Superposition

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Jonathan P Dowling - One of the best experts on this subject based on the ideXlab platform.

  • ultra stable matter wave gyroscopy with counter rotating vortex Superpositions in bose einstein condensates
    arXiv: Quantum Physics, 2009
    Co-Authors: Sulakshana Thanvanthri, Kishore T Kapale, Jonathan P Dowling
    Abstract:

    Matter-wave interferometers are, in principle, orders of magnitude more sensitive than their optical counterparts. Nevertheless, creation of matter-wave currents to achieve such a sensitivity is a continuing challenge. Here, we propose the use of Optical Angular Momentum (OAM) induced vortex Superpositions in Bose-Einstein Condensates (BECs) as an alternative to atom interferometers for gyroscopy. The coherent Superposition of two counter-rotating vortex states of a trapped condensate leads to an interference pattern that rotates by an angle proportional to the angular velocity of the rotating trap \mdash in accordance with the Sagnac effect. We show that the rotation rate can be easily read out and that the device is highly stable. The signal-to-noise ratio and sensitivity of the scheme are also discussed.

  • vortex phase qubit generating arbitrary counterrotating coherent Superpositions in bose einstein condensates via optical angular momentum beams
    Physical Review Letters, 2005
    Co-Authors: Kishore T Kapale, Jonathan P Dowling
    Abstract:

    We propose a scheme for the generation of arbitrary coherent Superpositions of vortex states in Bose-Einstein condensates (BEC) using the orbital-angular-momentum states of light. We devise a scheme to generate coherent Superpositions of two such counterrotating states of light using well-known experimental techniques. We show that a specially designed Raman scheme allows for transfer of the optical vortex-Superposition state onto an initially nonrotating BEC. This creates an arbitrary and coherent Superposition of a vortex and antivortex pair in the BEC. The ideas presented here could be extended to generate entangled vortex states, design memories for the orbital-angular-momentum states of light, and perform other quantum information tasks. Applications to inertial sensing are also discussed.

Alex Ayet - One of the best experts on this subject based on the ideXlab platform.

  • the single particle density matrix of a quantum bright soliton from the coordinate bethe ansatz
    Journal of Statistical Mechanics: Theory and Experiment, 2017
    Co-Authors: Alex Ayet, Joachim Brand
    Abstract:

    We present a novel approach for computing reduced density matrices for Superpositions of eigenstates of a Bethe-ansatz solvable model by direct integration of the wave function in coordinate representation. A diagrammatic approach is developed to keep track of relevant terms and identify symmetries, which helps to reduce the number of terms that have to be evaluated numerically. As a first application we compute with modest numerical resources the single-particle density matrix and its eigenvalues including the condensate fraction for a quantum bright soliton with up to N = 10 bosons. The latter are constructed as Superpositions of string-type Bethe-ansatz eigenstates of nonrelativistic bosons in one spatial dimension with attractive contact interaction. Upon delocalising the Superposition in momentum space we find that the condensate fraction reaches maximum values larger than 97% with weak particle-number dependence in the range of particles studied. The presented approach is suitable for studying time-dependent problems and generalises to higher-order correlation functions.

  • the single particle density matrix of a quantum bright soliton from the coordinate bethe ansatz
    arXiv: Mathematical Physics, 2015
    Co-Authors: Alex Ayet, Joachim Brand
    Abstract:

    We present a novel approach for computing reduced density matrices for Superpositions of eigenstates of a Bethe-ansatz solvable model by direct integration of the wave function in coordinate representation. A diagrammatic approach is developed to keep track of relevant terms and identify symmetries, which helps to reduce the number of terms that have to be evaluated numerically. As a first application we compute with modest numerical resources the single-particle density matrix and its eigenvalues including the condensate fraction for a quantum bright soliton with up to $N=10$ bosons. The latter are constructed as Superpositions of string-type Bethe-ansatz eigenstates of nonrelativistic bosons in one spatial dimension with attractive contact interaction. Upon delocalising the Superposition in momentum space we find that the condensate fraction reaches maximum values larger than 97\% in the range of particles studied. The presented approach is suitable for studying time-dependent problems and generalises to higher-order correlation functions.

Joachim Brand - One of the best experts on this subject based on the ideXlab platform.

