The Cold Molecule Group

David Röser visits to measure isotope shifts in Zinc (01/2023)

David Röser, a graduate student at the University of Bonn and a UVQuanT collaborator, visited us for two weeks to measure isotope shifts in atomic Zn using our buffer gas beam. He brought along an ultrastable Menlo ORC cavity, with which we were able to ensure a narrow laser linewidth (~10 kHz) and highly linear detection laser scan.

Max Doppelbauer defends his PhD thesis in Njimegen (12/2022)

Congratulations to Max Doppelbauer, who successfully defended is his PhD thesis at Radboud University, Njimegen! Max's thesis is titled "The AlF molecule as a candidate for laser cooling and trapping”, and brings together much of the work in the group over the past five years. He will continue to work as a Postdoctoral Researcher in the group.

A continuous source of AlF molecules (10/2022)

Whilst AlF can be produced at high temperatures via a chemical reaction, this method has so far not been used to generate a continuous molecular beam in our group. After a few different attempts, we found a method of generating a stable beam of AlF molecules capable of operating for several days. This enabled us to take a 2 THz-wide spectrum of the rovibrational structure of the A-X transition with a precision of 10 MHz, containing an enormous amount of information (more than 300 resolved rovibrational lines!). We hope that this source will prove useful for further experiments with AlF.

Dr Stefan Truppe begins Senior lecturehip at Imperial College (07/2022)

Stefan Truppe leaves the institute to take up a permanent position as Senior Lecturer at Imperial College London. Congratulations Stefan! We will continue working closely together on all things AlF and DUV laser related.

Russell Thomas joins the group (03/2022)

We are excited to have Russell Thomas from the UK joining the institute, where we will work as a laser engineer in our group and support others across the Molecular Physics department. He has extensive extensive experience in installing, testing and optimising DUV laser systems relevant for laser cooling AlF molecules. Welcome Russell!

UVQuanT laser development funding (03/2022)

Dr Stefan Truppe secures funding for deep ultraviolet laser development in a industry/acadmemic partnership within the Horizon program of the European Union. Together with teams at the University of Bonn, University of Firenze, Chalmers University, and three industrial partners, we will push continuous laser technological capabilities in the 230-185 nm range. The project is entitled Deep Ultraviolet Lasers for Quantum Technology (UVQuanT), and is a four year program beginning in October 2022.

Experiments with MgF molecules (07/2021)

As part of an investigation into molecule production in buffer gas sources, we produced a beam of cold MgF molecules in the same machine we use to generate AlF. Like AlF, MgF is a laser cooling candidate, but much less is known about its first electronically excited state. We undertook a study to measure the rotational and hyperfine structure of the first electronically excited state, and its dipole moment. We found that excited states of opposite parity are much closer in energy than would be naively expected, and this has consequences for optical cycling with MgF.

Eduardo Padilla joins the group (07/2021)

We are delighted that Jose Eduardo Padilla-Castillo from Cozumel, Mexico has joined us as a new PhD student. Eduardo completed his Masters at Mexico City studying quantum degenerate gases of ⁶Li₂ Feshbach molecules, making the first Bose Einstein Condensate ever produced in Mexico. He will work on laser cooling and trapping of cadmium atoms and AlF molecules. Welcome Eduardo!

Our first MOT of cadmium atoms (04/2021)

We loaded our first magneto-optical trap (MOT) of cadmium atoms, by direct loading from a cryogenic buffer gas beam. We are able to separately trap all stable isotopes using the strong deep ultraviolet transition near 228 nm. This is a convenient test platform for future experiments on the AlF molecule.

First signal from the improved buffer gas machine (09/2020)

We have designed and assembled an upgraded cryogenic molecular beam source. This enables faster thermal cycling of the machine, more detailed measurements of the molecules in and outside of the buffer gas cell, and straightforward comparison of the production efficiency of various species.

08/20 Publication
The b³Σ⁺ state of AlF allows for efficient spectroscopic detection of molecules in the a³Π state and is a candidate for optical cycling. We determined its radiative lifetime, fine and hyperfine structure spectroscopically. We observed and described the perturbation between the b³Σ⁺ and the nearby A¹Π state that arises from spin-orbit coupling with a constant Aso of 10 cm-1.
Mol. Phys., accepted, Preprint.

11/19 Publication
The AlF spectroscopy paper is finally finished and published.
We measured the detailed energy level structure of AlF in the X¹Σ⁺ electronic ground state, in the A¹Π state, and in the metastable a³Π state that are relevant for our laser cooling and trapping experiments. In our study, we determined the rotational, vibrational and electronic branching ratios from the A¹Π state and concluded that AlF is an excellent candidate for laser cooling on any Q-line of the A¹Π - X¹Σ⁺ transition and for trapping at high densities.
Read it at PRA with open access: Link. Preprint available at arXiv.

11/19 Lab Update
We report the transverse deflection of a cryogenic beam of AlF molecules by scattering photons on the Q(1) line of the main cooling transition. The deflection in the preliminary picture on the left corresponds to 40 scattered photons and a deflection of 1.7mm.

11/17 Lab Update
First laser system to produce up to 200 mW of 227nm light is installed. Picture by Eike Mucha.

07/17 Lab Update
First signal of our new favourite molecule: AlF. We drive the a3Pi1 - X1Sigma transition near 367 nm with a doubled pulsed dye laser and ionize the molecules with an excimer laser.