@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}, } @article{14320, abstract = {The development of two-dimensional materials has resulted in a diverse range of novel, high-quality compounds with increasing complexity. A key requirement for a comprehensive quantitative theory is the accurate determination of these materials' band structure parameters. However, this task is challenging due to the intricate band structures and the indirect nature of experimental probes. In this work, we introduce a general framework to derive band structure parameters from experimental data using deep neural networks. We applied our method to the penetration field capacitance measurement of trilayer graphene, an effective probe of its density of states. First, we demonstrate that a trained deep network gives accurate predictions for the penetration field capacitance as a function of tight-binding parameters. Next, we use the fast and accurate predictions from the trained network to automatically determine tight-binding parameters directly from experimental data, with extracted parameters being in a good agreement with values in the literature. We conclude by discussing potential applications of our method to other materials and experimental techniques beyond penetration field capacitance.}, author = {Henderson, Paul M and Ghazaryan, Areg and Zibrov, Alexander A. and Young, Andrea F. and Serbyn, Maksym}, issn = {2469-9969}, journal = {Physical Review B}, number = {12}, publisher = {American Physical Society}, title = {{Deep learning extraction of band structure parameters from density of states: A case study on trilayer graphene}}, doi = {10.1103/physrevb.108.125411}, volume = {108}, year = {2023}, } @article{14321, abstract = {We demonstrate the possibility of a coupling between the magnetization direction of a ferromagnet and the tilting angle of adsorbed achiral molecules. To illustrate the mechanism of the coupling, we analyze a minimal Stoner model that includes Rashba spin–orbit coupling due to the electric field on the surface of the ferromagnet. The proposed mechanism allows us to study magnetic anisotropy of the system with an extended Stoner–Wohlfarth model and argue that adsorbed achiral molecules can change magnetocrystalline anisotropy of the substrate. Our research aims to motivate further experimental studies of the current-free chirality induced spin selectivity effect involving both enantiomers.}, author = {Al Hyder, Ragheed and Cappellaro, Alberto and Lemeshko, Mikhail and Volosniev, Artem}, issn = {1089-7690}, journal = {The Journal of Chemical Physics}, keywords = {Physical and Theoretical Chemistry, General Physics and Astronomy}, number = {10}, publisher = {AIP Publishing}, title = {{Achiral dipoles on a ferromagnet can affect its magnetization direction}}, doi = {10.1063/5.0165806}, volume = {159}, year = {2023}, } @article{14486, abstract = {We present a minimal model of ferroelectric large polarons, which are suggested as one of the mechanisms responsible for the unique charge transport properties of hybrid perovskites. We demonstrate that short-ranged charge–rotor interactions lead to long-range ferroelectric ordering of rotors, which strongly affects the carrier mobility. In the nonperturbative regime, where our theory cannot be reduced to any of the earlier models, we reveal that the polaron is characterized by large coherence length and a roughly tenfold increase of the effective mass as compared to the bare mass. These results are in good agreement with other theoretical predictions for ferroelectric polarons. Our model establishes a general phenomenological framework for ferroelectric polarons providing the starting point for future studies of their role in the transport properties of hybrid organic-inorganic perovskites.}, author = {Koutentakis, Georgios and Ghazaryan, Areg and Lemeshko, Mikhail}, issn = {2643-1564}, journal = {Physical Review Research}, number = {4}, publisher = {American Physical Society}, title = {{Rotor lattice model of ferroelectric large polarons}}, doi = {10.1103/PhysRevResearch.5.043016}, volume = {5}, year = {2023}, } @article{14513, abstract = {Cold atomic gases have become a paradigmatic system for exploring fundamental physics, which at the same time allows for applications in quantum technologies. The accelerating developments in the field have led to a highly advanced set of engineering techniques that, for example, can tune interactions, shape the external geometry, select among a large set of atomic species with different properties, or control the number of atoms. In particular, it is possible to operate in lower dimensions and drive atomic systems into the strongly correlated regime. In this review, we discuss recent advances in few-body cold atom systems confined in low dimensions from a theoretical viewpoint. We mainly focus on bosonic systems in one dimension and provide an introduction to the static properties before we review the state-of-the-art research into quantum dynamical processes stimulated by the presence of correlations. Besides discussing the fundamental physical phenomena arising in these systems, we also provide an overview of the calculational and numerical tools and methods that are commonly used, thus delivering a balanced and comprehensive overview of the field. We conclude by giving an outlook on possible future directions that are interesting to explore in these correlated systems.