Yan Chen

Spontaneous emission was long considered fickle: a quantum dot emits a photon, obeying only probability. The Purcell effect allowed amplifying it by placing the emitter in a resonator, but that only changed the rate, not the spectral shape.

The transistor in your phone works like a faucet: open it and electrons flow, close it and they stop. But an ordinary metal faucet always leaks a little: even when closed, current seeps through. That drains the battery and heats up the chip. A cool metal is a faucet with a perfect seal. Its electronic structure has a gap near the level where electrons can move freely.

Building a light chip is like a game where you have to guide a beam through a maze of tiny mirrors and beam splitters. Each element acts like a railroad switch: it either lets light pass straight through or directs it to an adjacent track. The goal is to produce a specific light pattern at the output while using as few 'switches' as possible. Usually, engineers spend years finding the shortest route for each task.