Large-scale quantum entanglement in an optical beam
일 시 : 2023년 05월 24일 수요일 16:30
연 사 : 라 영 식 교수 (KAIST 물리학과)
장 소 : 자연과학관 B117호
HOST : 박 문 집 교수님
Photonic quantum systems have various advantages for developing quantum information technologies: room-temperature operation, the fastest transmission speed, and highly precise control. For harnessing photonic quantum systems, there are mainly two different approaches. One is the discrete-variable approach where single photons carry quantum information, and the other is the continuous-variable approach where electric fields are employed for encoding quantum information. In particular, the continuous-variable approach has a unique advantage for generating large-scale quantum entanglement: squeezed light and linear optics can be used to generate large entanglement in a deterministic and scalable way. Recently, this continuous-variable approach has attracted much attention for developing quantum simulation (Gaussian Boson Sampling [1,2]) as well as quantum computing (measurement-based quantum computing [3,4]).
In this colloquium, I will present our recent experiments about generating large-scale quantum entanglement in an optical beam. We employ time-frequency modes of ultrashort pulses to exploit a large number of modes contained in a single beam . Using the flexibility of the time-frequency modes, we have generated various quantum entangled states of light (e.g., cluster states). The generated continuous-variable entanglement will find a wide range of applications in quantum technologies: quantum metrology  and quantum communication  as well as quantum computing [1-4].
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3. M. V., Larsen, et al., Science 366, 369–372 (2019).
4. W. Asavanant, et al., Science 366, 373–376 (2019).
5. Y.-S. Ra, et al., Nat. Phys. 16, 144–147 (2020).
6. M. Barbieri, PRX Quantum 3, 010202 (2022).
7. O. Kovalenko, et al., Photon. Res. 9, 2351–2359 (2021).