Producing high fidelity single photons with optimal brightness via waveguided parametric down-conversion

Area of Science:

• Quantum optics
• Non-linear optics
• Quantum information science

Background:

• Parametric down-conversion (PDC) is a key source for generating non-Gaussian quantum states, like Fock states.
• Conventional PDC methods face limitations in state fidelity due to strict correlations from energy and momentum conservation.

Purpose of the Study:

• To optimize the preparation of single-photon Fock states using waveguided PDC.
• To investigate the impact of spectral filtering on reducing correlations and improving state fidelity.
• To experimentally quantify the fidelity of the prepared Fock states.

Main Methods:

• Utilizing waveguided parametric down-conversion (PDC) for photon generation.
• Implementing spectral filtering to reduce frequency and photon number correlations.
• Employing photon number resolving detection and quantum interference for analysis.
• Performing interference with a coherent state to measure fidelity.

Main Results:

• Spectral filtering effectively reduces mixedness in the generated states.
• Photon number resolving detection and quantum interference confirm the reduction of correlations.
• An experimental fidelity of 78% was achieved for the single-photon Fock state.

Conclusions:

• Spectral filtering is a viable technique to enhance the quality of Fock states from PDC.
• Optimized waveguided PDC sources show promise for advanced quantum information applications.
• The study provides a method for evaluating and improving the fidelity of generated quantum states.