Book of Abstracts and Poster List
FINESS 2026
19–23 July 2026 • Boulder, Colorado, United States
Monday, 20 July 2026
Session Chair: Ana M. Rey
09:00–09:40 | Sebastian Will
Self-Bound Droplets in a Bose-Einstein Condensate of Dipolar Molecules
Author: Sebastian Will, Columbia University, Department of Physics, New York, NY, USA
Ultracold dipolar molecules offer access to strong long-range interactions and have
been envisioned as a powerful platform for many-body quantum physics. However,
cooling molecules to quantum degeneracy has been challenging.
Recently, we have created the first BEC of dipolar molecules [1]. We evaporatively
cool a gas of sodium-cesium molecules to below 10 nanokelvin, deep in the quantum
degenerate regime, with lifetimes of several seconds. This dramatic improvement
over previous molecular cooling efforts is enabled by collisional shielding via
microwave dressing, suppressing inelastic losses by four orders of magnitude [2].
Microwave dressing also provides an exceptional level of tunability of dipole-dipole
interactions, opening the door to novel phases of matter in molecular quantum
liquids. Most recently, we have observed self-bound droplets and droplet arrays in a
gas of strongly dipolar molecules [3].
In this talk, I will describe our experimental approach, discuss recent results, and give
an outlook on new opportunities enabled by molecular BECs for quantum simulation
and many-body quantum physics.
References:
[1] Bigagli, Yuan, Zhang, et al., Observation of Bose-Einstein condensation of
dipolar molecules, Nature 631, 289-293 (2024)
[2] Yuan, Zhang, et al., Extreme loss suppression and wide tunability of dipolar
interactions in an ultracold molecular gas, arXiv:2505.08773 (2025)
[3] Zhang, Yuan, et al., Observation of self-bound droplets of ultracold dipolar
molecules, Nature, 651,601-606 (2026)
09:40–10:20 | Adam Kaufman
A new approach to programmable Hubbard systems
Author: Adam Kaufman, JILA and University of Colorado Boulder
References:
10:20–10:40 | Piotr Deuar
New perspectives for simulations of quantum dynamics and LHY physics in Wigner and positive-P phase space
Authors: Piotr Deuar, Institute of Physics, Polish Academy of Sciences
Recent years have seen a re-invigoration of the use of phase-space representations to simulate many-mode quantum dynamics using approaches such as truncated Wigner and positive-P methods. Two of the reasons for this have been: i) A shift to the study of open many-mode systems and hybrid setups consisting of mutually coupled open and Hamiltonian subsystems --- for which previously onerous instabilities are pacified and full quantum dynamics is seen to be stable with sufficient dissipation, and ii) A wider appreciation of the importance of the study of single many-body realizations affected by quantum fluctuations --- something that is accessible far more easily with a phase-space approach.
I will present some recent developments: - "Phase" diagrams of driven dissipative Bose-Hubbard and Jaynes-Cummings spin lattices showing regions in which scalable quantum dynamics are possible [1,2]. - Use of the truncated Wigner to access single self-organized realizations of cavity bosons beyond the adiabatic elimination approximation -- and surprising evidence that its accuracy actually grows strongly with system size [3]. - Use of positive-P approaches to accurately simulate noisy intermediate-scale quantum optical neural networks [4] and X-ray superfluorescence initiated by pulses of XFELs (X-ray free-electron lasers) [5]. - Finally: a successful attempt to use the Wigner representation to generate single realizations of Bose gases and quantum droplets that display LHY physics without use of the LHY functional or a local density approximation. This allows us to study the limits of accuracy of the extended GPE (EGPE) model [6,7].
References:
[1] P. Deuar, A. Ferrier, M. Matuszewski, G. Orso, M.H. Szymanska, Fully Quantum Scalable Description of Driven-Dissipative Lattice Models, PRX Quantum 2, 010319 (2021).
[2] A. Ferrier, Yi Shi, M.H. Szymańska, P. Deuar, Positive-P Simulations for Open Quantum Spin Systems, arXiv:2603.xxxxx
[3] G. Orso, J. Zakrzewski, P. Deuar, Self-Organized Cavity Bosons beyond the Adiabatic Elimination Approximation, Phys. Rev. Lett. 134, 183405 (2025)
[4] S. Swierczewski, W. Verstraelen, P. Deuar, B. Pietka, T. C. H. Liew, M. Matuszewski, A. Opala, Phase-space framework for noisy intermediate-scale quantum optical neural networks, arXiv:2507.07684
[5] S. Chuchurka, A. Benediktovitch, S. Krusic, A. Halavanau, N. Rohringer. Stochastic modeling of x-ray superfluorescence. Phys. Rev. A 109, 033725 (2024)
[6] King Lun Ng, M.B. Kruk, P. Deuar, Lee-Huang-Yang dynamics emergent from a direct Wigner representation, arXiv:2603.yyyyy
[7] King Lun Ng, M.B. Kruk, P. Deuar, Quantum droplets emergent from a Wigner representation of a Bose gas without local density assumptions, arXiv:260z.zzzzz
Session Chair: Haoqing Zhang
11:00–11:40 | Axel Pelster
On the open-dissipative nature of photon Bose-Einstein condensates
Authors: Axel Pelster, Physics Department and Research Center OPTIMAS, RPTU Kaiserslautern-Landau, Germany
Photon condensation was first observed in 2010 within a dye-filled microcavity at room temperature and gained interest since then. A deeper understanding is particularly needed as to whether the stationary states are of equilibrium or non-equilibrium nature. To this end we examine at first how the driven-dissipative nature of a photon Bose–Einstein condensate modifies the condensation process [1]. To this end, we consider a rate-equation model, which can be derived microscopically [2]. It depends on external parameters such as emission and absorption rates as well as cavity photon losses. In steady state, the photon occupation follows an open-dissipative Bose–Einstein distribution whose chemical potential is set self-consistently by the dye’s ground- and excited-state populations. We show that driven-dissipative parameters strongly alter the distribution and use these results to distinguish photonic condensation from both atomic condensation and lasing. Although open-dissipative quantum fluids have extensively been studied numerically, analytical descriptions are rare. Here we show that generalizing the standard optimization method for closed systems yields a projection optimization method, which is applicable for open-dissipative systems [3]. As an example we analyze a complex Gross–Pitaevskii equation that heuristically models a harmonically trapped photon Bose–Einstein condensate. Together with established methods from hydrodynamics, we obtain an approximate dynamical vortex solution and demonstrate how open-dissipative parameters affect both vortex size and stability. The resulting information is useful for possibly realizing vortices in photon Bose-Einstein condensates.
References:
[1] J. Krauß, E. Stein, and A. Pelster, Europ. Phys. J. Spec. Top. In Memoriam Hermann Haken: Synergetics and Self-organisation in Complex Systems (2026), https://doi.org/10.1140/epjs/s11734-026-02185-2 [2] M. Randonjić, W. Kopylov, A. Balaž, and A. Pelster, New J. Phys. 20, 055014 (2018).[3] J. Krauß, M.A.G. dos Santos Filho, F.E.A. dos Santos, and A. Pelster, Phys.Rev. Res. 7, 033007 (2025).
