Two-particle entanglement in capacitively coupled Mach-Zehnder interferometers

TL;DR

This paper proposes a mesoscopic device with coupled Mach-Zehnder interferometers in a quantum Hall system that generates and analyzes on-demand entangled electron pairs, demonstrating Bell inequality violation despite Fermi sea effects.

Contribution

The study introduces a novel device design for on-demand electron entanglement and provides a detailed analysis of entanglement generation, including effects of Fermi seas and optimal conditions for Bell violation.

Findings

Maximal Bell parameter of 2.18 indicating entanglement.

Device can produce and detect entangled electron pairs.

Fermi sea effects reduce but do not eliminate Bell violation.

Abstract

We propose and analyze a mesoscopic device producing on-demand entangled pairs of electrons. The system consists of two capacitively coupled Mach-Zehnder interferometers implemented in a quantum Hall structure. A pair of electron wave-packets is injected into the chiral edge states of two (of the four) incoming arms; scattering on the incoming interferometers splits the wave-packets into four components of which two interact. The resulting interaction phase associated with this component leads to the entanglement of the state; the latter is scattered at the outgoing beam splitter and analyzed in a Bell violation test measuring the presence of particles in the four outgoing leads. We study the two-particle case and determine the conditions to reach and observe full entanglement. We extend our two-particle analysis to include the underlying Fermi seas in the quantum Hall device; the change in shape of the wave-function, the generation of electron-hole pairs in the interaction regime, and a time delay between the pulses all reduce the degree of visible entanglement and the violation of the Bell inequality, effects which we analyze quantitatively. We determine the device settings optimizing the entanglement and the Bell test and find that violation is still possible in the presence of the Fermi seas, with a maximal Bell parameter reaching ${\cal B} = 2.18 > 2$ in our setup.