Circuit apparatus for calibrating unequal-arm interferometer, and quantum communication device

A quantum communication device, the quantum communication device comprising:

• a circuit apparatus for calibrating an unequal-arm interferometer, wherein the circuit apparatus comprises:
• a constant-voltage power supply;
• a heater, provided on a short arm of the unequal-arm interferometer;
• and
• a diode, reversely connected between a positive electrode and a negative electrode of output ends of the constant-voltage power supply, and connected in series with the heater, so as to provide, to the heater, a reverse saturation current which changes along with a change in ambient temperature,
• wherein by means of a change amount of the reverse saturation current provided by the diode, the circuit apparatus counteracts an excess amount of an optical path change on a long arm of the unequal-arm interferometer under the effect of the change in the ambient temperature, relative to an optical path change on the short arm of the unequal-arm interferometer under the effect of the change in the ambient temperature.