Magnetic Vortex Becomes a Quantum Bit ⚡ экспресс
Abrikosov vortices with fully suppressed superconducting gap in the core are typically dissipative and semi-classical. This work shows that in granular superconducting films, vortices can become two-level quantum systems with coherence times on the order of microseconds and energy relaxation times up to fractions of a millisecond. These data support a theoretical model of superconductors with granularity on the coherence-length scale as networks of tunnel junctions, leading to the formation of 'gapped' vortices with an energy gap. Using circuit quantum electrodynamics, coherent control and quantum non-demolition readout of vortex states were demonstrated in microwave resonators made from granular aluminum. The results open perspectives for quantum information processing, precision materials science, and new sensors.
Magnetic vortices in superconductors, like whirlpools in water, typically scatter energy and quickly vanish due to internal friction—dissipation. This hampers their use in quantum chips. But in a film of tiny aluminum grains, a vortex gets trapped and resembles a whirlpool in a narrow well—it spins either one way or the other. Quantum nature allows it to spin both ways at once until measured. This double life lasts for milliseconds—an eternity in the micro-world. Scientists have learned to flip the vortices with microwave pulses (spectroscopy) and read out their state without loss. Each vortex carries exactly one quantum of magnetic flux—a billionth of Earth's field. The idea of Alexei Kitaev to use such structures for noise-tolerant quantum computing has been directly confirmed.
🎯 Each such vortex carries just one quantum of magnetic flux—about a billionth of Earth's magnetic field.