11:40–12:00 | Krzysztof Pawłowski
Fluctuations and correlations in ultracold gas at equilibrium
Author: Krzysztof Pawłowski
Fluctuations and correlations play a central role in characterizing quantum many-body systems. While they effectively capture intrinsic many-body features, they also serve as sensitive indicators of thermal effects and the specific physical constraints of the experimental setup.In standard statistical physics curricula and foundational textbooks, the analysis of fluctuations is typically conducted within the Grand Canonical Ensemble, following the original approach used by A. Einstein to derive Bose-Einstein condensation. However, this theoretical framework fails significantly when applied to a quantity as fundamental as the condensate atom number fluctuations in an isolated ideal gas - systems that closely resemble current experimental realizations. These discrepancies between ensemble predictions and physical reality are now being explored with increasing precision. Our joint theoretical and experimental team performed the world first observation of condensate atom number fluctuations [1], subsequently providing the first experimental evidence of their microcanonical nature [2]. To further the study of these phenomena, we have recently developed advanced numerical techniques, summarized in our comprehensive review [3], and established theoretical descriptions based on saddle-point approximations extended by higher-order cumulants (1D and 3D), the Yang-Yang approximation (1D), and the classical field approach.I will present these results alongside our current theoretical predictions regarding phase and density-density correlations. Specifically, I will address how these correlations behave in both ideal and interacting gases, highlighting the role of system dimensionality and experimental constraints.
References:
[1] On the fluctuations of the number of atoms in the condensate
MB Kruk, P Kulik, MF Andersen, P Deuar, M Gajda, K Pawłowski* (Corresponding Author), E. Witkowska, J. Arlt, K. Rzążewski
Reports on Progress in Physics 88, 106401 (2026)
[2] Observation of atom number fluctuations in a Bose-Einstein condensate
M.. Kristensen, M. B. Christensen, M. Gajdacz, M. Iglicki, K.Pawłowski, C. Klempt, J. F. Sherson, K. Rzążewski, A. J. Hilliard
Phys. Rev. Lett. 122, 163601 (2019)
[3] Observation of Microcanonical Atom Number Fluctuations in a Bose-Einstein Condensate
M. B. Christensen, T. Vibel , A.J. Hilliard, M.B. Kruk, K. Pawłowski, D. Hryniuk, K. Rzążewski, M. A. Kristensen, and J. J. Arlt
Phys. Rev. Lett. 126, 153601 (2021)
12:00–12:20 | Jonathan Mortlock
Dipolar molecules and Bose mixtures in a dual-species quantum gas microscope
Authors: Jonathan M. Mortlock*, Adarsh P. Raghuram, Francesca M. Blondell, Benjamin P. Maddox, Philip D. Gregory, and Simon L. Cornish. Department of Physics. Durham University
Quantum gas microscopes have transformed our ability to study strongly correlated quantum matter through single-particle-resolved detection [1]. Extending this capability to polar molecules and multi-component mixtures opens new directions in quantum many-body physics. We have built a dual-species quantum gas microscope for Rb and Cs to address this challenge.
We have demonstrated detection of individual RbCs molecules in a bulk sample by pinning molecules in an optical lattice, and then dissociating them to image either a Rb or Cs atom from each molecule [2]. By controlling the state-selective dissociation process we can map the internal state of the molecule to the recovered atomic species to realise spin and site resolved readout. I will discuss how this platform enables studies of dipolar interactions in molecular gases where long-range interactions give rise to rich spin-diffusion dynamics in a variety of settings. Another direction of interest I will cover is the study of the miscibility transition with microscopic readout of both components, where our platform allows access to a mixture with tuneable interactions and species-specific potentials.
References:
[1] Gross, Christian, and Waseem S. Bakr. ‘Quantum Gas Microscopy for Single Atom and Spin Detection’. Nature Physics 17, 12 (2021) https://doi.org/10.1038/s41567-0
[2] Mortlock, Jonathan M., Adarsh P. Raghuram, Benjamin P. Maddox, Philip D. Gregory, and Simon L. Cornish. ‘Multi-State Detection and Spatial Addressing in a Microscope for Ultracold Molecules’. Nature Communications 17, 518 (2026) https://doi.org/10.1038/s41467-025-67212-7.
Session Chair: Daniel Arrufat
14:00–14:40 | Thomas Pohl
Quantum phases of microwave-dressed molecules
Author: Thomas Pohl,Institute for Theoretical Physics, Vienna University of Technology, 1040 Vienna, Austria
Recent experimental breakthroughs in preparing and stabilizing ultracold ensembles of heteronuclear molecules have opened new avenues for investigating strongly dipolar quantum matter. In particular, the high degree to which the long-range interactions between molecules can be controlled and shaped with precisely tuned microwave fields suggests unique possibilities to explore new phases of dipolar matter and can yield conditions that challenge traditional descriptions of weakly interacting quantum gases. Here, we discuss these prospects from different angles. On the one hand, we employ path-integral quantum Monte Carlo simulations to study the phase diagram of microwave-dressed molecules, covering regimes from weak to strong interactions and from small to large particle numbers. The peculiar shape of micro-wave induced interaction is shown to stabilize self-bound quantum droplet states and drive transitions to two-dimensional superfluid phases or superfluid membranes, floating in free space with a thickness of a single molecule – and which can eventually undergo a transition to a crystalline monolayer that remains self-bound without external confinement. Moreover, consider the symmetries of the long-range interaction that arises for a given microwave configurations and discuss their consequence for the emerging phases of molecular ensembles. Based on these results, we present direct comparisons to recent experiments on molecular Bose-Einstein condensates under microwave dressing. Quantum fluctuations play a key role for the often exotic behavior of dipolar condensates. Yet, a consistent theoretical description of quantum fluctuations and their stabilizing role in dipolar quantum gases has remained incomplete. We discuss the major conceptual challenges in developing such a theory and present corresponding solutions that address this long-standing problem. The presented framework permits to go beyond the popularly employed local-density approximation to the Lee-Huang-Yang (LHY) energy-correction and, thereby, enables a self-consistent determination of the equation of state. For the first time, this yields the phase diagram of dipolar Bose-Einstein condensates and resolves deviations between current LHY-predictions and observations.
References:
14:40–15:00 | Davide Proment
Roberts-Jonessolitarywavesonthetwo-dimensionalsphere
Author:DavideProment,NoelCuadra,Ruprecht-KarlsUniversitätHeidelberg ThomasGasenzer,Ruprecht-KarlsUniversitätHeidelbergAlbertoVillois,UniversityofEastAnglia DavideProment*,UniversityofEastAnglia
Roberts-Jones solitary waves, also known as Roberts-Jones solitons, are localised traveling wave so-lutions of the defocusing nonlinear Schrödinger equation in two and three spatial dimensions [1].At low speeds, these waves exhibit a vortex dipole (in 2D) or a vortex ring (in 3D), creating topologicalexcitations in the field’s phase.As the wave speed increases to a critical value, the vortex structuredisappears, and the solitary wave transforms into a simple field’s amplitude dip.In this work,we investigate the existence of Roberts-Jones solitary waves in curved spatial ge-ometries, specifically on the two-dimensional sphere.These findings provide crucial insights into the behaviour of fully nonlinear localised excitations in recent experimental realisations of cold gases, orany other exotic quantum fluid, confined within spherical shells.
References:
[1]Jones,C.A.,&Roberts,P.H.:MotionsinaBosecondensate.IV.Axisymmetricsolitarywaves.Journalof-PhysicsA:MathematicalandGeneral,15(8),2599(1982).
