Gonna take a shot in the dark and say "quantum sensors."

So if you read the article it says in many quantum test setups you need a powerful laser and microwave generator, so you need an external power source to run the experiment. These researchers designed an alternative test setup that uses sunlight in place of the powerful laser and the earth magnetic field in place of the microwave generator to perform similar tests, so you don't need much external power to run the tests anymore.