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Physics Seminar

Hexagonal boron nitride for integrated quantum photonics

Speaker: Sejeong Kim (University of Melbourne)
Date: Wednesday 2 February 2022
Time: 11:00
Venue: Zoom

Integrated quantum photonic circuitry is an emerging topic that requires efficient coupling of quantum light sources to waveguides and optical resonators. So far, great effort is devoted to engineering on-chip systems from 3D crystals such as diamond or gallium arsenide. In this work, the room-temperature coupling is demonstrated of quantum emitters embedded in layered hexagonal boron nitride to on-chip photonic waveguides and cavities. The results serve as the foundation for integrating layered materials to on-chip components and realizing integrated quantum photonic circuitry.
Implementation of quantum technologies, such as quantum networks and photonic processors, require interfacing multiple single photons on a chip. For this purpose, efficient integration between quantum light sources and photonic devices, such as waveguides and cavities, is essential. A new emerging approach is the use of single-photon emitters in 2D materials. 2D materials can be transferred onto any photonic structure via exfoliation and stamping, which typically is a challenging task for bulk materials due to lattice constant mismatch.
Hexagonal boron nitride (hBN), a 2D crystalline sheet consisting of alternating boron and nitrogen atoms, is emerging as a promising candidate for integrated quantum photonics due to its bright single-photon emission at room temperature [1]. These emitters benefit from weak electron-phonon coupling indicated by the high intensity of zero phonon lines (ZPL) and weak intensity in the phonon sideband. Here, we present the hBN quantum emitters integrated into photonic waveguides and photonic cavities [2-4].

[1] T. T. Tran, K. Bray, M. J. Ford, M. Toth, and I. Aharonovich, 'Quantum emission from hexagonal boron nitride monolayers,' Nature Nanotechnology, Letter vol. 11, pp. 37-41, 2016.
[2] Sejeong Kim, Johannes E Fröch, Joe Christian, Marcus Straw, James Bishop, Daniel Totonjian, Kenji Watanabe, Takashi Taniguchi, Milos Toth, Igor Aharonovich, 'Photonic crystal cavities from hexagonal boron nitride', Nature Communications, 9, 1, 2623, 2018
[3] Johannes E Fröch, Sejeong Kim, Noah Mendelson, Mehran Kianinia, Milos Toth, Igor Aharonovich, 'Coupling Hexagonal Boron Nitride Quantum Emitters to Photonic Crystal Cavities', ACS Nano, 14, 6, 7085-7091, 2020
[4] Chi Li, Johannes E Fröch, Milad Nonahal, Thinh N Tran, Milos Toth, Sejeong Kim, Igor Aharonovich, 'Integration of hBN quantum emitters in monolithically fabricated waveguides', ACS Photonics, online published, 2021

Bio: Sejeong Kim is a lecturer (= Assistant prof) at the University of Melbourne, Australia. She obtained her PhD in Physics from Korea Advanced Institute of Science and Technology (KAIST) in 2014. She was a research fellow at the University of Technology Sydney (UTS) from 2017 to 2020. Her research focuses on exploring light-matter interaction at the nanoscale, particularly using optical/plasmonic cavities. This includes studies of photonic crystal cavities for microlasers, sensors and quantum applications, as well as developing an integrated photonics platform. She won the Excellence Award for a Young Scientist (2018) and the Best Emerging Scientist Award in Photonics and Quantum Electronics (2017) from Korea. In 2019, she was selected as the 30 Rising Stars by the Optical Society of Korea. Last year, she won iCANX Global Young Scientist Award. She is appointed as the Editorial Advisory Board member of APL Photonics and elected as one of the Technical Group Leaders of OPTICA