Entanglement entropy in dynamic quantum-coherent conductors

TL;DR

This paper studies how entanglement entropy evolves in a quantum conductor with a quantum point contact, linking it to charge transfer statistics, and explores observable effects and suppression phenomena with single-particle excitations.

Contribution

It provides a numerically exact analysis of entanglement entropy dynamics in non-interacting electrons, connecting theoretical predictions with measurable quantities and exploring interference effects with levitons.

Findings

Logarithmic growth of entanglement entropy can be observed under certain conditions.

Interfering levitons can suppress entanglement entropy similarly to Hong-Ou-Mandel interference.

Entanglement entropy relates to full counting statistics, enabling experimental measurement.

Abstract

We investigate the entanglement and the R\'enyi entropies of two electronic leads connected by a quantum point contact. For non-interacting electrons, the entropies can be related to the cumulants of the full counting statistics of transferred charge which in principle are measurable. We consider the entanglement entropy generated by operating the quantum point contact as a quantum switch which is opened and closed in a periodic manner. Using a numerically exact approach we analyze the conditions under which a logarithmic growth of the entanglement entropy predicted by conformal field theory should be observable in an electronic conductor. In addition, we consider clean single-particle excitations on top of the Fermi sea (levitons) generated by applying designed pulses to the leads. We identify a Hong-Ou-Mandel-like suppression of the entanglement entropy by interfering two levitons on a quantum point contact tuned to half transmission.