Prof Jacek Szczytko, "Liquid crystal cavities in the Rashba-Dresselhaus spin-orbit coupling regime."

Prof. Jacek Szczytko of the University of Warsaw (Poland) discusses his work on lasing from non-separable states in liquid crystal microcavities and sums up recent results on optical gain in doped structures in the Rashba-Dresselhaus spin-orbit coupling regime. Abstract: The non-separability of classical states lies at the heart of the concept of classical entanglement. Although this concept has been criticized by many authors, it has inspired an intensive research on fundamental differences between classical and quantum systems. We created an inseparable state between the valley and polarization degrees of freedom of cavity photons. We investigated microcavities with a birefringent liquid crystal layer enclosed between two parallel distributed Bragg reflectors. By tuning two photonic modes of opposite parity and polarization into resonance their mixing becomes described by an effective equal Rasha-Dresselhaus spin-orbit coupling resulting in a distinctive spin-split entangled dispersion [1]. Our experimental observations and analytical calculations demonstrate that the strong polarization-valley coupling (i.e. non-separability) directly results in the appearance of the persistent spin helix (PSH) – the long-range polarization (or pseudo-spin) textures of the in-plane traveling photons [2]. By dispersing a molecular dye in a liquid-crystal microcavity we introduced optical gain and demonstrated optical persistent spin helix lasing in the Rashba-Dresselhaus regime [3]. [1] K. Rechcińska, JSz et al. Photonic Engineering of Spin-Orbit Synthetic Hamiltonians in Liquid Crystal, Science 366, 727 (2019) [2] M. Król, JSz et al. Realizing Optical Persistent Spin Helix and Stern-Gerlach Deflection in an Anisotropic Liquid Crystal Microcavity hysical Review Letters, 127, 190401 (2021) [3] M. Muszyński, JSz, et al. Lasing in the Rashba-Dresselhaus spin-orbit coupling regime in a dye-filled liquid crystal optical microcavity, https://arxiv.org/abs/2109.07338 Bio: Prof. Jacek Szczytko [Yatzek Shtchitko] works at the Faculty of Physics, University of Warsaw, Poland. After his PhD on spintronics in 2001 he went for a postdoc to the group of Benoit Deveaud at EPFL in Switzerland, where he was working on ultra-fast spectroscopy of excitons. At 2005 he come back to the University of Warsaw. In 2010, together with Barbara Piętka, he founded Polariton Laboratory at the Faculty of Physics and in 2016 he established collaboration with the Military University of Technology in Warsaw on birefringent liquid crystal microcavities. Prof. Jacek Szczytko is the founder and the head of Nanoengineering studies at the Faculty of Physics. https://www.fuw.edu.pl/~szczytko/ http://polariton.fuw.edu.pl