In the 1960s, researchers at the science lab of the Ford Motor Company developed the superconducting quantum interference device, also known as a “SQUID.” It was the first usable sensor to take advantage of a quantum mechanical property—in this case, superconductivity.
That made the SQUID one of the first generation of quantum sensors: devices that use a quantum system, quantum properties or quantum phenomena to make a physical measurement. Physicists took the idea and ran with it, coming up with new types of sensors they continue to use and improve today.
SQUIDs have played a key role in the development of ultrasensitive electric and magnetic measurement systems and are still in use. For example, they amplify the detector signals for the Super Cryogenic Dark Matter Search. “As particle physicists, we’ve been using quantum sensing techniques for decades,” says SuperCDMS physicist Lauren Hsu of the US Department of Energy’s Fermi National Accelerator Laboratory.
But SQUIDs are no longer the only quantum sensors around. One important recent development in quantum sensing is known as quantum squeezing—a way to circumvent quantum limitations that even quantum sensors have faced in the past.
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