is currently being characterized. We will discuss the...
Reconfigurable Brillouin laser for line width narrowing and microwave-spaced frequency combs
We present recent improvements of the systematic lattice light shift in our strontium lattice clock, reaching a fractional uncertainty on the order of $1\times10^{-18}$. A series of independent determinations of the E2-M1 polarisability $\Delta \alpha_{\mathrm{qm}}$ by different groups, including our own experimental measurement, has narrowed down the limits for the correct value of $\Delta...
We propose a method for performing complex quantum simulations utilising 2D ion crystals in a Penning trap through engineered spin-spin interactions. This has potential applications in the study of computationally intractable condensed-matter phenomena such as two-dimensional superconductivity.
We have developed a frequency comb for future long-term missions in space having a volume of 6.5l, a weight of 7.5kg and a power intake of 30-55W, depending on mission and application. The system will be part of the COMPASSO mission by the German space arospace center (DLR), testing future optical clock and quantum technologies on the BARTOLOMEO platform located outside of the ISS. After...
Two Sr optical lattice clocks are being built at NIM. The systematic shift uncertainty of Sr1 is 2.9E-17, and 7.2E-18 for Sr2. A comparison between these two clocks is in progress. The absolute frequency measurements of optical clocks have been carried out at NIM referenced to both the local cesium fountains and the PSFS in Circular T bulletin through a satellite link.
Stable frequency standards have important applications in gravitational wave detection, precise navigation timing, and verification of relativity principles. Effectively utilizing the present fiber network resource to construct the stable radio frequency (RF) transfer system has been explored by many researchers. As the transmission distance is extended, the noise induced by the fiber link...
The cryogenic sapphire oscillator (CSO) is a highly specialized oscillator delivering a microwave signal exhibiting extremely low instability. The Allan deviation $σ_y(τ)$ is of parts in $10^{-15}$ at 1 s, with a flicker floor of parts in $10^{-16}$, and some drift beyond a few hours.
After the results shown at the 8th Frequency Standard and Metrology Symposium, we spent a significant effort...
Status report is given on the Yb optical lattice clocks developed at KRISS. KRISS-Yb1 is being operated regularly to contribute to International Atomic Time (TAI). KRISS-Yb2 was developed to reach the 10^-18 uncertainty level overcoming the BBR shift uncertainty of KRISS-Yb1. Preliminary uncertainty evaluation results of KRISS-Yb2 will be presented at the conference.
In this study, we present a high-performance laser frequency stabilization method that utilizes modulation transfer spectroscopy (MTS) on the rubidium 87 D$_2$ transition line. The frequency instability is evaluated with beating signal of two frequency-locked external cavity diode lasers (ECDL), and reached a short-term stability of 4.5×10$^{−14}$/√τ and did not exceed 2×10$^{−12}$ until...
Today's unsurpassed timekeepers are passive optical atomic clocks, which rely on frequency stabilization of an external optical local oscillator on an atomic transition. However, overcoming their technical limitations, such as the Dick effect and cavity instabilities, is a challenging task.
To circumvent the issues related to the local oscillator frequency instability, a promising idea is to...
In order to make optical comb work for long time under severe temperature changes environment, meeting some needs that require using optical comb under harsh environment, this paper proposes a scheme for repetition-rate locking of optical frequency combs based on delay line, temperature control and PZT.
An Oven Controlled Crystal Oscillator (OCXO) is a precision timing circuit based on a high Q quartz resonator enclosed in an oven to provide the best phase noise performance and high short-term stability.
OCXOs provide good short-term stability and clean frequency references for frequency standards, whether Rb [1], Cs, or Hydrogen Maser atomic clocks [2]. By locking the OCXO reference to...
In this work, we will present the test of local Lorentz invariance using the precision measurements of oscillation masses of particles (phonons). The experiment utilizes two ultra-stable Bulk Acoustic Wave (BAW) quartz oscillators placed orthogonally to each other on a turntable and search for LIV by comparing their relative frequency shift. The resonant frequency of mechanical resonators...
We are presenting a low-vibration closed-cycle cryostat setup for the characterization of mirror coatings performance and direct Brownian thermal noise measurements from room-temperature to 4 K.
