Purification of a single-photon nonlinearity.

Area of Science:

• Quantum Information Science
• Solid-State Physics
• Nanophotonics

Background:

• Semiconductor quantum dots in optical microcavities are key for integrated quantum information processing.
• Finite quantum dot lifetime and coupling issues currently limit fidelity in these systems.

Purpose of the Study:

• To investigate methods for restoring high fidelity in quantum dot-based optical systems.
• To enhance the generation of strongly correlated photons for quantum information applications.

Main Methods:

• Utilized a nearly polarization degenerate microcavity in the weak coupling regime.
• Implemented polarization pre- and postselection techniques.
• Analyzed the interference of orthogonally polarized transmission amplitudes.

Main Results:

• Achieved high fidelity by canceling un-interacted light through controlled polarization interference.
• Transformed coherent light into a stream of strongly correlated photons with a second-order correlation value up to 40.
• Demonstrated correlations exceeding previous experimental results, even in the strong-coupling regime.

Conclusions:

• Polarization pre- and postselection effectively restores high fidelity in quantum dot microcavities.
• This purification technique significantly enhances photon correlation, surpassing prior experimental limits.
• The method shows promise for improving fidelity in quantum dot-based logic gates for quantum computing.