TY - JOUR
T1 - Distinct universal conductances in tunneling to quantum Hall states
T2 - The role of contacts
AU - de C. Chamon, Claudio
AU - Fradkin, Eduardo
PY - 1997
Y1 - 1997
N2 - We show that different universal values can be obtained for the two-terminal conductance of a fractional quantum Hall (FQH) state. At large voltages, or strong coupling, the conductance of a pointlike tunneling junction between an electron gas reservoir and a Laughlin FQH state at filling fraction v saturates to a universal value G = [2v/( v+1)]e2lh. We use this result to show that devices with different types of contacts between the reservoir and the FQH state lead to distinct universal values of saturation conductance that are rational multiples of e2lh. The particular fraction e2lh is obtained for the case of electron tunneling in and out of a FQH liquid through two point contacts. We demonstrate that the problem of tunneling between an electron gas and a FQH state through an impurity is exactly equivalent to the problem of tunneling between a chiral Fermi liquid and a chiral Luttinger liquid. We investigate in detail the case of tunneling to a v=1/3 FQH state, which we show to be equivalent to the problem of tunneling between two g=1/2 chiral Luttinger liquids. This system provides an experimental realization of this important exactly solvable case. We use the results of the single impurity problem to consider the case of many tunneling centers coupled independently to an electron reservoir, which is relevant to recent experiments by A. Chang et al. We derive an explicit universal expression for the voltage and temperature-dependent conductance that exhibits a crossover reminiscent of a Kondo effect. This universal curve fits the experimental data over the full range of probed voltages.
AB - We show that different universal values can be obtained for the two-terminal conductance of a fractional quantum Hall (FQH) state. At large voltages, or strong coupling, the conductance of a pointlike tunneling junction between an electron gas reservoir and a Laughlin FQH state at filling fraction v saturates to a universal value G = [2v/( v+1)]e2lh. We use this result to show that devices with different types of contacts between the reservoir and the FQH state lead to distinct universal values of saturation conductance that are rational multiples of e2lh. The particular fraction e2lh is obtained for the case of electron tunneling in and out of a FQH liquid through two point contacts. We demonstrate that the problem of tunneling between an electron gas and a FQH state through an impurity is exactly equivalent to the problem of tunneling between a chiral Fermi liquid and a chiral Luttinger liquid. We investigate in detail the case of tunneling to a v=1/3 FQH state, which we show to be equivalent to the problem of tunneling between two g=1/2 chiral Luttinger liquids. This system provides an experimental realization of this important exactly solvable case. We use the results of the single impurity problem to consider the case of many tunneling centers coupled independently to an electron reservoir, which is relevant to recent experiments by A. Chang et al. We derive an explicit universal expression for the voltage and temperature-dependent conductance that exhibits a crossover reminiscent of a Kondo effect. This universal curve fits the experimental data over the full range of probed voltages.
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U2 - 10.1103/PhysRevB.56.2012
DO - 10.1103/PhysRevB.56.2012
M3 - Article
AN - SCOPUS:0042849738
SN - 1098-0121
VL - 56
SP - 2012
EP - 2025
JO - Physical Review B - Condensed Matter and Materials Physics
JF - Physical Review B - Condensed Matter and Materials Physics
IS - 4
ER -