Long-lived Bloch oscillations with bosonic Sr atoms and application to gravity measurement at micrometer scale

We report on the observation of Bloch oscillations on the unprecedented time scale of severalseconds. The experiment is carried out with ultra-cold bosonic strontium-88 loaded into a vertical optical standing wave. The negligible atom-atom elastic cross section and the absence of spin makes $^{88}$Sr an almost ideal Bose gas insensitive to typical mechanisms of decoherence due to thermalization and to external stray fields. The small size enables precision measurements of forces at micrometer scale. This is a challenge in physics for studies of surfaces, Casimir effects, and searches for deviations from Newtonian gravity predicted by theories beyond the standard model

Test of Einstein Equivalence Principle for 0-spin and half-integer-spin atoms: Search for spin-gravity coupling effects

We report on a conceptually new test of the equivalence principle performed by measuring the acceleration in Earth's gravity field of two isotopes of strontium atoms, namely, the bosonic $^{88}$Sr isotope which has no spin vs the fermionic $^{87}$Sr isotope which has a half-integer spin. The effect of gravity upon the two atomic species has been probed by means of a precision differential measurement of the Bloch frequency for the two atomic matter waves in a vertical optical lattice. We obtain the values $\eta = (0.2\pm 1.6)\times10^{-7}$ for the E\"otv\"os parameter and $k=(0.5\pm1.1)\times10^{-7}$ for the coupling between nuclear spin and gravity. This is the first reported experimental test of the equivalence principle for bosonic and fermionic particles and opens a new way to the search for the predicted spin-gravity coupling effects.Comment: 5 pages, 4 figures. New spin-gravtity coupling analysis on the data added to the manuscrip

Precision measurement of gravity with cold atoms in an optical lattice and comparison with a classical gravimeter

We report on a high precision measurement of gravitational acceleration using ultracold strontium atoms trapped in a vertical optical lattice. Using amplitude modulation of the lattice intensity, an uncertainty $\Delta g /g \approx 10^{-7}$ was reached by measuring at the 5$^{th}$ harmonic of the Bloch oscillation frequency. After a careful analysis of systematic effects, the value obtained with this microscopic quantum system is consistent with the one we measured with a classical absolute gravimeter at the same location. This result is of relevance for the recent interpretation of related experiments as tests of gravitational redshift and opens the way to new tests of gravity at micrometer scale.Comment: 4 pages, 4 figure

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.

Cooling of Sr to high phase-space density by laser and sympathetic cooling in isotopic mixtures

Based on an experimental study of two-body and three-body collisions in ultracold strontium samples, a novel optical-sympathetic cooling method in isotopic mixtures is demonstrated. Without evaporative cooling, a phase-space density of $6\times10^{-2}$ is obtained with a high spatial density that should allow to overcome the difficulties encountered so far to reach quantum degeneracy for Sr atoms.Comment: 5 pages, 4 figure

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

Laser cooling and trapping of atomic strontium for ultracold atom physics, high-precision spectroscopy and quantum sensors

This review describes the production of atomic strontium samples at ultra-low temperature and at high phase-space density, and their possible use for physical studies and applications. We describe the process of loading a magneto-optical trap from an atomic beam and preparing the sample for high precision measurements. Particular emphasis is given to the applications of ultracold Sr samples, spanning from optical frequency metrology to force sensing at micrometer scale

Pengaruh Konsentrasi Larutan Garam NaCl Terhadap Pertumbuhan Dan Kualitas Bibit Lima Kultivar Asparagus (the Effect of NaCl Salt Solution Concentrations on Growth and Seedling Quality of Five Asparagus Cultivars)

Kondisi iklim tropis seperti di Indonesia yang memiliki suhu dan kelembaban udara yang tinggi, memicu penyebaran penyakit yang merupakan masalah utama pada pertanaman asparagus. Penggunaan air garam (kondisi salin) pada media tanam dapat mengendalikan penyakit busuk akar dan memperbaiki pertumbuhan tanaman asparagus. Percobaan ini bertujuan menguji ketahanan salinitas dari lima kultivar asparagus untuk memilih kultivar asparagus yang menghasilkan pertumbuhan bibit yang baik ditanam di Indonesia. Percobaan dilaksanakan di kecamatan Cisarua, Bandung dengan tinggi tempat 1.100 meter di atas permukaan laut dari bulan April sampai September 2014. Rancangan yang digunakan adalah Acak Kelompok Faktorial dengan tiga ulangan. Faktor pertama adalah kultivar asparagus terdiri dari lima kultivar yaitu Atlas F1; De Paoli F1 Hybrid; Jing Green No. 1 Hybrid F1; San Knight Hybrid F1 dan Jaleo. Faktor kedua adalah konsentrasi larutan garam terdiri dari tiga taraf yaitu 1.0 g L-1; 4.0 g L-1 dan 7.0 g L-1. Hasil percobaan menunjukkan tidak adanya interaksi antara jenis kultivar dan konsentrasi larutan garam. Pengaruh mandiri dari perlakuan menunjukkan bahwa kultivar De Paoli F1 Hybrid menghasilkan bobot segar bibit, tinggi bibit, jumlah batang, bobot shoot, bobot crown, volume crown, panjang akar dan jumlah akar yang lebih tinggi dibandingkan kultivar lainnya. Kultivar San Knight Hybrid F1 menghasilkan bibit yang lebih rendah dari semua komponen pengamatan dibandingkan kultivar lainnya. Aplikasi konsentrasi larutan garam 4 dan 7 g L-1 menunjukkan tinggi bibit, jumlah batang, bobot segar bibit, bobot shoot, bobot crown dan volume crown lebih rendah dibandingkan konsentrasi larutan garam 1 g L-1. Pengaruh konsentrasi larutan garam 7 g L-1 nyata menekan pertumbuhan panjang akar dan jumlah akar.KeywordsKultivar Asparagus officinalis L.; Bibit Asparagus officinalis L.; Konsentrasi air gara