Skyrmions are localized, particle-like excitations in materials that retain their structure due to topological constraints (i.e., restrictions arising from properties that remain unchanged under smooth deformations). These quasiparticles, first introduced in high-energy physics and quantum field theory, have since attracted intense interest in condensed matter physics and photonics, owing to their potential as robust carriers for information storage and manipulation.

Researchers at Sun Yat-sen University and Tianjin University recently reported the first experimental realization of single-photon quantum skyrmions (i.e., localized light structures) in a semiconductor cavity quantum electrodynamics (QED) system. Their paper, published in Nature Physics, could open new possibilities for the study of quantum light-matter interactions, while also contributing to the advancement of photonic quantum devices.

“Our work was motivated by the longstanding challenge of realizing topological photonic structures—specifically skyrmions—at the quantum level,” Ying Yu, co-senior author of the paper, told Phys.org.

MIT physicists confirm that, like Superman, light has two identities that are impossible to see at once. Physicists at MIT recreated the double-slit experiment using individual photons and atoms held in laser light, uncovering the true limits of light’s wave–particle duality. Their results proved Einstein’s proposal wrong and confirmed a core prediction of quantum mechanics.

MIT physicists have performed an idealized version of one of the most famous experiments in quantum physics. Their findings demonstrate, with atomic-level precision, the dual yet evasive nature of light. They also happen to confirm that Albert Einstein was wrong about this particular quantum scenario.

The experiment in question is the double-slit experiment, which was first performed in 1801 by the British scholar Thomas Young to show how light behaves as a wave. Today, with the formulation of quantum mechanics, the double-slit experiment is now known for its surprisingly simple demonstration of a head-scratching reality: that light exists as both a particle and a wave. Stranger still, this duality cannot be simultaneously observed. Seeing light in the form of particles instantly obscures its wave-like nature, and vice versa.

Some phases of matter cannot be described using the conventional framework of symmetry breaking and exhibit a so-called quantum order. One type of quantum order, known as topological order, is characterized by long-range entanglement between particles across an entire system, a ground state degeneracy that depends on the global shape of the system, and a robustness against local disturbances.

Topological phases of matter primarily occur at zero temperature, as thermal fluctuations tend to destroy them and disrupt their underlying order. In a recent paper published in Physical Review Letters, however, researchers at Nanjing University, Yale University and other institutes reported a new 3D topological phase of matter characterized by an anomalous two-form symmetry that occurs at non-zero temperatures.

“In the last several years, we have made substantial progress in our ability to control quantum systems —over a range of different platforms: superconducting qubits, trapped ions, neutral atoms, photonics, and so on,” Tyler D. Ellison, senior author of the paper, told Phys.org.