The critical value of the mobility for which the ν = 5/2 quantum Hall effect is destroyed by short range disorder is determined from an earlier calculation of the entanglement entropy. The value μ = 2.0 ×106 cm 2/ Vs agrees well with experiment. This agreement is particularly significant in that there are no adjustable parameters. Entanglement entropy versus disorder strength for ν = 1/2, ν = 9/2 and ν = 7/3 is calculated. For ν = 1/2 there is no evidence for a transition for the disorder strengths considered; for ν = 9/2 there appears to be a stripe-liquid transition. For ν = 7/3 there again appears to be a transition at similar value of the disorder strength as the ν = 5/2 transition but there are stronger finite size effects.
The entanglement entropy of
ν=1/2 and
ν=9/2 quantum Hall states in the presence of short range disorder has been calculated by direct diagonalization. Spin polarized electrons are confined to a single Landau level and interact with long range Coulomb interaction. For
ν=1/2 the entanglement entropy is a smooth monotonic function of disorder strength. For
ν=9/2 the entanglement entropy is non monotonic suggestive of a solid-liquid phase transition. As a model of the transition at
ν=1/2 free fermions with disorder in 2 dimensions were studied. Numerical evidence suggests the entanglement entropy scales as
L rather than the
LlnL as in the disorder free case.