Magnetic 'Headphones' for Qubits: A New Way to Fight Quantum Noise ⚡ экспресс
Nanophotonic structures can be used to control dephasing—a process that destroys quantum information due to noise. Researchers created metasurfaces from a magnetic alloy CoFeB and suppressed low-frequency magnetic fluctuations (~MHz) in NV centers in diamond. Unlike the Purcell effect (which accelerates emission), here the emission rate wasn't changed, but the nature of dephasing was. These structures act like a filter that selectively blocks magnetic noise at certain frequencies. This result paves the way for more stable qubits without complex isolation.
Quantum bits (qubits) are like delicate music in a noisy factory. Ambient magnetic fields constantly 'drown out' their quantum state, turning a coherent signal into cacophony. Usually, this destructive process is slowed by retuning the qubits themselves to different frequencies, but that doesn't always work. The new approach is like not changing the music, but putting on noise-canceling headphones: a thin magnetic film cancels the interference before it reaches the qubit.
Scientists created such magnetic 'headphones' from a CoFeB alloy—a film thinner than a hair, covered with a clever nanopattern. Placing it next to NV centers in diamond (defects that act as single-atom radio beacons), they used spectroscopy (light emission analysis) to measure how much longer the qubits maintain quantum clarity. The pattern is specifically designed to absorb the most harmful low-frequency magnetic oscillations. The result: the quantum lifetime increased severalfold, and the measure of disorder (entropy) in the system decreased.
🎯 Paradoxically, the magnetic alloy CoFeB used in regular films actually speeds up quantum state decay. But with a cleverly designed nanopattern, it transforms into a shield, effectively soaking up stray magnetic fields.