15:00–15:20 | David Baur
CoalescingRoton-LikeModesinaDriven–DissipativeBEC–Cavity System
Author:DavidBaur*,ETHZurich SimonHertlein,ETHZurichAlexanderBaumgärtner,ETHZurich JustynaStefaniak,ETHZurich TilmanEsslinger,ETHZurich GabrieleNatale,ETHZurichTobiasDonner,ETHZurich
Driven–dissipative many-body systems exhibit non-equilibrium phases of matter, where the inter-playofcoherentdynamics,externaldriving,anddissipationcangiverisetophenomenawithout equilibrium counterparts, such as dynamical instabilities, synchronization, and non-Hermitian criti-cality.We realize such a system by loading a Bose–Einstein condensate of [87]Rb into a high-finesse optical cavity and driving it with a transverse pump.The resulting cavity-mediated, long-range in-teractions generate two distinct roton-like excitation modes [1].Using Bragg spectroscopy, we simultaneously probe these two low-lying excitations and observe theirindividualsofteningasthesystemapproachestwoseparatesuperradiantphasetransitions, each accompanied by a diverging susceptibility.These modes can be understood as precursor excitations of the respective ordered phases.Owing to intrinsic dissipation of cavities through photon loss, themodesdo notremain independent:astheir energiesapproach eachother,theyhybridize andultimatelysynchronize,leadingtomodecoalescenceatanexceptionalpointandtheemergenceofa $\mathcal{PT}$-symmetry-brokendynamicalphase[2].Exploiting the full tunability of our setup, we access the regimewherethis coalescence occurs and directly observe the associated dynamical instability.To support our experimental findings, we de-velopamean-fieldmodelbasedonbandtheory, whichcapturesboththeoriginofthetwomodesand their merging into a single collective excitation [3].This framework further reveals the crucial role of the angle between the cavity mode and the transverse pump, providing a microscopic understandingof the rich behavior that arises when this angle deviates from $90^\circ$.
References:
- L.~Xiangliang {\sl et al.},\emph{Phys.Rev.Res.}\textbf{3},L012024 (2021)
- G.~Natale{\sletal.},Arxiv,2504.17730(2025)
- D.~Baur{\sletal.},Arxiv,2504.17731(2025)
Session Chair: Edwin Chaparro
15:40–16:00 | Lukas Homeier
Probing the coherence of quantum spin liquids with time-reversal protocols
Authors: Lukas Homeier, JILA and University of Colorado Boulder; Simon Linsel, LMU Munich; Michael Hermele, University of Colorado Boulder; Lode Pollet, LMU Munich; Ana Maria Rey, JILA, NIST and University of Colorado Boulder;
Quantum simulators have reached levels of coherence and control over large system sizes enabling them to target quantum spin liquids -- phases of matter characterized by their structure of entanglement rather than a local order parameter. Universal, robust and accessible observables are a major obstacle to fully characterize the phases, such as the coherences between loop configurations in the toric code. Here, we propose an experimental readout protocol to measure multiple quantum coherences (MQCs), first developed in nuclear magnetic resonances and recently implemented in trapped ions via time reversal. MQCs measure the coherences between many-body configurations and can be seen as a type of out-of-time-order correlator. We benchmark our method from snapshots of the extended toric code obtained by large-scale quantum Monte Carlo simulations. Our protocol detects the topological phase transition requiring only few samples, and hence serves as a novel, experimentally accessible, and genuine quantum diagnostic. Our methods provide complementary and necessary signatures to identify quantum spin liquids in quantum simulators.
References:
Homeier, Linsel, Hermele, Pollet, Rey, in preparation
16:00–16:40 | Anatoli Polkovnikov
Understanding chaos and integrability through adiabatic transformations and operator spreading
Author: Anatoli Polkovnikov
TBA
References:
Tuesday, 21 July 2026
Session Chair: John Bohn
09:00–09:40 | Francesca Ferlaino
Vortices and Supersolidity in Dipolar Quantum Gases
Authors:Francesca Ferlaino, Institut für Experimentalphysik, Universität Innsbruck, Austria, IQOQI- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, Innsbruck, Austria
Long-range dipolar interactions provide a powerful route to explore strongly correlated quantum matter beyond the paradigms accessible with short-range interacting gases. Ultracold gases of highly magnetic atoms such as erbium and dysprosium have emerged as a versatile platform for investigating many-body dipolar physics thanks to their large magnetic moments and complex internal structure. These systems allow access to regimes where anisotropic dipole–dipole interactions dominate the many-body behavior and give rise to novel quantum phases and collective phenomena. A striking example is vortex physics in dipolar quantum fluids. Quantized vortices are a universal hallmark of superfluidity, appearing across systems from liquid helium and superconductors to Bose–Einstein condensates and neutron stars. Recently, we added a new element to the understanding of the supersolid phase of matter, which combines crystalline order with macroscopic phase coherence. In this system we observe quantized vortices and investigate their properties. I will discuss the peculiar features of vortex nucleation in a supersolid and a new technique to rotate dipolar gases, known as magnetostirring, and contrast these observations with the behavior of an unmodulated dipolar gas. Recent advances such as ultrafast quantum gas microscopy for strongly dipolar species and the development of Rydberg-tweezer platforms will also be shortly discussed.
09:40–10:20 | Eugene Demler
TBA
Author: Eugene Demler, ETH, Zurich
References:
10:20–10:40 | Duncan O'Dell
Phonons on a sphere: Maxwell Fish-Eye Lens in a Bose-Einstein Condensate
Authors: Jelte Duchêne$^1$, Elinor Kath$^1$, Floriane Arrouas$^1$, Hanyi Jang$^1$, Helmut Strobel$^1$, Markus K. Oberthaler$^1$, Jay Mehta$^2$, Liam M. Farrell$^2$, Wyatt Kirkby$^{1,3}$, and Duncan H.J. O'Dell$^2$. 1=Kirchhoff-Institut für Physik, Universität Heidelberg, Heidelberg, Germany, 2=Department of Physics and Astronomy, McMaster University, 1280 Main St. W., Hamilton, ON, Canada L8S 4M1, 3=Physikalisches Institut, Universität Heidelberg, Heidelberg, Germany
We theoretically and experimentally study a matter-wave analogue of an optical Maxwell fish-eye lens (MFEL) using an atomic Bose–Einstein condensate (BEC). A MFEL is characterized by a radially symmetric, spatially varying refractive index with the remarkable property that rays emitted from any point within the lens are perfectly focused at their antipodal points. While the implementation of such gradient-index lenses is challenging in conventional optical systems, BECs offer a highly tunable platform in which the spatially varying speed of sound of collective excitations -- phonons, the matter-wave analogues of photons -- can be engineered and their dynamics observed in real time. Time-resolved measurements of phonon wavefronts reveal focusing behavior and show good agreement with analytical theory and numerical simulations. This work provides both a geometric and physical framework for engineering effective refractive indices using ultracold atoms. Furthermore, wave propagation in an MFEL can be mapped to free motion on a sphere, opening up the possibility of simulating wave propagation on effective spherical geometries.
References:
Session Chair: Ming Yuan
11:00–11:40 | Cindy Regal
Motional Kerr-Cat States of an Atom in an Optical Tweezer with Tunable Nonlinearity
Authors:Cindy Regal*, University of Colorado at Boulder
Precise control over the motional states of neutral atoms in optical tweezers is one of many frontiers in advancing the fidelity and versatility of neutral atom quantum information platforms. I will discuss recent experiments in which we generate non-classical motional cat states of a single neutral atom by leveraging the tunable Kerr nonlinearity of a single shallow optical tweezer. In particular we create Schrodinger cat states and institute parity rotations via modulation of the confining potential. Our results establish programmable control of individual optical tweezers as a resource for quantum state synthesis within the motional oscillator space.
