Researchers observe heat exchange in an exotic material

April 18, 2017 by Kevin Stacey, Brown University
Researchers observe heat exchange in an exotic material
Researchers developed a device to measure heat flow at the quantum level in an exotic form of matter. Credit: Mitali Banerjee

In an article published today in the journal Nature, physicists report the first ever observation of heat conductance in a material containing anyons, quantum quasiparticles that exist in two-dimensional systems.

The work confirms about how anyons behave. That confirmation is important because scientists hope to one day harness the behavior of anyons to create self-correcting computers, which could perform calculations far more complex than digital computers can.

Dima Feldman, associate professor of physics at Brown, is a coauthor of the research with researchers at the Weizmann Institute of Science in Israel. He spoke about the research in an interview.

Could you summarize what you and your colleagues discovered?

In technical language, we observed the quantization of heat conductance in a strongly interacting system. So what does that mean? Everyone knows about conductance. It's simply the transfer of heat from a hot object to a cold object. In science, you can learn a lot about the nature of a material by understanding how fast it conducts heat. So here, we observed how this works at a quantum level among anyons, which are essentially fractional states of electrons in two-dimensional topological materials. Quantization of heat conductance had been observed before in systems where particle interaction is unimportant, but this is the first time it's been observed in a system dominated by electric interaction.

Why is the finding important?

It's important for two reasons. The first is more philosophical. We've arrived at a universal number for the quantization of anyonic heat flow, and physicists love universal numbers. When you arrive at a universal number, you've found order and harmony in nature. That's really what physics is all about.

More concretely, we performed our experiment in a topological material, and there's an idea for using topological in quantum computing. Quantum states are easily disrupted, which in a quantum computer means that it makes lots of errors. Correcting those errors is a big challenge. But there's this idea of using to harness quantum states of anyons, which we think will be much less fragile and can therefore do error-free calculations.

Understanding how heat flows gives us new information about anyons. There had been theoretical predictions about transport, and we were able to demonstrate them experimentally. So this is a big step toward understanding how anyons work.

What was your role in the work?

I was a theorist on the project, and theorists have several roles on something like this. I helped the group to understand what we want to measure, and I worked to help devise the experiment. But I think mainly where I helped was to understand the data we got from the experiment. Some of our results were surprising, so it was my job to help make sense of that.

What's next for this line of research?

The next step would be taking this to the second Landau level, meaning a higher energy electron state. Anyons are interesting at the first Landau level where our work was done, but they get even more interesting at the second level. So what people want to understand is what anyons are, because those are the potential keys to self-correcting quantum computer. But our research was a critical step in the process.

Explore further: Quantum computing with braids in flatland

More information: Observed quantization of anyonic heat flow, Nature (2017). nature.com/articles/doi:10.1038/nature22052

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