JP4845131B2 - Quantum efficiency measurement method and apparatus - Google Patents
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本発明は、光子検出器を必要とする光通信・情報処理分野（量子暗号等）、レーザーライダー等の極微弱光検出を必要とする光応用計測分野、等で必要となる正確な光子検出を行うための量子効率測定方法および装置に関する。 The present invention provides accurate photon detection required in the field of optical communication and information processing that requires a photon detector (quantum cryptography, etc.), the field of optical application measurement that requires extremely weak light detection, such as a laser lidar, etc. The present invention relates to a method and apparatus for measuring quantum efficiency.
従来、極微弱な光子を正確に検出するために以下のような量子効率測定方法が提案されている。
特許文献１では、極微弱コヒーレント光を光子検出器に入射して得られる光子検出時刻の時間間隔分析から量子効率を求めている。
非特許文献１では、極微弱コヒーレント光を光子検出器に入射して求められる単独検出事象発生率（「単計数率」という）の入射光子依存性から量子効率を測定している。
Conventionally, the following quantum efficiency measurement methods have been proposed in order to accurately detect extremely weak photons.
In patent document 1, quantum efficiency is calculated | required from the time interval analysis of the photon detection time obtained by making very weak coherent light inject into a photon detector.
In Non-Patent Document 1, the quantum efficiency is measured from the incident photon dependence of the single detection event occurrence rate (referred to as “single counting rate”) obtained by making extremely weak coherent light incident on a photon detector.
非特許文献２では、相関光子対を利用して二台の光子検出器の量子効率を測定している。図１は非特許文献２の量子効率測定法の説明図である。図１では、光子対発生用非線形結晶（Ｎｏｎｌｉｎｅａｒ Ｃｒｙｓｔａｌ）に入射した周波数ωｐの一つの光子は、周波数ω１とω２のそれぞれ１つの光子（周波数ω１のシグナル光子、周波数ω２のアイドラ光子）として出力される。つまり、短い波長の１つの光子を入射すると、かならず波長の長い２つの光子を同時に出射する。周波数ω１のシグナル光子は光子検出器（ＤＵＴ）で検出され、計数器（Ｃｏｕｎｔｅｒ）により、単計数率（ＳＡ、ＩＡ）が測定される。周波数ω２のアイドラ光子は光子検出器（Ｔｒｉｇｇｅｒ）で検出され、計数器（Ｃｏｕｎｔｅｒ）により、単計数率（ＳＡ、ＩＡ）が測定される。両計数器（Ｃｏｕｎｔｅｒ）のカウント値に基づき同時計数器（Ｃｏｉｎｃｉｄｅｎｃｅ Ｃｏｕｎｔｅｒ）により、同時検出事象発生率（以下、「同時計数率」という）（ＣＡ）が測定される。透過率が、ｆ＝ｇ＝１であれば、η１＝ＣＡ／ＩＡ、η２＝ＣＡ／ＳＡとなり、量子効率を求めることができる。 In Non-Patent Document 2, the quantum efficiency of two photon detectors is measured using a correlated photon pair. FIG. 1 is an explanatory diagram of the quantum efficiency measurement method of Non-Patent Document 2. In Figure 1, one of the photons of frequency omega p incident on photon pair generating non-linear crystal (Nonlinear Crystal), the frequency omega 1 and omega 2 of each single photon (frequency omega 1 of the signal photon, the frequency omega 2 of the idler Photon). That is, when one photon having a short wavelength is incident, two photons having a long wavelength are always emitted simultaneously. A signal photon having a frequency ω 1 is detected by a photon detector (DUT), and a single count rate (SA, IA) is measured by a counter. An idler photon having a frequency ω 2 is detected by a photon detector (Trigger), and a single count rate (SA, IA) is measured by a counter (Counter). A coincidence counter occurrence rate (hereinafter referred to as “coincidence rate”) (CA) is measured by a coincidence counter based on the count values of both counters (Counter). When the transmittance is f = g = 1, η 1 = CA / IA and η 2 = CA / SA, and the quantum efficiency can be obtained.
非特許文献２は、相関光子対を利用して二台の光子検出器の量子効率を測定している。但し、光子対発生用非線形結晶（Ｎｏｎｌｉｎｅａｒ Ｃｒｙｓｔａｌ）に対して励起光源は片側にのみ設置され、計数器（Ｃｏｕｎｔｅｒ）により、単計数率（ＳＡ、ＩＡ）が測定され、同時計数器（Ｃｏｉｎｃｉｄｅｎｃｅ Ｃｏｕｎｔｅｒ）により、同時計数率（ＣＡ）が測定される。このとき、シグナル光子を検出する光子検出器（ＤＵＴ）の量子効率をη１、アイドラ光子を検出する光子検出器（Ｔｒｉｇｇｅｒ）の量子効率をη２とし、光子対発生率をμと記述すれば、単計数率は、ＳＡ＝ｆ・η１・μ、ＩＡ＝ｇ・η２・μで与えられ、同時計数率は、ＣＡ＝ｆｇ・η１・η２・μとなる。但し、非線形結晶と光子検出器（ＤＵＴ）との間で発生する透過率、及び、非線形結晶と光子検出器（Ｔｒｉｇｇｅｒ）との間で発生する透過率を、それぞれ、ｆ、ｇで示す。透過率が、ｆ＝ｇ＝１であれば、η１＝ＣＡ／ＩＡ、η２＝ＣＡ／ＳＡとなり、量子効率を求めることができる。尚、図中のω１、ω２は、それぞれ、シグナル光子、アイドラ光子の周波数、ωｐは励起光源の周波数である。
特許文献１では、極微弱コヒーレント光を光子検出器に入射して得られる光子検出時刻の時間間隔分析から量子効率を求めているが、入射光子数が既知でなければ量子効率を求めることができない。
非特許文献１では、極微弱コヒーレント光を光子検出器に入射して求められる単計数率の入射光子依存性から量子効率を測定しているが、特許文献１同様、入射光子数が既知でなければ量子効率を求めることができない。
非特許文献２は、透過率が、ｆ＝ｇ＝１であれば、η１＝ＣＡ／ＩＡ、η２＝ＣＡ／ＳＡとなり、量子効率を求めることができるが、一般には、非線形結晶から各光子検出器までの間で発生する伝搬損失は避けられない。このため、伝搬損失に基づいて透過率がｆ≠１、損失ｇ≠１となり、量子効率の測定も不正確になる。また、透過率ｆ、透過率ｇを正確に測定する手段も提供されていない。
In Patent Document 1, quantum efficiency is obtained from time interval analysis of photon detection time obtained by making very weak coherent light incident on a photon detector, but quantum efficiency cannot be obtained unless the number of incident photons is known. .
In Non-Patent Document 1, the quantum efficiency is measured from the incident photon dependence of the single count rate obtained by making very weak coherent light incident on the photon detector, but as in Patent Document 1, the number of incident photons must be known. For example, quantum efficiency cannot be obtained.
In Non-Patent Document 2, when the transmittance is f = g = 1, η 1 = CA / IA and η 2 = CA / SA, and the quantum efficiency can be obtained. Propagation loss occurring up to the photon detector is inevitable. For this reason, the transmittance becomes f ≠ 1 and the loss g ≠ 1 based on the propagation loss, and the measurement of the quantum efficiency becomes inaccurate. Also, no means for accurately measuring the transmittance f and the transmittance g is provided.