11:40–12:00 | Sarah Sab
Revival or decay of the condensate during relaxation of a far-from-equilibrium trapped atomic superfluid
Author:Vanderlei Bagnato,University of Sao Paulo, Brazil, and Texas A&M University, USA
Understanding the initial conditions that drive many-body quantum systems out of equilibrium is essential for getting into their thermalization dynamics. In this work [1,2,3,4], we identify two excitation regimes that lead a trapped Bose–Einstein condensate into turbulence, evolution, and distinct final states. In the subcritical regime, the condensate partially reemerges after turbulence, whereas in the supercritical regime, it dissolves completely into a thermal state. Despite these differences, both cases exhibit relaxation stages with common features: a direct energy cascade, the emergence of a nonthermal fixed point (characterized by identical scaling exponents), a prethermalization plateau, and eventual thermalization. Our results show that turbulence relaxation develops independently of the system’s initial conditions or its ultimate state. At late times, both regimes display universal scaling dynamics consistent with predictions from wave turbulence theory. Finally, by analyzing the time evolution of the condensate’s center-of-mass momentum distribution, we demonstrate that kinetic-energy dominance reflects the thermalized nature of the final states in each regime. The present results advance the field by showing that thermalization in far-from-equilibrium quantum systems follows universal dynamics and pathways, even when final states differ, thereby deepening our understanding of the time evolution of many-body quantum system thermalization. We shall present a new possible interpretation of pre-thermalization, as well as an analysis of the construction of the coherent length during the last stage of the system's thermalization
References:
[1] M. A. Moreno-Armijos et al - Phys.Rev. Lett. 134. 023401 (2025)
[2] L. Madeira et al - Proc. Nat, Acad. Sci. -PNAS 121, 24044828121 (2024)
[3] A. D. GarcÃa-Orozco et al - Phys.Rev. A 106, 023314(2022)
[4] S. Sab et al – Submitted for publication (Dec-2025)
12:00–12:20 | Michael Fleischhauer
Many-body dynamics of interacting, dissipative spin systems and the Truncated Wigner Approximation for Spins
Authors: Michael Fleischhauer, RPTU University Kaiserslautern-Landau
The many-body dynamics of (dissipative) quantum spin systems is of key importance in many areas of physics and technology ranging from non-equilibrium phase transitions to solving optimization problems to collective radiative interactions. Its exact numerical treatment is however extremely challenging, being restricted either to small systems or to the classical limit of strong dephasing, which can be tackled by classical Monte Carlo methods. In this talk I discuss a semiclassical approach, termed truncated Wigner approximation (TWA) for spins, that allows to describe the coherent and dissipative many-body dynamics while taking into account lowest-order quantum effects. It is an extension of the discrete TWA (DTWA) [1], to include dissipative [2] and collective [3] spin processes. Based on continuous phase-space it allows to represent states with a positive quasi-probability distribution that do not have one in discrete space and thus can faithfully describe a broader class of processes even including the dynamical generation of entanglement. I discuss the application of this method to the superradiant decay of a spatially extended ensemble of atoms [4,5] including the simulation of multi-time correlations, the simulation of quantum annealing to the ground state of frustrated Ising models on large graphs, which is an NP-hard problem, and discuss the TWA in imaginary time [6].
References:
[1] J. Schachenmayer, et al. Phys. Rev. X 5, 011022 (2015).
[2] C. D. Mink, et al. Phys. Rev. Res. 4, 043136 (2022)
[3] C. D. Mink and M. Fleischhauer, SciPost Physics 15, 233 (2023)
[4] F. Tebbenjohanns et al., Phys. Rev. A 110, 043713 (2024)
[5] Y. Spahn et al. arxiv:2603.03028
[6] T. Schlegel et al. arxiv:2603.03950
Session Chair: Connal McCabe
14:00–14:40 | Andrew Daley
TBA
Author: Andrew Daley
TBA
References:
14:40–15:00 | Alberto Tabarelli
Generation of Laughlin states of ultracold atoms exploiting coherent driving
Author: Alberto Tabarelli de Fatis
Fractional quantum Hall (FQH) systems are an exceptionally rich platform for studying exotic many-body phenomena, exhibiting topologically protected, quantised charge transport at their edges and (non)-abelian anyonic excitations. Realising such states in a well-controlled environment, like neutral ultracold atoms, has therefore long been a key goal. However, it has so far proven extremely challenging, e.g., due to topological gap closing and the difficulty of generating strong enough synthetic gauge fields, restricting the experimental realizations to states of a very small number of particles N=2,3.
I present a proposal to generate a bosonic half-filling Laughlin states in an FQH system exploting an adiabatic path in a larger Fock space with variable particle number, by coupling the system to a weakly-interacting BEC reservoir via an angular-momentum-selective coherent Raman pump. By adiabatically varying the strength and detuning of the incident driving field, the initial vacuum state of the system can be converted into a Laughlin state, without changing the system Hamiltonian. The novelty of this method is to avoid gap closing associated with the topological phase transition, and exploit a gap opening due to the pump coupling.
With typical experimental parameters, I show that this scheme allows the generation of quite large (of order N=10) Laughlin state with excellent fidelity, and the same strategy can be used to generate quasihole excitations on top of it. Since we rely on an adiabatic evolution, there is no strict requirement on the fine-tuning of the driving parameters, which makes our scheme robust. An experimental realization of our proposal will open new perspectives in the use of ultracold atoms as quantum simulators of condensed matter systems and its extension to non-Abelian states will provide a powerful platform for topological quantum computing.
References:
15:00–15:20 | Ben Ripley
Finite-temperaturetheoriesforsupersolidsystems
Author:B.T.E.Ripley,Dodd-WallsCentreforPhotonicandQuantumTechnologies, Dunedin9054,NewZealandandDepartment ofPhysics,UniversityofOtago,Dunedin9016,NewZealand
Supersolids, which exhibit simultaneous crystalline order and superfluidity, have previously been welldescribedbytheoryinthezero-temperatureregime.However,recentresearchhasdemonstrated increased interest in the finite-temperature regime:experiments suggest it may be advantageous tocooldirectly intothe supersolidregime [1-3]and workby Sánchez-Baenaet al.(2023)[4] indicates that thermal fluctuations may reinforce supersolid modulation.Our work focuses on finite-temperature mean-field theories describing supersolid systems withsoft-core interactions.In one dimension, these interactions confer a continuous transition betweentheuniformandsupersolidregimes,governedbyasingleorderparameterdependentonlyondensityand interaction strength.Recent work by Peotta et al.[5] utilised the Hartree-Fock approximation;we also implement and evaluate other related theories in the family of Hartree-Fock-Bogoliubov ap-proximations.Wefindsignificantdifferencesbetweenthesetheories, includingthenumberofgapless modes and the magnitude and character of non-condensate effects.Weaimtocomparetheseresultstoexistingsemi-classicalmean-fieldtheories[4,6-8]andto classical field theories such as the application of the stochastic Gross-Pitaevskii equation (SGPE). Anextensionofthesetheoriestoincludedipolarinteractionsisalsoofinterest.
References:
- L.Chomaz etal., Phys.Rev.X9, 021012(2019).
- M.Sohmenet al.,Phys.Rev.Lett.126,233401 (2021).
- M.A.Norciaetal., Nature596,357(2021).
- J.Sánchez-Baenaetal.,Nat.Comm.14,1868(2023).
- S.Peottaetal.,Phys. Rev.B112,184506(2025).
- J.Sánchez-Baena,T.Pohl,andF.Maucher,Phys.Rev.Res.6,023183(2024).
- L.-J.Heetal.,Phys.Rev.Res.7,023019(2025).
- J.Sánchez-Baenaetal.,Phys.Rev.Res.7,033080(2025).
