Atom interferometry with ultracold Mg atoms: frequency standard and quantum sensors

Abstract

The results of theoretical and experimental studies aimed at the creation of matter wave interferometers with Mg atoms are presented. Atom-optical interferometers based on the Ramsey-Bordé scheme are of great interest for the development of optical frequency standards. Ultracold Mg atoms are promising for the development of an optical frequency standard with relative uncertainty and long-term frequency instability at a level of 10−17 − 10−18. A long-term frequency stability of 3·10−15 is obtained at an averaging time τ = 103 s while stabilizing the frequency of a ‘clock’ laser at 457 nm (1 S 0 → 3 P 1 transition) to narrow Ramsey-Bordé resonances of Mg atoms cooled and localized in a magneto-optical trap. The measured frequency stability is determined by the stability of the measurement system based on an optical frequency comb stabilized to the optical frequency of a Yb:YAG/I2 standard. We also present the results of theoretical studies aimed at the use of Mg atom interferometers based on Bragg diffraction for quantum sensing.

Low loss silicon nitride photonics for short wavelengths

“…Over 12 hours of annealing at 1050 °C is performed for hydrogen passivation and defect removal. Other methods to obtain high quality top cladding oxide have been employed [5,6]. Here we study two other methods i.e., tetraethyl orthosilicate (TEOS)-PECVD which reduces O-H bond contamination, and possesses low surface roughness and uniform stoichiometry, and PECVD.…”

“…All three of these samples underwent a similar high-temperature anneal step. For applications where substrates cannot undergo high temperatures, it has been shown that good quality oxide can be achieved using deuterated silane as a precursor gas in Inductively Coupled Plasma-PECVD (ICP-PECVD) at temperatures as low as 250 o C. In this case, low loss waveguiding ~ 2 dB/m was achieved at 1550 nm with no annealing required [5]. While the losses of this oxide type have not been studied at shorter wavelengths, it may be preferable for substrates that cannot undergo high temperatures.…”