New ultrathin metasurface boosts photon generation for next-gen quantum chips

Columbia Engineering researchers have developed an ultrathin metasurface device that significantly enhances nonlinear optical effects at the nanoscale, advancing the miniaturization of quantum hardware. Building on prior work where a 3.4-micrometer-thick crystalline device generated entangled photon pairs, the team has now reduced the thickness to just 160 nanometers by introducing metasurfaces—artificial nanoscale patterns etched into ultrathin crystals. This approach boosts second harmonic generation by nearly 150 times compared to unpatterned samples, enabling more efficient photon generation at telecom wavelengths, which is crucial for future quantum devices. The research focuses on transition metal dichalcogenides, specifically molybdenum disulfide flakes, which are atomically thin but previously limited in photon generation efficiency. By etching repeating nanoscale lines into these flakes, the team achieved strong nonlinear optical effects beyond traditional methods, while simplifying fabrication using standard cleanroom tools. This breakthrough paves the way for compact, integrable quantum phot