Exact low temperature results for transport properties of the interacting resonant level model

Using conformal field theory and integrability ideas, we give a full characterization of the low temperature regime of the anisotropic interacting resonant level (IRLM) model. We determine the low temperature corrections to the linear conductance exactly up to the 6th order. We show that the structure displays 'Coulomb deblocking' at resonance, i.e., a strong impurity-wire capacitive coupling enhances the conductance at low temperature.Comment: 4 pages, 2 figure

Bound States for a Magnetic Impurity in a Superconductor

We discuss a solvable model describing an Anderson like impurity in a BCS superconductor. The model can be mapped onto an Ising field theory in a boundary magnetic field, with the Ising fermions being the quasi-particles of the Bogoliubov transformation in BCS theory. The reflection S-matrix exhibits Andreev scattering, and the existence of bound states of the quasi-particles with the impurity lying inside the superconducting gap.Comment: 7 pages, Plain Te

Thermodynamics of the 3-State Potts Spin Chain

We demonstrate the relation of the infrared anomaly of conformal field theory with entropy considerations of finite temperature thermodynamics for the 3-state Potts chain. We compute the free energy and compute the low temperature specific heat for both the ferromagnetic and anti-ferromagnetic spin chains, and find the central charges for both.Comment: 18 pages, LaTex. Preprint # ITP-SB-92-60. References added and first section expande

Transport in Quantum Dots from the Integrability of the Anderson Model

In this work we exploit the integrability of the two-lead Anderson model to compute transport properties of a quantum dot, in and out of equilibrium. Our method combines the properties of integrable scattering together with a Landauer-Buttiker formalism. Although we use integrability, the nature of the problem is such that our results are not generically exact, but must only be considered as excellent approximations which nonetheless are valid all the way through crossover regimes. The key to our approach is to identify the excitations that correspond to scattering states and then to compute their associated scattering amplitudes. We are able to do so both in and out of equilibrium. In equilibrium and at zero temperature, we reproduce the Friedel sum rule for an arbitrary magnetic field. At finite temperature, we study the linear response conductance at the symmetric point of the Anderson model, and reproduce Costi et al.'s numerical renormalization group computation of this quantity. We then explore the out-of-equilibrium conductance for a near-symmetric Anderson model, and arrive at quantitative expressions for the differential conductance, both in and out of a magnetic field. We find the expected splitting of the differential conductance peak into two in a finite magnetic field, $H$. We determine the width, height, and position of these peaks. In particular we find for H >> T_k, the Kondo temperature, the differential conductance has maxima of e^2/h occuring for a bias V close to but smaller than H. The nature of our construction of scattering states suggests that our results for the differential magneto-conductance are not merely approximate but become exact in the large field limit.Comment: 88 pages, 16 figures, uses harvmac.te