Washington, Nov 18 : Johns Hopkins researchers have come up with a new theory which, if harnessed, could pave way for computer chips that emit less heat and better biosensors to detect bio-hazards and medical conditions.
The researchers theorised that on being struck by laser light under certain circumstances, atoms in a crystal will counter uniformity.
Under the right conditions, the electrons of such atoms will begin moving apart and then joining together again repeatedly like lively swing partners on a dance floor.
Such behaviour is quite unlike the usual back and forth movement of electrons in a regular pattern, when struck by laser light. "By choosing particular atoms in the proper configuration and directing the right laser light at them, we could control the behavior of these 'nano-dancers. The essential thing is, these are completely designable atomic structures,'" said Alexander E. Kaplan, a professor in the Department of Electrical and Computer Engineering in Johns Hopkins' Whiting School of Engineering.
The researchers claimed that the "nano-riot" idea contradicts the widely accepted Lorentz-Lorenz theory, which asserts that the atomic electrons in a crystal, exposed to a laser beam, will move back and forth in tandem in a uniform way under any conditions.
"But we've concluded that under certain circumstances, the nearest atoms will behave much differently. Their electrons will move violently apart and come back together again, staging a sort of 'nano-riot," he said.
The critical conditions needed for such behaviour are: First, the system must be very small, typically involving no more than a few hundred atoms, and the atoms must be arranged in a one-dimensional or two-dimensional configuration.
The atoms must be grouped in a sufficiently close concentration; interestingly, though, this arrangement may allow more space between atoms than exists in a typical crystal.
Also, the frequency of the laser driving the atoms must be closely tuned to one of the specific frequencies of the atomic electrons -- the so-called atomic resonance -- in the way that a radio receiver might be tuned to a particular station.
When these critical conditions are met, the interacting excited atomic electrons get strongly "coupled," and their motion is affected by one another.
The atomic dance partners begin to match or counter-match the motion of each other, while still being driven by the laser's "music."
"Fortunately, once this atomic structure is built, the 'dancing style' of the atoms can be controlled by the laser tuning. Furthermore, if the laser intensity is sufficient, we believe the atoms in this lattice will engage in so-called nonlinear behavior. That means they can be made to behave like switches in a computer. They will act like a computer's memory or logic components, assuming the positions of either 1 or 0, depending on the initial conditions," said Kaplan.
If confirmed, the researchers believe that their theory may pave the way for other applications for these nanoscale atomic systems.
Harnessing this behavior could lead to cooler computer chips, better bio-sensors, the boffins said.
The study is published in the journal Physical Review Letters.