@article{14845, abstract = {We study a linear rotor in a bosonic bath within the angulon formalism. Our focus is on systems where isotropic or anisotropic impurity-boson interactions support a shallow bound state. To study the fate of the angulon in the vicinity of bound-state formation, we formulate a beyond-linear-coupling angulon Hamiltonian. First, we use it to study attractive, spherically symmetric impurity-boson interactions for which the linear rotor can be mapped onto a static impurity. The well-known polaron formalism provides an adequate description in this limit. Second, we consider anisotropic potentials, and show that the presence of a shallow bound state with pronounced anisotropic character leads to a many-body instability that washes out the angulon dynamics.}, author = {Dome, Tibor and Volosniev, Artem and Ghazaryan, Areg and Safari, Laleh and Schmidt, Richard and Lemeshko, Mikhail}, issn = {2469-9969}, journal = {Physical Review B}, number = {1}, publisher = {American Physical Society}, title = {{Linear rotor in an ideal Bose gas near the threshold for binding}}, doi = {10.1103/PhysRevB.109.014102}, volume = {109}, year = {2024}, } @article{14851, abstract = {Die Quantenrotation ist ein spannendes Phänomen, das in vielen verschiedenen Systemen auftritt, von Molekülen und Atomen bis hin zu subatomaren Teilchen wie Neutronen und Protonen. Durch den Einsatz von starken Laserpulsen ist es möglich, die mathematisch anspruchsvolle Topologie der Rotation von Molekülen aufzudecken und topologisch geschützte Zustände zu erzeugen, die unerwartetes Verhalten zeigen. Diese Entdeckungen könnten Auswirkungen auf die Molekülphysik und physikalische Chemie haben und die Entwicklung neuer Technologien ermöglichen. Die Verbindung von Quantenrotation und Topologie stellt ein aufregendes, interdisziplinäres Forschungsfeld dar und bietet neue Wege zur Kontrolle und Nutzung von quantenmechanischen Phänomenen.}, author = {Karle, Volker and Lemeshko, Mikhail}, issn = {1521-3943}, journal = {Physik in unserer Zeit}, keywords = {General Earth and Planetary Sciences, General Environmental Science}, number = {1}, pages = {28--33}, publisher = {Wiley}, title = {{Die faszinierende Topologie rotierender Quanten}}, doi = {10.1002/piuz.202301690}, volume = {55}, year = {2024}, } @article{15004, abstract = {The impulsive limit (the “sudden approximation”) has been widely employed to describe the interaction between molecules and short, far-off-resonant laser pulses. This approximation assumes that the timescale of the laser-molecule interaction is significantly shorter than the internal rotational period of the molecule, resulting in the rotational motion being instantaneously “frozen” during the interaction. This simplified description of the laser-molecule interaction is incorporated in various theoretical models predicting rotational dynamics of molecules driven by short laser pulses. In this theoretical work, we develop an effective theory for ultrashort laser pulses by examining the full time-evolution operator and solving the time-dependent Schrödinger equation at the operator level. Our findings reveal a critical angular momentum, lcrit, at which the impulsive limit breaks down. In other words, the validity of the sudden approximation depends not only on the pulse duration but also on its intensity, since the latter determines how many angular momentum states are populated. We explore both ultrashort multicycle (Gaussian) pulses and the somewhat less studied half-cycle pulses, which produce distinct effective potentials. We discuss the limitations of the impulsive limit and propose a method that rescales the effective matrix elements, enabling an improved and more accurate description of laser-molecule interactions.}, author = {Karle, Volker and Lemeshko, Mikhail}, issn = {2469-9934}, journal = {Physical Review A}, number = {2}, publisher = {American Physical Society}, title = {{Modeling laser pulses as δ kicks: Reevaluating the impulsive limit in molecular rotational dynamics}}, doi = {10.1103/PhysRevA.109.023101}, volume = {109}, year = {2024}, } @article{15045, abstract = {Coupling of orbital motion to a spin degree of freedom gives rise to various transport phenomena in quantum systems that are beyond the standard paradigms of classical physics. Here, we discuss features of spin-orbit dynamics that can be visualized using a classical model with two coupled angular degrees of freedom. Specifically, we demonstrate classical ‘spin’ filtering through our model and show that the interplay between angular degrees of freedom and dissipation can lead to asymmetric ‘spin’ transport.}, author = {Varshney, Atul and Ghazaryan, Areg and Volosniev, Artem}, issn = {1432-5411}, journal = {Few-Body Systems}, keywords = {Atomic and Molecular Physics, and Optics}, publisher = {Springer Nature}, title = {{Classical ‘spin’ filtering with two degrees of freedom and dissipation}}, doi = {10.1007/s00601-024-01880-x}, volume = {65}, year = {2024}, } @article{15053, abstract = {Atom-based quantum simulators have had many successes in tackling challenging quantum many-body problems, owing to the precise and dynamical control that they provide over the systems' parameters. They are, however, often optimized to address a specific type of problem. Here, we present the design and implementation of a 6Li-based quantum gas platform that provides wide-ranging capabilities and is able to address a variety of quantum many-body problems. Our two-chamber architecture relies on a robust combination of gray molasses and optical transport from a laser-cooling chamber to a glass cell with excellent optical access. There, we first create unitary Fermi superfluids in a three-dimensional axially symmetric harmonic trap and characterize them using in situ thermometry, reaching temperatures below 20 nK. This allows us to enter the deep superfluid regime with samples of extreme diluteness, where the interparticle spacing is sufficiently large for direct single-atom imaging. Second, we generate optical lattice potentials with triangular and honeycomb geometry in which we study diffraction of molecular Bose-Einstein condensates, and show how going beyond the Kapitza-Dirac regime allows us to unambiguously distinguish between the two geometries. With the ability to probe quantum many-body physics in both discrete and continuous space, and its suitability for bulk and single-atom imaging, our setup represents an important step towards achieving a wide-scope quantum simulator.}, author = {Jin, Shuwei and Dai, Kunlun and Verstraten, Joris and Dixmerias, Maxime and Al Hyder, Ragheed and Salomon, Christophe and Peaudecerf, Bruno and de Jongh, Tim and Yefsah, Tarik}, issn = {2643-1564}, journal = {Physical Review Research}, keywords = {General Physics and Astronomy}, number = {1}, publisher = {American Physical Society}, title = {{Multipurpose platform for analog quantum simulation}}, doi = {10.1103/physrevresearch.6.013158}, volume = {6}, year = {2024}, }