  • the single particle density matrix of a quantum bright soliton from the coordinate bethe ansatz
    Journal of Statistical Mechanics: Theory and Experiment, 2017
    Co-Authors: Alex Ayet, Joachim Brand
    Abstract:

    We present a novel approach for computing reduced density matrices for Superpositions of eigenstates of a Bethe-ansatz solvable model by direct integration of the wave function in coordinate representation. A diagrammatic approach is developed to keep track of relevant terms and identify symmetries, which helps to reduce the number of terms that have to be evaluated numerically. As a first application we compute with modest numerical resources the single-particle density matrix and its eigenvalues including the condensate fraction for a quantum bright soliton with up to N = 10 bosons. The latter are constructed as Superpositions of string-type Bethe-ansatz eigenstates of nonrelativistic bosons in one spatial dimension with attractive contact interaction. Upon delocalising the Superposition in momentum space we find that the condensate fraction reaches maximum values larger than 97% with weak particle-number dependence in the range of particles studied. The presented approach is suitable for studying time-dependent problems and generalises to higher-order correlation functions.

  • the single particle density matrix of a quantum bright soliton from the coordinate bethe ansatz
    arXiv: Mathematical Physics, 2015
    Co-Authors: Alex Ayet, Joachim Brand
    Abstract:

    We present a novel approach for computing reduced density matrices for Superpositions of eigenstates of a Bethe-ansatz solvable model by direct integration of the wave function in coordinate representation. A diagrammatic approach is developed to keep track of relevant terms and identify symmetries, which helps to reduce the number of terms that have to be evaluated numerically. As a first application we compute with modest numerical resources the single-particle density matrix and its eigenvalues including the condensate fraction for a quantum bright soliton with up to $N=10$ bosons. The latter are constructed as Superpositions of string-type Bethe-ansatz eigenstates of nonrelativistic bosons in one spatial dimension with attractive contact interaction. Upon delocalising the Superposition in momentum space we find that the condensate fraction reaches maximum values larger than 97\% in the range of particles studied. The presented approach is suitable for studying time-dependent problems and generalises to higher-order correlation functions.

Christina Manolatou - One of the best experts on this subject based on the ideXlab platform.

  • many body theory of radiative lifetimes of exciton trion Superposition states in doped two dimensional materials
    Physical Review B, 2021
    Co-Authors: Farhan Rana, Okan Koksal, Minwoo Jung, Gennady Shvets, Christina Manolatou
    Abstract:

    Optical absorption and emission spectra of doped two-dimensional (2D) materials exhibit sharp peaks that are often mistakenly identified with pure excitons and pure trions (or charged excitons), but both peaks have been recently attributed to Superpositions of two-body exciton and four-body trion states and correspond to the approximate energy eigenstates in doped 2D materials. In this paper, we present the radiative lifetimes of these exciton-trion Superposition energy eigenstates using a many-body formalism that is appropriate given the many-body nature of the strongly coupled exciton and trion states in doped 2D materials. Whereas the exciton component of these Superposition eigenstates are optically coupled to the material ground state and can emit a photon and decay into the material ground state provided the momentum of the eigenstate is within the light cone, the trion component is optically coupled only to the excited states of the material and can emit a photon even when the momentum of the eigenstate is outside the light cone. In an electron-doped 2D material, when a four-body trion state with momentum outside the light cone recombines radiatively, and a photon is emitted with a momentum inside the light cone, the excess momentum is taken by an electron-hole pair left behind in the conduction band. The radiative lifetimes of the exciton-trion Superposition states with momenta inside the light cone are found to be in the few hundred femtoseconds to a few picoseconds range and are strong functions of the doping density. The radiative lifetimes of exciton-trion Superposition states with momenta outside the light cone are in the few hundred picoseconds to a few nanoseconds range and are again strongly dependent on the doping density. The doping density dependence of the radiative lifetimes of the two peaks in the optical emission spectra follows the doping density dependence of the spectral weights of the same two peaks observed in the optical absorption spectra, as both have their origins in the Coulomb coupling between the excitons and trions in doped 2D materials.

L M Duan - One of the best experts on this subject based on the ideXlab platform.

  • Large quantum Superpositions of a levitated nanodiamond through spin-optomechanical coupling
    Physical Review A - Atomic Molecular and Optical Physics, 2013
    Co-Authors: Zhang Qi Yin, Tongcang Li, Xiang Zhang, L M Duan
    Abstract:

    We propose a method to generate and detect large quantum Superposition states and arbitrary Fock states for the oscillational mode of an optically levitated nanocrystal diamond. The nonlinear interaction required for the generation of non-Gaussian quantum states is enabled through the spin-mechanical coupling with a built-in nitrogen-vacancy center inside the nanodiamond. The proposed method allows the generation of large Superpositions of nanoparticles with millions of atoms and the observation of the associated spatial quantum interference under reasonable experimental conditions.