Scientists Reveal Hidden Structure of a Quantum Fluid

In a groundbreaking study published in Nature, scientists from Lawrence Berkeley National Laboratory (Berkeley Lab) and other institutions have revealed a hidden structure within a quantum fluid formed by excitons at high temperatures. Bose-Einstein Condensates (BECs), often dubbed as a "fifth state of matter," were previously achieved at sub-zero temperatures using supercooled gases.

However, this new research demonstrates the formation of a tunable BEC of excitons – electron-hole pairs – in an atomically thin semiconductor at a relatively warmer temperature near absolute zero.

The team, led by Feng Wang, a faculty senior scientist at Berkeley Lab's Materials Sciences Division, discovered that these excitons can form a BEC even in a solid-state device, a feat previously unattainable in controllable semiconductor systems. The excitons were engineered to occupy the ground state rather than the short-lived excited state, enabling them to reach equilibrium and persist as a BEC.

Through magneto-optical spectroscopy, researchers observed the exciton condensate's behavior under the influence of a magnetic field. Surprisingly, the condensate displayed two distinct components with different spin-valley structures, leading to multiple distinct quantum phases. These phases can be switched on and off by applying a magnetic field, providing researchers with a new platform to study quantum fluids in solid materials, as well as potential applications in quantum simulations, coherent optoelectronics, and exciton-based devices for faster, more efficient computing.

This discovery has significant implications for future research in quantum technology, potentially leading to advancements in superconducting-based quantum devices and circuits. The findings could pave the way for breakthroughs in telecommunications, computing, and other emerging technologies that rely on quantum phenomena.