We report on the use of an ultracold ensemble of \(^{87}\)Rb atoms trapped in a vertical lattice as a source for a quantum force sensor based on a Ramsey-Raman type interferometer. We reach spatial ...resolution in the low micrometer range in the vertical direction thanks to evaporative cooling down to ultracold temperatures in a crossed optical dipole trap. In this configuration, the coherence time of the atomic ensemble is degraded by inhomogeneous dephasing arising from atomic interactions. By weakening the confinement in the transverse direction only, we dilute the cloud and drastically reduce the strength of these interactions, without affecting the vertical resolution. This allows to maintain an excellent relative sensitivity on the Bloch frequency, which is related to the local gravitational force, of \(5\times10^{-6}\) at 1\,s which integrates down to \(8\times10^{-8}\) after one hour averaging time.
We perform high-resolution spectroscopy of the \(3\)d\(~^2\)D\(_{3/2} - 3\)d\(~^2\)D\(_{5/2}\) interval in all stable even isotopes of \(^A\)Ca\(^+\) (A = 40, 42, 44, 46 and 48) with an accuracy of ...\(\sim\) 20 Hz using direct frequency-comb Raman spectroscopy. Combining these data with isotope shift measurements of the 4s\(~^2\)S\(_{1/2} \leftrightarrow 3\)d\(~^2\)D\(_{5/2}\) transition, we carry out a King plot analysis with unprecedented sensitivity to coupling between electrons and neutrons by bosons beyond the Standard Model. Furthermore, we estimate the sensitivity to such bosons from equivalent spectroscopy in Ba\(^+\) and Yb\(^+\). Finally, the data yield isotope shifts of the 4s\(~^2\)S\(_{1/2} \leftrightarrow 3\)d\(~^2\)D\(_{3/2}\) transition at 10 part-per-billion through combination with recent data of Knollmann et al (2019).
We perform Ramsey interferometry on an ultracold 87Rb ensemble confined in an optical dipoletrap. We use a \pi-pulse set at the middle of the interferometer to restore the coherence of the ...spinensemble by canceling out phase inhomogeneities and creating a spin echo in the contrast. However,for high atomic densities, we observe the opposite behavior: the \pi-pulse accelerates the dephasingof the spin ensemble leading to a faster contrast decay of the interferometer. We understand thisphenomenon as a competition between the spin-echo technique and an exchange-interaction drivenspin self-rephasing mechanism based on the identical spin rotation effect. Our experimental data iswell reproduced by a numerical model.
In this work, the use of the Z2-FET (Zero subthreshold swing and Zero impact ionization FET) for Electro-Static Discharge (ESD) protections is demonstrated. The device, fabricated with Ultra-Thin ...Body and Buried Oxide (UTBB) Silicon-On-Insulator technology, features an extremely sharp off-on switch and an adjustable triggering voltage (Vt1). The principle of operation, relying on the modulation of electron and hole injection barriers, is reviewed. The impact of process modules and design parameters on electrical characteristics is analyzed with TCAD simulations, showing that very low leakage current (Ileak) and triggering capability adapted to local protection schemes are achievable. Experimental results validate the possible use of this device as an ESD protection in the 28nm FDSOI technology.
In this work, the use of the Z super(2)-FET (Zero subthreshold swing and Zero impact ionization FET) for Electro-Static Discharge (ESD) protections is demonstrated. The device, fabricated with ...Ultra-Thin Body and Buried Oxide (UTBB) Silicon-On-Insulator technology, features an extremely sharp off-on switch and an adjustable triggering voltage (V sub(t) sub(1)). The principle of operation, relying on the modulation of electron and hole injection barriers, is reviewed. The impact of process modules and design parameters on electrical characteristics is analyzed with TCAD simulations, showing that very low leakage current (I sub(leak)) and triggering capability adapted to local protection schemes are achievable. Experimental results validate the possible use of this device as an ESD protection in the 28 nm FDSOI technology.
