Steering coherence in quantum dots by carriers injection via tunneling

Area of Science:

• Quantum optics
• Quantum information processing
• Semiconductor nanostructures

Background:

• Coherent control is crucial for quantum technologies.
• Tunneling injection (TI) improves quantum dot (QD) lasers by providing cold carriers.
• The effect of TI on QD coherence time was previously unexamined.

Purpose of the Study:

• Investigate the impact of tunneling injection on the coherence time of semiconductor quantum dot ensembles.
• Explore a new degree of freedom for coherent control in quantum dot systems.
• Demonstrate sub-picosecond coherence switching using TI processes.

Main Methods:

• Utilized tunneling injection (TI) processes for charge carrier delivery to quantum dots (QDs).
• Investigated coherent light-matter interactions via Rabi oscillations under varying excitation and bias conditions.
• Analyzed the influence of cold carrier injection rate on QD coherence time.

Main Results:

• Demonstrated that the injection rate of incoherent cold carriers via TI dictates QD coherence time.
• Observed Rabi oscillations in absorption and weak gain regimes.
• Found that strong excitation diminishes Rabi oscillations by increasing stimulated emission, shortening coherence time.

Conclusions:

• Tunneling injection offers a new method for controlling coherence time in room-temperature quantum dots.
• Coherence time can be actively managed by optical excitation and electrical bias.
• This research enables TI-based coherence switching on a sub-picosecond timescale in nanometric structures.