A courtroom interpreter must convey every word without being distracted by the noise in the room. In the quantum world, a superconducting resonator plays the role of such an interpreter: it must lose photons strictly on schedule, without being thrown off by extraneous effects. Previously, this was done with a microwave pump, but the pump itself created noise, as if the interpreter started shouting out the audience's remarks.

Now scientists have found a quieter way. Instead of a loud pump, they applied a DC voltage to the superconducting circuit. When a pair of electrons passes through the junction, it releases energy that can be precisely tuned so that two photons from the memory resonator are converted into one photon in the buffer resonator. The buffer resonator quickly loses that photon, and the system settles into the desired state.

This approach opens the way to stabilizing cat-state qubits, which are needed for quantum error correction. Whereas previously the pump itself introduced errors, now the DC voltage works like a perfect interpreter: precise, quiet, and without unnecessary words.