Postselection-Loophole-Free Bell Violation with Genuine Time-Bin Entanglement

Area of Science:

• Quantum Information Science
• Quantum Optics
• Fundamental Physics

Background:

• Entanglement is crucial for quantum information protocols and physics tests.
• Time-bin entanglement is widely used due to its robustness and simplicity.
• Existing time-bin entanglement methods suffer from a postselection loophole.

Purpose of the Study:

• To experimentally violate Bell's inequality using genuine time-bin entanglement.
• To eliminate the postselection loophole in time-bin entanglement experiments.

Main Methods:

• Development of novel interferometers acting as fast synchronized optical switches.
• Implementation of a scheme to generate and measure time-bin entangled photons.
• Experimental violation of Bell's inequality.

Main Results:

• First experimental violation of Bell's inequality with genuine time-bin entanglement.
• Achieved a postselection-loophole-free Bell violation exceeding 9 standard deviations.
• Demonstrated a scheme compatible with standard fiber optics and integrated photonics.

Conclusions:

• The presented method overcomes the postselection loophole in time-bin entanglement.
• This work paves the way for distributing genuine time-bin entanglement over long distances.
• The findings support the advancement of device-independent secure communication and fundamental physics tests.