Periodic Reporting for period 2 - Q-Sense (Quantum sensors - from the lab to the field)
Reporting period: 2018-01-01 to 2019-12-31
1) Space Optical Clock (SOC2): It is based on cold Sr atoms and aimed to pave the way for an ultra-stable and ultra-precise clock on the International Space Station and in space. The setup has reached a landmark stability of 3 parts in 10^18, meaning that the clock will deviate less than a second over the age of the universe (~14B years). This has become one of the most stable clocks in the world, the other two being ~1 part in 10^18. However these two clocks are based on Lab based setups. 2) Sub 10 mHz Laser: Ultra stable quantum clocks also require ultra stable clock lasers. This is typically achieved by stabilising the laser to a passive Fabry-Pérot resonator with the Pound-Drever-Hall (PDH) stabilization technique. We follow this approach by stabilizing a commercial DFB fiber laser to a Fabry-Pérot resonator made of single-crystal silicon cooled to 124 K. Both the cavity spacer and the mirror substrates are made out of the same crystal. We demonstrate unprecedented fractional frequency instability of 4×10-17 with the linewidth at 1.5 μm is 10 mHz, corresponding to a coherence time of 100s. This is a world record so far and achieves the coherence times required to do gravitational wave astronomy using quantum clocks. This work benefits from the knowledge exchange between Europe (PTB, Germany) and the US (University of Colorado). 3) Effect of Space-Time Curvature on an Atomic Wave function- Einstein’s theory of gravity utilizes the concept that space-time is curved. For the first time, the effect of it has been measurement on the wavefunction of a single atom. 1nrad phase with the gradiometer resolution of 3 × 10−9 s−2 per shot, has been measured. This work benefits from the knowledge exchange between Europe (UoB (UK), ULM & ULUH (Germany)). 4) Humanitarian Demining: Gravity mapping and gravity measurements are extremely useful for human demining and civil engineering work. Gravity sensors response is different for different soil type and whether is the soil is dry or wet. Joint Research Centre (Ispra, Italy) provides such a facility with x-y scanner. A sub-site within the JRC was identified by Adam Lewis (JRC) as having potential for obtaining field gravity data, both with current commercial gravimeters and future quantum gravimeters and gradiometers. Leica GPS equipment and a Scintrex CG-5 spring based gravimeter were taken to the site.This work has a possibility to impact policy making at the EU level. JRC work and reporting typically feeds into policy making. We have 8 publications including the high impact journals like PRLs (these publications are published in OpenAire Zenodo website).