本発明の目的は、上記従来例の問題点に鑑み、光子検出器への入射光子数が未知であっても、更に、伝搬損失が避けられないような状況下でも、二台の光子検出器の量子効率を同時に、正確に測定するために必要な量子効率測定装置を提供することにある。 An object of the present invention is to provide two photon detectors even in a situation where propagation loss is unavoidable even when the number of incident photons to the photon detector is unknown, in view of the problems of the conventional example. It is another object of the present invention to provide a quantum efficiency measuring apparatus necessary for accurately measuring the quantum efficiency of the same.
本発明は、上記課題を解決するために、以下の解決手段を採用する。
（１）量子効率測定方法は、相関光子対を発生するための非線形導波路とその両側に配置した一対の光ファイバからなる相関光子対発生装置と、前記非線形導波路を励起する励起光源と、前記相関光子対をシグナル光子とアイドラ光子に分離し、それぞれ異なる光子検出器に入射させる無偏光ビームスプリッタと、前記シグナル光子とアイドラ光子をそれぞれ個別に検出する２つの光子検出器と、前記それぞれの光子検出器の検出出力を個別に計数する２つの計数器と、前記両計数器の同時に出力される出力信号を取り込んで所定の処理を行う同時計数器とを有する装置において、前記励起光源と前記非線形導波路の間および前記非線形導波路と前記無偏光ビームスプリッタの間を着脱自在に光ファイバで接続すると共に、前記無偏光ビームスプリッタの前記それぞれの光子の出力側をそれぞれ前記光子検出器に接続し、前記相関光子対発生装置で発生した前記シグナル光子とアイドラ光子を前記それぞれの光子検出器で検出し、その検出したデータをそれぞれの光子検出器に個別に接続した計数器により計数して単計数率を求め、前記両計数器の同時に出力される出力信号を取り込んで所定の処理を行う同時計数器により計数して同時計数率を求め、前記励起光源と前記相関光子対発生装置の間および前記相関光子対発生装置と前記無偏光ビームスプリッタ間に対して、前記光ファイバを切り替えて接続した状態で前記相関光子対発生装置で発生した前記シグナル光子とアイドラ光子を前記それぞれの光子検出器で検出し、その検出したデータをそれぞれの光子検出器に個別に接続した計数器により計数して単計数率を求め、前記両計数器の同時に出力される出力信号を取り込んで所定の処理を行う同時計数器により計数して同時計数率を求めて、前記それぞれの単計数率と前記同時計数率との関係から前記シグナル光子とアイドラ光子を検出する前記それぞれの光子検出器における量子効率を求めることを特徴とする。
The present invention employs the following means for solving the above-described problems.
(1) A quantum efficiency measurement method includes: a non-linear waveguide for generating a correlated photon pair; a correlated photon pair generating device including a pair of optical fibers disposed on both sides thereof; an excitation light source for exciting the non-linear waveguide; A non-polarizing beam splitter that separates the correlated photon pair into a signal photon and an idler photon and is incident on different photon detectors; two photon detectors that individually detect the signal photon and idler photon; In the apparatus having two counters that individually count the detection outputs of the photon detectors, and a simultaneous counter that takes in output signals output simultaneously from both counters and performs a predetermined process, the excitation light source and the The nonlinear waveguide and between the nonlinear waveguide and the non-polarized beam splitter are detachably connected by an optical fiber, and the non-polarized beam The output side of each photon of the splitter is connected to the photon detector, the signal photon and idler photon generated by the correlation photon pair generator are detected by the respective photon detector, and the detected data is Count by a counter individually connected to each photon detector to obtain a single count rate, and take the output signals output simultaneously from both counters and count them by a simultaneous counter that performs a predetermined process. The correlated photon pair generating device in a state where the optical fiber is switched and connected between the excitation light source and the correlated photon pair generating device and between the correlated photon pair generating device and the non-polarized beam splitter. The signal photons and idler photons generated in step 1 are detected by the respective photon detectors, and the detected data are individually connected to the respective photon detectors. The single counting rate is obtained by counting with the counters obtained, and the simultaneous counting rate is obtained by counting with the simultaneous counter that takes in the output signals output simultaneously from the two counters and performs a predetermined process. The quantum efficiency in each of the photon detectors for detecting the signal photon and idler photon is obtained from the relationship between the count rate and the coincidence rate.
（２）上記（１）記載の量子効率測定方法は、前記非線形導波路とその両側に配置した前記一対の光ファイバのそれぞれとの間の透過率ｐ、ｑがｐ≠１、ｑ≠１であることを特徴とする。
（３）上記（１）又は（２）記載の量子効率測定方法は、上記光子検出器が開ゲート時のみ光子検出を行い、光子検出と同期して電圧パルスを発生し、上記二台の計数器は単位ゲート当たりの単計数率をそれぞれ独立に測定し、上記同時計数器により同時刻に発生した前記電圧パルスに対して、単位ゲート当たりの同時計数率を求めることを特徴とする。
（４）上記（１）乃至（３）のいずれか１項記載の量子効率測定方法は、無偏光ビームスプリッタを透過した光子をシグナル光子、反射した光子をアイドラ光子としたとき、上記相関光子対発生装置で発生した光子対に対して、分岐比５０％の無偏光ビームスプリッタが上記光子対出射側に設置され、確率５０％で、光子対が、シグナル・アイドラ光子に分離されるようにしたことを特徴とする。
(2) In the quantum efficiency measurement method according to (1), the transmittances p and q between the nonlinear waveguide and each of the pair of optical fibers arranged on both sides thereof are p ≠ 1 and q ≠ 1. It is characterized by being.
(3) In the quantum efficiency measurement method according to (1) or (2), the photon detector performs photon detection only when the gate is open, generates a voltage pulse in synchronization with the photon detection, and counts the two units. The measuring device independently measures a single count rate per unit gate, and obtains a coincidence rate per unit gate for the voltage pulses generated at the same time by the simultaneous counter.
(4) The quantum efficiency measurement method according to any one of (1) to (3), wherein the photon transmitted through the non-polarizing beam splitter is a signal photon, and the reflected photon is an idler photon. A non-polarizing beam splitter having a branching ratio of 50% is installed on the emission side of the photon pair with respect to the photon pair generated by the generator, and the photon pair is separated into a signal idler photon with a probability of 50%. It is characterized by that.
