44 research outputs found
Properties of Non-Abelian Fractional Quantum Hall States at Filling
We compute the physical properties of non-Abelian Fractional Quantum Hall
(FQH) states described by Jack polynomials at general filling
. For , these states are identical to the
Read-Rezayi parafermions, whereas for they represent new FQH states. The
states, multiplied by a Vandermonde determinant, are a non-Abelian
alternative construction of states at fermionic filling . We
obtain the thermal Hall coefficient, the quantum dimensions, the electron
scaling exponent, and show that the non-Abelian quasihole has a well-defined
propagator falling off with the distance. The clustering properties of the Jack
polynomials, provide a strong indication that the states with can be
obtained as correlators of fields of \emph{non-unitary} conformal field
theories, but the CFT-FQH connection fails when invoked to compute physical
properties such as thermal Hall coefficient or, more importantly, the quasihole
propagator. The quasihole wavefuntion, when written as a coherent state
representation of Jack polynomials, has an identical structure for \emph{all}
non-Abelian states at filling .Comment: 2 figure
Spinon-Holon Attraction in the Supersymmetric t-J Model with 1/r^2-Interaction
We derive the coordinate representation of the one-spinon one-holon
wavefunction for the supersymmetric model with -interaction. This
result allows us to show that spinon and holon attract each other at short
distance. The attraction gets stronger as the size of the system is increased
and, in the thermodynamic limit, it is responsible for the square root
singularity in the hole spectral function.Comment: 4 pages, 1 .eps figur
The Anatomy of Abelian and Non-Abelian Fractional Quantum Hall States
We deduce a new set of symmetries and relations between the coefficients of
the expansion of Abelian and Non-Abelian Fractional Quantum Hall (FQH) states
in free (bosonic or fermionic) many-body states. Our rules allow to build an
approximation of a FQH model state with an overlap increasing with growing
system size (that may sometimes reach unity!) while using a fraction of the
original Hilbert space. We prove these symmetries by deriving a previously
unknown recursion formula for all the coefficients of the Slater expansion of
the Laughlin, Read Rezayi and many other states (all Jacks multiplied by
Vandermonde determinants), which completely removes the current need for
diagonalization procedures.Comment: modify comment in Ref. 1
Central Charge and Quasihole Scaling Dimensions From Model Wavefunctions: Towards Relating Jack Wavefunctions to W-algebras
We present a general method to obtain the central charge and quasihole
scaling dimension directly from groundstate and quasihole wavefunctions. Our
method applies to wavefunctions satisfying specific clustering properties. We
then use our method to examine the relation between Jack symmetric functions
and certain W-algebras. We add substantially to the evidence that the (k,r)
admissible Jack functions correspond to correlators of the conformal field
theory W_k(k+1,k+r), by calculating the central charge and scaling dimensions
of some of the fields in both cases and showing that they match. For the Jacks
described by unitary W-models, the central charge and quasihole exponents match
the ones previously obtained from analyzing the physics of the edge
excitations. For the Jacks described by non-unitary W-models the central charge
and quasihole scaling dimensions obtained from the wavefunctions differ from
the ones obtained from the edge physics, which instead agree with the
"effective" central charge of the corresponding W-model.Comment: 22 pages, no figure
Highest weight Macdonald and Jack Polynomials
Fractional quantum Hall states of particles in the lowest Landau levels are
described by multivariate polynomials. The incompressible liquid states when
described on a sphere are fully invariant under the rotation group. Excited
quasiparticle/quasihole states are member of multiplets under the rotation
group and generically there is a nontrivial highest weight member of the
multiplet from which all states can be constructed. Some of the trial states
proposed in the literature belong to classical families of symmetric
polynomials. In this paper we study Macdonald and Jack polynomials that are
highest weight states. For Macdonald polynomials it is a (q,t)-deformation of
the raising angular momentum operator that defines the highest weight
condition. By specialization of the parameters we obtain a classification of
the highest weight Jack polynomials. Our results are valid in the case of
staircase and rectangular partition indexing the polynomials.Comment: 17 pages, published versio
