Quantum Light Fluid: A New State of Matter Enabling Frictionless Light Flow

Quantum Light Fluid: A New State of Matter Enabling Frictionless Light Flow. Researchers from the University of Cambridge and international institutions have successfully created a room-temperature polariton Bose-Einstein condensate, resulting in a new state of matter known as quantum light fluid. In this state, photons (light) behave like a superfluid, flowing without friction or vortices. This discovery, published in *Nature Physics*, paves the way for ultra-fast photonic technologies, optical quantum computing, and energy-lossless information processing.. Introduction: When Light Becomes a Fluid For centuries, light has been perceived as a straight-moving electromagnetic wave or as massless photon particles. However, recent discoveries in quantum physics have revealed a stranger and more astonishing side of light: light can transform into a fluid. Not an ordinary fluid like water, but a quantum fluid known as a polariton Bose-Einstein condensate BEC . In this state, photons merge with excitons electron-hole pairs in a semiconductor to form quasiparticles called polaritons. When these polaritons are cooled to extremely low temperatures, they enter a state of matter where all particles behave as a single, coherent giant wave, allowing light to flow without friction and form vortices like a superfluid. What is Quantum Light Fluid? Quantum light fluid, or more precisely, a polariton Bose-Einstein condensate, is a state of matter that exists at cryogenic temperatures typically a few degrees above absolute zero . However, a recent study published in Nature Physics in 2024 by a team of researchers from the University of Cambridge, along with collaborators from the University of Pittsburgh and the University of Würzburg, successfully created a polariton BEC at room temperature. This is a major leap, as previously, BECs could only be achieved at temperatures near absolute zero using lasers and evaporative cooling. The team utilized optical microcavities made from metal halide perovskites, a semiconductor material known for its high efficiency in solar cells. Within these cavities, photons are trapped and interact strongly with excitons, forming polaritons stable enough to reach condensation at room temperature. Latest Experiment at Cambridge: Creating a Photon Superfluid In an experiment led by Dr. Rajiv Singh and Professor Sir John Pendry, the Cambridge team designed microcavities a few micrometers thick filled with a layer of perovskite. When pulsed lasers were shone into the cavities, polaritons formed and began to condense into the same quantum state. The research team then employed high-resolution imaging techniques to observe the dynamics of the condensate. They found that this polariton condensate exhibited superfluid properties: it flowed through obstacles without any friction, and when rotated, it formed stable quantum vortices. "This is the first time we have observed quantum vortices in a light fluid at room temperature," Dr. Singh stated in a university press release. "These vortices are clear evidence that we have achieved a superfluid state, where light loses its individual particle nature and acts as a single quantum entity." Implications for Future Technology The discovery of quantum light fluid at room temperature carries profound implications across various technological fields. Firstly, in photonics, light superfluids could be used to create optical circuits that do not suffer from energy loss due to scattering or absorption. This means light signals could travel within photonic chips without degradation, enabling data processing at the speed of light with near-perfect energy efficiency. Secondly, in quantum computing, polariton condensates could serve as highly stable qubits. Since polaritons are quasiparticles that can be manipulated with lasers, they offer a more straightforward way to create quantum logic gates compared to ion traps or superconducting circuits. Thirdly, in sensing, quantum vortices in light fluids could be used to measure rotation or magnetic fields with extreme precision, opening applications in navigation and medical imaging. Challenges and Research Directions While this discovery is exciting, several challenges need to be overcome before this technology can be commercialized. One major challenge is the stability of the polariton condensate at room temperature. Although the Cambridge team succeeded in creating it, the condensate only lasted for a few picoseconds before losing its coherence. Researchers are now working to extend the lifetime of the condensate by optimizing the cavity design and perovskite materials. Furthermore, controlling quantum vortices remains difficult; the team needs to develop techniques to create and manipulate vortices deterministically. The University of Cambridge has announced a collaboration with the National Photonics Laboratory in Japan to build the first superfluid photonic chip prototype within the next five years. Conclusion: A New Frontier in Quantum Physics Quantum light fluid is not merely an exotic laboratory phenomenon; it represents a new frontier in our understanding of matter and energy. With the ability to control light at the quantum level without energy loss, we may witness a revolution in how we process information, communicate, and measure the world. This discovery also reminds us that the universe still holds many surprises, where something that seems impossible—light flowing like a liquid—can become a reality through scientific creativity and perseverance. For Malaysia, this field offers an opportunity to invest in quantum photonic research, especially with existing expertise in perovskite materials at local universities. Perhaps one day, we will see Malaysian-made superfluid photonic chips powering the nation's digital economy.