No Arabic abstract
A custom, flat field, extreme ultraviolet EUV spectrometer built specifically for use with low power light sources that operate under ultrahigh vacuum conditions is reported. The spectral range of the spectrometer extends from 4 nm to 40 nm. The instrument optimizes the light gathering power and signal to noise ratio while achieving good resolution. A detailed description of the spectrometer and design considerations are presented, as well as a novel procedure that could be used to obtain a synthetic wavelength calibration with the aid of only a single known spectral feature. This synthetic wavelength calibration is compared to a standard wavelength calibration obtained from previously reported spectral lines of Xe, Ar and Ne ions recorded with this spectrometer.
We examine a range of effects arising from ac magnetic fields in high precision metrology. These results are directly relevant to high precision measurements, and accuracy assessments for state-of-the-art optical clocks. Strategies to characterize these effects are discussed and a simple technique to accurately determine trap-induced ac magnetic fields in a linear Paul trap is demonstrated using $^{171}mathrm{Yb}^+$
Cold-atom inertial sensors target several applications in navigation, geoscience and tests of fundamental physics. Reaching high sampling rates and high inertial sensitivities, obtained with long interrogation times, represents a challenge for these applications. We report on the interleaved operation of a cold-atom gyroscope, where 3 atomic clouds are interrogated simultaneously in an atom interferometer featuring a 3.75 Hz sampling rate and an interrogation time of 801 ms. Interleaving improves the inertial sensitivity by efficiently averaging vibration noise, and allows us to perform dynamic rotation measurements in a so-far unexplored range. We demonstrate a stability of $3times 10^{-10}$ rad.s$^{-1}$, which competes with the best stability levels obtained with fiber-optics gyroscopes. Our work validates interleaving as a key concept for future atom-interferometry sensors probing time-varying signals, as in on-board navigation and gravity-gradiometry, searches for dark matter, or gravitational wave detection.
We report the design of a radio-frequency induction-heated rod casting furnace that permits the preparation of polycrystalline ingots of intermetallic compounds under ultra-high vacuum compatible conditions. The central part of the system is a bespoke water-cooled Hukin crucible supporting a casting mold. Depending on the choice of mold, typical rods have a diameter between 6 mm and 10 mm and a length up to 90 mm, suitable for single-crystal growth by means of float-zoning. The setup is all-metal sealed and may be baked out. We find that the resulting ultra-high vacuum represents an important precondition for processing compounds with high vapor pressures under a high-purity argon atmosphere up to 3 bar. Using the rod casting furnace, we succeeded to prepare large high-quality single crystals of two half-Heusler compounds, namely the itinerant antiferromagnet CuMnSb and the half-metallic ferromagnet NiMnSb.
A nonlinear interaction between photons is observed in a process that involves charge sources. To observe this process in a vacuum, there are a growing number of theoretical and experimental studies. This process may contain exotic contribution from new physics beyond the Standard Model of particle physics, and is probed by experiments using a high-power laser or a high-field magnet, and more recently using an X-ray Free-Electron Laser (XFEL). Here, we review the present status of our experiments testing various vacuum processes. We describe four experiments with a focus on those using an XFEL: (i) photon-photon scattering in the x-ray region, (ii) laser-induced birefringence and diffraction of x rays, (iii) vacuum birefringence induced by a high-field magnet, and (iv) a dedicated search for axion-like particles using the magnet and x rays.
There is an increasing demand for precise molecular spectroscopy, in particular in the mid-infrared fingerprint window that hosts a considerable number of vibrational signatures, whether it be for modeling our atmosphere, interpreting astrophysical spectra or testing fundamental physics. We present a high-resolution mid-infrared spectrometer traceable to primary frequency standards. It combines a widely tunable ultra-narrow Quantum Cascade Laser (QCL), an optical frequency comb and a compact multipass cell. The QCL frequency is stabilized onto a comb controlled with a remote near-infrared ultra-stable laser, transferred through a fiber link. The resulting QCL frequency stability is below 10-15 from 0.1 to 10s and its frequency uncertainty of 4x10-14 is given by the remote frequency standards. Continuous tuning over ~400 MHz is reported. We use the apparatus to perform saturated absorption spectroscopy of methanol in the low-pressure multipass cell and demonstrate a statistical uncertainty at the kHz level on transition center frequencies, confirming its potential for driving the next generation technology required for precise spectroscopic measurements.