Two-photon interference of weak coherent laser pulses recalled from separate solid-state quantum memories

Area of Science:

• Quantum Information Science
• Quantum Optics
• Solid-State Physics

Background:

• Quantum memories are essential for quantum repeaters, networks, and computing, enabling reversible quantum state transfer between light and matter.
• Previous research focused on faithful quantum information transfer but lacked confirmation of photon suitability for two-photon interference.

Purpose of the Study:

• To demonstrate that quantum memories preserve the photonic wavefunction, ensuring suitability for two-photon interference measurements.
• To validate the use of thulium-doped lithium niobate waveguides as solid-state quantum memories for quantum information processing.

Main Methods:

• Utilized pairs of single-photon level laser pulses.
• Reversibly mapped laser pulses to separate thulium-doped lithium niobate waveguides.
• Performed two-photon interference and Bell-state measurements on re-emitted photons.

Main Results:

• Demonstrated successful two-photon interference and Bell-state measurements after mapping pulses to quantum memories.
• Observed interference visibility consistently near the theoretical maximum.
• Confirmed that the quantum memories preserve the entire photonic wavefunction.

Conclusions:

• Solid-state quantum memories in thulium-doped lithium niobate waveguides faithfully map quantum information.
• These quantum memories preserve the photonic wavefunction, making them suitable for two-photon interference applications.
• The findings support the development of quantum information processing technologies requiring robust quantum memories.