An orchestra where every musician plays their own part, and the conductor tries to catch the overall melody. That's roughly how physicists view electrons in cuprates — ceramic materials that conduct electricity without resistance at temperatures above liquid nitrogen. The main actors are copper and oxygen atoms. Electrons hop between them, interact, and create a remarkable effect. But in a real crystal, there are too many instruments, and the melody gets lost in the noise.
To hear it clearly, scientists build quantum simulators — artificial "crystals" made of light and ultracold atoms. Here, atoms replace electrons, and the crossing points of laser beams create a perfect lattice for them, like a honeycomb. In the new work, they propose a scheme where beams with different wavelengths and polarizations arrange not simple cells but complex "apartments" with two rooms — one for "copper" and one for "oxygen" atoms. This structure exactly replicates the three-band Emery model, which describes cuprates far more realistically than simplified single-story houses.
The authors didn't just propose a blueprint: they tested it in action using computer simulations. First, they tracked how a single atom wanders through the lattice and confirmed that its paths match theoretical predictions. Then they "heated" the system and observed a transition from conductor to insulator, just like in real cuprates. Near this transition, the seeds of magnetic order emerged: the spins of the atoms (their tiny magnetic arrows) began to align in a checkerboard pattern.
The cleverest trick is the "Hamiltonian learning" protocol. It works like a translator: it takes the complex three-band model and recasts it in the language of a simple single-band one. This will allow experimentalists to compare results with existing data and more quickly find the key to high-temperature superconductivity.
So the light orchestra begins to play the electrons' melody. And the more precisely we tune our instruments, the closer we get to the answer, and, along the way, to superconductors that don't require deep cold.
The highest superconducting temperature in cuprates reaches -140°C: that's warmer than the surface of Mars, but still colder than your freezer.
In Liu Cixin's novel "The Three-Body Problem," aliens create superconducting computers to bypass the limitations of conventional electronics — simulators like these could be a first step toward such technology.