An ordinary ultra-sensitive magnetic field sensor is like a scale that starts lying when you put too heavy a weight on it. The signal becomes distorted, and you have to add complex electronics to straighten out the readings. That electronics adds noise and slows things down.
The new sensor, bi-SQUIPT, works differently. Inside, two superconducting loops are connected so that the distortions from each cancel each other out. The result is a clean signal with no extra artifacts. The sensor changes its current by 120 microvolts, like a needle moving a noticeable distance without jitter. And it sips power: less than one trillionth of a watt, like a firefly glowing on its own reserves.
The sensor's precision rivals a whole array of conventional sensors, yet it takes up less space and doesn't need bulky circuitry. That matters for quantum computers, where every extra wire and every extra watt of heat disrupts operations. The bi-SQUIPT could become that tiny, precise "compass" that keeps quantum circuits on track.
At 600 millikelvin (that's -272.55 °C), many metals become superconductors, and electric current flows through them without loss, like water through a perfectly smooth pipe.