A new paper from MIT lays out a novel means of computing by using heat transfer in specially designed silicon structures.
It won't replace regular transistors any time soon, but it's not intended to. Instead, the project could let future computing turn waste heat into extra compute power. That's especially important in the era of gigawatt data centers and their absurd cooling requirements. In fact, this work is the culmination of prior research into computational chip design, which created an algorithm that iteratively created and tested simulated geometries.
When given a target functionality, usually a particular pattern of heat conductivity, this algorithm can slowly hone in on the best possible design. The researchers refer to this as "inverse design," since they start with a goal and work backwards to a technology.
Using this approach, the team can inversely design a structure that conducts heat in very specific ways, including ways that allow analog computing. Put simply, heat transfer across these complex silicon structures produces a continuously varying heat signal that can be read out and interpreted, not unlike the electrical activity in a classical transistor.
By feeding their design algorithm a matrix of target values corresponding to a mathematical function, it can design a structure that naturally conducts heat in a pattern that yields the correct output value. This means that these new silicon nanostructures are physically fabricated for specific operations and cannot be reprogrammed after manufacturing.
Data centers are becoming absurdly large, and cooling is probably the biggest reason why.Credit: Google
That's another reason this seems most relevant to data centers, in the long term; the researchers do note that they can't currently fabricate chips large enough for data center-scale jobs, saying that the most realistic up-front applications would be things like fault detection in microelectronics. Still, data centers not only generate a lot of waste heat but also perform large amounts of very similar work, which could require such a high volume that it makes sense to install a whole chip just for that one task.
One intriguing problem the team encountered was that they could not control the direction of heat flow, because heat will always transfer from a cooler to a hotter environment. In their interpretation of heat in the system, this amounted to a restriction to using only positive numbers; the team got around this by putting all negative numbers into a separate, positive-signed matrix and then, downstream, subtracting those values from the positive matrix.
Whether it's to generate extra computing power or extra electricity , there are plenty of projects out there looking to use waste heat productively. Heck, these days even the Large Hadron Collider is getting in on the trend.
