Screening Nuclear Field Fluctuations in Quantum Dots for Indistinguishable Photon Generation

Area of Science:

• Quantum Optics
• Condensed Matter Physics
• Semiconductor Nanostructures

Background:

• Semiconductor quantum dots are promising sources for generating highly coherent and indistinguishable single photons.
• Intrinsic dephasing mechanisms, such as hyperfine interaction with nuclear spins, degrade photon indistinguishability and reduce two-photon interference visibility.

Purpose of the Study:

• To directly investigate the impact of fluctuating nuclear spins on photon scattering spectra from a resident electron in a quantum dot.
• To demonstrate a method for mitigating nuclear spin noise to achieve high-visibility two-photon interference.

Main Methods:

• Direct probing of elastic and inelastic scattered photon spectra from a single quantum dot containing a resident electron.
• Analysis of the influence of the nuclear Overhauser field on photon scattering and interference visibility.
• Implementation of nuclear spin noise screening techniques.

Main Results:

• The in-plane nuclear Overhauser field causes detuned Raman scattered photons, broadening the spectrum and reducing two-photon interference visibility.
• These Raman photons are distinguishable from elastic scattering and resonance fluorescence.
• Successful screening of nuclear spin noise was achieved.

Conclusions:

• Nuclear spin fluctuations are a significant source of dephasing that limits the coherence of single photons from quantum dots.
• Effective screening of nuclear spin noise enables the generation of coherent single photons with high two-photon interference visibility.
• This work paves the way for improved quantum information processing applications using semiconductor quantum dots.