Imagine holding one of our most precise quantum devices at a fixed position outside a black hole. A Josephson junction—two superconductors separated by an ultrathin barrier—can turn a voltage into a quantum oscillation with extraordinary precision. Would intense gravity change that quantum rule, or only change how a faraway observer reads the device?

In our study published in the Journal of High Energy Physics, we found a clean answer. The local Josephson physics remains intact. Gravity instead changes the translation between measurements made beside the circuit and measurements assigned by an observer far from the black hole.