TY - JOUR AB - 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. AU - Dome, Tibor AU - Volosniev, Artem AU - Ghazaryan, Areg AU - Safari, Laleh AU - Schmidt, Richard AU - Lemeshko, Mikhail ID - 14845 IS - 1 JF - Physical Review B SN - 2469-9950 TI - Linear rotor in an ideal Bose gas near the threshold for binding VL - 109 ER - TY - JOUR AB - 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. AU - Karle, Volker AU - Lemeshko, Mikhail ID - 14851 IS - 1 JF - Physik in unserer Zeit KW - General Earth and Planetary Sciences KW - General Environmental Science SN - 0031-9252 TI - Die faszinierende Topologie rotierender Quanten VL - 55 ER - TY - JOUR AB - 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. AU - Karle, Volker AU - Lemeshko, Mikhail ID - 15004 IS - 2 JF - Physical Review A SN - 2469-9926 TI - Modeling laser pulses as δ kicks: Reevaluating the impulsive limit in molecular rotational dynamics VL - 109 ER - TY - JOUR AB - Brownian motion of a mobile impurity in a bath is affected by spin-orbit coupling (SOC). Here, we discuss a Caldeira-Leggett-type model that can be used to propose and interpret quantum simulators of this problem in cold Bose gases. First, we derive a master equation that describes the model and explore it in a one-dimensional (1D) setting. To validate the standard assumptions needed for our derivation, we analyze available experimental data without SOC; as a byproduct, this analysis suggests that the quench dynamics of the impurity is beyond the 1D Bose-polaron approach at temperatures currently accessible in a cold-atom laboratory—motion of the impurity is mainly driven by dissipation. For systems with SOC, we demonstrate that 1D spin-orbit coupling can be gauged out even in the presence of dissipation—the information about SOC is incorporated in the initial conditions. Observables sensitive to this information (such as spin densities) can be used to study formation of steady spin polarization domains during quench dynamics. AU - Ghazaryan, Areg AU - Cappellaro, Alberto AU - Lemeshko, Mikhail AU - Volosniev, Artem ID - 12534 IS - 1 JF - Physical Review Research SN - 2643-1564 TI - Dissipative dynamics of an impurity with spin-orbit coupling VL - 5 ER - TY - JOUR AB - 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. AU - Wei, Yujing AU - Volosniev, Artem AU - Lorenc, Dusan AU - Zhumekenov, Ayan A. AU - Bakr, Osman M. AU - Lemeshko, Mikhail AU - Alpichshev, Zhanybek ID - 13251 IS - 27 JF - The Journal of Physical Chemistry Letters KW - General Materials Science KW - Physical and Theoretical Chemistry TI - Bond polarizability as a probe of local crystal fields in hybrid lead-halide perovskites VL - 14 ER - TY - JOUR AB - Lead halide perovskites enjoy a number of remarkable optoelectronic properties. To explain their origin, it is necessary to study how electromagnetic fields interact with these systems. We address this problem here by studying two classical quantities: Faraday rotation and the complex refractive index in a paradigmatic perovskite CH3NH3PbBr3 in a broad wavelength range. We find that the minimal coupling of electromagnetic fields to the k⋅p Hamiltonian is insufficient to describe the observed data even on the qualitative level. To amend this, we demonstrate that there exists a relevant atomic-level coupling between electromagnetic fields and the spin degree of freedom. This spin-electric coupling allows for quantitative description of a number of previous as well as present experimental data. In particular, we use it here to show that the Faraday effect in lead halide perovskites is dominated by the Zeeman splitting of the energy levels and has a substantial beyond-Becquerel contribution. Finally, we present general symmetry-based phenomenological arguments that in the low-energy limit our effective model includes all basis coupling terms to the electromagnetic field in the linear order. AU - Volosniev, Artem AU - Shiva Kumar, Abhishek AU - Lorenc, Dusan AU - Ashourishokri, Younes AU - Zhumekenov, Ayan A. AU - Bakr, Osman M. AU - Lemeshko, Mikhail AU - Alpichshev, Zhanybek ID - 12723 IS - 10 JF - Physical Review Letters KW - General Physics and Astronomy SN - 0031-9007 TI - Spin-electric coupling in lead halide perovskites VL - 130 ER - TY - JOUR AB - We use general symmetry-based arguments to construct an effective model