Highly stable and pure single-photon emission with 250 ps optical coherence times in InP colloidal quantum dots

Area of Science:

• Quantum photonics
• Materials science
• Nanotechnology

Background:

• Quantum technologies require efficient single-photon sources.
• Epitaxial quantum dots offer high performance but lack scalability.
• Colloidal quantum dots are scalable but suffer from poor emission properties.

Purpose of the Study:

• To demonstrate spectrally stable, pure, and narrow-linewidth single-photon emission from colloidal quantum dots.
• To overcome the limitations of existing colloidal quantum dot single-photon sources.

Main Methods:

• Fabrication of InP/ZnSe/ZnS colloidal quantum dots.
• Photon correlation Fourier spectroscopy at 4 K.
• Measurement of linewidths, optical coherence time (T2), spectral diffusion, and single-photon purity (g(2)(τ=0)).

Main Results:

• Achieved single-dot linewidths as narrow as ~5 µeV.
• Observed a lower-bounded optical coherence time (T2) of ~250 ps.
• Demonstrated minimal spectral diffusion and maintained narrow linewidths for up to 50 ms.
• Attained single-photon purities (g(2)(τ=0)) between 0.077-0.086 without spectral filtering.

Conclusions:

• InP/ZnSe/ZnS colloidal quantum dots exhibit unprecedented spectral stability and narrow linewidths.
• These heavy-metal-free colloidal QDs show significant potential as efficient single-photon sources for quantum applications.
• This work advances the development of scalable and high-performance colloidal quantum dot-based quantum technologies.