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Physics Colloquium: Narrowband photon pairs with energy-time entanglement: generation, manipulation, and applications
Wednesday, Feb. 19
4 p.m. - 5 p.m. Location: SLC 1.102

Dr. Shengwang Du (Hong Kong University of Science and Technology)

Entangled paired photons (biphotons) have become a benchmark tool not only for understanding fundamental quantum physics but also for realizing practical quantum information applications. In this talk, I will review our developed narrow-band energy-time entangled biphoton source from spontaneous four-wave mixing with electromagnetically induced transparency in a cold atomic ensemble or hot atomic vapor cell. The long temporal coherence time (up to 4000 ns) of these biphotons allows for engineering their quantum waveforms with time-domain and space-domain modulations. We developed a quantum-state tomography for measuring the biphoton temporal wave function]. Recently, we produced biphotons with polarization-frequency-coupled hyperentanglement. We tested the Bell inequality on frequency-bin entangled photon pairs, for the first time with time-resolved detection. These photons can be further hyperentangled in time-frequency, polarization, and space-momentum. We derived a formulism for analysing the quantum-state purity of heralded single photons produced form frequency-anticorrelated biphotons, and proved that these heralded single photons can be in a high quantum-state purity and corrected a long-time misunderstanding in quantum optics. Using these heralded single photons, for the first time, we observed single-photon optical precursors and verified the information speed limit of a single photon. We demonstrated the coherent control of single-photon absorption and reemission in atomic ensemble, the application in differential-phase-shift quantum key distribution, loading a single photon into a single-sided Fabry-Perot cavity with an efficiency of 87%, and the efficient photon-atom quantum interface with a single-photon polarization qubit memory efficiency of >85%. We recently confirmed the energy-time entanglement satisfies the Einstein-Podolsky-Rosen steering inequality. The works were supported by the Hong Kong Research Grants Council (Project Nos. 16303417, 16304817, 16308118, and C6005-17G).

Persons with disabilities may submit a request for accommodations to participate in this event at UT Dallas' ADA website. You may also call (972) 883-5331 for assistance or send an email to [email protected]. All requests should be received no later than 2 business days prior to the event.
Contact Info:
Michael Kesden, 972-883-3598
Questions? Email me.

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