Magnons Achieve 18-Microsecond Lifetimes, Advancing Quantum Computing Miniaturization

Magnons, which are waves of magnetization traveling through magnetic solids, have been observed with lifetimes up to 18 microseconds—nearly one hundred times longer than previously recorded. This development could allow quantum computers to be reduced to the size of a one-cent coin.

Unlike photons that move through empty space or optical fibers, magnons propagate within magnetic materials, with wavelengths that can reach the nanometer scale. This property suggests the possibility of integrating magnonic circuits onto chips comparable in size to those in modern smartphones. Additionally, magnons interact naturally with various quasiparticles such as phonons and photons, making them promising for hybrid quantum systems and quantum metrology.

Extending Magnon Lifetimes Through Cooling and Material Purity

The breakthrough was achieved by generating short wavelength magnons, which are less susceptible to surface defects that previously limited their lifetimes. The research team placed highly pure yttrium iron garnet (YIG) spheres inside a mixed phase cryostat and cooled them to 30 millikelvin, a temperature just above absolute zero, effectively suppressing thermal processes that degrade magnons.

Tests on three YIG spheres with varying purity levels demonstrated that impurities within the crystal, rather than fundamental physical laws, set the upper limit on magnon lifetimes. Even the least pure sample surpassed all prior lifetime records, indicating that further enhancements will likely depend on advances in materials science.

Implications for Quantum Computing and Hybrid Systems

With lifetimes reaching 18 microseconds, magnons may transition from transient signals to reliable quantum information carriers, comparable to superconducting qubits used in current quantum processors. This extended lifetime could enable magnons to function as quantum memories and communication channels on chips, potentially linking hundreds of qubits via a shared quantum bus for scalable quantum computing.

Moreover, magnons' solid-state nature and their ability to interact with diverse quantum systems position them as potential universal translators within hybrid quantum architectures, facilitating communication between otherwise incompatible technologies.