（５）上記（１）乃至（４）のいずれか１項記載の量子効率測定方法は、シグナル光子用の光子検出器の量子効率をα、アイドラ光子用の単一光子検出器の量子効率をβとし、相関光子対発生装置の光子対発生率をμとし、上記記載の励起光源と無偏光ビームスプリッタに対して相関光子対発生装置を一定の接続状態としたとき、前記無偏光ビームスプリッタにより分離される光子対に対して、光子対発生率をμＢとし、各単計数率を、それぞれＳＡ＝ｐαμＢ、ＩＡ＝ｐβμＢで与え、分離成功確率を５０％とし、同時計数率をＣＡ＝０．５ｐ２αβμＢで与え、ｐを非線形導波路と前記一定の接続状態で接続している光ファイバに関する透過率で与え、前記一定の接続状態と逆の接続状態にしたとき、無偏光ビームスプリッタにより分離された光子対に対して、光子対発生率をμＡとし、各単計数率を、それぞれＳＢ＝ｑαμＡ、ＩＢ＝ｑβμＡで与え、分離成功確率を５０％とし、同時計数率をＣＢ＝０．５ｑ２αβμＡで与え、ｑを非線形導波路と前記一定の接続状態と逆の接続状態で接続している光ファイバに関する透過率で与えるとき、同時計数率ＣＡとＣＢの積が、
ＣＡ・ＣＢ＝０．２５ｐ２ｑ２α２β２μＡμＢ
で与えられ、Ｚ＝ｐｑとすれば
ＪＣ≡ＣＡ・ＣＢ＝０．２５Ｚ２α２β２μＡμＢ
となり、単計数率ＳＡとＳＢの積が、
ＪＳ≡ＳＡ・ＳＢ＝ｐｑα２μＡμＢ＝Ｚα２μＡμＢ
となり、ＪＣとＪＳの比が
ＪＣ／ＪＳ＝０．２５Ｚβ２
となり、光子検出器の量子効率βが
β＝２√（ＪＣ／ＪＳ／Ｚ）
で求められることを特徴とする。
(5) In the quantum efficiency measurement method according to any one of (1) to (4), the quantum efficiency of the photon detector for signal photons is α, and the quantum efficiency of the single photon detector for idler photons is When β is set, and the photon pair generation rate of the correlated photon pair generator is μ, and the correlated photon pair generator is in a fixed connection state with respect to the excitation light source and the non-polarized beam splitter, the non-polarized beam splitter For the photon pairs to be separated, the photon pair generation rate is μ B , each single count rate is given by SA = pαμ B and IA = pβμ B , the separation success probability is 50%, and the coincidence rate is CA. = 0.5 p 2 αβμ B , p is given as the transmittance for the optical fiber connected to the nonlinear waveguide in the constant connection state, and when the connection state is opposite to the constant connection state, the non-polarized light Separated by beam splitter Against photon pairs, the photon pair generation rate and mu A, each single counting rate, respectively SB = qαμ A, given by IB = qβμ A, the separation success probability of 50% the coincidence ratio CB = 0 .5q 2 αβμ A , and q is given by the transmittance for the optical fiber connected to the nonlinear waveguide in the connection state opposite to the fixed connection state, the product of the coincidence rate CA and CB is
CA · CB = 0.25p 2 q 2 α 2 β 2 μ A μ B
Given, Z = if pq JC≡CA · CB = 0.25Z 2 α 2 β 2 μ A μ B with
The product of the single count rate SA and SB is
JS≡SA · SB = pqα 2 μ A μ B = Zα 2 μ A μ B
And the ratio of JC to JS is JC / JS = 0.25Zβ 2
The quantum efficiency β of the photon detector is β = 2√ (JC / JS / Z)
It is calculated | required by.
（６）上記（１）乃至（５）のいずれか１項記載の量子効率測定方法は、シグナル光子用の光子検出器の量子効率をα、アイドラ光子用の単一光子検出器の量子効率をβとし、相関光子対発生装置の光子対発生率をμとし、
両側の励起光源と無偏光ビームスプリッタに対して相関光子対発生装置を一定の接続状態としたとき、前記無偏光ビームスプリッタにより分離される光子対に対して、光子対発生率をμＢとし、各単計数率を、それぞれＳＡ＝ｐαμＢ、ＩＡ＝ｐβμＢで与え、分離成功確率を５０％とし、同時計数率をＣＡ＝０．５ｐ２αβμＢで与え、ｐを非線形導波路と前記一定の接続状態で接続している光ファイバに関する透過率で与え、
前記一定の接続状態と逆の接続状態にしたとき、無偏光ビームスプリッタにより分離された光子対に対して、光子対発生率をμＡとし、各単計数率を、それぞれＳＢ＝ｑαμＡ、ＩＢ＝ｑβμＡで与え、分離成功確率を５０％とし、同時計数率をＣＢ＝０．５ｑ２αβμＡで与え、ｑを非線形導波路と前記一定の接続状態と逆の接続状態で接続している光ファイバに関する透過率で与えるとき、
同時計数率ＣＡとＣＢの積が、
ＣＡ・ＣＢ＝０．２５ｐ２ｑ２α２β２μＡμＢ
で与えられ、Ｚ＝ｐｑから
ＪＣ≡ＣＡ・ＣＢ＝０．２５Ｚ２α２β２μＡμＢ
となり、単計数率ＩＡとＩＢの積が、
ＪＩ≡ＩＡ・ＩＢ＝ｐｑβ２μＡμＢ＝Ｚβ２μＡμＢ
となり、ＪＣとＪＩの比が
ＪＣ／ＪＩ＝０．２５Ｚα２
となり、光子検出器の量子効率αが
α＝２√（ＪＣ／ＪＩ／Ｚ）
で求められることを特徴とする。
(6) In the quantum efficiency measurement method according to any one of (1) to (5), the quantum efficiency of the photon detector for signal photons is α, and the quantum efficiency of the single photon detector for idler photons is β, and the photon pair generation rate of the correlated photon pair generator is μ,
When the correlated photon pair generation device is in a fixed connection state with respect to the excitation light source and the non-polarizing beam splitter on both sides, the photon pair generation rate is μ B for the photon pair separated by the non-polarizing beam splitter, Each single count rate is given by SA = pαμ B and IA = pβμ B , the separation success probability is 50%, the coincidence rate is given by CA = 0.5p 2 αβμ B , and p is the above-mentioned constant with the nonlinear waveguide It is given by the transmittance for the optical fiber connected in the connection state of
When the connection state is opposite to the constant connection state, the photon pair generation rate is μ A for the photon pairs separated by the non-polarizing beam splitter, and the single count rates are SB = qαμ A and IB, respectively. = Qβμ A , separation success probability is 50%, coincidence rate is given by CB = 0.5q 2 αβμ A , and q is connected to the non-linear waveguide in a connection state opposite to the fixed connection state. When given by the transmittance for an optical fiber,
The product of coincidence rate CA and CB is
CA · CB = 0.25p 2 q 2 α 2 β 2 μ A μ B
Given, Z = JC≡CA · from pq CB = 0.25Z 2 α 2 β 2 μ A μ B with
The product of the single count rate IA and IB is
JI≡IA · IB = pqβ 2 μ A μ B = Zβ 2 μ A μ B
And the ratio of JC to JI is JC / JI = 0.25Zα 2
The quantum efficiency α of the photon detector is α = 2√ (JC / JI / Z)
It is calculated | required by.
（７）上記（１）乃至（６）のいずれか１項記載の量子効率測定方法は、参照光源の光強度を単位ゲート当たりの光子数νで表すとき、前記相関光子対と同じ波長を持つ参照光源と前記二台の光子検出器の一方を接続し、単計数率Ｘ＝ανを測定し、参照光源と前記光子検出器の間に前記相関光子対発生装置を設置して、導波路透過後の単計数率Ｙ＝ｐｑανを測定し、前記相関光子対発生装置の透過率Ｚ＝ｐｑを求めることを特徴とする。
（８）上記（１）乃至（７）のいずれか１項記載の量子効率測定方法は、前記単計数率を、Ｘ＜＜１、及び、Ｙ＜＜１となるように前記参照光源の光強度を調整することを特徴とする。
(7) The quantum efficiency measurement method according to any one of (1) to (6) has the same wavelength as the correlated photon pair when the light intensity of the reference light source is expressed by the number of photons ν per unit gate. Connect a reference light source and one of the two photon detectors, measure the single count rate X = αν, install the correlated photon pair generator between the reference light source and the photon detector, and transmit through the waveguide The subsequent single count rate Y = pqαν is measured to determine the transmittance Z = pq of the correlated photon pair generator.