suitable for studying optical properties of lead halide perovskites. To build the model, we identify an atomic-level interaction between electromagnetic fields and the spin degree of freedom that should be added to a minimally coupled k⋅p Hamiltonian. As a first application, we study two basic optical characteristics of the material: the Verdet constant and the refractive index. Beyond these linear characteristics of the material, the model is suitable for calculating nonlinear effects such as the third-order optical susceptibility. Analysis of this quantity shows that the geometrical properties of the spin-electric term imply isotropic optical response of the system, and that optical anisotropy of lead halide perovskites is a manifestation of hopping of charge carriers. To illustrate this, we discuss third-harmonic generation. AU - Volosniev, Artem AU - Shiva Kumar, Abhishek AU - Lorenc, Dusan AU - Ashourishokri, Younes AU - Zhumekenov, Ayan AU - Bakr, Osman M. AU - Lemeshko, Mikhail AU - Alpichshev, Zhanybek ID - 12724 IS - 12 JF - Physical Review B SN - 2469-9950 TI - Effective model for studying optical properties of lead halide perovskites VL - 107 ER - TY - JOUR AB - We show that the simplest of existing molecules—closed-shell diatomics not interacting with one another—host topological charges when driven by periodic far-off-resonant laser pulses. A periodically kicked molecular rotor can be mapped onto a “crystalline” lattice in angular momentum space. This allows us to define quasimomenta and the band structure in the Floquet representation, by analogy with the Bloch waves of solid-state physics. Applying laser pulses spaced by 1/3 of the molecular rotational period creates a lattice with three atoms per unit cell with staggered hopping. Within the synthetic dimension of the laser strength, we discover Dirac cones with topological charges. These Dirac cones, topologically protected by reflection and time-reversal symmetry, are reminiscent of (although not equivalent to) that seen in graphene. They—and the corresponding edge states—are broadly tunable by adjusting the laser strength and can be observed in present-day experiments by measuring molecular alignment and populations of rotational levels. This paves the way to study controllable topological physics in gas-phase experiments with small molecules as well as to classify dynamical molecular states by their topological invariants. AU - Karle, Volker AU - Ghazaryan, Areg AU - Lemeshko, Mikhail ID - 12788 IS - 10 JF - Physical Review Letters SN - 0031-9007 TI - Topological charges of periodically kicked molecules VL - 130 ER - TY - JOUR AB - The angulon, a quasiparticle formed by a quantum rotor dressed by the excitations of a many-body bath, can be used to describe an impurity rotating in a fluid or solid environment. Here, we propose a coherent state ansatz in the co-rotating frame, which provides a comprehensive theoretical description of angulons. We reveal the quasiparticle properties, such as energies, quasiparticle weights, and spectral functions, and show that our ansatz yields a persistent decrease in the impurity’s rotational constant due to many-body dressing, which is consistent with experimental observations. From our study, a picture of the angulon emerges as an effective spin interacting with a magnetic field that is self-consistently generated by the molecule’s rotation. Moreover, we discuss rotational spectroscopy, which focuses on the response of rotating molecules to a laser perturbation in the linear response regime. Importantly, we take into account initial-state interactions that have been neglected in prior studies and reveal their impact on the excitation spectrum. To examine the angulon instability regime, we use a single-excitation ansatz and obtain results consistent with experiments, in which a broadening of spectral lines is observed while phonon wings remain highly suppressed due to initial-state interactions. AU - Zeng, Zhongda AU - Yakaboylu, Enderalp AU - Lemeshko, Mikhail AU - Shi, Tao AU - Schmidt, Richard ID - 12831 IS - 13 JF - The Journal of Chemical Physics TI - Variational theory of angulons and their rotational spectroscopy VL - 158 ER - TY - JOUR AB - 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. AU - Agafonova, Sofya AU - Lemeshko, Mikhail AU - Volosniev, Artem