}, author = {Mistakidis, S. I. and Volosniev, Artem and Barfknecht, R. E. and Fogarty, T. and Busch, Th and Foerster, A. and Schmelcher, P. and Zinner, N. T.}, issn = {0370-1573}, journal = {Physics Reports}, pages = {1--108}, publisher = {Elsevier}, title = {{Few-body Bose gases in low dimensions - A laboratory for quantum dynamics}}, doi = {10.1016/j.physrep.2023.10.004}, volume = {1042}, year = {2023}, } @article{14650, abstract = {We study the out-of-equilibrium quantum dynamics of dipolar polarons, i.e., impurities immersed in a dipolar Bose-Einstein condensate, after a quench of the impurity-boson interaction. We show that the dipolar nature of the condensate and of the impurity results in anisotropic relaxation dynamics, in particular, anisotropic dressing of the polaron. More relevantly for cold-atom setups, quench dynamics is strongly affected by the interplay between dipolar anisotropy and trap geometry. Our findings pave the way for simulating impurities in anisotropic media utilizing experiments with dipolar mixtures.}, author = {Volosniev, Artem and Bighin, Giacomo and Santos, Luis and Peña Ardila, Luisllu A.}, issn = {2542-4653}, journal = {SciPost Physics}, keywords = {General Physics and Astronomy}, number = {6}, publisher = {SciPost Foundation}, title = {{Non-equilibrium dynamics of dipolar polarons}}, doi = {10.21468/scipostphys.15.6.232}, volume = {15}, year = {2023}, } @article{14658, abstract = {We investigate spin-charge separation of a spin- 1 2 Fermi system confined in a triple well where multiple bands are occupied. We assume that our finite fermionic system is close to fully spin polarized while being doped by a hole and an impurity fermion with opposite spin. Our setup involves ferromagnetic couplings among the particles in different bands, leading to the development of strong spin-transport correlations in an intermediate interaction regime. Interactions are then strong enough to lift the degeneracy among singlet and triplet spin configurations in the well of the spin impurity but not strong enough to prohibit hole-induced magnetic excitations to the singlet state. Despite the strong spin-hole correlations, the system exhibits spin-charge deconfinement allowing for long-range entanglement of the spatial and spin degrees of freedom.}, author = {Becker, J. M. and Koutentakis, Georgios and Schmelcher, P.}, issn = {2643-1564}, journal = {Physical Review Research}, number = {4}, publisher = {American Physical Society}, title = {{Spin-charge correlations in finite one-dimensional multiband Fermi systems}}, doi = {10.1103/PhysRevResearch.5.043039}, volume = {5}, year = {2023}, } @article{14756, abstract = {We prove the r-spin cobordism hypothesis in the setting of (weak) 2-categories for every positive integer r: the 2-groupoid of 2-dimensional fully extended r-spin TQFTs with given target is equivalent to the homotopy fixed points of an induced Spin 2r -action. In particular, such TQFTs are classified by fully dualisable objects together with a trivialisation of the rth power of their Serre automorphisms. For r=1, we recover the oriented case (on which our proof builds), while ordinary spin structures correspond to r=2. To construct examples, we explicitly describe Spin 2r​-homotopy fixed points in the equivariant completion of any symmetric monoidal 2-category. We also show that every object in a 2-category of Landau–Ginzburg models gives rise to fully extended spin TQFTs and that half of these do not factor through the oriented bordism 2-category.}, author = {Carqueville, Nils and Szegedy, Lorant}, issn = {1663-487X}, journal = {Quantum Topology}, keywords = {Geometry and Topology, Mathematical Physics}, number = {3}, pages = {467--532}, publisher = {European Mathematical Society}, title = {{Fully extended r-spin TQFTs}}, doi = {10.4171/qt/193}, volume = {14}, year = {2023}, } @article{13233, abstract = {We study the impact of finite-range physics on the zero-range-model analysis of three-body recombination in ultracold atoms. We find that temperature dependence of the zero-range parameters can vary from one set of measurements to another as it may be driven by the distribution of error bars in the experiment, and not by the underlying three-body physics. To study finite-temperature effects in three-body recombination beyond the zero-range physics, we introduce and examine a finite-range model based upon a hyperspherical formalism. The systematic error discussed in this Letter may provide a significant contribution to the error bars of measured three-body parameters.