(8) In the quantum efficiency measurement method according to any one of (1) to (7), the light of the reference light source is set so that the single count rate is X << 1 and Y << 1. The strength is adjusted.
（９）量子効率測定装置は、相関光子対を発生するための非線形導波路とその両側に配置した一対の光ファイバからなる相関光子対発生装置と、前記非線形導波路を励起する励起光源と、前記相関光子対をシグナル光子とアイドラ光子に分離し、それぞれ異なる光子検出器に入射させる無偏光ビームスプリッタと、前記シグナル光子とアイドラ光子をそれぞれ個別に検出する２つの光子検出器と、前記それぞれの光子検出器の検出出力を個別に計数する２つの計数器と、前記両計数器の同時に出力される出力信号を取り込んで所定の処理を行う同時計数器とを有する装置において、前記励起光源と前記非線形導波路の間および前記非線形導波路と前記無偏光ビームスプリッタの間を着脱自在に光ファイバで接続すると共に、前記無偏光ビームスプリッタの前記それぞれの光子の出力側をそれぞれ前記光子検出器に接続し、前記相関光子対発生装置で発生した前記シグナル光子とアイドラ光子を前記それぞれの光子検出器で検出し、その検出したデータをそれぞれの光子検出器に個別に接続した計数器により計数して単計数率を求め、前記両計数器の同時に出力される出力信号を取り込んで所定の処理を行う同時計数器により計数して同時計数率を求め、前記励起光源と前記相関光子対発生装置の間および前記相関光子対発生装置と前記無偏光ビームスプリッタ間に対して、前記光ファイバを切り替えて接続した状態で前記相関光子対発生装置で発生した前記シグナル光子とアイドラ光子を前記それぞれの光子検出器で検出し、その検出したデータをそれぞれの光子検出器に個別に接続した計数器により計数して単計数率を求め、前記両計数器の同時に出力される出力信号を取り込んで所定の処理を行う同時計数器により計数して同時計数率を求めて、前記それぞれの単計数率と前記同時計数率との関係から前記シグナル光子とアイドラ光子を検出する前記それぞれの光子検出器における量子効率を求めることを特徴とする。 (9) A quantum efficiency measurement device includes a nonlinear waveguide for generating a correlated photon pair and a correlated photon pair generating device including a pair of optical fibers disposed on both sides thereof, an excitation light source for exciting the nonlinear waveguide, A non-polarizing beam splitter that separates the correlated photon pair into a signal photon and an idler photon and is incident on different photon detectors; two photon detectors that individually detect the signal photon and idler photon; In the apparatus having two counters that individually count the detection outputs of the photon detectors, and a simultaneous counter that takes in output signals output simultaneously from both counters and performs a predetermined process, the excitation light source and the The nonlinear waveguide and between the nonlinear waveguide and the non-polarized beam splitter are detachably connected by an optical fiber, and the non-polarized beam The output side of each photon of the splitter is connected to the photon detector, the signal photon and idler photon generated by the correlation photon pair generator are detected by the respective photon detector, and the detected data is Count by a counter individually connected to each photon detector to obtain a single count rate, and take the output signals output simultaneously from both counters and count them by a simultaneous counter that performs a predetermined process. The correlated photon pair generating device in a state where the optical fiber is switched and connected between the excitation light source and the correlated photon pair generating device and between the correlated photon pair generating device and the non-polarized beam splitter. The signal photons and idler photons generated in step 1 are detected by the respective photon detectors, and the detected data are individually connected to the respective photon detectors. The single counting rate is obtained by counting with the counters obtained, and the simultaneous counting rate is obtained by counting with the simultaneous counter that takes in the output signals output simultaneously from the two counters and performs a predetermined process. The quantum efficiency in each of the photon detectors for detecting the signal photon and idler photon is obtained from the relationship between the count rate and the coincidence rate.
（１０）上記（９）記載の量子効率測定装置は、前記非線形導波路とその両側に配置した前記一対の光ファイバのそれぞれとの間の透過率ｐ、ｑがｐ≠１、ｑ≠１であることを特徴とする。
（１１）上記（９）又は（１０）記載の量子効率測定装置は、上記光子検出器が開ゲート時のみ光子検出を行い、光子検出と同期して電圧パルスを発生し、上記二台の計数器は単位ゲート当たりの単計数率をそれぞれ独立に測定し、上記同時計数器により同時刻に発生した前記電圧パルスに対して、単位ゲート当たりの同時計数率を求めることを特徴とする。
（１２）上記（９）乃至（１１）のいずれか１項記載の量子効率測定装置は、無偏光ビームスプリッタを透過した光子をシグナル光子、反射した光子をアイドラ光子としたとき、上記相関光子対発生装置で発生した光子対に対して、分岐比５０％の無偏光ビームスプリッタが上記光子対出射側に設置され、確率５０％で、光子対が、シグナル・アイドラ光子に分離されるようにしたことを特徴とする。
(10) In the quantum efficiency measurement apparatus according to (9), the transmittances p and q between the nonlinear waveguide and each of the pair of optical fibers arranged on both sides thereof are p ≠ 1 and q ≠ 1. It is characterized by being.
(11) In the quantum efficiency measurement apparatus according to (9) or (10), the photon detector performs photon detection only when the gate is open, generates a voltage pulse in synchronization with the photon detection, and counts the two units. The measuring device independently measures a single count rate per unit gate, and obtains a coincidence rate per unit gate for the voltage pulses generated at the same time by the simultaneous counter.
(12) The quantum efficiency measurement apparatus according to any one of (9) to (11), wherein the photon transmitted through the non-polarizing beam splitter is a signal photon, and the reflected photon is an idler photon. A non-polarizing beam splitter having a branching ratio of 50% is installed on the emission side of the photon pair with respect to the photon pair generated by the generator, and the photon pair is separated into a signal idler photon with a probability of 50%. It is characterized by that.