Using a high-finesse optical resonator as well as multiple techniques to circumvent technical noise sources related to vibration and temperature fluctuations this facility will enable the...
We use phonons in Bose-Einstein condensates to measure rotation.
The coupling of the orbit and the clock offset seriously affects the clock offset measurement of geostationary orbit (GEO) navigation satellites, and even makes the L-band measurement data unusable [1-2]. To solve the coupling problem, we propose a dual-carrier differential method, which is a further utilization of orbit determination by transfer tracking [3-5]. The dual-carrier differential...
This paper introduces the development of the Faraday laser, which is a novel external cavity diode laser that uses the Faraday anomalous dispersion optical filter as the frequency selective element based on the quantum technology. This paper also demonstrates the advantages of the Faraday laser compared to the traditional ECDLs which are usually based on gratings, Fabry-Pérot etalons and...
I will discuss the hyperfine anomaly, and its relevance to tests of the standard model and searches for new physics in precision atomic experiments. I will focus on several of our recent works on the topic [1,2,3]. The hyperfine anomaly gives the finite-nuclear-size contribution to the hyperfine structure, and is difficult to quantify at the required level of accuracy from nuclear structure...
Singly ionized lutetium (176Lu+) is a unique clock candidate with several attractive features for clock applications [1-6]. It provides three independent clock transitions allowing consistency checks of error budgets through frequency comparisons within the one system [6]. Recently, the systematic uncertainties of two lutetium frequency references have been calibrated to the mid 10-19...
The cold atom microwave clocks play important roles in the field of primary frequency standards, space exploration, satellite navigation, time keeping and fundamental physics, in which the microwave local oscillator drives the transitions between two well-defined cold atomic states using a Ramsey microwave interrogation sequence. Through decades of both theoretical and experimental...
The ORGAN experiment is a microwave cavity axion haloscope that searches for dark matter particles called axions. The experiment's initial phase sets an upper limit on the coupling between axions and photons, excluding a specific axion-like particle model for dark matter within a certain mass range. The recent phase 1b search further excludes the same model within a different mass range.
The minimum axion mass detectable by existing photonic dark matter searches is set by the detector's frequency and hence size, which places the lower limit around $10^{-7}$ eV, leaving the ultra-light dark matter (ULDM) parameter space relatively unexplored. In this work, a new class of electromagnetic resonator is described; the Anyon Cavity Resonator, which has the potential to couple to...
We report on a recent international collaboration in which three emerging optical clock technologies were trialed at sea as part of an international naval exercise.
Each system included an integrated optical frequency comb for synthesis of microwave clock signals, and three-cornered hat measurements were made of both optical and microwave outputs over more than six weeks of operation.
This...
We report the current development of a sub-kelvin Fabry-Perot silicon cavity. This devel-opment aims to reduce thermal noise-limited frequency instability and by this way address the cur-rent limitations of ultrastable lasers, aiming to set the ground for the next generation of these devic-es with frequency instabilities below 1×10-17 [1]. However, silicon cavities with crystalline mirror...
We report the uncertainty evaluation of the atomic gravimeter KRISS-AGRb-1 developed at KRISS with the total uncertainty of below 30 nm/s^2 which is mainly limited by a wavefront distortion, and we present the way to overcome the uncertainty limited by the wavefront distortion and reach the accuracy of below 10 nm/s^2, by combining adjusting beam size of a detection laser and compensating the...
While in terrestrial applications optical frequency references are already being established in many fields, the situation is different for space applications. Here, reliability, size, weight, and power budgets are key considerations in addition to the performance. We will present the ongoing development of two different types of optical frequency references towards space compatibility. This...
Quantum Secure Time Transfer (QSTT) ensures the authenticity of time signals and offers protection against spoofing attacks. This project aims to create a portable QSTT system to establish a two-way free-space quantum connection between two mobile transceivers spanning 10 km. The system consists of multiple beacon lasers, a single-photon source, and adaptive fast-steering optical mirrors, all...
In this article, we have been using a high-power low-RIN laser, a long fiber loop, and an ultra-low noise optical connection to generate an OEO with a phase noise of -162.5dBc/Hz@10kHz at a frequency of 10 GHz to investigate the optoelectronic oscillator's single-loop structure, meanwhile, more significant factors on OEO have been explored.
