The uncertainties imposed by quantum mechanics, though unavoidable, take the form of a trade-off: It’s always possible, at least in theory, to reduce the uncertainty in a parameter of interest (a particle’s position, say) at the expense of increasing the uncertainty of something else (its momentum).
In optics, the trade-off gives rise to so-called squeezed states of light, which can be constructed, for example, with lower uncertainty in their amplitude and higher uncertainty in their phase, or vice versa. More generally, if the waveform is written as Xcos(ωt) + Ysin(ωt), where t is time and ω is the wave’s frequency, then X and Y, called the quadratures, are the requisite pair of noncommuting quantities whose uncertainties can be manipulated. The ability to produce squeezed light using nonlinear optics enables greater sensitivity in optical measurements such as those made by large interferometers (see Physics...