（１３）上記（９）乃至（１２）のいずれか１項記載の量子効率測定装置は、シグナル光子用の光子検出器の量子効率をα、アイドラ光子用の単一光子検出器の量子効率をβとし、相関光子対発生装置の光子対発生率をμとし、上記記載の励起光源と無偏光ビームスプリッタに対して相関光子対発生装置を一定の接続状態としたとき、前記無偏光ビームスプリッタにより分離される光子対に対して、光子対発生率をμＢとし、各単計数率を、それぞれＳＡ＝ｐαμＢ、ＩＡ＝ｐβμＢで与え、分離成功確率を５０％とし、同時計数率をＣＡ＝０．５ｐ２αβμＢで与え、ｐを非線形導波路と前記一定の接続状態で接続している光ファイバに関する透過率で与え、前記一定の接続状態と逆の接続状態にしたとき、無偏光ビームスプリッタにより分離された光子対に対して、光子対発生率をμＡとし、各単計数率を、それぞれＳＢ＝ｑαμＡ、ＩＢ＝ｑβμＡで与え、分離成功確率を５０％とし、同時計数率をＣＢ＝０．５ｑ２αβμＡで与え、ｑを非線形導波路と前記一定の接続状態と逆の接続状態で接続している光ファイバに関する透過率で与えるとき、同時計数率ＣＡとＣＢの積が、
ＣＡ・ＣＢ＝０．２５ｐ２ｑ２α２β２μＡμＢ
で与えられ、Ｚ＝ｐｑとすれば
ＪＣ≡ＣＡ・ＣＢ＝０．２５Ｚ２α２β２μＡμＢ
となり、単計数率ＳＡとＳＢの積が、
ＪＳ≡ＳＡ・ＳＢ＝ｐｑα２μＡμＢ＝Ｚα２μＡμＢ
となり、ＪＣとＪＳの比が
ＪＣ／ＪＳ＝０．２５Ｚβ２
となり、光子検出器の量子効率βが
β＝２√（ＪＣ／ＪＳ／Ｚ）
で求められることを特徴とする。
(13) The quantum efficiency measuring apparatus according to any one of (9) to (12), wherein the quantum efficiency of the photon detector for signal photons is α, and the quantum efficiency of the single photon detector for idler photons is When β is set, and the photon pair generation rate of the correlated photon pair generator is μ, and the correlated photon pair generator is in a fixed connection state with respect to the excitation light source and the non-polarized beam splitter, the non-polarized beam splitter For the photon pairs to be separated, the photon pair generation rate is μ B , each single count rate is given by SA = pαμ B and IA = pβμ B , the separation success probability is 50%, and the coincidence rate is CA. = 0.5 p 2 αβμ B , p is given as the transmittance for the optical fiber connected to the nonlinear waveguide in the constant connection state, and when the connection state is opposite to the constant connection state, the non-polarized light Split by beam splitter Against photon pairs is, the photon pair generation rate and mu A, each single counting rate, respectively given by SB = qαμ A, IB = qβμ A, the separation success probability of 50% the coincidence rate CB = When q is given by 0.5q 2 αβμ A and q is given by the transmittance for the optical fiber connected to the nonlinear waveguide in the connection state opposite to the constant connection state, the product of the coincidence rate CA and CB is
CA · CB = 0.25p 2 q 2 α 2 β 2 μ A μ B
Given, Z = if pq JC≡CA · CB = 0.25Z 2 α 2 β 2 μ A μ B with
The product of the single count rate SA and SB is
JS≡SA · SB = pqα 2 μ A μ B = Zα 2 μ A μ B
And the ratio of JC to JS is JC / JS = 0.25Zβ 2
The quantum efficiency β of the photon detector is β = 2√ (JC / JS / Z)
It is calculated | required by.
（１４）上記（８）乃至（１３）のいずれか１項記載の量子効率測定装置は、シグナル光子用の光子検出器の量子効率をα、アイドラ光子用の単一光子検出器の量子効率をβとし、相関光子対発生装置の光子対発生率をμとし、両側の励起光源と無偏光ビームスプリッタに対して相関光子対発生装置を一定の接続状態としたとき、前記無偏光ビームスプリッタにより分離される光子対に対して、光子対発生率をμＢとし、各単計数率を、それぞれＳＡ＝ｐαμＢ、ＩＡ＝ｐβμＢで与え、分離成功確率を５０％とし、同時計数率をＣＡ＝０．５ｐ２αβμＢで与え、ｐを非線形導波路と前記一定の接続状態で接続している光ファイバに関する透過率で与え、前記一定の接続状態と逆の接続状態にしたとき、無偏光ビームスプリッタにより分離された光子対に対して、光子対発生率をμＡとし、各単計数率を、それぞれＳＢ＝ｑαμＡ、ＩＢ＝ｑβμＡで与え、分離成功確率を５０％とし、同時計数率をＣＢ＝０．５ｑ２αβμＡで与え、ｑを非線形導波路と前記一定の接続状態と逆の接続状態で接続している光ファイバに関する透過率で与えるとき、同時計数率ＣＡとＣＢの積が、
ＣＡ・ＣＢ＝０．２５ｐ２ｑ２α２β２μＡμＢ
で与えられ、Ｚ＝ｐｑから
ＪＣ≡ＣＡ・ＣＢ＝０．２５Ｚ２α２β２μＡμＢ
となり、単計数率ＩＡとＩＢの積が、
ＪＩ≡ＩＡ・ＩＢ＝ｐｑβ２μＡμＢ＝Ｚβ２μＡμＢ
となり、ＪＣとＪＩの比が
ＪＣ／ＪＩ＝０．２５Ｚα２
となり、光子検出器の量子効率αが
α＝２√（ＪＣ／ＪＩ／Ｚ）
で求められることを特徴とする。
（１５）上記（８）乃至（１４）のいずれか１項記載の量子効率測定装置は、参照光源の光強度を単位ゲート当たりの光子数νで表すとき、前記相関光子対と同じ波長を持つ参照光源と前記二台の光子検出器の一方を接続し、単計数率Ｘ＝ανを測定し、参照光源と前記光子検出器の間に前記相関光子対発生装置を設置して、導波路透過後の単計数率Ｙ＝ｐｑανを測定し、前記相関光子対発生装置の透過率Ｚ＝ｐｑを求めることを特徴とする。
（１６）上記（８）乃至（１５）のいずれか１項記載の量子効率測定装置は、前記単計数率を、Ｘ＜＜１、及び、Ｙ＜＜１となるように前記参照光源の光強度を調整することを特徴とする。
(14) The quantum efficiency measurement apparatus according to any one of (8) to (13), wherein the quantum efficiency of the photon detector for signal photons is α, and the quantum efficiency of the single photon detector for idler photons is When β is the photon pair generation rate of the correlated photon pair generator, and the correlation photon pair generator is connected to the excitation light source and the non-polarized beam splitter on both sides, they are separated by the non-polarized beam splitter. The photon pair generation rate is μ B , the single count rates are given by SA = pαμ B and IA = pβμ B , the separation success probability is 50%, and the coincidence rate is CA = When p is given by 0.5p 2 αβμ B and p is given by the transmittance of the optical fiber connected to the nonlinear waveguide in the constant connection state, the non-polarized beam is obtained when the connection state is opposite to the constant connection state. Separated by splitter Against photon pairs, the photon pair generation rate and mu A, each single counting rate, respectively SB = qαμ A, given by IB = qβμ A, the separation success probability of 50% the coincidence ratio CB = 0 .5q 2 αβμ A , and q is given by the transmittance for the optical fiber connected to the nonlinear waveguide in the connection state opposite to the fixed connection state, the product of the coincidence rate CA and CB is
CA · CB = 0.25p 2 q 2 α 2 β 2 μ A μ B
Given, Z = JC≡CA · from pq CB = 0.25Z 2 α 2 β 2 μ A μ B with
The product of the single count rate IA and IB is
JI≡IA · IB = pqβ 2 μ A μ B = Zβ 2 μ A μ B
And the ratio of JC to JI is JC / JI = 0.25Zα 2
The quantum efficiency α of the photon detector is α = 2√ (JC / JI / Z)
It is calculated | required by.
(15) The quantum efficiency measurement apparatus according to any one of (8) to (14), wherein the light intensity of the reference light source is represented by the number of photons ν per unit gate, and has the same wavelength as the correlated photon pair. Connect a reference light source and one of the two photon detectors, measure the single count rate X = αν, install the correlated photon pair generator between the reference light source and the photon detector, and transmit through the waveguide The subsequent single count rate Y = pqαν is measured to determine the transmittance Z = pq of the correlated photon pair generator.
