One of the most recent breakthroughs in the field of condensed matter systems involves the spontaneous formation and synchronization of multiple quantum vortices in optically excited semiconductor microcavities. This groundbreaking research was conducted by a team of researchers from various institutions, including Skoltech, Universitat Politècnica de València, Institute of Spectroscopy of RAS, University of Warsaw, and University of Iceland. The research findings were published in the prestigious journal Science Advances.
The research team demonstrated that polariton quantum vortices formed in neighboring cells of optically generated lattices exhibit an intriguing behavior – they tend to have an opposite topological vortex charge, effectively being “antiferromagnetically coupled.” This phenomenon opens up new possibilities for the study and simulation of condensed matter systems by leveraging the orbital angular momentum of the polariton condensate in place of spin angular momentum.
To conduct their experiments, the researchers utilized a semiconductor planar microcavity, which consists of two highly reflective mirrors enclosing InGaAs quantum wells. Through optical excitation, the formation of quasiparticles known as exciton-polaritons or microcavity polaritons was induced in the system. By employing a spatial light modulation technique, the researchers were able to pattern a laser beam into a hexagonal lattice structure, thus creating a triangular lattice with 22 cells containing trapped polariton condensates.
Upon analyzing the behavior of the quantum vortices within the lattice, the researchers made a fascinating discovery. While the vortices in a single cell exhibited equal probabilities for vortex and antivortex states, those in neighboring cells interacted to form stable solutions with opposite topological charges. This observation led the researchers to suspect a potential extended antiferromagnetic order in the lattice.
To confirm their hypothesis, the researchers conducted a series of experiments to measure the vortex charge of each condensate across the lattice cells. The results revealed a significant correlation between the observed orbital angular momentum in the vortex lattice and the low-energy configurations of the Ising spin Hamiltonian, providing strong evidence for extended antiferromagnetic order in the system.
The study of spontaneous formation and synchronization of quantum vortices in optically excited semiconductor microcavities represents a significant advancement in the field of condensed matter physics. The findings of this research not only contribute to a deeper understanding of complex quantum phenomena but also pave the way for the development of novel platforms for simulating and studying condensed matter systems.