Quantum-randomized polarization of laser pulses derived from zero-point diamond motion

Area of Science:

• Quantum Information Science
• Quantum Optics
• Condensed Matter Physics

Background:

• Intrinsic randomness in quantum systems is crucial for quantum cryptography and information processing.
• Current methods for randomizing polarization states rely on external randomness sources, limiting direct quantum applications.
• Quantum key distribution protocols often require modulated polarization states derived from external random number generators.

Purpose of the Study:

• To present a novel Raman-based device for directly generating laser pulses with quantum-randomized polarizations.
• To demonstrate a method that bypasses the need for external randomness in quantum polarization control.
• To explore the potential of spontaneous symmetry breaking in quantum systems for generating intrinsic randomness.

Main Methods:

• Utilizing a Raman-based device employing crystals with diamond lattice symmetry.
• Exploiting the isotropic Raman gain at a specific operating point.
• Leveraging quantum-random zero-point motion to initiate spontaneous symmetry breaking and determine output polarization.

Main Results:

• Demonstrated direct generation of laser pulses with quantum-randomized polarizations.
• Confirmed isotropic Raman gain in diamond lattice symmetry crystals.
• Experimental measurements showed polarization distributions consistent with an independent and identically uniform distribution.
• Estimated a quantum entropy rate of 3.8 bits/pulse.

Conclusions:

• The developed Raman-based device successfully generates intrinsic quantum randomness in laser polarizations.
• Diamond lattice symmetry crystals offer a unique platform for exploiting quantum zero-point motion for polarization randomization.
• This work provides a direct, on-chip source of quantum randomness for advanced quantum information protocols.