Imagine a flock of birds as they wheel across the sky: surging into a mass, flowing into ribbons that twist and turn again into fantastic shapes. If you follow one bird within the flock, you can describe its actions, the way it flaps its wings or uses its tail to brake. Yet, even if you could minutely account for the behavior of each individual bird, the shapes and patterns of their collective flight would still evade understanding.
Electrons don’t flock like birds. But Debanjan Chowdhury, assistant professor of physics, faces a similar challenge when trying to describe how electrons behave in quantum materials.
For decades, scientists have been studying electrons by looking at common materials like silicon and observing one electron at a time. “Despite the complexity of electrons in silicon, we can effectively describe the material’s measurable properties by focusing on each individual electron as if the others don’t exist,” Chowdhury says.
But lately, scientists have been excited by so-called quantum materials, in which trillions of electrons interact and influence each other-behavior that is evident in high-temperature superconductors. “These new materials exhibit counterintuitive properties that can’t be described by treating these electrons one at a time,” Chowdhury says. “Instead, we have to treat the electrons in these materials as one collective fluid in which electrons are strongly entangled with one another. We don’t even have the right kinds of technical tools and mathematical machinery to describe their properties reliably yet.”
For Chowdhury, who is a theoretical physicist, quantum materials are at once puzzles and pathways to innovation. “These materials are exciting,” he says. “They hold a lot of promise to further our basic understanding of quantum mechanics as it applies to trillions of interacting electrons. They also could potentially drive the next generation of quantum technologies.”
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