An electric circuit includes a first superconducting component, a second superconducting component, a first electrically-insulating component that thermally couples the first superconducting component and the second superconducting component such that heat produced in response to the first superconducting component transitioning to a non-superconducting state is transferred through the first electrically-insulating component to the second superconducting component, and a photon detector coupled to the first superconducting component. The photon detector is configured to output a first current to the first superconducting component upon detection of a threshold number of photons. The electric circuit further includes an output component coupled to the second superconducting component. The output component is configured to be responsive to a voltage drop across the second superconducting component.