TY - CONF
AB - We demonstrate robust retention of valley coherence and its control via polariton pseudospin precession through the optical TE-TM splitting in bilayer WS2 microcavity exciton polaritons at room temperature.
AU - Khatoniar, Mandeep
AU - Yama, Nicholas
AU - Ghazaryan, Areg
AU - Guddala, Sriram
AU - Ghaemi, Pouyan
AU - Menon, Vinod
ID - 6646
SN - 9781943580576
T2 - CLEO: Applications and Technology
TI - Room temperature control of valley coherence in bilayer WS2 exciton polaritons
ER -
TY - JOUR
AB - Dipolar coupling plays a fundamental role in the interaction between electrically or magnetically polarized species such as magnetic atoms and dipolar molecules in a gas or dipolar excitons in the solid state. Unlike Coulomb or contactlike interactions found in many atomic, molecular, and condensed-matter systems, this interaction is long-ranged and highly anisotropic, as it changes from repulsive to attractive depending on the relative positions and orientation of the dipoles. Because of this unique property, many exotic, symmetry-breaking collective states have been recently predicted for cold dipolar gases, but only a few have been experimentally detected and only in dilute atomic dipolar Bose-Einstein condensates. Here, we report on the first observation of attractive dipolar coupling between excitonic dipoles using a new design of stacked semiconductor bilayers. We show that the presence of a dipolar exciton fluid in one bilayer modifies the spatial distribution and increases the binding energy of excitonic dipoles in a vertically remote layer. The binding energy changes are explained using a many-body polaron model describing the deformation of the exciton cloud due to its interaction with a remote dipolar exciton. The surprising nonmonotonic dependence on the cloud density indicates the important role of dipolar correlations, which is unique to dense, strongly interacting dipolar solid-state systems. Our concept provides a route for the realization of dipolar lattices with strong anisotropic interactions in semiconductor systems, which open the way for the observation of theoretically predicted new and exotic collective phases, as well as for engineering and sensing their collective excitations.
AU - Hubert, Colin
AU - Baruchi, Yifat
AU - Mazuz-Harpaz, Yotam
AU - Cohen, Kobi
AU - Biermann, Klaus
AU - Lemeshko, Mikhail
AU - West, Ken
AU - Pfeiffer, Loren
AU - Rapaport, Ronen
AU - Santos, Paulo
ID - 6786
IS - 2
JF - Physical Review X
TI - Attractive dipolar coupling between stacked exciton fluids
VL - 9
ER -
TY - JOUR
AB - We study few-body bound states of charged particles subject to attractive zero-range/short-range plus repulsive Coulomb interparticle forces. The characteristic length scales of the system at zero energy are set by the Coulomb length scale D and the Coulomb-modified effective range r eff. We study shallow bound states of charged particles with D >> r eff and show that these systems obey universal scaling laws different from neutral particles. An accurate description of these states requires both the Coulomb-modified scattering length and the effective range unless the Coulomb interaction is very weak (D -> ). Our findings are relevant for bound states whose spatial extent is significantly larger than the range of the attractive potential. These states enjoy universality – their character is independent of the shape of the short-range potential.
AU - Schmickler, C.H.
AU - Hammer, H.-W.
AU - Volosniev, Artem
ID - 6955
JF - Physics Letters B
SN - 0370-2693
TI - Universal physics of bound states of a few charged particles
VL - 798
ER -
TY - JOUR
AB - We study the effect of a linear tunneling coupling between two-dimensional systems, each separately
exhibiting the topological Berezinskii-Kosterlitz-Thouless (BKT) transition. In the uncoupled limit, there
are two phases: one where the one-body correlation functions are algebraically decaying and the other with
exponential decay. When the linear coupling is turned on, a third BKT-paired phase emerges, in which one-body correlations are exponentially decaying, while two-body correlation functions exhibit power-law
decay. We perform numerical simulations in the paradigmatic case of two coupled XY models at finite
temperature, finding evidences that for any finite value of the interlayer coupling, the BKT-paired phase is
present. We provide a picture of the phase diagram using a renormalization group approach.
AU - Bighin, Giacomo
AU - Defenu, Nicolò
AU - Nándori, István
AU - Salasnich, Luca
AU - Trombettoni, Andrea
ID - 6940
IS - 10
JF - Physical Review Letters
SN - 0031-9007
TI - Berezinskii-Kosterlitz-Thouless paired phase in coupled XY models
VL - 123
ER -
TY - JOUR
AB - We developed a method to calculate two-photon processes in quantum mechanics that replaces the infinite summation over the intermediate states by a perturbation expansion. This latter consists of a series of commutators that involve position, momentum, and Hamiltonian quantum operators. We analyzed several single- and many-particle cases for which a closed-form solution to the perturbation expansion exists, as well as more complicated cases for which a solution is found by convergence. Throughout the article, Rayleigh and Raman scattering are taken as examples of two-photon processes. The present method provides a clear distinction between the Thomson scattering, regarded as classical scattering, and quantum contributions. Such a distinction lets us derive general results concerning light scattering. Finally, possible extensions to the developed formalism are discussed.
AU - Fratini, Filippo
AU - Safari, Laleh
AU - Amaro, Pedro
AU - Santos, José
ID - 294
IS - 4
JF - Physical Review A - Atomic, Molecular, and Optical Physics
TI - Two-photon processes based on quantum commutators
VL - 97
ER -
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 -