Two electrons interacting at a mesoscopic beam splitter

Area of Science:

• Quantum physics
• Mesoscopic systems
• Quantum metrology

Background:

• Controlling individual particle interactions is crucial for quantum engineering and metrology.
• Nonlinear responses in beam splitters are key to quantum applications but challenging to manage at the particle level.

Purpose of the Study:

• To probe coincidence correlations between individual ballistic electrons at a mesoscopic constriction.
• To quantify parametric nonlinearity arising from unscreened Coulomb interactions.
• To explore interaction-mediated energy exchange using full counting statistics.

Main Methods:

• Experimental probing of coincidence correlations in a mesoscopic constriction.
• Utilizing full counting statistics of joint detection.
• Analytical modeling and numerical simulations of electron interactions.

Main Results:

• Observed an increase in coincidence counts from 50% to 70% between on-demand sources.
• Identified a correlation signature consistent with independent tomography of electron emission.
• Confirmed experimental results align with Coulomb interactions in a quadratic saddle potential.

Conclusions:

• Unscreened Coulomb interactions significantly influence electron correlations at mesoscopic scales.
• The demonstrated figure of merit, based on Coulomb repulsion and beam splitter dispersion, is sufficient for advanced quantum applications.
• The findings enable future developments in single-shot in-flight detection and quantum logic gates.