Skip to content
BuildY

Stable Entangled Photon Transmission for 30+ Hours

Idea Proposed

Continuous Entanglement Distribution Over Fiber Networks

  • Challenge: Quantum networks rely on polarization-encoded entanglement, but environmental factors (temperature changes, fiber stress, etc.) cause polarization drift, disrupting entanglement.
  • Solution: An automatic polarization compensation (APC) system that continuously corrects for these drifts, stabilizing quantum entanglement over long distances and durations.
  • Impact: This system enables stable quantum communications, a key requirement for quantum cryptography, secure data transmission, and the quantum internet.

How It Works

1. Automatic Polarization Compensation (APC) System

  • Uses dim reference signals (low-power classical light) alongside the quantum signals in wavelength-multiplexed channels.
  • Reference signals continuously monitor polarization drift in the fiber and adjust it in real time using fiber squeezers or liquid crystal retarders.
  • A heterodyne detection system extracts polarization information from reference signals, feeding it into a multi-axis PID control loop that applies corrections.
  • Result: Stable polarization transformation, ensuring that quantum entanglement remains intact for over 30 hours without downtime.

2. Quantum Entanglement Distribution

  • The system transmits polarization-entangled photons through a metropolitan-scale quantum network.
  • An entangled photon source generates pairs of photons with correlated quantum states.
  • One photon is sent through a fiber link with the APC system, while the other is used as a reference for quantum state measurement.
  • High-fidelity quantum state tomography confirms that entanglement is preserved over long durations and distances.

3. Key Innovations

  • No downtime: Unlike traditional compensation methods, which periodically pause for recalibration, this system continuously operates.
  • Minimal added noise: The reference signals are designed to avoid interference with quantum signals, maintaining high-fidelity entanglement.
  • Multi-wavelength compatibility: Works across the C-band and L-band fiber-optic channels, making it versatile for real-world quantum networking.

How We Can Implement It

1. Scaling Up Quantum Networks

  • Deploying automatic polarization compensation in quantum fiber networks allows stable entanglement transmission over city-scale or intercontinental distances.
  • Could be used in satellite-to-ground quantum communication, where polarization fluctuations due to atmospheric effects are a challenge.

2. Secure Quantum Cryptography

  • Enables continuous quantum key distribution (QKD) for unbreakable encryption in banking, defense, and secure communications.
  • Improves entanglement-based QKD by eliminating polarization drift, ensuring stable key generation rates.

3. Quantum Cloud Computing & Distributed Quantum Processing

  • Can be used for linking remote quantum computers in a scalable, error-resistant quantum cloud network.
  • Essential for building a fault-tolerant quantum internet, where quantum information is transferred reliably between different quantum processing nodes.

Sources & citation

Joseph C. Chapman, Muneer Alshowkan, Kazi Reaz, Tian Li, and Mariam Kiran, “Continuous automatic polarization channel stabilization from heterodyne detection of coexisting dim reference signals,” Opt. Express 32, 47589-47619 (2024)