Junction of Three Quantum Wires: Restoring Time-Reversal Symmetry by Interaction

We investigate the transport of correlated fermions through a junction of three one-dimensional quantum wires pierced by a magnetic flux. We determine the flow of the conductance as a function of a low-energy cutoff in the entire parameter space. For attractive interactions and generic flux the fixed point with maximal asymmetry of the conductance is the stable one, as conjectured recently. For repulsive interactions and arbitrary flux we find a line of stable fixed points with vanishing conductance as well as stable fixed points with symmetric conductance $(4/9)(e^2/h)$.

Figure 1

Symmetric junction of three quantum wires.

Figure 2

Flow of $g$. Arrows indicate the direction for $U<0$. For $U>0$ it is reversed. For details see the text.

Figure 3

Scaling exponents close to FPs.