Photon count identification system, photon count identification method, and photon count identification processing program
A photon number resolving system includes: a plurality of pixels of which each includes a photoelectric conversion element and an amplifier for amplifying the electric charges converted by the photoelectric conversion element and converting the electric charges to a voltage; an A/D converter configured to convert a voltage output from the amplifier of each of the plurality of pixels to a digital value; a first deriving unit configured to derive a provisional value of a photon number in each pixel of the plurality of pixels based on the digital value; and a second deriving unit configured to derive a confirmed value of a photon number in a target pixel based on a first probability based on optical shot noise and a second probability based on reading noise.
1 . A photon number resolving system comprising:
a plurality of pixels of which each includes a photoelectric conversion element for converting input light to electric charges and an amplifier for amplifying the electric charges converted by the photoelectric conversion element and converting the electric charges to a voltage;
an A/D converter configured to convert a voltage output from the amplifier of each of the plurality of pixels to a digital value; and
a computing device comprising a first derivation unit and a second derivation unit, wherein:
the first deriving unit of the computing device configured to derive a provisional value of a photon number in each of the plurality of pixels based on the digital value; and
the second deriving unit of the computing device configured to derive a confirmed value of a photon number in a target pixel which is one of the plurality of pixels based on a first probability and a second probability,
wherein the first probability is an observation probability for each photoelectron number in the target pixel based on a probability distribution of the photon number,
wherein the probability distribution of the photon number is derived based on the digital value when the light is input to a reference pixel which is at least one of the plurality of pixels,
wherein the second probability is an observation probability for each photoelectron number at the provisional value of the target pixel based on a probability distribution of a photoelectron number accompanying reading noise in the target pixel,
wherein the first deriving unit derives the provisional value of photon number from the digital value based on threshold value data, and
wherein the second derivation unit calculates a probability for each photoelectron number when the target pixel indicates the provisional value by calculating a product of the first probability and the second probability and determines the confirmed value based on the calculated probability.
2 . The photon number resolving system according to claim 1 , wherein the reading noise of the reference pixel is smaller than an average of the reading noise of all the plurality of pixels.
3 . The photon number resolving system according to claim 1 , wherein the reading noise of the reference pixel is equal to or less than 0.8 e-rms.
4 . The photon number resolving system according to claim 1 , wherein the light is output from a quantum light source.
5 . The photon number resolving system according to claim 1 , wherein a probability distribution of the photoelectron number accompanying the reading noise of the target pixel is a normal distribution.
6 . The photon number resolving system according to claim 1 , wherein the second deriving unit includes a noise map indicating the reading noise of each of the plurality of pixels.
7 . A photon number resolving method comprising:
deriving a provisional value of a photon number in each of a plurality of pixels based on digital values corresponding to the plurality of pixels output from a two-dimensional image sensor including the plurality of pixels; and
deriving a confirmed value of the photon number in a target pixel which is one of the plurality of pixels based on a first probability and a second probability,
wherein the deriving of the confirmed value includes
calculating an observation probability for each photoelectron number in the target pixel based on a probability distribution of the photon number as the first probability, and
calculating an observation probability for each photoelectron number at the provisional value of the target pixel as the second probability based on a probability distribution of the photoelectron number accompanying the reading noise of the target pixel,
wherein the probability distribution of the photon number is derived based on the digital value when light is input to a reference pixel which is at least one of the plurality of pixels,
wherein the deriving of the provisional value of photon number includes deriving the provisional value of photon number from the digital value based on threshold value data, and
wherein the deriving of the confirmed value includes calculating a probability for each photoelectron number when the target pixel indicates the provisional value by calculating a product of the first probability and the second probability and determining the confirmed value based on the calculated probability.
8 . The photon number resolving method according to claim 7 , wherein the reading noise of the reference pixel is smaller than an average of the reading noise of all the plurality of pixels.
9 . The photon number resolving method according to claim 7 , wherein the reading noise of the reference pixel is equal to or less than 0.8 e-rms.
10 . The photon number resolving method according to claim 7 , wherein the light is output from a quantum light source.
11 . The photon number resolving method according to claim 7 , wherein the deriving of the confirmed value includes calculating a probability for each photoelectron number when the target pixel indicates the provisional value using a product of the first probability and the second probability and determining the confirmed value based on the calculated probability.
12 . The photon number resolving method according to claim 7 , wherein the deriving of the confirmed value uses a normal distribution as a probability distribution of the photoelectron number accompanying the reading noise of the target pixel.
13 . The photon number resolving method according to claim 7 , wherein the deriving of the confirmed value includes referring to a noise map indicating the reading noise of each of the plurality of pixels.
14 . A photon number resolving program, stored on a non-transitory storage medium, for causing a computer to perform a process of resolving a photon number based on digital values corresponding to a plurality of pixels output from a two-dimensional image sensor including the plurality of pixels, the program causing the computer to perform:
a first deriving process of deriving a provisional value of a photon number in each of a plurality of pixels based on the digital values; and
a second deriving process of deriving a confirmed value of the photon number in a target pixel which is one of the plurality of pixels based on a first probability and a second probability,
wherein the first probability is an observation probability for each photoelectron number in the target pixel based on a probability distribution of the photon number,
wherein the probability distribution of the photon number is derived based on the digital value when the light is input to a reference pixel which is at least one of the plurality of pixels, and
wherein the second probability is an observation probability for each photoelectron number at the provisional value of the target pixel based on a probability distribution of a photoelectron number accompanying reading noise in the target pixel,
wherein the first derivation process derives the provisional value of photon number from the digital value based on threshold value data, and
wherein the second derivation process calculates a probability for each photoelectron number when the target pixel indicates the provisional value by calculating a product of the first probability and the second probability and determines the confirmed value of photon number based on the calculated probability.