A New Hidden State of Matter Could Make Computers 1,000x Faster

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A new study highlights the remarkable ability of the quantum material tantalum disulfide, or 1T-TaS_₂, to achieve a “hidden metallic state” that allows it to transition from metallic conductor to an insulator and vice versa.
This could have huge implications for computing, as scientists expect it could push processors into the terahertz realm and improve computing speeds by a factor of 1,000.
This mixed phase still requires temperatures around -63 degrees Celsius to stay stable, which is very cold, but much easier for engineers to work with that the near-absolute-zero temperatures required by other, related states.

In December of 1947, scientists at Bell Laboratories in New Jersey tested the very first transistor. Although they likely didn’t understand the full importance of that moment, it kickstarted a technological revolution that reshaped the world. That’s because transistors—essentially on/off switches in electrical circuits—eventually allowed computers to downsize from room-scale behemoths to something that fits in our pocket.

Now, a new study—led by scientists at Northeastern University—is investigating the next era of transistors that utilize a “hidden metallic state” capable of rapidly transitioning from a conductor to an insulator. If engineers are able to one day mass produce such devices, the study’s authors suggest they could replace silicon components and speed-up electronics by at least a factor of 1,000. The results of this study were published in the journal Nature Physics.

“Processors work in gigahertz right now,” Northeastern University Alberto de la Torre, lead author of the study, said in a press statement. “The speed of change that this would enable would allow you to go to terahertz.”

The breakthrough relies on a quantum material called tantalum disulfide, or 1T-TaS₂. Researchers used a technique called “thermal quenching,” which essentially allows this material to switch from a conductor to an insulator instantaneously. It was achieved by heating and then rapidly cooling the material across a critical temperature threshold, allowing for the “hidden metallic state” to also exist alongside its insulating attribute. “The idea is to heat the system above a phase transition and then cool it fast enough that it doesn’t have time to fully reorganize,” de la Torre told IEEE Spectrum.

As the tantalum disulfide lattice cools at a rate of about 120 Kelvin per second (a.k.a. thermal quenching), electrons bunch together in some regions while spreading out in others. This forms a wave pattern known as a charge density wave (CDW) phase, and some of these phases can be conducting while others are insulating.

This attribute is immensely useful, as current electric components typically need both conductive and insulating materials for a device that is connected by some sort of interface. This quantum material essentially removes the need for those components, and instead uses one material controlled by light itself.

“Everyone who has ever used a computer encounters a point where they wish something would load faster,” Gregory Fiete, a co-author of the study from Northeastern University, said in a press statement. “There’s nothing faster than light, and we’re using light to control material properties at essentially the fastest possible speed that’s allowed by physics.”

This mixed phase is only stable up to -63 degrees Celsius (210 Kelvin)—which is definitely cold, but much warmer than the near-absolute-zero temperatures required by other, related states. The material also remains in this programmed state for months, so it can feasibly be used in computing devices in the near future. This discovery could also be a major boon for artificial intelligence, which expends a lot of energy just moving data between memory and processors. Materials like 1T-TaS₂ could theoretically pull off “in-memory computing” and drastically reduce power consumption, IEEE Spectrum reports.

The era of transistors and silicon components completely changed the world, but that nearly 80-year-old breakthrough is itself just one step on our journey to master the subatomic. The method of loading silicon wafers with transistors is possibly approaching the end of its usefulness, and the authors argue that it might be time for a new approach.

“We’re at a point where in order to get amazing enhancements in information storage or the speed of operation, we need a new paradigm,” Fiete said in a press statement. “Quantum computing is one route for handling this and another is to innovate in materials. That’s what this work is really about.”

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