[ad_1]
In a discovery published in the journal Nature, an international team of researchers have described a new molecular device with exceptional computing prowess.
Reminiscent of the plasticity of connections in the human brain, the device can be reconfigured on the fly for different computational tasks by simply changing the applied voltages. Moreover, because nerve cells can store memories, the same device can also hold information for future recovery and treatment.
“The brain has the remarkable ability to alter its wiring by making and breaking connections between nerve cells. Achieving something comparable in a physical system has been extremely difficult, ”said Dr. R. Stanley Williams, professor in the Department of Electrical and Computer Engineering at Texas A&M University. “We have now created a molecular device with spectacular reconfigurability, which is achieved not by changing physical connections as in the brain, but by reprogramming its logic.”
Dr T. Venkatesan, Director of the Center for Quantum Research and Technology (CQRT) at the University of Oklahoma, Scientific Affiliate at Gaithersburg National Institute of Standards and Technology and Assistant Professor of Electrical and Computer Engineering at the The National University of Singapore added that their molecular device could in the future help design next-generation processing chips with improved computing power and speed, but consuming considerably less power.
Whether it’s the familiar laptop or a sophisticated supercomputer, digital technologies face a common enemy, the von Neumann bottleneck. This delay in computer processing is a consequence of current computer architectures, in which the memory, containing data and programs, is physically separated from the processor. As a result, computers spend a lot of time commuting between the two systems, causing the bottleneck. Additionally, despite extremely fast processor speeds, these units can remain idle for long periods of time during periods of information exchange.
As an alternative to conventional electronic parts used in the design of memory units and processors, devices called memristors offer a way around the von Neumann bottleneck. Memristors, such as those made of niobium dioxide and vanadium dioxide, change from an insulator to a conductor at a set temperature. This property gives these types of memristors the ability to perform calculations and store data.
However, despite their many advantages, these metal oxide memristors are made of rare earth elements and can only operate under constrained temperature regimes. Therefore, there has been an ongoing search for promising organic molecules that can perform a comparable memristive function, Williams said.
Dr Sreebrata Goswami, professor at the Indian Association for the Cultivation of Science, designed the material used in this work. The compound has a central metal atom (iron) bound to three organic phenyl azo pyridine molecules called ligands.
“It behaves like an electron sponge that can reversibly absorb up to six electrons, resulting in seven different redox states,” Sreebrata said. “The interconnectivity between these states is the key to the reconfigurability shown in this work.”
National University of Singapore researcher Dr Sreetosh Goswami designed this project by creating a small electrical circuit made up of a 40-nanometer layer of molecular film sandwiched between a layer of gold on top and a nanodisk infused with gold and indium and tin oxide at the bottom.
Applying negative voltage to the device, Sreetosh witnessed a current-voltage profile unlike anything anyone had seen before. Unlike metal oxide memristors which can switch from metal to insulator at a single fixed voltage, organic molecular devices could switch from insulator to conductor at multiple discrete sequential voltages.
“So if you think of the device as an on-off switch, as we swept the voltage more negatively, the device first went from on to off, then from on to on, then from on to. off, then back to on. I will say that we were thrown out of our seat, ”Venkatesan said. “We had to convince ourselves that what we were seeing was real. “
Sreetosh and Sreebrata studied the molecular mechanisms underlying the curious switching behavior using an imaging technique called Raman spectroscopy. In particular, they looked for spectral signatures in the vibrational movement of the organic molecule that could explain the multiple transitions. Their investigation found that the negative voltage sweep triggered a series of electron reduction, or gain, events that caused the molecule to transition from the off state to the on state.
Next, to mathematically describe the extremely complex current-voltage profile of the molecular device, Williams deviated from the conventional approach of equations based on basic physics. Instead, he described the behavior of molecules using a decision tree algorithm with “if-then-else” statements, a line of code common in several computer programs, especially games. digital.
“Video games have a structure where you have a character doing something and then something happens as a result. And so if you write that in a computer algorithm, it’s if-then-else statements, ”Williams said. “Here, the molecule switches from one lit state to another due to the applied voltage, and that’s when I had the eureka moment to use decision trees to describe these devices. , and it worked really well. “
But the researchers went further by harnessing these molecular devices to run programs for various real-world computational tasks. Sreetosh has shown experimentally that their devices can perform fairly complex calculations in a single time step, and then be reprogrammed to perform another task the next instant.
“It was quite extraordinary; our device was doing something like what the brain does, but in a very different way, ”Sreetosh said. “When you learn something new or when you make a decision, the brain can actually reconfigure and change the physical wiring. Likewise, we can logically reprogram or reconfigure our devices by giving them a different voltage pulse than they saw before.
Venkatesan noted that it would take thousands of transistors to perform the same computational functions as one of their molecular devices with its different decision trees. Therefore, he said their technology could first be used in portable devices, such as cellphones and sensors, and other applications where power is limited.
Reference: “Decision trees within a molecular memristor” by Sreetosh Goswami, Rajib Pramanick, Abhijeet Patra, Santi Prasad Rath, Martin Foltin, A. Ariando, Damien Thompson, T. Venkatesan, Sreebrata Goswami and R. Stanley Williams, September 1, 2021, Nature.
DOI: 10.1038 / s41586-021-03748-0
Other research contributors include Dr Abhijeet Patra and Dr Ariando of the National University of Singapore; Dr Rajib Pramanick and Dr Santi Prasad Rath from the Indian Association for the Culture of Science; Dr. Martin Foltin of Hewlett Packard Enterprise, Colorado; and Dr Damien Thompson from the University of Limerick, Ireland.
Venkatesan said this research is indicative of future findings from this collaborative team, which will include the Indian Institute of Science’s Nanoscience and Engineering Center and NIST’s Division of Microsystems and Nanotechnology.
This multidisciplinary and multinational research was supported by the Singapore National Research Foundation within the framework of competitive research programs; Scientific and Technical Research Council, India; the X-Grants program of the President’s Excellence Fund of Texas A&M; Science, Technology and Research, Singapore, under its Advanced Manufacturing and Engineering Individual Research Grant; seed fund at CQRT University of Oklahoma; and the Science Foundation, Ireland.
[ad_2]
Source link