Wednesday, 22 July 2026
Session Chair: Anjun Chu
09:00–09:40 | Markus Oberthaler
Driven non-equilibrium superfluids: bouncing universes, super-liquid crystals and sine-Gordon solitons
Authors: Markus Oberthaler, Heidelberg University, Germany
Systems being driven far from equilibrium can have very different properties distinct from the same system at equilibrium. New phases of matter can emerge with new material properties. Here, I will report on our recent findings with our quantum field simulation platforms of a quasi-two-dimensional quantum gas of potassium atoms and quasi-one-dimensional spinor superfluid realized with rubidium. The potassium platform allows the detailed investigation of the emergent many particle dynamics when the microscopic interaction strength is modulated periodically. The initial dynamics is well capture with a perturbative description and can be understood as particle generation in a relativistic scalar field theory with oscillating cosmological Friedmann-Lemaître-Robertson-Walker spacetime metric [1-2]. But, the platform allows going beyond the perturbative regime. There we have discovered, that the homogeneity and isotropy of the initial situation, is spontaneously broken and a periodic spatial modulation of the metric emerges [3]. We show that this phenomenon can be understood as a drift towards an attractive nonlinear fixed point, which is theoretically discussed in the framework of multi-scale analysis [4]. Since the capability of our quantum field simulator also allows the preparation of the system at the theoretically predicted fixed point as well as the local control of the order parameter we can probe the excitation spectrum and with that characterize the emergent state of matter. We find that the spontaneously formed crystalline structure has both superfluid and lattice excitation as expected for a one-dimensional supersolid [5]. Since the system also allows the preparation and stabilization of a stripe phase, we can in detail study and confirm the recent theoretical predictions of a superfluid smectic-A liquid crystal phase [6]. The rubidium platform has the unique feature that all eight generators of the spin-1 system are experimentally accessible with high spatial resolution for each single realization. With the additional local control of the spin-1 degrees we have been able to demonstrate the generation of sine-Gordon type solitons and their systematic study in propagation and collision. This insight also allows the understanding of the universal coarsening dynamics of spin-1 within an effective model closely related to a sine-Gordon model [7].
References:
[1]C. Viermann, et al. , Quantum field simulator for dynamics in curved spacetime, Nature, 611, 260 (2022)
[2] M. Sparn, et al., Experimental particle production in time-dependent spacetimes: a one-dimensional scattering problem, PRL 133, 260201 (2024)
[3]N. Liebster, et al. Observation of pattern stabilization in a driven superfluid, PRX 15, 011026 (2025)
[4] K. Fuji, et al. Phys. Rev. A, Stable-fixed-point description of square-pattern formation in driven two-dimensional Bose-Einstein condensates, 109, L051301 (2024)
[5] N. Liebster, et al. Supersolid-like sound modes in a driven quantum gas, Nature Physics 21, 1064 (2025)
[6]J. Hoffmann, and W. Zwerger, Hydrodynamics of a superfluid smectic, J. Stat. Mech., 2021, 033104 (2021)
[7] I. Siovitz, at al. Double sine-Gordon class of universal coarsening dynamics in a spin-1 Bose gas PRA 112, 023304 (2025)
09:40–10:20 | Leticia Tarruell
Excitations in supersolid spin-orbit-coupled Bose-Einstein condensates
Authors: Leticia Tarruell, ICFO and ICREA
Supersolidity is a quantum phase of matter that combines the frictionless flow of a superfluid with the crystalline structure of a solid. Spin–orbit-coupled Bose–Einstein condensates constitute a versatile experimental platform to investigate it [1], as they host this phase in the form of the so-called stripe phase [2]. However, the excitation spectrum of the stripe phase, which contains key fingerprints of supersolidity, had remained out of experimental reach until now.
In my talk, I will present how, by combining the favorable scattering properties of 41K atoms with matter-wave optics, we have been able to image in situ the stripe pattern of a spin–orbit-coupled sytem for the first time [3]. By directly resolving the density modulation and its dynamics, we observe both superfluid and crystalline excitations, providing direct evidence of the dual broken symmetries that characterize this phase.
Remarkably, we identify and characterize a stripe compression mode associated with the existence of phonons in the crystal [3]. The observation of this mode confirms the genuine supersolid character of the stripe phase, which has been the subject of recent debate in the community [4]. Moreover, its frequency softening as a function of the spin–orbit-coupling strength allows us to accurately locate the supersolid phase transition [3]. Our results establish spin–orbit-coupled systems as ideal platforms to explore supersolidity and its rich dynamics.
References:
[1] Y. J. Lin, K. Jiménez-Garcéa, and I. B. Spielman, Nature 471, 83 (2011).
[2] J.-R. Li, J. Lee, W. Huang, S. Burchesky, B. Shteynas, F. Ç. Top, A. O. Jamison, and W. Ketterle, Nature 543, 91 (2017).
[3] C. S. Chisholm*, S. Hirthe*, V. B. Makhalov*, R. Ramos*, R. Vatré*, J. Cabedo, A. Celi, and L. Tarruell, Science 391, 480 (2026).
[4] K. T. Geier, G. I. Martone, P. Hauke, W. Ketterle, and S. Stringari, Phys. Rev. Lett. 130, 156001 (2023).
10:20–10:40 | Haoqing Zhang
New directions in quantum simulation and sensing via cavity-mediated interactions
Author: Haoqing Zhang , JILA and University of Colorado Boulder;
Cavity-QED systems have emerged as a powerful platform for generating highly entangled states, with significant implications for quantum metrology and quantum simulation. By harnessing atomic momentum states as an effective qubit degree of freedom in an cavity quantum simulator, we propose schemes to realize all-to-all interactions and experimentally observe (i) many-body gap protection against Doppler-induced dephasing, (ii) two-axis counter-twisting dynamics and the realization of an arbitrary collective XYZ Hamiltonian, and (iii) controllable three- and four-body interactions. The versatility of our platform in incorporating additional momentum states, together with the flexibility to engineer effective Hamiltonians via multiple cavity tones, opens up rich opportunities for quantum information processing and quantum sensing based on photon-mediated interactions in synthetic momentum space.
References:
Session Chair: Lukas Homeier
11:00–11:40 | Giacomo Roati
Tunneling effects in strongly-correlated Fermi superfluids
Author: Giacomo Roati,CNR-INO and LENS, Sesto Fiorentino, Italy
Quantum mechanical tunneling underlies a wide range of fundamental phenomena and enables the operation of diverse electronic devices, from flash memories to SQUID magnetometers [1]. Its simplest realization is the tunnel junction, formed by coupling two conductors through a thin insulating barrier. As a minimal and well-controlled architecture, tunnel junctions provide direct access to the many-body processes governing mesoscopic quantum transport [2], which are ultimately set by the spectrum of elementary excitations above the ground state. Here, we present tunneling experiments in strongly interacting atomic Fermi gases across the superfluid transition. We demonstrate that supercurrents and normal currents reflect their connection to the superfluid order parameter amplitude, the pair condensate density, and the associated excitation modes [3, 4]. Finally, by periodically modulating the atomic junction with an ac drive, we show the onset of Shapiro steps dynamics, revealing their origin in the synchronization between the relative phase of the two reservoirs and the external drive [5]
References:
11:40–12:00 | Russell Bisset
Quantum vortex channels as Josephson junctions
Authors: Natalia Masalaeva, University of Innsbruck; Wyatt Kirkby, University of Heidelberg; Francesca Ferlaino, University of Innsbruck; Russell N. Bisset (*), University of Innsbruck.
