Check out our latest work on the trapping of strontium atoms in optical tweezer arrays generated via holographic metasurfaces. We demonstrate a high degree of array uniformity in terms of trap depth, trap frequency, and positional accuracy. Furthermore, we show that - due to sub-micrometer pixel sizes and high pixel densities - holographic metasurfaces open a path towards optical tweezer arrays with more than 100,000 traps. A big thank you to the TweeSr team and our collaborators at the Nanfang Yu lab for the amazing work! 

Link: arXiv:2411.05321

In this work, we study three-body collisions in a gas of ultracold dipolar molecules. Our data shows that three-body recombination can explain performance limits of microwave-shielding, which have so far been unexplained. We compare experimental data of three-body loss rates with the results of a classical trajectory model for recombination and find excellent agreement. The insights are efficient cooling of dipolar molecules and point to rich three-body physics. 

https://arxiv.org/pdf/2407.04901

Recent work has shown that microwave dressing can massively enhance the collisional lifetime and enable Bose-Einstein condensation of molecules. In this work, we analyze the impact of microwave dressing on the  single molecule level. We develop dressed-state spectroscopy as a new spectroscopic method and find that a magic rotational transition can be engineered in NaCs molecules by controlling their optical polarizability with microwave fields. All details in our preprint: 

https://arxiv.org/pdf/2406.19308

Link to manuscript Nature (2024) 

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In collaboration with the Nanfang Yu Lab at Columbia, we have developed a technique to trap atoms in optical tweezer arrays, generated via holographic metasurfaces. The picture shows a flouresence image of Sr atoms,  cooled and trapped in a metasurface tweezer array with a mean tweezer spacing of 3 um. The technique allows creation of atom arrays with arbitrary geometry and high laser power. Congrats to the entire TweeSr and Yu Lab Team on this wonderful achievement! 

Our latest preprint is out - we report the first creation of a Bose-Einstein condensate of dipolar ground state molecules. We evaporatively cool a gas of NaCs molecules from 700 nK to 6 nK above absolute zero. At this point the molecular gas forms a Bose-Einstein condensate, the coldest molecular gas to date. The lifetime of the BEC is ~2 sec. This becomes possible with an enhanced collisional shielding method that suppresses loss by 4 orders of magnitude. Thanks so much to the entire NaCs team - past and present members - for all the amazing work on this monumental project! https://arxiv.org/abs/2312.10965

We are extremely grateful that the Betty and Gordon Moore Foundation is supporting our effort on ultracold dipolar molecules, in particular the creation and investigation of Bose-Einstein condensates of dipolar molecules. Thank you to the entire NaCs team - past and current members - for driving this project forward with so much dedication and energy! 

Read more here: Sebastian Will Is on a Quest for Ultracold Quantum Control

We propose and demonstrate a graph-based method that allows for the automated detection of laser cooling schemes in complex molecular spectra. The method leverages a change of representation, reinterpreting quantum states and transitions between them as a network graph that can be efficiently searched with modern search tools. We are excited for use cases with molecules, but the method may actually be more generally applicable, for any quantum systems with a discrete spectra. Kudos to Anna and Niccolò for spearheading this effort! 

Link: https://arxiv.org/abs/2311.08381

Our paper reporting microwave shielding and first evaporative cooling of bosonic dipolar ground state molecules just came out in Nature Physics! We observe sample lifetimes of 1 second (100x improvement compared to previous) and cool bosonic molecules to the coldest temperatures yet (~30 nK above absolute zero), which should be an important stepping stone for further cooling towards quantum degeneracy. Congrats to the entire team and to Niccolò and Ian for leading this effort! 

Link: Nature Physics 19, 1579-1584 (2023)

Article by Ellen Neff: A Microwave Shield Yields Ultracold Dipolar Molecules

For microwave-shielding of NaCs molecules we developed a cloverleaf microwave antenna that can produce clean circularly polarized microwave fields. Clean circular polarization can be helpful for quantum control applications with atoms and molecules, and potentially other quantum hardware systems. Congrats to the entire team and thank you to Weijun and Siwei for leading this! Link: https://arxiv.org/abs/2306.14791

Our paper on the efficient creation of ultracold NaCs molecules just appeared in New Journal of Physics. We show STIRAP transfer to the absolute ground state with almost 90% efficiency. We are very excited about this as it allows the preparation of dipolar NaCs molecules at colder temperatures and efficient detection. Congrats to the entire team and to Claire for leading this effort! Link: New J. Phys. 25, 053036 (2023)

In this work, we demonstrate that holographic metasurfaces can generate versatile optical tweezer arrays. We demonstrate exotic lattice geometries in 1D, 2D, and 3D, including necklace, triangular, Kagome, honeycomb, twisted bilayer. We are excited to apply this for the generation of atomic tweezer arrays. In collaboration with our Columbia colleagues Nanfang Yu and Ana Asenjo-Garcia, and thanks to Xiaoyan Huang and Weijun Yuan for leading this effort! Link: Prog. Quantum Electron. 100470 (2023)

