The ‘Beat’ Of A Graphene Drum Leads To Energy Transfer

The sound a nanometer-scale drum makes may not be music to the ears, but it could mean improvements in quantum information processing. 

AsianScientist (Jun. 21, 2016) - Researchers from the Tata Institute of Fundamental Research in India have manipulated the vibrations of a drum of nanometer-scale thickness.

The work, published in Nature Nanotechnology, could lead to improvements in the sensitivity of small detectors of mass, particularly in detecting small molecules like viruses, as well as provide further insights into fundamental physics.

Using graphene, a one-atom thick carbon material, the researchers fabricated drums with a diameter of 0.003 mm, or 30 times smaller than the diameter of human hair. The small size of the drum gives rise to high vibrational frequencies in the range of 100 megahertz, implying that this drum vibrates 100 million times in one second.

The experiment consisted of studying the mechanical vibrational modes, or ‘notes,’ similar to a musical drum. Mr. John Mathew, a PhD student in the nanoelectronics group led by Professor Mandar Deshmukh, showed that the notes of these drums could be controlled by making use of an electrical force that bends or strains the drum.

The bending of the drum caused different modes of the drum to interact with each other, which led to a ‘sloshing’ of energy between two notes.

“Using this interaction, we now show that energy can be transferred between the modes leading to the creation of new ‘notes’ in the drum,” said Deshmukh.

In additiom, the use of mechanical coupling allowed the researchers to manipulate the energy lost to the environment and amplify the vibrational motion, equivalent to an increase in sound from the drum.

The coupling between various notes of the drum could also be engineered to work as mechanical logic circuits and lead to improvements in quantum information processing, while the ability to amplify the mechanical motion will also help improve the sensitivity of sensors based on nanoscale drums.