In quantum gases, weak links are typically realized with externally imposed optical potentials. We show that, in rotating binary condensates, quantized vortices in one component form hollow channels that act as self-induced weak links for the other, enabling superflow through otherwise impenetrable, phase-separated domains. This introduces a novel barrier mechanism: quantum pressure creates an effective barrier inside the vortex channel, set by the constriction width, which controls the superflow. Tuning the interspecies interaction strength drives a crossover from the hydrodynamic transport to Josephson tunneling regime. Long-range dipolar interactions further tune the weak-link properties, enabling both short links and two coupled junctions in series. Circuit models quantitatively capture the dc current-phase relations for both configurations. These results establish vortices as reconfigurable, interaction-controlled Josephson elements in superfluids.
References:
N. Masalaeva, W. Kirkby, F. Ferlaino, and R. N. Bisset, Quantum vortex channels as Josephson junctions, arXiv:2602.01889 (2026).
12:00–12:20 | Jia Wang
Exact Polaron Theory: From BCS Superfluids to Quantum Hall Fluids
Authors: Jia Wang*, Centre for Quantum Technology Theory, Swinburne University of Technology, Melbourne, Australia;
Xia-Ji Liu, Centre for Quantum Technology Theory, Swinburne University of Technology, Melbourne, Australia;
Hui Hu, Centre for Quantum Technology Theory, Swinburne University of Technology, Melbourne, Australia
Polarons—impurities dressed by excitations of a quantum medium—provide a powerful probe of strongly correlated many-body systems. In this talk, I present exact results for polarons formed by infinitely heavy impurities in two distinct quantum fluids: a BCS superfluid [1] and a quantum Hall system [2]. For a static impurity immersed in a BCS Fermi superfluid, the problem admits an exact solution via the functional determinant approach. The superfluid gap qualitatively modifies impurity dressing compared to the normal Fermi gas, suppressing Anderson’s orthogonality catastrophe and enabling well-defined repulsive polarons. The spectral response exhibits sharp quasiparticle features, dark and molecule–hole continua, and, for magnetic impurities, features of subgap Yu–Shiba–Rusinov bound states. I will then discuss exact results for heavy impurities coupled to a quantum Hall fluid. Landau-level structure leads to highly nontrivial mediated impurity–impurity interactions, including regimes where interactions vanish and others where they display Coulomb-like short-distance behaviour governed by the magnetic length. Finally, I briefly note complementary developments for mobile impurities, including generalized Chevy-ansatz/T-matrix approaches [3] and exact Bethe-Ansatz solutions in one dimension [4].
References:
[1] Jia Wang, Xia-Ji Liu, and Hui Hu, Phys. Rev. Lett. 128, 175301 (2022)
[2] Jia Wang, Xia-Ji Liu, and Hui Hu, Phys. Rev. B 112, L041125 (2025)
[3] Hui Hu, Jia Wang, and Xia-Ji Liu, Phys. Rev. Lett. 133 083403 (2024)
[4] Hui Hu, Jia Wang, and Xia-Ji Liu, Phys. Rev. Lett. 134, 153403 (2025)
Session Chair: Jose Rodriguez
14:00–14:40 | Bruno Laburthe-Tolra
TBA
Author: Bruno Laburthe-Tolra
TBA
References:
14:40–15:00 | Seong-Ho Shinn
Spontaneous Quantum Turbulence in a Newborn Bose-Einstein Condensate via the Kibble-Zurek Mechanism
Authors: Seong-Ho Shinn*, University of Luxembourg; Matteo Massaro, University of Luxembourg; Mithun Thudiyangal, Christ University; Adolfo del Campo, Donostia International Physics Center
The Kibble-Zurek mechanism (KZM) predicts the spontaneous formation of topological defects in a continuous phase transition driven at a finite rate. We propose the generation of spontaneous quantum turbulence (SQT) via the KZM during Bose-Einstein condensation induced by a thermal quench. Using numerical simulations of the stochastic projected Gross-Pitaevskii equation in two spatial dimensions, we describe the formation of a newborn Bose-Einstein condensate proliferated by quantum vortices. We establish the nonequilibrium universality of SQT through the Kibble-Zurek and Kolmogorov scaling of the incompressible kinetic energy.
References:
arXiv:2506.21670 [cond-mat.quant-gas]
15:00–15:20 | Yi Zeng
ExoticQuantumStatisticsin1DBoseGases
Author: YiZeng*,InstitutfürExperimentalphysik,UniversitätInnsbruck Sudipta Dhar, Institutfür Experimentalphysik,Universität Innsbruck Milena Horvath, Institut für Experimentalphysik, Universität InnsbruckAlviseBastianello,CEREMADE,CNRS,UniversitéParis-Dauphine,UniversitéPSL ZekuiWang,InstitutfürExperimentalphysik,UniversitätInnsbruck;StateKeyLaboratoryofQuantumOpticsTechnologies and Devices, Institute of Opto-Electronics, Shanxi University XudongYu,InstitutfürExperimentalphysik, UniversitätInnsbruck Botao Wang, Center for Nonlinear Phenomena and Complex Systems, Université Libre de Bruxelles; International Solvay Institutes Amit Vashisht, Center for Nonlinear Phenomena and Complex Systems, Université Libre de Bruxelles; International Solvay Institutes Grigori E. Astrakharchik, Departament de Física, Universitat Politècnica de Catalunya Mikhail B.Zvonarev, Université Paris-Saclay,CNRS, LPTMS Nathan Goldman, Center forNonlinear Phenomena and Complex Systems,Université Libre de Bruxelles;InternationalSolvayInstitutes; Laboratoire Kastler Brossel, Collègede France,CNRS, ENS-UniversitéPSL, SorbonneUniversitéYanliangGuo,KeyLaboratoryofQuantumStateConstructionandManipulation(MinistryofEducation),SchoolofPhysics, Renmin University of China;Institut für Experimentalphysik,Universität Innsbruck, ManueleLandini,InstitutfürExperimentalphysik,UniversitätInnsbruck Hanns-Christoph Nägerl, Institut fürExperimentalphysik,UniversitätInnsbruck
Exoticquantum statisticsgeneralize thefamiliar dichotomyof bosonsand fermionsto aspectrum. On it lie anyons, allowing particles to partially share one state, and “super fermions”, where particles occupy several states.My talk explores how strongly interacting 1D Bose gases provide a platform to realize unconventional statistics.I present the observation of emergent anyonic correlations inducedbyspin-chargeseparation, whereamobileimpuritygeneratesasystemwithatunablestatistical phase [1,2], providing a continuous transmutation from bosons through anyons to fermions.This is revealed through an asymmetric momentum-distribution and dynamical fermionization.I thenreporttherealizationoffractionalFermiseas[3,4,5].Thesearemany-bodysystemsinwhicheach particleoccupiesanintegernumberofstateslargerthan1.Onemightcalltheresultingstatistics “super-fermionic”,under theframework ofHaldane’s generalizedexclusion statistics.Forthis, wedriveour1DBosesystemviarampinginteractioncyclesintoexcitedstates.Friedeloscillationsin the one-body correlationsdirectly expose the underlying Fermi surfaces.Together, these resultsdemonstrate a powerful and controllable route to exploring the full landscape of low-dimensional quantum statistics beyond the boson-fermion paradigm.
References:
- Sudipta Dhar, BotaoWang, Milena Horvath, Amit Vashisht,Yi Zeng,Mikhail B. Zvonarev, Nathan Goldman,Yan-liang Guo, Manuele Landini, and Hanns-Christoph Nägerl, Observing anyonization of bosons in a quantum gas, Nature 642, 53 (2025).
