Researchers from Joint Quantum Institute (National Institute of Standards and Technology (NIST) and the University of Maryland, College Park), the Neils Bohr Institute in Copenhagen, Denmark, and Harvard University have described a theoretical system that may allow the detection of very small electrical signals by utilizing laser light.
The technology framework uses a nano scale mechanical membrane that vibrates in response to an electrical signal, with the frequency proportional to the signal strength. Shining a laser onto the membrane will let you measure the vibration frequency, identifying the nature of the original signal. Because these sensors can be very small and remain cool, it may be possible to reduce the size, energy requirements, and improve all sorts of characteristics of MRI machines when their superconducting magnets are no longer necessary.
From the study abstract:
We explore a method for laser cooling and optical detection of excitations in a room temperature LC electrical circuit. Our approach uses a nanomechanical oscillator as a transducer between optical and electronic excitations. An experimentally feasible system with the oscillator capacitively coupled to the LC and at the same time interacting with light via an optomechanical force is shown to provide strong electromechanical coupling. Conditions for improved sensitivity and quantum limited readout of electrical signals with such an “optical loud speaker” are outlined.
Abstract in Physical Review Letters: Laser Cooling and Optical Detection of Excitations in a LC Electrical Circuit