28 research outputs found
Finite frequency noise in chiral Luttinger liquid coupled to phonons
We study transport between Quantum Hall (QH) edge states at filling factor
in the presence of electron-acoustic-phonon coupling. Performing a
Bogoliubov-Valatin (BV) trasformation the low-energy spectrum of interacting
electron-phonon system is presented. The electron-phonon interaction splits the
spectrum into charged and neutral "downstream" and neutral "upstream" modes
with different velocities. In the regimes of dc and periodic ac biases the
tunelling current and non-equilibrium finite frequency non-symmetrized noise
are calculated perturbatively in tunneling coupling of quantum point contact
(QPC). We show that the presence of electron-phonon interaction strongly
modifies noise and current relations compared to free-fermion case
Entropy production in one-dimensional quantum fluids
We study nonequilibrium thermodynamic properties of a driven one-dimensional
quantum fluid by combining nonlinear Luttinger liquid theory with the quantum
kinetic equation. In particular, we derive an entropy production consistent
with the laws of thermodynamics for a system subject to an arbitrary
perturbation varying slowly in space and time. Working in a basis of weakly
interacting fermionic quasiparticles, we show that the leading contribution to
the entropy production results from three-particle collisions, and we derive
its scaling law at low temperatures
Current correlations of Cooper-pair tunneling into a quantum Hall system
We study Cooper pair transport through a quantum point contact between a
superconductor and a quantum Hall edge state at integer and fractional filling
factors. We calculate the tunnelling current and its finite-frequency noise to
the leading order in the tunneling amplitude for dc and ac bias voltage in the
limit of low temperatures. At zero temperature and in case of tunnelling into a
single edge channel both the conductance and differential shot noise vanish as
a result of Pauli exclusion principle. In contrast, in the presence of two edge
channels, this Pauli blockade is softened and a non-zero conductance and shot
noise are revealed
Parafermion braiding in fractional quantum Hall edge states with a finite chemical potential
Parafermions are non-Abelian anyons which generalize Majorana fermions and hold great promise for topological quantum computation. We study the braiding of Z2n parafermions which have been predicted to emerge as localized zero modes in fractional quantum Hall systems at filling factor ν=1/n (n odd). Using a combination of bosonization and refermionization, we calculate the energy splitting as a function of distance and chemical potential for a pair of parafermions separated by a gapped region. Braiding of parafermions in quantum Hall edge states can be implemented by repeated fusion and nucleation of parafermion pairs. We simulate the conventional braiding protocol of parafermions numerically, taking into account the finite separation and finite chemical potential. We show that a nonzero chemical potential poses challenges for the adiabaticity of the braiding process because it leads to accidental crossings in the spectrum. To remedy this, we propose an improved braiding protocol which avoids those degeneracies