Energy-Degenerate Photon-Pair Generation from Individual CsPbBr₃ Quantum Dots

Area of Science:

• Quantum Optics
• Materials Science
• Solid-State Physics

Background:

• Generating correlated photon pairs is crucial for quantum technologies like teleportation and metrology.
• Individual quantum dots (QDs) are a common source, often relying on epitaxially grown structures.
• Colloidal QDs offer a scalable and solution-processable alternative.

Purpose of the Study:

• Investigate photon-pair generation via biexciton cascade in colloidal CsPbBr3 QDs.
• Demonstrate time-correlated and energy-degenerate photon pairs from these engineered quantum emitters.
• Understand the underlying mechanisms for photon generation.

Main Methods:

• Utilized colloidal CsPbBr3 quantum dots with matched biexciton binding and phonon energies.
• Performed pulsed excitation experiments at 4 K.
• Conducted Hanbury Brown and Twiss measurements to analyze photon correlations (g(2)(0)).
• Employed multicolor numerical calculations for quantitative analysis.

Main Results:

• Achieved generation of time-correlated and energy-degenerate photon pairs in large (>15 nm) CsPbBr3 QDs.
• Observed pronounced photon bunching with g(2)(0) up to 7 under pulsed excitation.
• Quantitatively reproduced excitation-density-dependent bunching using numerical models.
• Identified the biexciton cascade and phonon-mediated exciton decay as the likely origin.

Conclusions:

• Demonstrated efficient energy-degenerate photon-pair generation in scalable colloidal CsPbBr3 QDs.
• Provided insights into the quantum-optical processes within these engineered emitters.
• Marked significant progress towards utilizing these QDs in quantum-information technologies.