Optical Detection of Single-Electron Tunneling into a Semiconductor Quantum Dot

Area of Science:

• Quantum physics
• Optoelectronics
• Condensed matter physics

Background:

• Extracting maximum information from dynamic quantum systems requires real-time detection of quantum events.
• A key challenge is developing stable, sensitive detectors with high bandwidth.
• Statistical analysis of time traces provides insights into quantum system dynamics.

Purpose of the Study:

• To demonstrate an optical detection scheme for real-time quantum event monitoring.
• To achieve single-electron resolution with a high signal-to-noise ratio and high bandwidth.
• To enable the study of nonequilibrium dynamics in quantum dots.

Main Methods:

• Utilizing time-resolved resonance fluorescence on a single quantum dot.
• Implementing an optical detection scheme with a bandwidth of 10 kHz.
• Applying full counting statistics and factorial cumulants for data analysis.

Main Results:

• Achieved single-electron resolution with a 4σ confidence signal-to-noise ratio.
• Recorded individual quantum events in transport dynamics with the high-bandwidth detector.
• Gained access to nonequilibrium dynamics of spin relaxation in a singly charged quantum dot (γ_{↑↓}=3 ms⁻¹).

Conclusions:

• The developed optical detection scheme enables high-fidelity monitoring of quantum transport.
• This method provides access to nonequilibrium quantum dynamics, even during equilibrium measurements.
• It advances the capability for detailed statistical analysis of quantum events.