Research

We are interested in non-equilibrium dynamics and the quantum description of low-dimensional ultracold atoms in a continuum. Our multiple-RF (MRF) dressing technique provides a unique, highly configurable bilayer trap for creating, manipulating, and probing quantum many-body systems, featuring an extremely smooth trapping potential, a low heating rate, as well as the possibility to access curved geometry [1, 2].

[1] Ultracold atoms in multiple-radiofrequency dressed adiabatic potentials. Phys. Rev. A 97, 013616 (2018)

[2] Perspective: quantum simulations with bilayer 2D Bose gases in multiple-RF-dressed potentials. AVS Quantum Science 6, 030501 (2024)

Precision probe of continuous quantum systems

Thermal and quantum fluctuations of low-dimensional quantum gases are predominantly encoded in the complex phase of the wavefunction, yet their precise and local experimental probe remains a challenge, particularly in two dimensions. We have developed a selective matter-wave interferometry technique for two-dimensional (2D) Bose gases that directly probes the local relative phase between two atomic clouds [3], providing a precise measure of phase fluctuations and enabling detailed analysis such as extraction of two-point and higher-order correlation functions. The precise matter-wave interferometry technique and the stability of our experimental apparatus have also enabled us to identify universal non-Gaussian order parameter statistics down to the 0.1% level in probability density [4]. Complementing this, we have developed a novel noise interferometry scheme, in collaboration with theory partners, which directly probes common-mode phase fluctuations [5].

These experimental and data analysis methods together enable full statistical state readout of bilayer 2D quantum gases. Machine-learning-enhanced analysis is also being developed to extract information beyond the reach of conventional methods [6].

[3] Observation of the BKT transition in a 2D Bose gas via matter-wave interferometry. Phys. Rev. Lett. 128, 250402 (2022)

[4] Universal non-Gaussian order parameter statistics in 2D superfluids. arXiv:2601.16204 (2026)

[5] Detecting phase coherence of 2D Bose gases via noise correlations. Phys. Rev. Lett. 134, 183407 (2025)

[6] CNN-Based vortex detection in atomic 2D Bose gases in the presence of a phononic background. Mach. Learn.: Sci. Technol. 6, 015067 (2025)

Investigation of 2D Quantum Fields

The two layers of 2D quantum gases in our bilayer trap can be brought very close, providing precise control of the strength of quantum mechanical tunneling between the clouds. This introduces a distinct degree of freedom, the relative phase between the layers. Our MRF-dressed bilayer trap provides a uniquely clean and tunable platform to explore such physics, described by the sine-Gordon field model, a prototypical quantum field theory with topological excitations of wide relevance. This positions our bilayer system as a tunable quantum simulator for a range of important many-body models, as well as non-equilibrium phenomena of layered superconductors. So far, we have observed the emergence of interlayer coherence in a bilayer superfluid phase [7], an important signature of bilayer order in 2D.

[7] Observation of a bilayer superfluid with interlayer coherence. Nat. Commun. 16, 7201 (2025)

Universal non-equilibrium dynamics

Equilibration of classical systems has been described with great success, but there remain open questions about how quantum systems reach equilibrium: what role do local dynamics play in thermalisation, and over what timescale does thermalisation occur? Thermalisation close to a critical point is especially interesting since the corresponding equilibrium state is described by universal scaling laws, but it is not known to what extent universality remains valid out of equilibrium. Systems confined to two dimensions are particularly rich: in the ultracold gases we study, fluctuations play a large role and prevent true long-range order, yet a transition to quasi-long-range order exists. We investigate the relaxation dynamics in the presence of this critical point and compared them with real-time renormalisation-group theory predictions [8]. We have also probed universal dynamics in a coupled bilayer superfluid, where the dynamics is triggered by a sudden introduction of coherent Josephson coupling between the two 2D Bose gases [9].

[8] Universal scaling of the dynamic BKT transition in quenched 2D Bose gases. Science 382, 443 (2023)

[9] Coupling-induced universal dynamics in bilayer two-dimensional Bose gases. arXiv:2510.23600 (2025)