- Botao Wang, Amit Vashisht, Yanliang Guo, Sudipta Dhar, Manuele Landini, Hanns-Christoph Nägerl, Nathan Gold-man, Anyonization of bosons in one dimension:an effective swap model, Physical Review Letters 135, 253403 (2025).
- YiZeng,AlviseBastianello,SudiptaDhar,ZekuiWang,XudongYu,MilenaHorvath,GrigoriAstrakharchik,Yan-liangGuo,Hanns-ChristophNägerlandManueleLandini,RealizationofFractionalFermiSeas,arXiv:2602.17657
- MaciejMarciniak,GrigoriE.Astrakharchik,KrzysztofPawlowski,andBrunoJulia-Diaz,FermionizingtheidealBosegasviatopologicalpumping,arXiv:2504.19569.
- AlviseBastianello,YiZeng,SudiptaDhar,ZekuiWang,XudongYu,MilenaHorvath,GrigoriE.Astrakharchik,YanliangGuo,Hanns-ChristophNägerl,andManueleLandini,ExoticcriticalstatesasfractionalFermiseasinthe one-dimensional Bose gas, arXiv:2602.17656
Session Chair: Amit Vikram
15:40–16:00 | Catie LeDesma
Harnessing Machine Learning for Multidimensional Inertial Sensing in an Optical Lattice
Authors: Catie LeDesma*, University of Colorado Boulder, Kendall Mehling, University of Colorado Boulder, Murray Holland, University of Colorado Boulder
We are developing a precision atom interferometer based on loading a Bose-Einstein condensate into a three-dimensional optical lattice [1-4]. By translating this lattice in a controlled manner, we can implement all of the standard operations of atom interferometry: splitting, propagating, reflecting, and recombining a macroscopic quantum wave function. These atom-optic operations act as matter-wave gates: unitary transformations that can be optimized using modern artificial-intelligence techniques. In particular, we employ deep reinforcement learning as a central tool in our experimental design. The gate-set we realize is metrologically universal, analogous to universal gate-sets in quantum computing, and therefore is capable of sensing arbitrary signals. We confirm the designed operations experimentally through in situ imaging of the condensate's spatial evolution within the lattice, as well as through measurements of momentum-state populations after time-of-flight expansion. We further demonstrate applications to several fundamental quantum-sensing circuits, including those used to measure inertial forces, rotation, and gravity gradients. We refer to our sensor as a Bloch-Band Interferometer (BBI) because it manipulates atoms between the lowest Bloch eigenstates in the valence band, where atoms are effectively frozen, and the high-lying Bloch states in the conduction band, where atoms propagate over long distances as effectively free particles. This capability enables us to enclose large interferometric areas in a tiny sensor and thereby achieve high metrological sensitivity, and to do this in multiple dimensions simultaneously. Realizing such large areas requires long interrogation times; to support these durations, we "paint’" tailored optical potentials onto the lattice to emulate a microgravity environment on Earth. Furthermore the atoms interact opening the door to quantum advantaged sensing protocols. In this talk, I will report recent progress on the experiment including efforts to advance the precision and sensitivity in the lab.
References:
[1] C. LeDesma, K. Mehling, M. Holland, ‘Vector Atom Accelerometry in an Optical Lattice’, Science Advances 11 (23), eadt7480 (2025).
[2] Catie LeDesma, Kendall Mehling, Jieqiu Shao, John Drew Wilson, Penina Axelrad, Marco M Nicotra, Dana Z Anderson, Murray Holland, `Demonstration of a programmable optical lattice atom interferometer’, Physical Review Research 6, 43120 (2024).
[3] C. LeDesma, K. Mehling, J.D. Wilson, M. Nicotra, M. Holland, ‘Universal Gate Set for Optical Lattice Based Atom Interferometry’, accepted for Physical Review Research, available as arXiv preprint arXiv:2410.17472 (2024).
[4] Kendall Mehling, Murray Holland, Catie LeDesma, ‘High-Precision Phase Control of an Optical Lattice with up to 50 dB Noise Suppression’, Physical Review Applied 25 (2), 024008 (2026).
16:00–16:40 | Jun Ye
Game of dipoles - individual survival & collective dynamics
Authors: Jun Ye, JILA and University of Colorado Boulder
Thursday, 23 July 2026
Session Chair: James Thompson
09:00–09:40 | Qi Zhou
New synthetic gauge fields: complexand higher-rank tensors
Author: Qi Zhou, Purdue University
Synthetic gauge fields have been a central theme in ultracold atom physics over the past few decades. Most previous studies, however, have focused on real vector gauge fields. In this talk, I will describe how this framework can be extended to the largely unexplored regime of complex and higher-rank tensor gauge fields. I will present experimentally feasible schemes for realizing these synthetic fields and discuss the conceptually new phenomena that emerge from their coupling to exotic quantum phases
References:
09:40–10:20 | Blair Blakie
Supersolidity in Dipolar Bose-Einstein condensates
Authors: Blair Blakie, University of Otago, New Zealand
What happens when a solid starts flowing like a superfluid, yet still creaks like a crystal? This is the remarkable behaviour of a supersolid — a phase of matter that combines crystalline order with frictionless flow. Once a long-standing theoretical curiosity, supersolidity has now been realised in an exceptionally clean and tunable platform: dilute dipolar Bose–Einstein condensates of highly magnetic atoms such as dysprosium and erbium. Recent experiments have used the competing effects of short-range contact and long-range dipolar interactions to self-organise these ultracold gases into periodic density modulations, while maintaining global phase coherence.
In this talk, I’ll introduce two-dimensional dipolar supersolids, examining the ground state phase diagram and excitations. Due to the broken gauge and translational symmetries, these supersolids exhibit three gapless excitations branches with associated speeds of sound. I will discuss the application of hydrodynamic theories to describe the supersolid properties, and relate the speeds of sound to its elastic parameters. I will also explore some examples of nonequilibrium dynamics.
