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Related Experiment Video

Updated: Jun 28, 2026

Generation and Coherent Control of Pulsed Quantum Frequency Combs

Generation and Coherent Control of Pulsed Quantum Frequency Combs

Published on: June 8, 2018

Joint temporal density measurements for two-photon state characterization.

Onur Kuzucu¹, Franco N C Wong, Sunao Kurimura

¹Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.

Physical Review Letters

|November 13, 2008

Summary

This summary is machine-generated.

We developed a new method to characterize two-photon quantum states using joint temporal correlations. This technique measures the time-energy entanglement of photon pairs, improving quantum state analysis.

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Area of Science:

Quantum Optics
Quantum Information Science
Photonics

Background:

Characterizing quantum states is crucial for quantum information processing.
Existing methods often focus on frequency-domain correlations.
Time-resolved measurements offer complementary insights into photonic entanglement.

Purpose of the Study:

To demonstrate a novel technique for characterizing two-photon quantum states.
To measure the joint temporal density of entangled photon pairs for the first time.
To explore the manipulation of frequency entanglement via pump bandwidth.

Main Methods:

Utilizing joint temporal correlation measurements.
Employing time-resolved single-photon detection with femtosecond up-conversion.
Generating photon pairs via ultrafast spontaneous parametric down-conversion under extended phase-matching.

Main Results:

Successfully measured the joint temporal density of a two-photon entangled state.
Observed clear time anti-correlation in coincident-frequency entangled photon pairs.
Demonstrated manipulation of frequency entanglement by varying pump bandwidth, producing a nearly unentangled state.
Predicted a heralded single-photon state purity of 0.88.

Conclusions:

The developed time-domain correlation technique provides a comprehensive characterization of photonic entanglement.
This method complements existing frequency-domain measurements.
The technique allows for the generation of high-purity heralded single-photon states.