Postdoc on Continuous Optical Clocks

Are you eager to push optical atomic clocks to new levels in a lively, international research group? Do you enjoy creating complex machines that have never existed before? Do you want to explore physics that nobody else has seen? If yes, then you might want to join the Ultracold Strontium Group at the Institute of Physics as a postdoc on our exciting journey towards superradiant and zero-deadtime clocks.

Join Us!

Optical clocks have reached a precision of better than 10-18, which enables them to resolve the relativistic time dilation by only 1cm height difference in the gravitational field of earth. They are useful for searches of physics beyond the standard model, exploration of many-body physics, and societal applications, such as navigation. So far, clocks operate in a pulsed manner, preparing a sample of ultracold atoms and then interrogating that sample. Reaching the ultimate precision needs averaging of 10 thousand samples, taking several hours.

You will join a team building clocks that will overcome this limitation, effectively interrogating the atomic sample continuously. This enables reaching the ultimate precision already after just a few minutes, which is useful for many applications. We want to achieve this by creating clocks that can operate truly continuously, using technology that we have developed to achieve continuous Bose-Einstein condensation [Nature 606, 683 (2022)]. We are building two types of such clocks: a superradiant clock and a zero-deadtime clock. A superradiant clock is a laser that lases on an ultranarrow optical transition. You can read about our plans for this clock in Sheng Zhou’s PhD thesis. For the zero-deadtime clock, we supply atoms from a continuous ultracold Sr source to four clock interrogation zones that are in one vacuum chamber. Clock interrogation can always be executed in at least one zone, while others are reloaded with atoms, enabling continuous operation. With this postdoc position you can contribute to both efforts.

This is what you will do

You will join a team of several PhD students and potentially other postdocs to further develop our continuous optical clocks. This includes experimental work with the clocks, such as debugging and data taking, designing and constructing upgrades to the machines, data analysis, literature research, article writing, and contributing to the acquisition of funding. We ask you to become independent by taking initiatives and developing your own creative ideas. You will also take an active role in group activities, such as master and PhD student education, presentation of your work, maintenance of lab organization, and societal and stakeholder outreach.

What we ask of you

We are looking for someone who is excited about pushing novel types of ultracold atom experiments to new reals of AMO physics. You also should have

• a recent PhD in experimental ultracold atom or trapped ion physics.


• great team working skills.


• initiative and good time management skills.


• good communication skills in oral and written English.

This is what we offer you

We offer a temporary employment contract for 38 hours per week for a period of 24 months, with a probationary period of 12 months. The preferred starting date is Autumn 2026, but earlier or later can be discussed.   The gross monthly salary, based on 38 hours per week and dependent on relevant experience, ranges between € 3,546 to € 5,538 (Scale 10). This does not include 8% holiday allowance and 8,3% year-end allowance. The UFO profile Researcher is applicable. A favourable tax agreement, the ‘30% ruling’, may apply to non-Dutch applicants. The Collective Labour Agreement of Universities of the Netherlands is applicable.

You will work in this team

The Faculty of Science has a student body of around 8,000, as well as 1,800 members of staff working in education, research or support services. Researchers and students at the Faculty of Science are fascinated by every aspect of how the world works, be it elementary particles, the birth of the universe or the functioning of the brain.

The Institute of Physics (IoP) of the Faculty of Science combines the Van der Waals-Zeeman Institute (WZI), the Institute of Theoretical Physics (ITFA) and the Institute for High Energy Physics (IHEF) and is one of the large research institutes of the Faculty of Science at the University of Amsterdam. The Van der Waals - Zeeman Institute for Experimental Physics (IoP-WZI) is part of the IoP and home to three research clusters: Quantum Gases & Quantum Information (QG&QI), Quantum Materials (QMat), and Soft Matter (SM).

You will work in the Strontium Quantum Gases Group, part of the QG&QI cluster and headed by Prof. Dr. Florian Schreck. We exploit ultracold Sr gases for quantum sensing, the study of many-body physics and for quantum computing. We explore new ways to build sensors, such as superradiant clocks and collaborate with industry, startups and users to bring quantum technology to the market. This project is embedded in the Quantum Delta NL Ultracold Atom Quantum Sensing Testbed, which will allow you to contribute to many interesting projects related to clocks, such as creating a European optical time and frequency distribution network, or building an industry prototype of an optical clock. Our group is furthermore exploring continuously operating atom interferometers, quantum simulation experiments using Rb-Sr mixtures, single Sr atoms in optical tweezer arrays and improved ways to build optics. Your project will profit from synergy with all these activities.

If you feel the profile fits you, and you are interested in the job, we look forward to receiving your application. You can apply online via the button below. We accept applications until the position has been filled.

If you have any questions or do you require additional information? Please contact:

• Prof. Dr. Florian Schreck, [email protected]

Applications should include the following information (all files besides your cv should be submitted in one single pdf file):

• a detailed CV including the months (not just years) when referring to your education and work experience;


• a letter of motivation;

• a list of publications;


• the names and email addresses of two references who can provide letters of recommendation.

A knowledge security check can be part of the selection procedure (for details: national knowledge security guidelines).