References:
Honeycomb supersolid -- Dirac points and shear-instability induced crystal transitions, P Blair Blakie, Physical Review Letters 134, 013401 (2025)
Excitations of a two-dimensional supersolid, Elena Poli, Danny Baillie, Francesca Ferlaino, and P. Blair Blakie, Physical Review A 110, 023320 (2024)
Excitations of a binary supersolid, W. Kirkby, Au-Chen Lee, D. Baillie, T. Bland, F. Ferlaino, P. B. Blakie, and R. N. Bisset, Physical Review Letters 133, 103401 (2024)
Excitations and phase ordering of the spin-stripe phase of a binary dipolar condensate, Au-Chen Lee, D. Baillie, and P. B. Blakie, Physical Review A 109, 023323 (2024)
Two-dimensional supersolidity in a planar dipolar Bose gas, B. T. E. Ripley, D. Baillie, and P. B. Blakie, Physical Review A 108, 053321 (2023)
10:20–10:40 | Simon Haine
A Quantum Control Toolbox for Superfluid Turbulence
Authors: Simon Haine, Kaiwen Zhu, Zain Mehdi
Superfluid turbulence in dilute-gas Bose–Einstein condensates (BECs) provides a uniquely clean and controllable setting for exploring fundamental questions surrounding energy transport, cascade dynamics, and non-equilibrium behaviour in quantum fluids. Unlike classical turbulence—where energy typically flows from large to small scales—superfluid systems can exhibit dramatically different transport pathways, including inverse energy cascades driven by quantised vortex dynamics. Understanding and controlling these processes is central to developing BECs as quantum simulators of complex fluid phenomena and non-equilibrium field theories. In this talk, I present a new theoretical framework for studying superfluid turbulence under active quantum control. The key idea is to combine coherent driving, used to inject excitations and generate turbulent states, with tailored feedback mechanisms that selectively damp unwanted modes. This protocol creates a flexible non-equilibrium environment in which energy flows, vortex dynamics, and cascade behaviour can be precisely manipulated and probed. Such controlled turbulence opens the door to systematically exploring long-standing questions about the fundamental structure of turbulent spectra in compressible superfluids, and about the role of measurement backaction in driven-dissipative quantum systems. A major obstacle in this programme has been the difficulty of accurately modelling measurement and feedback processes in large many-body systems. Conventional phase-space methods either become computationally intractable for realistic system sizes or suffer from severe under-sampling issues, particularly when simulating conditional dynamics and measurement-induced state updates. To overcome this, we introduce a scalable field-theoretic simulation technique that extends existing phase-space representations to efficiently handle non-destructive measurements and feedback. This method incorporates both measurement backaction and spontaneous emission effects arising from phase-contrast imaging—the dominant experimental tool for real-time probing of BECs. We validate the method in a number of steps. First, we compare it against exact solutions in a two-mode model, demonstrating excellent agreement across a range of moments of pseudospin operators. Second, we benchmark it against the Number-Phase Wigner particle filter, the leading technique currently used for simulating controlled quantum systems. Our approach achieves comparable accuracy while offering improved stability and scalability to higher-dimensional systems. Using this framework, we simulate feedback cooling and driven-dissipative dynamics in quasi-1D and 2D geometries, demonstrating the formation of condensates from low-fraction thermal states. We then apply the method to turbulent regimes, showing how driving and feedback can be used to shape energy spectra and manipulate vortex distributions. These results illustrate how quantum control offers a powerful toolbox for probing fundamental aspects of superfluid turbulence, including energy cascades and emergent scaling laws. Finally, we outline optimal choices for measurement strength, rate, and detector resolution that maximise control performance, and discuss prospects for experimental realisation in current cold-atom platforms.
References:
Simulating feedback cooling of incoherent quantum mixtures, K Zhu, Z Mehdi, J Hope, S Haine, Phys. Rev. A 111 013014 (2025
Session Chair: Raphael Kaubrugeer
11:00–11:40 | James Thompson
Photon-Mediated Interactions for Quantum Simulation and Sensing
Author: James Thompson,JILA, NIST, and Dept. of Physics, University of Colorado, Boulder
Photons bouncing back and forth many times between highly reflecting mirrors provides a novel way to mediate interactions between laser-cooled atoms held between the mirrors. Such photon-mediated interactions provide a unique set of tools for both quantum simulation and sensing. In this talk, I will discuss our efforts to sculpt these interactions in order to expand the palette of cavity-mediated interactions that can be a realized, including exchange interactions [1, 2], many-body gap protection [1-3], XYZ interactions [4], 3 & 4-body interactions [5], and dissipative interactions [6-7]. I will high light applying these interactions to simulate dynamical phases of superconductors [8,9] and enhancing matterwave interferometers [2-5, 10] and optical clocks [11].
References:
1] Norcia et al, Science 361 259 (2018)
[2] Luo et al, Science384 551 (2024)
[3] Niu et al, Phy. Rev. Lett. 134 (11) 113403 (2025)
[4] Luo et al, Nature Physics21 916 (2025)
[5] Luo et al, Science390 925(2025)
[6] Schafer et al, Nature Physics 21 902 (2025)
[7] Song et al, Science Adv.11, eadu5799 (2025)
[8] Young et al, Nature625, 679-684 (2024)
[9] Young et al, Phys. Rev. Lett.134 (18) 183404 (2025)
[10] Greve et al, Nature610 472-477 (2022)
[11] Robinson et al, Nature Physics 20 208-213 (2024)
11:40–12:00 | Vladimir Yurovsky
Non-monotonic equilibrium energy distributions in strongly-interacting chaotic lattice gases
Author: Vladimir Yurovsky
We demonstrate [1] that eigenstate thermalization in strongly interacting many-body chaotic systems can result in non-monotonic energy distributions, qualitatively different from the Fermi-Dirac and Bose-Einstein forms. The effect emerges in systems with finite energy spectra, supporting both positive and negative temperatures. General results are obtained for chaotic systems in the quantum ergodicity regime, assuming the Gaussian local density of states. Orbital occupations for two-dimensional Fermi-Hubbard model and one- and two-dimensional Bose-Hubbard models are considered as examples. The results are supported by exact diagonalization calculations for chaotic Fermi-Hubbard and Bose-Hubbard models, when they have Wigner-Dyson statistics of energy spectra and demonstrate eigenstate thermalization. The proposed effects may be observed in experiments with cold atoms in optical lattices.
References:
[1]. Vladimir A. Yurovsky and Amichay Vardi, Phys. Rev. Res. 7, 043354 (2025)
12:00–12:20 | Nick Proukakis
Modelling Dynamical Fluctuating Quantum Gases with Long-Range Interactions
Authors: Alex Soto, Gary Liu, Milos Indjin, Adi Verma, Gerasimos Rigopoulos and Nick Proukakis (*), Newcastle University, UK
Dynamical modelling of coherent quantum systems exhibiting generic long-range interactions poses numerous challenges, particularly in the presence of quantum and thermal fluctuations. We (i) present such a generalised dynamical framework simultaneously addressing both coherent and incoherent degrees of freedom of such a quantum fluid through a stochastic extended Gross-Pitaevskii equation coupled to an appropriate quantum Boltzmann equation under generic long-range interactions with a full quasiparticle spectrum [1], (ii) review the implications of such a model for locally-interacting systems [2], and (iii) focus on relevant applications with effective long-range interactions [1-3].
The main motivation relates to trapped ultracold quantum gases with long-range dipolar interactions. While current modelling approaches have led to significant successes of finite-temperature experimental findings, such finite temperature approaches are typically restricted to the static framework of the extended Gross-Pitaevskii equation with explicit quantum and thermal quasiparticle contributions, or to an (underived) dynamical phenomenological stochastic extended Gross-Pitaevskii equation. We have previously derived a dynamical dipolar gas formalism [2] geared primarily towards the thermal fluctuations. Here we analytically extend this by explicitly including in a systematic manner both the full quasiparticle spectrum, and the Lee-Huang-Yang quantum-fluctuation corrections. As such our model is shown to encompass all numerically-implemented dipolar gas models to date, allowing us to critically re-assess the approximations made in reducing the full formalism to such effective models [1]. We believe that such identification may contribute to further addressing open quantitative questions in systems with dipolar interactions, including, for example, the role of thermal fluctuations in dipolar droplets, or the dynamical phase transition between normal, superfluid and supersolid behaviour.
The general nature of the derived formalism, which also facilitates the competing effects of local and nonlocal interactions, may have potential applications in other settings, such as polar molecules, Rydberg systems, or charged superfluids. As an example we briefly touch upon the somewhat unexpected application of our formalism in the cosmological context [3], where gravity simultaneously plays the role of an effective long-range interaction and an effective, self-consistently determined, confining potential. In this context, it has been argued that possible `short-scale’ shortcoming of the standard Cold Dark Matter model may be cured by describing the underpinning dark matter component of galaxies as gravitationally-bound superfluids of an ultralight boson, with such galactic solitonic cores somewhat reminiscent of quantum droplets embedded within an incoherent medium – an analogy we critically revisit here.
Funding: European Union, Leverhulme Trust, UKRI
References:
[1] Proukakis et al., In Preparation (2026).
[2] Proukakis et al., arXiv:2407.20178v2
[3] Proukakis et al., PRD 111, 023505 (2025).
Posters