(16) In the quantum efficiency measurement device according to any one of (8) to (15), the light of the reference light source is set so that the single count rate is X << 1 and Y << 1. The strength is adjusted.
本発明の量子効率測定装置は、光子検出器への入射光子数が未知であっても、更に、伝搬損失が避けられないような状況下でも、非線形導波路からなる相関光子対発生装置の透過率や二台の光子検出器の量子効率を同時に、正確に測定することができる。
非特許文献２は、透過率が、ｆ＝ｇ＝１であれば、η１＝ＣＡ／ＩＡ、η２＝ＣＡ／ＳＡとなり、量子効率を求めることができるが、一般には、非線形結晶から各光子検出器までの間で発生する伝搬損失は避けられない。このため、伝搬損失に基づいて透過率がｆ≠１、損失ｇ≠１となり、量子効率の測定も不正確になる。また、透過率ｆ、透過率ｇを正確に測定する手段も提供されていない。しかし、本発明は、伝搬損失を考慮した正確な量子効率の測定ができるようになる。
The quantum efficiency measurement apparatus of the present invention can transmit a correlated photon pair consisting of a nonlinear waveguide even if the number of incident photons to the photon detector is unknown or even in a situation where propagation loss is unavoidable. The rate and the quantum efficiency of the two photon detectors can be accurately measured simultaneously.
In Non-Patent Document 2, when the transmittance is f = g = 1, η 1 = CA / IA and η 2 = CA / SA, and the quantum efficiency can be obtained. Propagation loss occurring up to the photon detector is inevitable. For this reason, the transmittance becomes f ≠ 1 and the loss g ≠ 1 based on the propagation loss, and the measurement of the quantum efficiency becomes inaccurate. Also, no means for accurately measuring the transmittance f and the transmittance g is provided. However, according to the present invention, accurate quantum efficiency can be measured in consideration of propagation loss.
本発明の基本的な実施の形態について以下詳細に説明する。
量子効率測定方法および装置は、相関光子対を発生するための非線形導波路とその両側に配置した一対の光ファイバからなる相関光子対発生装置と、前記非線形導波路を励起する励起光源と、前記相関光子対をシグナル光子とアイドラ光子に分離し、それぞれ異なる光子検出器に入射させる無偏光ビームスプリッタと、前記シグナル光子とアイドラ光子をそれぞれ個別に検出する２つの光子検出器と、前記それぞれの光子検出器の検出出力を個別に計数する２つの計数器と、前記両計数器の同時に出力される出力信号を取り込んで所定の処理を行う同時計数器とを有する装置において、前記励起光源と前記非線形導波路の間および前記非線形導波路と前記無偏光ビームスプリッタの間を着脱自在に光ファイバで接続すると共に、前記無偏光ビームスプリッタの前記それぞれの光子の出力側をそれぞれ前記光子検出器に接続し、前記相関光子対発生装置で発生した前記シグナル光子とアイドラ光子を前記それぞれの光子検出器で検出し、その検出したデータをそれぞれの光子検出器に個別に接続した計数器により計数して単計数率を求め、前記両計数器の同時に出力される出力信号を取り込んで所定の処理を行う同時計数器により計数して同時計数率を求め、前記励起光源と前記相関光子対発生装置の間および前記相関光子対発生装置と前記無偏光ビームスプリッタ間に対して、前記光ファイバを切り替えて接続した状態で前記相関光子対発生装置で発生した前記シグナル光子とアイドラ光子を前記それぞれの光子検出器で検出し、その検出したデータをそれぞれの光子検出器に個別に接続した計数器により計数して単計数率を求め、前記両計数器の同時に出力される出力信号を取り込んで所定の処理を行う同時計数器により計数して同時計数率を求めて、前記それぞれの単計数率と前記同時計数率との関係から前記シグナル光子とアイドラ光子を検出する前記それぞれの光子検出器における量子効率を求めることを特徴とする。また、上記（１）記載の量子効率測定方法及び上記（８）記載の量子効率測定装置は、前記非線形導波路とその両側に配置した前記一対の光ファイバのそれぞれとの間の透過率ｐ、ｑをｐ≠１、ｑ≠１であることを特徴とする。
A basic embodiment of the present invention will be described in detail below.
A quantum efficiency measurement method and apparatus includes a non-linear waveguide for generating a correlated photon pair and a correlated photon pair generating device including a pair of optical fibers arranged on both sides thereof, an excitation light source for exciting the non-linear waveguide, A non-polarizing beam splitter that separates a correlated photon pair into a signal photon and an idler photon and enters each different photon detector; two photon detectors that individually detect the signal photon and idler photon; and the respective photons In the apparatus having two counters for individually counting the detection outputs of the detectors, and a coincidence counter that takes in output signals output simultaneously from both counters and performs predetermined processing, the excitation light source and the nonlinear The waveguide and the nonlinear waveguide and the non-polarization beam splitter are detachably connected by an optical fiber, and the non-polarization beam is connected. The output side of each photon of the image splitter is connected to the photon detector, and the signal photon and idler photon generated by the correlated photon pair generator are detected by the respective photon detector, and the detected data Are counted by a counter individually connected to each photon detector to obtain a single count rate, and simultaneously counted by a simultaneous counter that takes in output signals output simultaneously from both counters and performs predetermined processing. The counting rate is obtained, and the correlated photon pair is generated while the optical fiber is switched and connected between the excitation light source and the correlated photon pair generator and between the correlated photon pair generator and the non-polarized beam splitter. The signal photons and idler photons generated by the device are detected by the respective photon detectors, and the detected data are individually transmitted to the respective photon detectors. Counting by a connected counter to obtain a single count rate, taking in output signals output simultaneously from both counters, counting by a simultaneous counter that performs a predetermined process, and obtaining a simultaneous count rate, The quantum efficiency in each photon detector that detects the signal photon and idler photon is obtained from the relationship between a single count rate and the coincidence rate. The quantum efficiency measurement method according to (1) and the quantum efficiency measurement device according to (8) described above may include transmittance p between the nonlinear waveguide and each of the pair of optical fibers arranged on both sides thereof. q is characterized in that p ≠ 1 and q ≠ 1.
