System and method for quantum absorption spectroscopy

A system for quantum absorption spectroscopy, the system comprising:

• a quantum interferometer configured to cause quantum interference between a plurality of physical processes in each of which a quantum entangled photon pair of a signal photon and an idler photon is generated by irradiation with pump light;
• a photodetector that includes a light receiving surface on which a plurality of pixels are disposed and configured to detect the signal photon;
• a memory that stores a correspondence between a parameter indicating a position of each pixel on the light receiving surface and a wavelength of the signal photon detected by the pixel;
• and
• a processor configured to execute arithmetic processing for calculating a spectral characteristic of a sample disposed on an optical path of the idler photon, wherein
• the quantum interferometer includes a modulator configured to apply modulation to a phase of the quantum interference, the modulator includes a moving mirror configured to reflect one of the signal photon and the idler photon to temporally modulate the phase of the quantum interference according to a displacement amount of the moving mirror,
• and
• the processor is configured to:
• acquire, from a predetermined number of pixels disposed on the light receiving surface, a variation in a detection intensity of the signal photon caused by the modulation by displacement of the moving mirror, and
• calculate the spectral characteristic based on visibility of the quantum interference obtained from the variation and the correspondence.

A system for quantum absorption spectroscopy, the system comprising:

• a quantum interferometer configured to cause quantum interference between a plurality of physical processes in each of which a quantum entangled photon pair of a signal photon and an idler photon is generated by irradiation with pump light;
• a photodetector that includes a light receiving surface on which a plurality of pixels are disposed and configured to detect the signal photon;
• a memory that stores a correspondence between a parameter indicating a position of each pixel on the light receiving surface and a wavelength of the signal photon detected by the pixel;
• and
• a processor configured to execute arithmetic processing for calculating a spectral characteristic of a sample disposed on an optical path of the idler photon, wherein
• the quantum interferometer includes
• a modulator configured to apply modulation to a phase of the quantum interference, and
• a plurality of nonlinear optical elements having mutually different phase matching conditions,
• the system further comprises a plurality of filter elements provided in the photodetector, the plurality of filter elements corresponding to the plurality of nonlinear optical elements, and
• each of the plurality of filter elements is configured to selectively transmit a signal photon generated by a corresponding one of the plurality of nonlinear optical elements,
• the processor is configured to:
• acquire, from a predetermined number of pixels disposed on the light receiving surface, a variation in a detection intensity of the signal photon caused by the modulation by the modulator, and
• calculate the spectral characteristic based on visibility of the quantum interference obtained from the variation and the correspondence.