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Experimental Demonstration of Conjugate-Franson Interferometry.
Changchen Chen1, Jeffrey H Shapiro1, Franco N C Wong1
1Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Physical Review Letters
|September 10, 2021
Summary
Researchers developed conjugate-Franson interferometry, a new quantum measurement technique. This method measures photon arrival times, complementing existing frequency measurements for certifying time-energy entanglement with high visibility.
Area of Science:
- Quantum Optics
- Quantum Information Science
Background:
- Franson interferometry is a standard quantum measurement technique.
- It probes photon-pair frequency correlations to certify time-energy entanglement.
Purpose of the Study:
- To introduce and validate conjugate-Franson interferometry (CFI).
- To demonstrate CFI's ability to measure photon-pair arrival-time correlations.
- To establish CFI as an alternative method for certifying time-energy entanglement.
Main Methods:
- Demonstration of conjugate-Franson interferometry for the first time.
- Generation of entangled photon pairs via spontaneous parametric down-conversion.
- Measurement of interference visibility without background subtraction.
Main Results:
- Achieved a conjugate-Franson interference visibility of 96±1%.
- Exceeded the quantum-classical threshold by 25 standard deviations.
- Observed a 21% reduction in CFI visibility for biphoton states with spectral phase variation.
Conclusions:
- Conjugate-Franson interferometry is a valuable addition to quantum measurement techniques.
- CFI is sensitive to spectral phase variations, unlike other interferometry methods.
- CFI shows potential for applications in photonic entanglement, quantum communications, and networking.
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