A thermal imager typically works like a thermometer with a sensor array: it measures how much each pixel heats up and turns that into a picture. But this method has a limit — the device's own noise obscures faint heat.
A conventional thermal camera is like a thermometer that slowly heats up and cools down. It shows where heat is well, but it can't keep up with fast motion. The new sensor works differently: it counts individual quanta of heat, like a droplet counter during rain.
Quantum bits (qubits) are like delicate music in a noisy factory. Ambient magnetic fields constantly 'drown out' their quantum state, turning a coherent signal into cacophony. Usually, this destructive process is slowed by retuning the qubits themselves to different frequencies, but that doesn't always work.
A spotlight blazes straight into your eyes, and a few steps away a tiny firefly flickers. That's roughly what it's like hunting for an Earth-like planet around a neighboring star: the planet is a hundred million to ten billion times fainter than its star, and in the sky they almost merge into a single point.