Light, Nanoscale Speakers Could Revolutionize Electricity Studies

By using light and a device resembling a nanoscale loudspeaker, detecting weak electrical fields could become easier and more effective than ever, says a collaboration of international researchers. The approach could also be used to cool down electrical circuits.

What this means is that the technique could be used for a variety of real-world applications, including the development of quantum computers and related devices, improving Magnetic Resonance Imaging (MRI), and detecting extremely faint radio signals.

The approach has yet to be tested in practice, since researchers only developed a theoretical framework of how light and the nanoscale structures could work together to achieve these objectives. But the team is convinced that their work will hold up to scientific scrutiny.

The investigation was carried out by experts at the Harvard University, the Neils Bohr Institute in Copenhagen, and the Joint Quantum Institute (JQI) – a project created by the University of Maryland, the National Institute of Standards and Technology (NIST) and the Laboratory for Physical Sciences.

Details of the theoretical framework were published in a paper called “Laser cooling and optical detection of excitations in a LC electrical circuit,” which appears in the December 27, 2011 online issue of the esteemed journal Physical Review Letters.

“We envision coupling a nanomechanical membrane to an electrical circuit so that an electrical signal, even if exceedingly faint, will cause the membrane to quiver slightly as a function of the strength of that signal,” JQI physicist Jake Taylor explains.

“We can then bounce photons from a laser off that membrane and read the signal by measuring the modulation of the reflected light as it is shifted by the motion of the membrane. This leads to a change in the wavelength of the light,” he goes on to say.

These devices could contribute to improving MRI scans while reducing the size of the scanners themselves. The same approach would help investigators develop a setup where photons loaded with data could be moved from one quantum bit (qubit) to another.

In the latter scenario, the nanoscale speaker would essentially take low-energy signals from a quantum processor and then convert them into photons at optical wavelengths. This would ensure an easy data transfer between qubits.