}, author = {Agafonova, Sofya and Lemeshko, Mikhail and Volosniev, Artem}, issn = {2469-9934}, journal = {Physical Review A}, number = {6}, publisher = {American Physical Society}, title = {{Finite-range bias in fitting three-body loss to the zero-range model}}, doi = {10.1103/PhysRevA.107.L061304}, volume = {107}, year = {2023}, } @article{13251, abstract = {A rotating organic cation and a dynamically disordered soft inorganic cage are the hallmark features of organic-inorganic lead-halide perovskites. Understanding the interplay between these two subsystems is a challenging problem, but it is this coupling that is widely conjectured to be responsible for the unique behavior of photocarriers in these materials. In this work, we use the fact that the polarizability of the organic cation strongly depends on the ambient electrostatic environment to put the molecule forward as a sensitive probe of the local crystal fields inside the lattice cell. We measure the average polarizability of the C/N–H bond stretching mode by means of infrared spectroscopy, which allows us to deduce the character of the motion of the cation molecule, find the magnitude of the local crystal field, and place an estimate on the strength of the hydrogen bond between the hydrogen and halide atoms. Our results pave the way for understanding electric fields in lead-halide perovskites using infrared bond spectroscopy.}, author = {Wei, Yujing and Volosniev, Artem and Lorenc, Dusan and Zhumekenov, Ayan A. and Bakr, Osman M. and Lemeshko, Mikhail and Alpichshev, Zhanybek}, issn = {1948-7185}, journal = {The Journal of Physical Chemistry Letters}, keywords = {General Materials Science, Physical and Theoretical Chemistry}, number = {27}, pages = {6309--6314}, publisher = {American Chemical Society}, title = {{Bond polarizability as a probe of local crystal fields in hybrid lead-halide perovskites}}, doi = {10.1021/acs.jpclett.3c01158}, volume = {14}, year = {2023}, } @misc{13275, abstract = {We introduce a generic and accessible implementation of an exact diagonalization method for studying few-fermion models. Our aim is to provide a testbed for the newcomers to the field as well as a stepping stone for trying out novel optimizations and approximations. This userguide consists of a description of the algorithm, and several examples in varying orders of sophistication. In particular, we exemplify our routine using an effective-interaction approach that fixes the low-energy physics. We benchmark this approach against the existing data, and show that it is able to deliver state-of-the-art numerical results at a significantly reduced computational cost.}, author = {Rammelmüller, Lukas and Huber, David and Volosniev, Artem}, publisher = {SciPost Foundation}, title = {{Codebase release 1.0 for FermiFCI}}, doi = {10.21468/scipostphyscodeb.12-r1.0}, year = {2023}, } @article{13276, abstract = {We introduce a generic and accessible implementation of an exact diagonalization method for studying few-fermion models. Our aim is to provide a testbed for the newcomers to the field as well as a stepping stone for trying out novel optimizations and approximations. This userguide consists of a description of the algorithm, and several examples in varying orders of sophistication. In particular, we exemplify our routine using an effective-interaction approach that fixes the low-energy physics. We benchmark this approach against the existing data, and show that it is able to deliver state-of-the-art numerical results at a significantly reduced computational cost.}, author = {Rammelmüller, Lukas and Huber, David and Volosniev, Artem}, issn = {2949-804X}, journal = {SciPost Physics Codebases}, publisher = {SciPost Foundation}, title = {{A modular implementation of an effective interaction approach for harmonically trapped fermions in 1D}}, doi = {10.21468/scipostphyscodeb.12}, year = {2023}, } @article{13278, abstract = {We present a numerical analysis of spin-1/2 fermions in a one-dimensional harmonic potential in the presence of a magnetic point-like impurity at the center of the trap. The model represents a few-body analogue of a magnetic impurity in the vicinity of an s-wave superconductor. Already for a few particles we find a ground-state level crossing between sectors with different fermion parities. We interpret this crossing as a few-body precursor of a quantum phase transition, which occurs when the impurity "breaks" a Cooper pair. This picture is further corroborated by analyzing density-density correlations in momentum space. Finally, we discuss how the system may be realized with existing cold-atoms platforms.