Our paper on the creation of ultracold NaCs ground state molecules just appeared in Physical Review Letters. Among other things, we show strong microwave coupling for rotational states (~45 MHz Rabi frequency). Congrats to Ian and the entire team on the amazing work! Link: Phys. Rev. Lett. 130, 113003 (2023)

In this week's Nature magazine Tanya Zelevinsky and Sebastian discuss newly discovered resonance phenomena in ultracold molecular gases and give an outlook on their impact on future research in quantum chemistry and quantum simulation with molecules. Link: Nature, 614, 35-36 (2023)

Our TweeSr Lab is greeting the New Year with strontium atoms trapped in optical tweezer arrays! The array is generated with a crossed AOD setup. Congrats to the entire TweeSr team on this wonderful achievement & Happy New Year to everyone! 

Sebastian and Prof. Henry Yuan from the Columbia Computer Science department comment on the history, accomplishment, and impact of John Clauser's work for quantum science and technology today. Clauser conceived his concept to experimentally test Bell's inquality while being a grad student at Columbia University in the 60s. Together with Alain Aspect and Anton Zeilinger, he received the Physics Nobel Prize 2022. Watch the video here: https://youtu.be/z-qJiNQIquc

In this preprint, we present a new cold atom source for strontium based on a two-dimensional magneto-optical trap (2D MOT) that is directly loaded from the atom jet of a dispenser. The design addresses the importnat challenge of reducing the complexity of cold beam sources for strontium, which is relevant for optical atomic clocks and quantum simulation and computing devices based on ultracold Sr. Thanks to Minho and Aaron and the entire team for driving forward this approach! https://arxiv.org/abs/2210.14186

In this work, we propose metasurface holograms as a novel platform to generate optical trap arrays for cold atoms with high fidelity, efficiency, and thermal stability. We have characterized the resulting patterns of light which may find potential applications in atomic clocks, quantum optics, quantum simulation and quantum computing. Thank you to the entire team, especially to our collaborators from the Asenjo-Garcia and Yu groups! https://arxiv.org/abs/2210.07425 

Our latest preprint just appeared on arxiv reporting the first ultracold gases of NaCs ground state molecules ⚛️-⚛️. Ultracold gases of dipolar NaCs molecules open new exciting opportunities for quantum simulation and quantum information - and we cannot wait to explore them. Thanks a lot to the  NaCs team for all the amazing work that led to this!

https://arxiv.org/abs/2206.00652

We started the new "Quantum Simulation and Computing Lab" course this semester. Students gain hands-on experience with entangled photon pairs, learn about quantum computing hardware, quantum algorithms, and how to program quantum computers. Thanks a lot to our TA team - Aden, Joseph, Shuhan, and Arjun - for making it a great success! Here an article in Columbia News.

Aden Lam, our first grad student graduates! Thank you, Aden, for going on this crazy  journey as the first lab member, starting from an empty lab. Congratulations on the successful defense and on an impressive thesis that documents all the wonderful things that you achieved! 

The coldest place in New York City is our NaCs lab! Thanks a lot to Columbia for making this beautiful video and thanks to everyone in the lab, who helped making this wonderful instrument a reality! Watch the video here: Youtube.

Check out our latest preprint on arxiv - first high phase-space density gases of NaCs Feshbach molecules & an exciting step towards ultracold gases of dipolar NaCs ground state molecules ⚛️-⚛️. Thank you to the entire NaCs team for the amazing work! Link to the preprint: 

https://arxiv.org/abs/2202.03355

Check out our latest preprint - if you have ever wondered, whether carbon dimers can be laser cooled this paper may offer some answers. Thanks a lot, Niccolò, for leading this study! Link to the preprint: 

https://arxiv.org/abs/2112.10745

QPOP - Quantum Physics Outreach Program - that we have developed in collaboration with STEMteachersNYC is featured on the Columbia News. It has reached more than 100 teachers across the nation so far. Thank you, Claire and everyone involved!

Sebastian gives the first in-person seminar at the Joint Quantum Institute (JQI) at University of Maryland/NIST. The talk was also live streamed on Youtube. It is available here: JQI Seminar

We made our first 3D MOT of Strontium using a completely homebuilt source. Congrats to the entire TweeSr team, Minho, Aaron, Siwei, Weijun, Max, and Quan, on this great achievement!

Our paper on overlapping Bose-Einstein condensates of Na and Cs came out in PRA with an Editors' Suggestion. Congrats to the entire team for the amazing work! Check out the paper here:  Phys. Rev. A 104, 033302 (2021)

We received a  DURIP award from the Office of Naval Research supporting our NaCs molecule effort. Thanks a lot to the ONR DURIP program for the tremendous support! More information here.

We had a very successful DAMOP this year with Minho, Aden, Claire, Niccolò, Aaron, and Weijun all presenting on our recent developments. Nice job all!