Scientists at the Tata Institute of Fundamental Research (TIFR), Mumbai, have successfully manipulated the vibrations of a graphene drum of a nanometer scale thickness, achieving the most versatile and world's smallest drum.
This is an artist's impression of two coupled, vibrational modes of a graphene drum. The coupling can be tuned electrically to transfer energy between the modes and hybridize them. (CREDIT: Nanoelectronics group, TIFR Mumbai)
This latest study could provide new avenues to enhance the sensitivity of small mass detectors, which are critical for identifying the mass of tiny molecules such as viruses. It also shows promise for studying interesting new facets in the field of fundamental physics. The findings have been reported in the Nature Nanotechnology journal.
The study was performed using a wonder material graphene, which is a single atomic layer of graphite to create drums that posses highly tunable mechanical frequencies and coupling amongst many different modes. The coupling between the modes was portrayed to be controllable, as a result of which new, hybrid modes were created and also enabled amplification of the vibrations.
Experiments were carried out which involved analyzing the 'notes' or mechanical vibrational modes, akin to a musical drum. High vibrational frequencies in the range of 100 MHtz were produced as a result of the reduced size of the drum, which has a diameter 30 times smaller than the diameter of human hair. This indicates that this drum is capable of vibrating 100 million times in just a single second.
The study, performed by John Mathew, lead author and PhD student in the nanoelectronics group headed by professor Mandar Deshmukh, revealed that the notes of these drums may be regulated through an electrical force that strains or bends the drum. the bending of the drum also enabled various modes of the drum to communicate with each other. As a result, energy is sloshed between the 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.
Professor Mandar Deshmukh, TIFR
The speed at which energy is transferred can be controlled accurately through electrical signals that modify coupling. Additionally, mechanical mode coupling was also used to exploit the energy lost to the environment and amplification of vibrational motion, similar to an increase in sound from the drum, was demonstrated.
The high mechanical frequencies at low temperature will help to study energy transfer of a quantum mechanical nature between the notes. The coupling experienced between various notes holds potential to enhance quantum information processing and may also be designed to function as mechanical logic circuits. The capability to increase the mechanical motion between notes will also aid in enhancing the sensitivity of sensors built on the nanoscale drums.