Engineering high Pockels coefficients in thin-film strontium titanate for cryogenic quantum electro-optic applications
- Anja Ulrich
- Kamal Brahim
- Andries Boelen
- Michiel Debaets
- Ahmed Khalil
- Conglin Sun
- Yishu Huang
- Sandeep Seema Saseendran
- Marina Baryshnikova
- Paola Favia
- Thomas Nuytten
- Stefanie Sergeant
- Kasper Van Gasse
- Bart Kuyken
- Kristiaan De Greve
- Clement Merckling
- Christian Haffner
2025-10-23
Pockels materials are notable for their strong electro-optic interaction and rapid response times and are therefore used extensively in optical communications. However, at cryogenic temperatures, Pockels coefficients are reduced in many materials optimized for room-temperature operation, which is a major hurdle for emerging quantum technologies. Here, we show that strontium titanate (SrTiO 3 ) can be engineered to exhibit a Pockels coefficient of 345 picometers per volt at 20 hertz at cryogenic temperatures, a value twice as high as any other thin-film electro-optic material. By adjusting the stoichiometry, we were able to increase the Curie temperature and realize a ferroelectric phase yielding a high Pockels coefficient, so far with limited optical losses of decibels per centimeter. Our findings position SrTiO 3 as a promising material for cryogenic quantum photonics applications.