Abstract— A description and characteristics of the developed electronic control unit for laser cooling and an optical clock based on thulium atoms are presented. The form factor of the electronic control unit is compatible with a 19″ telecommunication rack. The electronic control unit includes a control module based on a single-board computer; modules of digital and analog outputs, RF synthesizers, current outputs, and thermistor inputs; and a feedback control module. The control program of the electronic control unit is launched on a built-in single-board computer and is available for connection from the local-area network with a web interface. The developed modules and the electronic control unit can be used in experiments on laser cooling of neutral atoms and ions as well as in quantum metrology and computers.
Abstract— A description and characteristics of the developed electronic control unit for laser cooling and an optical clock based on thulium atoms are presented. The form factor of the electronic control unit is compatible with a 19″ telecommunication rack. The electronic control unit includes a control module based on a single-board computer; modules of digital and analog outputs, RF synthesizers, current outputs, and thermistor inputs; and a feedback control module. The control program of the electronic control unit is launched on a built-in single-board computer and is available for connection from the local-area network with a web interface. The developed modules and the electronic control unit can be used in experiments on laser cooling of neutral atoms and ions as well as in quantum metrology and computers.
In this paper, we present description and characteristics of a compact control system for the transportable optical lattice clocks. The hardware of this system is based on the STM32 microcontroller and the software with a graphical interface implemented by the Python software language. The control system has more than twenty digital outputs, ten analog outputs and the ability to connect the additional modules. This system provides the generation of the digital signals with a time resolution of 10 μs with a high synchronization accuracy when the digital-to-analog converter operates simultaneously with digital signals. We compared our custom the microcontroller-based system with the commercial Real-Time National Instruments system, which is often used in experiments with ultracold atoms. Experiments have shown that using both systems allows to cool 87Sr atoms to a temperature of ∼14 μK. This is enough to load the atoms into an optical lattice and to perform the clock transition spectroscopy.
The method of laser cooling of atoms, first implemented in the early 1980s at the Institute of Spectroscopy of the Russian Academy of Sciences (ISAN), turned out to be an exceptionally powerful tool that provided revolutionary breakthroughs in such areas as quantum sensorics, the physics of Bose±Einstein and Fermi-condensates, quantum informatics, and many others.It was precisely due to the laser cooling method that atomic fountains Ð the most accurate microwave clocks Ð made their appearance, and impetus was lent to the area of optical frequency standards, which today have surpassed the relative error of 10 À18 .In this review, dedicated to the 55th anniversary of the founding of ISAN, we will present some modern methods and experimental results aimed at the development of optical clocks on thulium atoms.In addition to the review part, the paper demonstrates a new experimental protocol for the preparation of thulium atoms using sideband cooling of the spectrally narrow 506.2-nm transition.Ensembles of atoms in the initial states of clock transitions in the ground vibrational sublevel of the optical lattice have been attained.
Optical atomic clocks have already overcome the eighteenth decimal digit of instability and uncertainty demonstrating incredible control over external perturbations of the clock transition frequency. At the same time there is an increasing demand for atomic and ionic transitions with minimal sensitivity to external fields, with practical operational wavelengths and robust readout protocols. One of the goals is to simplify clock's operation maintaining its relative uncertainty at low 10-18 level. It is especially important for transportable and envisioned space-based optical clocks. We proved earlier that the 1.14um inner-shell magnetic dipole transition in neutral thulium possesses very low blackbody radiation shift compared to other neutrals. Here we demonstrate operation of a bi-colour thulium optical clock with extraordinary low sensitivity to the Zeeman shift due to a simultaneous interrogation of two clock transitions and data processing. Our experiment shows suppression of the quadratic Zeeman shift by at least three orders of magnitude. The effect of tensor lattice Stark shift can be also reduced to below 10-18 in fractional frequency units. All these features make thulium optical clock almost free from hard-to-control systematic shifts. Together with convenient cooling and trapping laser wavelengths, it provides great perspectives for thulium lattice clock as a high-performance transportable system.
Currently, the most accurate and stable clocks use optical interrogation of either a single ion or an ensemble of neutral atoms confined in an optical lattice.Here, we demonstrate a new optical clock system based on an array of individually trapped neutral atoms with single-atom readout, merging many of the benefits of ion and lattice clocks as well as creating a bridge to recently developed techniques in quantum simulation and computing with neutral atoms.We evaluate single-site-resolved frequency shifts and shortterm stability via self-comparison.Atom-by-atom feedback control enables direct experimental estimation of laser noise contributions.Results agree well with an ab initio Monte Carlo simulation that incorporates finite temperature, projective readout, laser noise, and feedback dynamics.Our approach, based on a tweezer array, also suppresses interaction shifts while retaining a short dead time, all in a comparatively simple experimental setup suited for transportable operation.These results establish the foundations for a third optical clock platform and provide a novel starting point for entanglement-enhanced metrology, quantum clock networks, and applications in quantum computing and communication with individual neutral atoms that require optical-clock-state control.
Quantum technologies are nowadays emerging as enabling tools for practical applications, such as quantum sensing, quantum computing and quantum metrology. Lasers play a central role in many of these technological platforms, e.g. for atomic clocks, ion-based or neutral atom-based quantum computers or atom interferometers. Here we present a complete laser system to cool, trap and control strontium atoms in an optical lattice or in tweezer arrays. A sub-Hz linewidth master laser, locked to a high-finesse optical cavity provides the frequency reference for an ultra-low noise comb. The rack-mounted laser system consists of all cooling, repumping, and clock lasers stabilized to the optical frequency comb. Each of the involved laser frequencies can therefore be tuned and mapped in the frequency domain with a high degree of stability. The system is controlled via a software interface, allowing to operate the cold-atom-based physics package autonomously. The system is tailored for the operation of 88Sr or 87Sr optical lattice clocks, or for quantum computing applications, but other sub-Hz lasers could be obtained by phase locking additional clock laser frequencies to the ultra-stable comb, enabling convenient and accurate optical frequency ratio measurements. The laser system architecture and the relevant characterization measurements will be presented, proposing some user-cases such as quantum computing and atom interferometry on strontium atoms. This represents a technological leap for quantum optics, allowing to explore further applications of quantum sensors outside a traditional lab.
We review the current research on precision spectroscopy and quantum optics applications of laser-cooled lanthanides. We discuss the specific electronic structure of hollow atoms, which determine prospects for application in optical frequency standards and in quantum simulators based on spin interactions in optical lattices. Using the example of the thulium atom, we describe the specifics of laser cooling, optical lattice trapping techniques, and clock transition spectroscopy using spectrally narrow lasers.