ID - 13233 IS - 6 JF - Physical Review A SN - 2469-9926 TI - Finite-range bias in fitting three-body loss to the zero-range model VL - 107 ER - TY - JOUR AB - 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. AU - Bighin, Giacomo AU - Ho, Quoc P AU - Lemeshko, Mikhail AU - Tscherbul, T. V. ID - 13966 IS - 4 JF - Physical Review B SN - 2469-9950 TI - Diagrammatic Monte Carlo for electronic correlation in molecules: High-order many-body perturbation theory with low scaling VL - 108 ER - TY - JOUR AB - 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. AU - Al Hyder, Ragheed AU - Cappellaro, Alberto AU - Lemeshko, Mikhail AU - Volosniev, Artem ID - 14321 IS - 10 JF - The Journal of Chemical Physics KW - Physical and Theoretical Chemistry KW - General Physics and Astronomy SN - 0021-9606 TI - Achiral dipoles on a ferromagnet can affect its magnetization direction VL - 159 ER - TY - JOUR AB - 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. AU - Vardi, Ofek AU - Maroudas-Sklare, Naama AU - Kolodny, Yuval AU - Volosniev, Artem AU - Saragovi, Amijai AU - Galili, Nir AU - Ferrera, Stav AU - Ghazaryan, Areg AU - Yuran, Nir AU - Affek, Hagit P. AU - Luz, Boaz AU - Goldsmith, Yonaton AU - Keren, Nir AU - Yochelis, Shira AU - Halevy, Itay AU - Lemeshko, Mikhail AU - Paltiel, Yossi ID - 14037 IS - 32 JF - Proceedings of the National Academy of Sciences of the United States of America TI - Nuclear spin effects in biological processes VL - 120 ER - TY - JOUR AB - 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. AU - Koutentakis, Georgios AU - Ghazaryan, Areg AU - Lemeshko, Mikhail ID - 14486 IS - 4 JF - Physical Review Research SN - 2643-1564 TI - Rotor lattice model of ferroelectric large polarons VL - 5 ER - TY - JOUR AB - 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. AU - Kranabetter, Lorenz AU - Kristensen, Henrik H. AU - Ghazaryan, Areg AU - Schouder, Constant A. AU - Chatterley, Adam S. AU - Janssen, Paul AU - Jensen, Frank AU - Zillich, Robert E. AU - Lemeshko, Mikhail AU - Stapelfeldt, Henrik ID - 14238 IS - 5 JF - Physical Review Letters SN - 0031-9007 TI - Nonadiabatic laser-induced alignment dynamics of molecules on a surface VL - 131 ER - TY - JOUR AB - We study an impurity with a resonance level whose position coincides with the Fermi energy of the surrounding Fermi gas. An impurity causes a rapid variation of the scattering phase shift for fermions at the Fermi surface, introducing a new characteristic length scale into the problem. We investigate manifestations of this length scale in the self-energy of the impurity and in the density of the bath. Our calculations reveal a model-independent deformation of the density of the Fermi gas, which is determined by the width of the resonance. To provide a broader picture, we investigate time evolution of the density in quench dynamics, and study the behavior of the system at finite temperatures. Finally, we briefly discuss implications of our findings for the Fermi-polaron problem. AU - Maslov, Mikhail AU - Lemeshko, Mikhail AU - Volosniev, Artem ID - 10845 JF - Physical Review Research SN - 2643-1564 TI - Impurity with a resonance in the vicinity of the Fermi energy VL - 4 ER - TY - JOUR AB - A critical overview of the theory of the chirality-induced spin selectivity (CISS) effect, that is, phenomena in which the chirality of molecular species imparts significant spin selectivity to various electron processes, is provided. Based on discussions in a recently held workshop, and further work published since, the status of CISS effects—in electron transmission, electron transport, and chemical reactions—is reviewed. For each, a detailed discussion of the state-of-the-art in theoretical understanding is provided and remaining challenges and research opportunities are identified. AU - Evers, Ferdinand AU - Aharony, Amnon AU - Bar-Gill, Nir AU - Entin-Wohlman, Ora AU - Hedegård, Per AU - Hod, Oded AU - Jelinek, Pavel AU - Kamieniarz, Grzegorz AU - Lemeshko, Mikhail AU - Michaeli, Karen AU - Mujica, Vladimiro AU - Naaman, Ron AU - Paltiel, Yossi AU - Refaely-Abramson, Sivan AU - Tal, Oren AU - Thijssen, Jos AU - Thoss, Michael AU - Van Ruitenbeek, Jan M. AU - Venkataraman, Latha AU - Waldeck, David H. AU - Yan, Binghai AU - Kronik, Leeor ID - 10771 IS - 13 JF - Advanced Materials SN - 09359648 TI - Theory of