Vacuum is often thought of as empty, but in fact it is teeming with fleeting energy fluctuations—virtual photons popping in and out of existence that can interact with matter, giving rise to new, potentially useful properties.

Researchers use optical cavities, structures made of mirrors facing one another, to confine these fluctuations, harnessing their effects to engineer new forms of matter.

Conventional optical cavities boost fluctuations, or vacuum fields, for both right-and left-handed circularly polarized light. Rice University researchers and collaborators have developed a new cavity design that selectively enhances the quantum vacuum fluctuations of circularly polarized light in a single direction, achieving chirality—a feat that typically requires the use of a strong magnetic field.