Inside certain insulating crystals hides a plasma of magnetic monopoles — particles with a single magnetic pole, like halves of a magnet. Their behavior resembles a multitude of tiny magnetic needles attached to springs within a rigid atomic lattice. Alone they barely budge, but when a radio wave of the right frequency comes along, all the needles start swinging in unison — a collective resonance emerges. This gives birth to a cold plasma that, unlike its scorching counterpart, doesn't conduct a steady current.

The frequency of this plasma response hinges on the thermal awakening of monopoles: the warmer it is, the more of them break free from entangled pairs and join the dance. The motion is governed by an invisible quantum field, akin to the electromagnetic one. When the wave hits the right beat, the plasma acts like a single quantum cloud and produces a sharp spike in wave absorption — captured by a spectrum analyzer. The most surprising fact: to observe the resonance, the crystal has to be cooled to thousandths of a degree above absolute zero — colder than interstellar space. Meanwhile, invisible magnetic threads between monopoles can snap and reconnect, like field lines on the Sun, adding extra mobility that was predicted long ago by Maxwell and Dirac. A precise radio measurement of such resonance will be the first irrefutable proof of a quantum spin liquid — a state where atomic spins constantly reside in a mixed position. From such matter, we can build topological qubits resistant to quantum information breakdown, forming the foundation of a future quantum computer.