The tiny aluminum device--only 40 microns long and 100 nanometers thick--in which Caltech researchers observed the quantum noise from microwaves.
Caltech researchers have found a way to make measurements that go beyond the limits imposed by quantum physics. Today, we are capable of measuring the position of an object with unprecedented accuracy, but quantum physics and the Heisenberg uncertainty principle place fundamental limits on our ability to measure. Noise that arises as a result of the quantum nature of the fields used to make those measurements imposes what is called the "standard quantum limit." This same limit influences both the ultrasensitive measurements in nanoscale devices and the kilometer-scale gravitational wave detector at LIGO. Because of this troublesome background noise, we can never know an object's exact location, but a recent study provides a solution for rerouting some of that noise away from the measurement. "If you want to know where something is, you have to scatter something off of it," explains Professor of Applied Physics Keith Schwab , who led the study. "For example, if you shine light at an object, the photons that scatter off provide information about the object. But the photons don't all hit and scatter at the same time, and the random pattern of scattering creates quantum fluctuations"-that is, noise.
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