Rubidium vapor EIT quantum memories

Slovenia-Croatia bilateral research project „Development of building blocks for new European quantum communication network“, funded by the ARRS and HRZZ



IPS-2020-01-2616 Razvoj gradivnih blokova za novu europsku kvantnu komunikacijsku mrežu

Duration: October, 1st 2020 – September, 30st 2023. Budget: 1.499.999,00 HRK

Project team:
prof. dr. Anton Ramšak, University of Ljubljana, Slovenia
Mario Stipčević (PI), Matej Peranić, Martin Lončarić – Ruđer Bošković Institute, Zagreb, Croatia
Ticijana Ban, Damir Aumiler, Danijel Buhin, Mateo Kruljac – Institute of physics

General objectives:
In a collaboration between partners in Ljubljana and Zagreb, we propose to realize central building blocks towards building a functioning quantum repeater for a future quantum network using existing telecom infrastructure. These include narrow-band sources of entangled photons of telecom photons and atom-based quantum memories to store these photons and the quantum information they carry for a sufficiently long time to facilitate connecting distant communication partners.

Specific objectives:
a) Building narrow-band sources of entangled photons at the telecom wavelength of 1550 nm. One in Ljubljana, one in Zagreb.
b) Build two types of atom-based quantum memories in Ljubljana and Zagreb based on existing expertise with two candidate atom types, respectively: Cesium (Cs) and Rubidium (Rb).
c) Realizing high-efficiency, narrow-band frequency converters to interface the quantum memories with the entangled sources.
d) Demonstrate entanglement swapping with photons retrieved from two distinct quantum memories to establish entanglement of telecom photons originating from independent sources. To this end, one of the two stored photons again needs to be frequency converted.

Our team participate in WP3 – Atom-based quantum memories

In WP3, quantum memories will be built and tested in Ljubljana and in Zagreb. These memories will use Cesium atoms and Rubidium atoms, respectively. This approach allows us to build on existing expertise at the IJS and the IFZg, and we will have the opportunity to compare the performance of these two complementary approaches. As an additional benefit, we will have the opportunity to test the feasibility of performing entanglement swapping with photons originating in two different types of quantum memories – a key building block for future quantum networks where the architectures used at different nodes may be different. Building and testing the quantum memories in Ljubljana and in Zagreb will be covered in separate tasks in this work package.

January 2021.
Laser has been set up and is ready for locking to the D1 Rb transition.



December 2020.
We have started our QM journey with setting up a new breadboard and laser with the wavelength of 795 nm.