具体的には、本発明の量子効率測定装置は、以下のような量子効率測定方法を含んで説明する。量子効率測定装置は、相関光子対を発生するための非線形導波路とその両側に配置した一対の光ファイバからなる相関光子対発生装置と、前記非線形導波路を励起する励起光源と、前記相関光子対をシグナル光子とアイドラ光子に分離し、それぞれ異なる光子検出器に入射させる無偏光ビームスプリッタと、前記シグナル光子とアイドラ光子をそれぞれ個別に検出する２つの光子検出器と、前記それぞれの光子検出器の検出出力を個別に計数する２つの計数器と、前記両計数器の同時に出力される出力信号を取り込んで所定の処理を行う同時計数器とを有する装置において、前記励起光源と前記非線形導波路の間および前記非線形導波路と前記無偏光ビームスプリッタの間を着脱自在に光ファイバで接続すると共に、前記無偏光ビームスプリッタの前記それぞれの光子の出力側をそれぞれ前記光子検出器に接続し、前記相関光子対発生装置で発生した前記シグナル光子とアイドラ光子を前記それぞれの光子検出器で検出し、その検出したデータをそれぞれの光子検出器に個別に接続した計数器により計数して単計数率を求め、前記両計数器の同時に出力される出力信号を取り込んで所定の処理を行う同時計数器により計数して同時計数率を求め、前記励起光源と前記相関光子対発生装置の間および前記相関光子対発生装置と前記無偏光ビームスプリッタ間に対して、前記光ファイバを切り替えて接続した状態で前記相関光子対発生装置で発生した前記シグナル光子とアイドラ光子を前記それぞれの光子検出器で検出し、その検出したデータをそれぞれの光子検出器に個別に接続した計数器により計数して単計数率を求め、前記両計数器の同時に出力される出力信号を取り込んで所定の処理を行う同時計数器により計数して同時計数率を求めて、前記それぞれの単計数率と前記同時計数率との関係から前記シグナル光子とアイドラ光子を検出する前記それぞれの光子検出器における量子効率を求める。
（実施例）
Specifically, the quantum efficiency measuring apparatus of the present invention will be described including the following quantum efficiency measuring method. The quantum efficiency measurement device includes a correlated photon pair generating device including a nonlinear waveguide for generating a correlated photon pair and a pair of optical fibers disposed on both sides thereof, an excitation light source for exciting the nonlinear waveguide, and the correlated photon A non-polarizing beam splitter that separates the pair into a signal photon and an idler photon and is incident on different photon detectors, two photon detectors that individually detect the signal photon and idler photon, and the respective photon detectors In the apparatus having two counters that individually count the detection outputs of the two and a simultaneous counter that takes in output signals output simultaneously from both counters and performs predetermined processing, the excitation light source and the nonlinear waveguide And the nonlinear waveguide and the non-polarizing beam splitter are detachably connected by an optical fiber, and the non-polarizing beam splitter is connected. The output side of each of the photons is connected to the photon detector, the signal photon and idler photon generated by the correlated photon pair generator are detected by the respective photon detector, and the detected data is Count by a counter individually connected to each photon detector to obtain a single count rate, and take the output signals output simultaneously from both counters and count them by a simultaneous counter that performs a predetermined process. The correlated photon pair generating device in a state where the optical fiber is switched and connected between the excitation light source and the correlated photon pair generating device and between the correlated photon pair generating device and the non-polarized beam splitter. The signal photons and idler photons generated in the above are detected by the respective photon detectors, and the detected data are individually connected to the respective photon detectors. A single counting rate is obtained by counting with a counter, and a simultaneous counting rate is obtained by counting with a simultaneous counter that takes in output signals output simultaneously from both counters and performs predetermined processing, and each of the single counting rates. The quantum efficiency in each photon detector that detects the signal photon and idler photon is obtained from the relationship between the rate and the coincidence rate.
(Example)
図２は本発明の量子効率測定装置を構成する相関光子対発生装置１の構成図であり、相関光子対を発生する非線形導波路２と、光ファイバ３，４と、必要に応じてレンズ５，６から構成されている。結合効率を高めるために、レンズ５，６を挿入する。また、以下の説明の便宜上、図に示す通り、光ファイバ３側をＡ側（左側）、光ファイバ４側をＢ側（右側）とする。また、非線形導波路２と光ファイバ３，４との結合効率は、Ａ側でＬＡ、Ｂ側でＬＢとする。仮に、ＬＡ＝ＬＢ＝１なら、結合最大となり、ＬＡ＝ＬＢ＝０のとき無結合となる。一般には、０＜ＬＡ＜１、０＜ＬＢ＜１となるが、このとき、ＬＡ＝ＬＢであるとは限らない。また、光ファイバ３の透過率をＴＡ，光ファイバ４の透過率をＴＢとする。非線形導波路２を中心として、相関光子対発生装置１のＡ側からみた透過率は、ｐ≡ＬＡＴＡで与えられ、相関光子対発生装置１のＢ側からみた透過率はｑ≡ＬＢＴＢで与えられる。
ここで、非線形導波路２は、図１における従来の光子対発生用非線形結晶（Ｎｏｎｌｉｎｅｏｒ Ｃｒｙｓｔａｌ）のように、短い波長の１つの光子を入射すると、かならず波長の長い２つの光子を同時に出射する。
但し、非線形導波路２では、波長の長い２つの光子は同方向に出射される。
FIG. 2 is a block diagram of the correlated photon pair generating device 1 constituting the quantum efficiency measuring apparatus of the present invention. The nonlinear waveguide 2 generating the correlated photon pair, the optical fibers 3 and 4, and the lens 5 as required. , 6. In order to increase the coupling efficiency, the lenses 5 and 6 are inserted. For convenience of the following description, as shown in the figure, the optical fiber 3 side is the A side (left side), and the optical fiber 4 side is the B side (right side). The coupling efficiency of the nonlinear waveguide 2 and the optical fiber 3 and 4, and L B on the A side L A, the B side. If L A = L B = 1, the coupling is maximum, and if L A = L B = 0, there is no coupling. In general, 0 <L A <1,0 < L B <1 and becomes, at this time, not necessarily the L A = L B. Further, the transmittance of the optical fiber 3 T A, the transmittance of the optical fiber 4 and T B. The transmittance seen from the A side of the correlated photon pair generating device 1 with the nonlinear waveguide 2 as the center is given by p≡L A T A , and the transmittance seen from the B side of the correlated photon pair generating device 1 is q≡L It is given by B T B.
Here, when one photon having a short wavelength is incident, the nonlinear waveguide 2 always emits two photons having a long wavelength simultaneously, as in the conventional nonlinear crystal for generating a photon pair (Nonlinear Crystal) in FIG.
However, in the nonlinear waveguide 2, two photons having a long wavelength are emitted in the same direction.
この図２の場合では、例えば、光ファイバ３に短い波長の１つのフォトンが入射されると、非線形導波路２に短い波長の１つの光子が入射され、その結果、非線形導波路２から光ファイバ４中へ前記入射した光子より長い波長の２つの光子が同方向に出射される。同方向のため、光ファイバ４内に収まる。 In the case of FIG. 2, for example, when one photon having a short wavelength is incident on the optical fiber 3, one photon having a short wavelength is incident on the nonlinear waveguide 2. 4, two photons having a longer wavelength than the incident photon are emitted in the same direction. Because it is in the same direction, it fits within the optical fiber 4.
図３は、光減衰器８通過後の参照光源７の光強度を求めるための回路図である。
図３の構成は、光減衰器８通過後の参照光源７の光強度を求めるための回路図であり、参照光源７と、光減衰器８と、光子検出器９を直列に光ファイバで接続して構成する。参照光源７の光強度は光減衰器８を介して光子検出器９で単計数率（Ｘ）として評価される。これにより、単位ゲート当たりの単計数率Ｘを求めることができる。
FIG. 3 is a circuit diagram for obtaining the light intensity of the reference light source 7 after passing through the optical attenuator 8.
3 is a circuit diagram for obtaining the light intensity of the reference light source 7 after passing through the optical attenuator 8. The reference light source 7, the optical attenuator 8, and the photon detector 9 are connected in series with an optical fiber. And configure. The light intensity of the reference light source 7 is evaluated as a single count rate (X) by the photon detector 9 via the optical attenuator 8. Thereby, the single count rate X per unit gate can be obtained.
