Physics World Weekly Podcast · Physics World

Building a quantum future using topological phases of matter and error correction

·25 min·2 clips

How can bosons team up to make a fermion, defying conventional particle physics expectations?

Host Hamish Johnston opens by distinguishing quantum matter from conventional quantum mechanics, explaining that most useful materials like silicon semiconductors require only single-particle quantum mechanics, while quantum matter involves the collective behavior of enormous numbers of interacting particles. Tim Shea introduces the concept of emergent phenomena, in which the interaction of many bodies produces phenomena impossible to predict from individual constituents alone, citing superconductivity and quantum spin liquids as key examples. He describes topological order, a particularly counterintuitive phase of matter where bosons whose wave functions can be decomposed into imaginary bound pairs of fermions interact so strongly that those fermions become de-confined and observable as independent quasiparticles, analogous to quark de-confinement in QCD. The fractional quantum Hall effect, discovered experimentally in the 1980s, provides the most concrete example, where electrons in a 2D plane under high magnetic field fractionalize into particles carrying one-third of the electron charge. Shea explains that this fractionalization is directly useful for quantum computing because encoding information non-locally across separated fractionalized quasiparticles makes it far more robust to environmental noise than encoding at the physical qubit level. He describes quantum error correction as a phase transition problem: the regime where a system can correct errors versus the regime where it cannot corresponds to a quantum phase transition, allowing condensed matter techniques to be applied to error correction research. Shea describes current progress in quantum computing hardware including trapped ions, superconducting qubits, and Rydberg arrays, noting that gate fidelities are improving rapidly and that theorists now have a genuine playground to discover new phases of matter in these systems. His personal wishlist for a future quantum computer centers on solving the Hubbard model, an effective description of high-temperature superconductors that remains too complex for classical computers, which could potentially guide the design of room-temperature superconducting materials.

As heard by us

A steady look at quantum information and quantum matter, with error correction kept firmly in view.

This episode circles a discussion at Perimeter Institute on quantum matter, emergent phenomena, quantum error correction, and quantum simulation.

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You want a patient route into quantum error correction and quantum matter.

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