Long-term stable continuous variable entanglement generation in type-II non-degenerate optical parametric amplifier

Area of Science:

• Quantum optics and information science.
• Development of robust quantum entanglement generation techniques.

Background:

• Long-term stable entanglement is essential for reliable quantum information processing.
• Continuous variable entanglement generation, particularly in type-II non-degenerate optical parametric amplifiers (OAs), has been a persistent challenge.
• Existing methods lack the long-term stability required for practical applications.

Purpose of the Study:

• To investigate the impact of temperature fluctuations on entanglement stability in type-II non-degenerate OAs.
• To develop and demonstrate a novel method for achieving long-term stable continuous variable entanglement.
• To advance the feasibility of continuous-variable quantum information processing.

Main Methods:

• Derivation of the relationship between entanglement and temperature fluctuations in the crystal of a type-II non-degenerate OA.
• Implementation of a novel temperature-locking technique for the optical parametric amplifier crystal.
• Experimental verification of the proposed method for stable entanglement generation.

Main Results:

• A stable entanglement of 5.4 dB was successfully generated and maintained for two hours.
• The developed temperature-locking method significantly improved entanglement stability.
• The experimental results validate the theoretical framework connecting temperature fluctuations and entanglement.

Conclusions:

• The proposed temperature-locking method effectively overcomes the limitations of long-term continuous variable entanglement generation in type-II non-degenerate OAs.
• This technique shows significant promise for generating entanglement levels above 10 dB, crucial for practical quantum information processing.
• The findings represent a significant step towards the realization of robust continuous-variable quantum information technologies.