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Updated: Sep 1, 2025
07:56
A Photonic System for Generating Unconditional Polarization-Entangled Photons Based on Multiple Quantum Interference
Published on: September 5, 2019
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Two-colour high-purity Einstein-Podolsky-Rosen photonic state
Tulio Brito Brasil1, Valeriy Novikov2,3, Hugo Kerdoncuff4
1Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark. tulio.brasil@nbi.ku.dk.
Nature Communications
|August 16, 2022
Summary
Researchers achieved high-purity Einstein-Podolsky-Rosen (EPR) states between light modes separated by over 200 nm. This demonstrates efficient EPR-steering across a wide frequency range, enabling advanced quantum protocols.
Area of Science:
- Quantum Optics
- Quantum Information Science
Background:
- Quantum entanglement, exemplified by Einstein-Podolsky-Rosen (EPR) states, is fundamental to quantum mechanics.
- EPR-steering describes a quantum phenomenon where measurements on one particle instantaneously influence the state of another, regardless of distance.
Purpose of the Study:
- To generate and characterize high-purity EPR states between light modes with significantly different wavelengths.
- To demonstrate efficient EPR-steering over an extended frequency range, from radio frequency (RF) to audio-band.
- To explore the potential of these states for novel quantum protocols.
Main Methods:
- Generation of entangled light modes with wavelengths separated by over 200 nm.
- Characterization of the quantum correlations using measurements of conditional variances.
- Quantification of two-mode squeezing and state purity.
Main Results:
- Achieved a high-purity EPR state with an overall state purity of 0.63 ± 0.16.
- Demonstrated highly efficient EPR-steering, with the product of conditional variances indicating strong correlations.
- Observed two-mode squeezing of -7.7 ± 0.5 dB.
- EPR-steering was confirmed across five octaves of sideband frequencies.
Conclusions:
- The study successfully generated and verified high-purity EPR states between spectrally distinct light modes.
- The demonstrated EPR-steering over a broad frequency range is a significant advancement for quantum information processing.
- These findings pave the way for new quantum protocols involving matter-light interactions.
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