A transportable strontium optical lattice clock

We report on a transportable optical clock, based on laser-cooled strontium atoms trapped in an optical lattice. The experimental apparatus is composed of a compact source of ultra-cold strontium atoms including a compact cooling laser set-up and a transportable ultra-stable laser for interrogating the optical clock transition. The whole setup (excluding electronics) fits within a volume of less than 2 m$^3$. The high degree of operation reliability of both systems allowed the spectroscopy of the clock transition to be performed with 10 Hz resolution. We estimate an uncertainty of the clock of $7\times10^{-15}$.Comment: 12 pages, 9 figures, to be published in Appl. Phys.

A compact and efficient strontium oven for laser-cooling experiments

Here we describe a compact and efficient strontium oven well suited for laser-cooling experiments. Novel design solutions allowed us to produce a collimated strontium atomic beam with a flux of 1.0\times10^13 s^-1 cm^-2 at the oven temperature of 450 {\deg}C, reached with an electrical power consumption of 36 W. The oven is based on a stainless-steel reservoir, filled with 6 g of metallic strontium, electrically heated in a vacuum environment by a tantalum wire threaded through an alumina multi-bore tube. The oven can be hosted in a standard DN40CF cube and has an estimated continuous operation lifetime of 10 years. This oven can be used for other alkali and alkaline earth metals with essentially no modifications.Comment: 6 pages, 6 figures, Review of Scientific Instruments, in pres

An atomic clock with 10−1810^{-18} instability

Atomic clocks have been transformational in science and technology, leading to innovations such as global positioning, advanced communications, and tests of fundamental constant variation. Next-generation optical atomic clocks can extend the capability of these timekeepers, where researchers have long aspired toward measurement precision at 1 part in $\bm{10^{18}}$. This milestone will enable a second revolution of new timing applications such as relativistic geodesy, enhanced Earth- and space-based navigation and telescopy, and new tests on physics beyond the Standard Model. Here, we describe the development and operation of two optical lattice clocks, both utilizing spin-polarized, ultracold atomic ytterbium. A measurement comparing these systems demonstrates an unprecedented atomic clock instability of $\bm{1.6\times 10^{-18}}$ after only $\bm{7}$ hours of averaging

Hyperpolarizability and operational magic wavelength in an optical lattice clock

Optical clocks benefit from tight atomic confinement enabling extended interrogation times as well as Doppler- and recoil-free operation. However, these benefits come at the cost of frequency shifts that, if not properly controlled, may degrade clock accuracy. Numerous theoretical studies have predicted optical lattice clock frequency shifts that scale nonlinearly with trap depth. To experimentally observe and constrain these shifts in an $^{171}$Yb optical lattice clock, we construct a lattice enhancement cavity that exaggerates the light shifts. We observe an atomic temperature that is proportional to the optical trap depth, fundamentally altering the scaling of trap-induced light shifts and simplifying their parametrization. We identify an "operational" magic wavelength where frequency shifts are insensitive to changes in trap depth. These measurements and scaling analysis constitute an essential systematic characterization for clock operation at the $10^{-18}$ level and beyond.Comment: 5 + 2 pages, 3 figures, added supplementa

Health-related quality of life burden in scleroderma patients treated with two different intravenous iloprost regimens

Systemic sclerosis (SSc)-related Raynaud's phenomenon (RP) and digital ulcers (DU) can impair health-related quality of life (HRQoL). The aim of our study was to estimate HRQoL in SSc patients treated with two different intravenous (IV) iloprost (ILO) regimens and in patients not treated with IV ILO. 96 consecutive SSc patients were enrolled in a pragmatic, prospective and non-randomized study, and divided into 3 groups: not requiring therapy with IV ILO (N=52), IV ILO once monthly (N=24) or IV ILO for 5 consecutive days every 3 months (N=20). Patients were followed up for three months. We assessed HRQoL using the generic preference-based questionnaire EQ-5D-5L. We conducted multiple regression analyses to estimate, in each treatment group, the mean general health (GH) and the mean utility index of the EQ-5D-5L, adjusting for possible confounders. The mean adjusted utility index and GH score, after three months' follow-up, were not different in the three groups: IV ILO was able to make patients requiring IV ILO similar to those not requiring it. Moreover, there was no difference in this model between the two ILO regimens (1 day monthly vs 5 consecutive days every 3 months). The two different IV ILO regimens (the most appropriate regimen was decided according to patients' characteristics and needs) were able to stabilize HRQoL in RP secondary to SSc non-adequately controlled by oral therapy

Demonstration of a Transportable 1 Hz-Linewidth Laser

We present the setup and test of a transportable clock laser at 698 nm for a strontium lattice clock. A master-slave diode laser system is stabilized to a rigidly mounted optical reference cavity. The setup was transported by truck over 400 km from Braunschweig to D\"usseldorf, where the cavity-stabilized laser was compared to a stationary clock laser for the interrogation of ytterbium (578 nm). Only minor realignments were necessary after the transport. The lasers were compared by a Ti:Sapphire frequency comb used as a transfer oscillator. The thus generated virtual beat showed a combined linewidth below 1 Hz (at 1156 nm). The transport back to Braunschweig did not degrade the laser performance, as was shown by interrogating the strontium clock transition.Comment: 3 pages, 4 figure

Solar panels as air Cherenkov detectors for extremely high energy cosmic rays

Increasing interest towards the observation of the highest energy cosmic rays has motivated the development of new detection techniques. The properties of the Cherenkov photon pulse emitted in the atmosphere by these very rare particles indicate low-cost semiconductor detectors as good candidates for their optical read-out. The aim of this paper is to evaluate the viability of solar panels for this purpose. The experimental framework resulting from measurements performed with suitably-designed solar cells and large conventional photovoltaic areas is presented. A discussion on the obtained and achievable sensitivities follows.Comment: 6 pages, 8 eps figures included with epsfig, uses espcrc2.sty. Talk given at the Sixth Topical Seminar on Neutrino and Astroparticle Physics, San Miniato, Italy, 17-21 May 199

A pyramid MOT with integrated optical cavities as a cold atom platform for an optical lattice clock

We realize a two-stage, hexagonal pyramid magneto-optical trap (MOT) with strontium, and demonstrate loading of cold atoms into cavity-enhanced 1D and 2D optical lattice traps, all within a single compact assembly of in-vacuum optics. We show that the device is suitable for high-performance quantum technologies, focusing especially on its intended application as a strontium optical lattice clock. We prepare 2 × 104 spin-polarized atoms of 87Sr in the optical lattice within 500 ms; we observe a vacuum-limited lifetime of atoms in the lattice of 27 s; and we measure a background DC electric field of 12 V m−1 from stray charges, corresponding to a fractional frequency shift of (−1.2 ± 0.8) × 10−18 to the strontium clock transition. When used in combination with careful management of the blackbody radiation environment, the device shows potential as a platform for realizing a compact, robust, transportable optical lattice clock with systematic uncertainty at the 10−18 level