Quantum Hall line junction with impurities as a multislit Luttinger liquid interferometer

We report on quantum interference between a pair of counterpropagating quantum Hall edge states that are separated by a high-quality tunnel barrier. Observed Aharonov-Bohm oscillations are analyzed in terms of resonant tunneling between coupled Luttinger liquids which creates bound electronic states between pairs of tunnel centers that act like interference slits. We place a lower bound in the range of 20–40 μm for the phase coherence length and directly confirm the extended phase coherence of quantum Hall edge states.

Figure 1

(Color online) (a) Schematic of the line junction tunneling structure based on the cleaved edge overgrowth. (b) Edge state and Aharonov-Bohm trajectories in the quantum Hall line junction under quantizing magnetic field. (c) Magnetic field sweep at 25 mK. Inset: An expanded view of the conductance fluctuations of the final conductance peak at 5.6 T.

Figure 2

(Color online) Quasiperiodic conductance oscillations obtained from different thermal cyclings. Insets: Fast Fourier transforms of the conductance data demonstrate that at least two large periods are visible in the conductance.

Figure 3

(Color online) Temperature evolution of the conductance fluctuations. Small-period oscillations disappear above 200 mK.