The University of Southampton

Physicists discover unique properties of light trapped in artificial magnetic fields

Published: 8 November 2019
The dependence of the energy on the angle for polarised light reflected from birefringent optical cavity. Image credit: Mateusz Kral.

An international research collaboration including physicists from the University of Southampton has created a tunable thin optical cavity filled with liquid crystals and used it to emulated the physics of more complex relativistic interactions in solid state systems.

Researchers found that when the two-dimensional system was modified by an external voltage, photons behaved like massive particles endowed with a magnetic moment, called 'spin', under the influence of an artificial magnetic field.

The collaboration, which includes Physics and Astronomy's Professor Pavlos Lagoudakis, published their findings today in Science Science, the journal of the American Association for the Advancement of Science.

The discovery of new phenomena involving the trapping of light in optically anisotropic cavities may enable the implementation of new optoelectronic devices that allow for propagation and manipulation of information in topologically protected states. The research area's prospect of creating a unique quantum state of matter - the Bose Einstein condensate - could also be used to perform calculations and simulations that are too difficult for modern computers.

Dr Jacek Szczytko, of the University of Warsaw, said: "We are hugely encouraged by the rapid progress we achieved in engineering tunable liquid crystal optical cavities and the rich physics we uncovered recently. Continuing our collaboration with Southampton, we are now working on integration of emitters within our devices to obtain Bose Einstein condensates (BEC) of polaritons opening new applications in quantum information processing and neuromorphic computation."

The international research combined scientists and students from the University of Warsaw, the University of Southampton, the Polish Military University of Technology, the Institute of Physics of the Polish Academy of Sciences and the Skolkovo Institute of Technology in Moscow.

Professor Pavlos Lagoudakis, of Physics and Astronomy at Southampton and Director of Hybrid Photonics at Skoltech, said: "Photons in a cavity behave as particles that experience polarisation mode splittings as effective magnetic fields, that in turn produce relativistic effects known as spin-orbit interactions. The physics of liquid crystal microcavities is extremely rich and offer a platform for emulation of more complex physical systems, a route that we actively pursue now in collaboration with IBM and our colleagues in Warsaw."

The project was funded by the Polish National Science Center, the Ministry of Science and Higher Education, and the Ministry of National Defense, with Southampton's involvement supported by Professor Lagoudakis' £5m Hybrid Polaritonics programme grant from the Engineering and Physical Sciences Research Council.

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