Shot noise on chaotic chiral devices

We investigate both the conductance and the shot-noise power of a confined chiral device that engenders subtle embedded backscattering mechanisms. We present analytical results and the correspondent numerical confirmation of the chiral electronic sublattice signal. Examples of quantum dots generating chiral symmetries include graphene sheets and topological insulators. The analytical results are universal and exhibit a robust and peculiar signal for an arbitrary number of open scattering channels. We also demonstrate a tunable mechanism of the valleytronics shot-noise power signal through perpendicular magnetic fields and/or the device symmetry edges. The results also indicate a “Fano factor” associated with the main quantum interference term with a universal value of $1/4$ for a quantum dot with symmetric contacts, regardless of external fields and the number of open channels.

Figure 1

The quantum dot of graphene connected to two electrochemical potentials through electronic terminals: an example of a chiral or Dirac device. The confinement generates a chaotic effect due to the random edges.

Figure 2

The ensemble average of the shot-noise power for a quantum graphene dot with symmetric contacts. The symbols are the numerical results data while the lines are the analytical results. Notice a separation between the lines in the three sets of data caused solely by the quantum interference term due to the sublattice symmetry.

Figure 3

The ensemble average of the shot-noise power for a quantum graphene dot with asymmetric contacts. The symbols are the numerical results data while the lines are the analytical results. Observe that the curves of the three universal ensembles are separated due to the quantum interference corrections.

Figure 4

The ensemble average of the shot-noise power for Schrödinger billiards with symmetric contacts. The symbols are the numerical results data while the lines are the analytical results. Observe that there is no separation between the curves, which characterizes that the quantum interference term disappears when the contacts are symmetrical.

Figure 5

The ensemble average of the shot-noise power for Schrödinger billiards with asymmetric contacts. The symbols are the numerical results data while the lines are the analytical results. Observe that the curves of the three Wigner-Dyson universal ensembles are separated due to the quantum interference corrections.