Conductance oscillations in strongly correlated fractional quantum Hall line junctions

We present a detailed theory of transport through line junctions formed by counterpropagating single-branch fractional–quantum Hall edge channels having different filling factors. Intriguing transport properties are exhibited when strong Coulomb interactions between electrons from the two edges are present. Such strongly correlated line junctions can be classified according to the value of an effective line-junction filling factor $\tilde{\nu }$ that is the inverse of an even integer. Interactions turn out to affect transport most importantly for $\tilde{\nu }=1/2\mathrm{}$ and $\tilde{\nu }=1/4.\mathrm{}$ A particularly interesting case is $\tilde{\nu }=1/4\mathrm{}$ corresponding to, e.g., a junction of edge channels having filling factor $1$ and $1/5,$ respectively. We predict its differential tunneling conductance to oscillate as a function of voltage. This behavior directly reflects the existence of Majorana-fermion quasiparticle excitations in this type of line junction. Experimental accessibility of such systems in current cleaved-edge overgrown samples enables direct testing of our theoretical predictions.