}, author = {Rammelmüller, Lukas and Huber, David and Čufar, Matija and Brand, Joachim and Hammer, Hans-Werner and Volosniev, Artem}, issn = {2542-4653}, journal = {SciPost Physics}, keywords = {General Physics and Astronomy}, number = {1}, publisher = {SciPost Foundation}, title = {{Magnetic impurity in a one-dimensional few-fermion system}}, doi = {10.21468/scipostphys.14.1.006}, volume = {14}, year = {2023}, } @article{13966, abstract = {We present a low-scaling diagrammatic Monte Carlo approach to molecular correlation energies. Using combinatorial graph theory to encode many-body Hugenholtz diagrams, we sample the Møller-Plesset (MPn) perturbation series, obtaining accurate correlation energies up to n=5, with quadratic scaling in the number of basis functions. Our technique reduces the computational complexity of the molecular many-fermion correlation problem, opening up the possibility of low-scaling, accurate stochastic computations for a wide class of many-body systems described by Hugenholtz diagrams.}, author = {Bighin, Giacomo and Ho, Quoc P and Lemeshko, Mikhail and Tscherbul, T. V.}, issn = {2469-9969}, journal = {Physical Review B}, number = {4}, publisher = {American Physical Society}, title = {{Diagrammatic Monte Carlo for electronic correlation in molecules: High-order many-body perturbation theory with low scaling}}, doi = {10.1103/PhysRevB.108.045115}, volume = {108}, year = {2023}, } @article{14037, abstract = {Traditionally, nuclear spin is not considered to affect biological processes. Recently, this has changed as isotopic fractionation that deviates from classical mass dependence was reported both in vitro and in vivo. In these cases, the isotopic effect correlates with the nuclear magnetic spin. Here, we show nuclear spin effects using stable oxygen isotopes (16O, 17O, and 18O) in two separate setups: an artificial dioxygen production system and biological aquaporin channels in cells. We observe that oxygen dynamics in chiral environments (in particular its transport) depend on nuclear spin, suggesting future applications for controlled isotope separation to be used, for instance, in NMR. To demonstrate the mechanism behind our findings, we formulate theoretical models based on a nuclear-spin-enhanced switch between electronic spin states. Accounting for the role of nuclear spin in biology can provide insights into the role of quantum effects in living systems and help inspire the development of future biotechnology solutions.}, author = {Vardi, Ofek and Maroudas-Sklare, Naama and Kolodny, Yuval and Volosniev, Artem and Saragovi, Amijai and Galili, Nir and Ferrera, Stav and Ghazaryan, Areg and Yuran, Nir and Affek, Hagit P. and Luz, Boaz and Goldsmith, Yonaton and Keren, Nir and Yochelis, Shira and Halevy, Itay and Lemeshko, Mikhail and Paltiel, Yossi}, issn = {1091-6490}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, number = {32}, publisher = {National Academy of Sciences}, title = {{Nuclear spin effects in biological processes}}, doi = {10.1073/pnas.2300828120}, volume = {120}, year = {2023}, } @article{14238, abstract = {We demonstrate that a sodium dimer, Na2(13Σ+u), residing on the surface of a helium nanodroplet, can be set into rotation by a nonresonant 1.0 ps infrared laser pulse. The time-dependent degree of alignment measured, exhibits a periodic, gradually decreasing structure that deviates qualitatively from that expected for gas-phase dimers. Comparison to alignment dynamics calculated from the time-dependent rotational Schrödinger equation shows that the deviation is due to the alignment dependent interaction between the dimer and the droplet surface. This interaction confines the dimer to the tangential plane of the droplet surface at the point where it resides and is the reason that the observed alignment dynamics is also well described by a 2D quantum rotor model.}, author = {Kranabetter, Lorenz and Kristensen, Henrik H. and Ghazaryan, Areg and Schouder, Constant A. and Chatterley, Adam S. and Janssen, Paul and Jensen, Frank and Zillich, Robert E. and Lemeshko, Mikhail and Stapelfeldt, Henrik}, issn = {1079-7114}, journal = {Physical Review Letters}, number = {5}, publisher = {American Physical Society}, title = {{Nonadiabatic laser-induced alignment dynamics of molecules on a surface}}, doi = {10.1103/PhysRevLett.131.053201}, volume = {131}, year = {2023}, }