Hierarchical structure in the orbital entanglement spectrum in Fractional Quantum Hall systems
We investigate the non-universal part of the orbital entanglement spectrum
(OES) of the nu = 1/3 fractional quantum Hall effect (FQH) ground-state with
Coulomb interactions. The non-universal part of the spectrum is the part that
is missing in the Laughlin model state OES whose level counting is completely
determined by its topological order. We find that the OES levels of the Coulomb
interaction ground-state are organized in a hierarchical structure that mimic
the excitation-energy structure of the model pseudopotential Hamiltonian which
has a Laughlin ground state. These structures can be accurately modeled using
Jain's "composite fermion" quasihole-quasiparticle excitation wavefunctions. To
emphasize the connection between the entanglement spectrum and the energy
spectrum, we also consider the thermodynamical OES of the model pseudopotential
Hamiltonian at finite temperature. The observed good match between the
thermodynamical OES and the Coulomb OES suggests a relation between the
entanglement gap and the true energy gap.Comment: 16 pages, 19 figure
Decomposition of fractional quantum Hall states: New symmetries and approximations
We provide a detailed description of a new symmetry structure of the monomial
(Slater) expansion coefficients of bosonic (fermionic) fractional quantum Hall
states first obtained in Ref. 1, which we now extend to spin-singlet states. We
show that the Haldane-Rezayi spin-singlet state can be obtained without exact
diagonalization through a differential equation method that we conjecture to be
generic to other FQH model states. The symmetry rules in Ref. 1 as well as the
ones we obtain for the spin singlet states allow us to build approximations of
FQH states that exhibit increasing overlap with the exact state (as a function
of system size). We show that these overlaps reach unity in the thermodynamic
limit even though our approximation omits more than half of the Hilbert space.
We show that the product rule is valid for any FQH state which can be written
as an expectation value of parafermionic operators.Comment: 22 pages, 8 figure
Scaling and non-Abelian signature in fractional quantum Hall quasiparticle tunneling amplitude
We study the scaling behavior in the tunneling amplitude when quasiparticles
tunnel along a straight path between the two edges of a fractional quantum Hall
annulus. Such scaling behavior originates from the propagation and tunneling of
charged quasielectrons and quasiholes in an effective field analysis. In the
limit when the annulus deforms continuously into a quasi-one-dimensional ring,
we conjecture the exact functional form of the tunneling amplitude for several
cases, which reproduces the numerical results in finite systems exactly. The
results for Abelian quasiparticle tunneling is consistent with the scaling
anaysis; this allows for the extraction of the conformal dimensions of the
quasiparticles. We analyze the scaling behavior of both Abelian and non-Abelian
quasiparticles in the Read-Rezayi Z_k-parafermion states. Interestingly, the
non-Abelian quasiparticle tunneling amplitudes exhibit nontrivial k-dependent
corrections to the scaling exponent.Comment: 16 pages, 4 figure
Entanglement entropy of integer Quantum Hall states in polygonal domains
The entanglement entropy of the integer Quantum Hall states satisfies the
area law for smooth domains with a vanishing topological term. In this paper we
consider polygonal domains for which the area law acquires a constant term that
only depends on the angles of the vertices and we give a general expression for
it. We study also the dependence of the entanglement spectrum on the geometry
and give it a simple physical interpretation.Comment: 8 pages, 6 figure
Supersymmetric Quantum Hall Liquid with a Deformed Supersymmetry
We construct a supersymmetric quantum Hall liquid with a deformed
supersymmetry. One parameter is introduced in the supersymmetric Laughlin
wavefunction to realize the original Laughlin wavefunction and the Moore-Read
wavefunction in two extremal limits of the parameter. The introduced parameter
corresponds to the coherence factor in the BCS theory. It is pointed out that
the parameter-dependent supersymmetric Laughlin wavefunction enjoys a deformed
supersymmetry. Based on the deformed supersymmetry, we construct a
pseudo-potential Hamiltonian whose groundstate is exactly the
parameter-dependent supersymmetric Laughlin wavefunction. Though the SUSY
pseudo-potential Hamiltonian is parameter-dependent and non-Hermitian, its
eigenvalues are parameter-independent and real.Comment: 14 pages, contribution to the proceedings of the Group 27 conference,
Yerevan, Armenia, August 13-19, 2008, published versio