March 2024

Abstracts of the Quantum Center Lunch Seminar

Date: Thursday, March 7, 2024
Place: ETH Zurich, Hönggerberg, HPF G 6
Time: 12:00 - 13:30

Synthetic space dynamics in fast-gain lasers

Alexander Dikopoltsev - Quantum Optoelectronics (Faist group), ETH Zurich

Photonic emulators facilitate solid-state phenomena exploration and the development of optical quantum-inspired devices. We propose and demonstrate that the ring fast-gain laser [1-3] can serve as a photonic emulator in synthetic space [4,5], incorporating a dissipative nonlinearity that results in equal filling of states in the momentum space, akin to Fermi-Dirac statistics in electronic systems. The study of the dynamics involves initiating a state, for example, one that occupies a single site in the synthetic frequency lattice, and then quenching the system to promote coupling between lattice sites, achieved through a sudden modulation [6]. We then introduce artificial gauge fields to study solid-state phenomenon like Wannier-stark ladder mode competition and Aharonov-Bohm interference, with dynamics facilitated by the fast-gain mechanism. Importantly, unlike linear or slow-gain systems, the interplay between complex dispersion and fast-gain results in a coherent action, implying that the state of the emulator is always a liquid of light [7].

[1] N. Opačak, et al., Phys. Rev. Lett. 123, 243902 (2019).
[2] U. Senica, et al., Laser Photonics Rev. 2300472 (2023).
[3] A. Hugi, et al., Nature 492, 229–233 (2012).
[4] T. Ozawa, et al., PRA 93, 043827 (2016); L. Yuan, et al., Opt. Lett. 41, 741-744 (2016).
[5] L. Yuan, et al. , Optica 3, 1014-1018 (2016).
[6] I. Heckelmann, M. Bertrand, A. Dikopoltsev, et al., Science 382, 434-438 (2023).
[7] H. Haus, IEEE J. Quantum Electron. 11, 323–330 (1975).

Lithium niobite-on-insulator photonics for optical quantum technology

Robert Chapman - Optical Nanomaterial (Grange group), ETH Zurich

Integrated photonic circuits have many applications in quantum information science, from quantum transduction and communication, to linear optical quantum computing. While silicon photonics has been successful in demonstrating small-scale quantum information processing, there are fundamental limitations of the platform for quantum technology. Lithium niobite-on-insulator (LNOI) is a breakthrough photonics technology that takes the excellent optical properties of lithium niobite, including electro-optic modulation and a second order nonlinearity, to a high index contrast platform for dense circuits. Here, we introduce our efforts towards optical quantum information processing with LNOI photonics. We first discuss our work on efficient heralded photon generation via spontaneous parametric down-conversion in periodically poled LNOI waveguides with tailored spectral correlations. We then demonstrate on-chip generation and quantum interference of single photons in programmable photonic circuit. Finally, we discuss our work towards applying this technology for quantum key distribution, and the outlook for LNOI quantum photonics for large-scale optical quantum computation.