TY - JOUR
AB - We demonstrate that identical impurities immersed in a two-dimensional many-particle bath can be viewed as flux-tube-charged-particle composites described by fractional statistics. In particular, we find that the bath manifests itself as an external magnetic flux tube with respect to the impurities, and hence the time-reversal symmetry is broken for the effective Hamiltonian describing the impurities. The emerging flux tube acts as a statistical gauge field after a certain critical coupling. This critical coupling corresponds to the intersection point between the quasiparticle state and the phonon wing, where the angular momentum is transferred from the impurity to the bath. This amounts to a novel configuration with emerging anyons. The proposed setup paves the way to realizing anyons using electrons interacting with superfluid helium or lattice phonons, as well as using atomic impurities in ultracold gases.
AU - Yakaboylu, Enderalp
AU - Lemeshko, Mikhail
ID - 195
IS - 4
JF - Physical Review B - Condensed Matter and Materials Physics
TI - Anyonic statistics of quantum impurities in two dimensions
VL - 98
ER -
TY - JOUR
AB - We present an approach to interacting quantum many-body systems based on the notion of quantum groups, also known as q-deformed Lie algebras. In particular, we show that, if the symmetry of a free quantum particle corresponds to a Lie group G, in the presence of a many-body environment this particle can be described by a deformed group, Gq. Crucially, the single deformation parameter, q, contains all the information about the many-particle interactions in the system. We exemplify our approach by considering a quantum rotor interacting with a bath of bosons, and demonstrate that extracting the value of q from closed-form solutions in the perturbative regime allows one to predict the behavior of the system for arbitrary values of the impurity-bath coupling strength, in good agreement with nonperturbative calculations. Furthermore, the value of the deformation parameter allows one to predict at which coupling strengths rotor-bath interactions result in a formation of a stable quasiparticle. The approach based on quantum groups does not only allow for a drastic simplification of impurity problems, but also provides valuable insights into hidden symmetries of interacting many-particle systems.
AU - Yakaboylu, Enderalp
AU - Shkolnikov, Mikhail
AU - Lemeshko, Mikhail
ID - 5794
IS - 25
JF - Physical Review Letters
SN - 00319007
TI - Quantum groups as hidden symmetries of quantum impurities
VL - 121
ER -
TY - JOUR
AB - We study a quantum impurity possessing both translational and internal rotational degrees of freedom interacting with a bosonic bath. Such a system corresponds to a “rotating polaron,” which can be used to model, e.g., a rotating molecule immersed in an ultracold Bose gas or superfluid helium. We derive the Hamiltonian of the rotating polaron and study its spectrum in the weak- and strong-coupling regimes using a combination of variational, diagrammatic, and mean-field approaches. We reveal how the coupling between linear and angular momenta affects stable quasiparticle states, and demonstrate that internal rotation leads to an enhanced self-localization in the translational degrees of freedom.
AU - Yakaboylu, Enderalp
AU - Midya, Bikashkali
AU - Deuchert, Andreas
AU - Leopold, Nikolai K
AU - Lemeshko, Mikhail
ID - 5983
IS - 22
JF - Physical Review B
SN - 2469-9950
TI - Theory of the rotating polaron: Spectrum and self-localization
VL - 98
ER -
TY - JOUR
AB - We introduce a diagrammatic Monte Carlo approach to angular momentum properties of quantum many-particle systems possessing a macroscopic number of degrees of freedom. The treatment is based on a diagrammatic expansion that merges the usual Feynman diagrams with the angular momentum diagrams known from atomic and nuclear structure theory, thereby incorporating the non-Abelian algebra inherent to quantum rotations. Our approach is applicable at arbitrary coupling, is free of systematic errors and of finite-size effects, and naturally provides access to the impurity Green function. We exemplify the technique by obtaining an all-coupling solution of the angulon model; however, the method is quite general and can be applied to a broad variety of systems in which particles exchange quantum angular momentum with their many-body environment.
AU - Bighin, Giacomo
AU - Tscherbul, Timur
AU - Lemeshko, Mikhail
ID - 6339
IS - 16
JF - Physical Review Letters
TI - Diagrammatic Monte Carlo approach to angular momentum in quantum many-particle systems
VL - 121
ER -
TY - JOUR
AB - Recently it was shown that a molecule rotating in a quantum solvent can be described in terms of the “angulon” quasiparticle [M. Lemeshko, Phys. Rev. Lett. 118, 095301 (2017)]. Here we extend the angulon theory to the case of molecules possessing an additional spin-1/2 degree of freedom and study the behavior of the system in the presence of a static magnetic field. We show that exchange of angular momentum between the molecule and the solvent can be altered by the field, even though the solvent itself is non-magnetic. In particular, we demonstrate a possibility to control resonant emission of phonons with a given angular momentum using a magnetic field.
AU - Rzadkowski, Wojciech
AU - Lemeshko, Mikhail
ID - 415
IS - 10
JF - The Journal of Chemical Physics
TI - Effect of a magnetic field on molecule–solvent angular momentum transfer
VL - 148
ER -