chirality induced spin selectivity: Progress and challenges VL - 34 ER - TY - JOUR AB - Rotational dynamics of D2 molecules inside helium nanodroplets is induced by a moderately intense femtosecond pump pulse and measured as a function of time by recording the yield of HeD+ ions, created through strong-field dissociative ionization with a delayed femtosecond probe pulse. The yield oscillates with a period of 185 fs, reflecting field-free rotational wave packet dynamics, and the oscillation persists for more than 500 periods. Within the experimental uncertainty, the rotational constant BHe of the in-droplet D2 molecule, determined by Fourier analysis, is the same as Bgas for an isolated D2 molecule. Our observations show that the D2 molecules inside helium nanodroplets essentially rotate as free D2 molecules. AU - Qiang, Junjie AU - Zhou, Lianrong AU - Lu, Peifen AU - Lin, Kang AU - Ma, Yongzhe AU - Pan, Shengzhe AU - Lu, Chenxu AU - Jiang, Wenyu AU - Sun, Fenghao AU - Zhang, Wenbin AU - Li, Hui AU - Gong, Xiaochun AU - Averbukh, Ilya Sh AU - Prior, Yehiam AU - Schouder, Constant A. AU - Stapelfeldt, Henrik AU - Cherepanov, Igor AU - Lemeshko, Mikhail AU - Jäger, Wolfgang AU - Wu, Jian ID - 11552 IS - 24 JF - Physical Review Letters SN - 00319007 TI - Femtosecond rotational dynamics of D2 molecules in superfluid helium nanodroplets VL - 128 ER - TY - JOUR AB - We investigate the ground-state properties of weakly repulsive one-dimensional bosons in the presence of an attractive zero-range impurity potential. First, we derive mean-field solutions to the problem on a finite ring for the two asymptotic cases: (i) all bosons are bound to the impurity and (ii) all bosons are in a scattering state. Moreover, we derive the critical line that separates these regimes in the parameter space. In the thermodynamic limit, this critical line determines the maximum number of bosons that can be bound by the impurity potential, forming an artificial atom. Second, we validate the mean-field results using the flow equation approach and the multi-layer multi-configuration time-dependent Hartree method for atomic mixtures. While beyond-mean-field effects destroy long-range order in the Bose gas, the critical boson number is unaffected. Our findings are important for understanding such artificial atoms in low-density Bose gases with static and mobile impurities. AU - Brauneis, Fabian AU - Backert, Timothy G. AU - Mistakidis, Simeon I. AU - Lemeshko, Mikhail AU - Hammer, Hans Werner AU - Volosniev, Artem ID - 11590 IS - 6 JF - New Journal of Physics SN - 1367-2630 TI - Artificial atoms from cold bosons in one dimension VL - 24 ER - TY - JOUR AB - Recently it became possible to study highly excited rotational states of molecules in superfluid helium through nonadiabatic alignment experiments (Cherepanov et al 2021 Phys. Rev. A 104 L061303). This calls for theoretical approaches that go beyond explaining renormalized values of molecular spectroscopic constants, which suffices when only the lowest few rotational states are involved. As the first step in this direction, here we present a basic quantum mechanical model describing highly excited rotational states of molecules in superfluid helium nanodroplets. We show that a linear molecule immersed in a superfluid can be seen as an effective symmetric top, similar to the rotational structure of radicals, such as OH or NO, but with the angular momentum of the superfluid playing the role of the electronic angular momentum in free molecules. The simple theory sheds light onto what happens when the rotational angular momentum of the molecule increases beyond the lowest excited states accessible by infrared spectroscopy. In addition, the model allows to estimate the effective rotational and centrifugal distortion constants for a broad range of species and to explain the crossover between light and heavy molecules in superfluid 4He in terms of the many-body wavefunction structure. Some of the above mentioned insights can be acquired by analyzing a simple 2 × 2 matrix. AU - Cherepanov, Igor AU - Bighin, Giacomo AU - Schouder, Constant A. AU - Chatterley, Adam S. AU - Stapelfeldt, Henrik AU - Lemeshko, Mikhail ID - 11998 IS - 7 JF - New Journal of Physics SN - 1367-2630 TI - A simple model for high rotational excitations of molecules in a superfluid VL - 24 ER -