Readout circuitry for photon number detectors

A method comprising:

• providing, from a first electrical source, a first current that flows through a plurality of readout components, the plurality of readout components being electrically connected to a plurality of reset components, a readout component of the plurality of readout components having an first electrical resistance value;
• providing, from a second electrical source, a second current that flows through a plurality of detector components that are in a superconductive state, the plurality of detector components being electrically coupled to a plurality of thermal components;
• absorbing one or more photons using the one or more of the plurality of detector components, the one or more of the plurality of detector components transitioning form the superconductive state to a non-superconductive state in response to absorbing the one or more photons, the one or more of the plurality of detector components having increased resistance due to the non-superconductive state such that a portion of the second current is directed to the plurality of thermal components;
• generating heat from the plurality of thermal components due to the portion of the second current;
• absorbing, by the plurality of readout components, the heat from the plurality of thermal components such that the plurality of readout components increase resistance from the first electrical resistance value to a second electrical resistance value that is higher than the first electrical resistance value, the plurality of reset components having a third electrical resistance value that is lower than the second electrical resistance value such that a portion of the first current is directed to the plurality of reset components;
• and
• measuring an electrical value from the plurality of reset components to determine a quantity of the plurality of detector components that absorbed the one or more photons, the plurality of reset components being connected to an electrical ground such that the portion of the first current is removed by the electrical ground and the plurality of readout components are reset based on a time constant that depends at least in part of the third electrical resistance value of the plurality of reset components.