Spectral Sum Rules and Magneto-Roton as Emergent Graviton in Fractional Quantum Hall Effect

Sep 10, 2013
17 pages
Published in:
  • JHEP 01 (2016) 021
  • Published: Jan 5, 2016
e-Print:
Report number:
  • EFI-13-22

Citations per year

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Abstract: (Springer)
We consider gapped fractional quantum Hall states on the lowest Landau level when the Coulomb energy is much smaller than the cyclotron energy. We introduce two spectral densities, ρT_{T} (ω) and ρT(ω) {\overline{\rho}}_T\left(\omega \right) , which are proportional to the probabilities of absorption of circularly polarized gravitons by the quantum Hall system. We prove three sum rules relating these spectral densities with the shift S \mathcal{S} , the q4^{4} coefficient of the static structure factor S4_{4}, and the high-frequency shear modulus of the ground state μ_{∞}, which is precisely defined. We confirm an inequality, first suggested by Haldane, that S4_{4} is bounded from below by S1/8 \left|\mathcal{S} - 1\right|/8 . The Laughlin wavefunction saturates this bound, which we argue to imply that systems with ground state wavefunctions close to Laughlin’s absorb gravitons of predominantly one circular polarization. We consider a nonlinear model where the sum rules are saturated by a single magneto-roton mode. In this model, the magneto-roton arises from the mixing between oscillations of an internal metric and the hydrodynamic motion. Implications for experiments are briefly discussed.
Note:
  • 17 pages, 2 figures
  • Field Theories in Lower Dimensions
  • Sum Rules
  • Effective field theories
  • density: spectral
  • sum rule: spectral
  • Hall effect: quantum
  • graviton
  • ground state
  • gravitation: emergence
  • Hall effect: fractional