図４は本発明の相関光子対発生装置１における非線形導波路とその両側の光ファイバとの間の光透過率を求めるための回路図である。
図４の回路は、参照光源７、光減衰器８、相関光子対発生装置１と、光子検出器９を直列に光ファイバで連結して構成されている。相関光子対発生装置１は、図２に示すとおりの、非線形導波路２、光ファイバ３，４、必要に応じてレンズ５，６で構成されている。
図３の回路では、相関光子対発生装置１を備えない回路における光子検出器９の検出出力を単位ゲート当たりの単計数率Ｘとして求めたが、図４の回路では、相関光子対発生装置１を備える回路における光子検出器９の検出出力を単位ゲート当たりの単計数率Ｙとして求める。
FIG. 4 is a circuit diagram for obtaining the light transmittance between the nonlinear waveguide and the optical fibers on both sides thereof in the correlated photon pair generating apparatus 1 of the present invention.
The circuit of FIG. 4 is configured by connecting a reference light source 7, an optical attenuator 8, a correlated photon pair generating device 1, and a photon detector 9 in series with an optical fiber. The correlated photon pair generating apparatus 1 includes a nonlinear waveguide 2, optical fibers 3 and 4, and lenses 5 and 6 as required, as shown in FIG.
In the circuit of FIG. 3, the detection output of the photon detector 9 in a circuit that does not include the correlated photon pair generator 1 is obtained as a single count rate X per unit gate. However, in the circuit of FIG. 4, the correlated photon pair generator 1 Is obtained as a single count rate Y per unit gate.
これにより、単位ゲート当たりの単計数率Ｙを求めることができる。単計数率が、Ｘ＜＜１、及び、Ｙ＜＜１となるように、参照光源７の光強度を光減衰器８で調整し、光子検出器９の飽和を避ける。但し、図３、図４間で光減衰器８の減衰率は変更しない。このとき、両者の比から図２のＡ端からＢ端までの透過率（Ｚ＝Ｙ／Ｘ）を求めることができる。相関光子対発生装置１の透過率は、Ａ側（非線形導波路２と光ファイバ３の組み合わせ構成）でｐ≡ＬＡＴＡ、Ｂ側（非線形導波路２と光ファイバ４の組み合わせ構成）でｑ≡ＬＢＴＢであるから、非線形導波路２が薄く、その内部損失が無視できる場合、Ｚ＝ｐ×ｑを得る。 Thereby, the single count rate Y per unit gate can be obtained. The light intensity of the reference light source 7 is adjusted by the optical attenuator 8 so that the single count rate becomes X << 1 and Y << 1, and saturation of the photon detector 9 is avoided. However, the attenuation factor of the optical attenuator 8 is not changed between FIGS. At this time, the transmittance (Z = Y / X) from the A end to the B end in FIG. 2 can be obtained from the ratio between the two. The transmittance of the correlated photon pair generation device 1 is p≡L A T A on the A side (combination configuration of the nonlinear waveguide 2 and the optical fiber 3), and on the B side (combination configuration of the nonlinear waveguide 2 and the optical fiber 4). Since q≡L B T B , if the nonlinear waveguide 2 is thin and its internal loss can be ignored, Z = p × q is obtained.
図５は本発明の測定手段を備えた量子効率測定装置の構成図である。
図５の装置は、励起光源１０と、相関光子対発生装置１と、相関光子対発生装置１で発生した相関光子対（アイドラ光子とシグナル光子）を分離し、それぞれ個別の光子検出器９，１１に入射させる無偏光ビームスプリッタ１２と、アイドラ光子又はシグナル光子を検出する光子検出器９、１１と、それぞれの光子検出器９、１１の光子検出出力をカウント（計数）し、そのカウントデータより単計数率を求める二台の計数器１３、１４と、計数器１３、１４のカウントデータに基づき同時計数率を求める同時計数器１５より構成されている。両計数器１３、１４の単計数率と、同時計数器１５の同時計数率から光子検出器９、１１の量子効率を求める。
FIG. 5 is a block diagram of a quantum efficiency measuring apparatus provided with the measuring means of the present invention.
The apparatus of FIG. 5 separates the excitation light source 10, the correlated photon pair generating apparatus 1, and the correlated photon pairs (idler photons and signal photons) generated by the correlated photon pair generating apparatus 1, and the individual photon detectors 9, 11 is used to count (count) the non-polarized beam splitter 12 that is incident on the photon detector 11, the photon detectors 9 and 11 that detect idler photons or signal photons, and the photon detection outputs of the photon detectors 9 and 11, respectively. It comprises two counters 13 and 14 for obtaining a single count rate, and a simultaneous counter 15 for obtaining a simultaneous count rate based on the count data of the counters 13 and 14. The quantum efficiency of the photon detectors 9 and 11 is obtained from the single count rate of both counters 13 and 14 and the coincidence count rate of the coincidence counter 15.
光子検出器９は図３、図４で使用した光子検出器９と同じもので構わない。光子検出器９、１１は、開ゲート時のみ光子検出を行い、光子検出と同期した電圧パルスを発生する。ここで、上記ゲートは、光子検出器９、１１の動作・非動作を切り替えるスイッチ機能素子をいう。二台の計数器１３，１４により、単計数率が、それぞれ、独立に求められ、同時刻に発生した（同期した）電圧パルスに対しては、同時計数器１５により同時検出率が求められる。
同時計数器１５は、両計数器１３、１４の計数値に基づき同時計数率を求めると共に、それぞれの単計数率と同時計数率との関係からシグナル光子とアイドラ光子における量子効率を求める。同時計数器１５は、ＣＰＵやメモリ、出力手段を備えて、必要な演算処理を行うことができる。励起光源１０から光子検出器９，１１までの接続には、無偏光ビームスプリッタ１２を除いて光ファイバを用いる。図５では、相関光子対発生装置１の右側（Ｂ側）に励起光源１０を設置し、左側（Ａ側）に設置された無偏光ビームスプリッタ１２により分離された光子対に対して、二台の光子検出器９，１１で、単計数率（ＳＡ、ＩＡ）と同時計数率（ＣＡ）が測定される。
光子検出器の量子効率を求めるために、測定時、図５の回路構成において、所定の測定データを求めた後、相関光子対発生装置１の励起光源１０への接続点と、相関光子対発生装置１の無偏光ビームスプリッタ１２への接続点を、相関光子対発生装置１の接続の向きを図６のように逆に変えて繋ぎ直し、同じように、所定の測定データを求める。
The photon detector 9 may be the same as the photon detector 9 used in FIGS. The photon detectors 9 and 11 perform photon detection only when the gate is opened, and generate voltage pulses synchronized with photon detection. Here, the gate refers to a switch function element that switches between operation and non-operation of the photon detectors 9 and 11. A single count rate is obtained independently by the two counters 13 and 14, and a simultaneous detection rate is obtained by the simultaneous counter 15 for voltage pulses generated (synchronized) at the same time.
The coincidence counter 15 obtains the coincidence count rate based on the count values of both the counters 13 and 14, and obtains the quantum efficiencies in the signal photons and idler photons from the relationship between the single count rate and the coincidence count rate. The coincidence counter 15 includes a CPU, memory, and output means, and can perform necessary arithmetic processing. For connection from the excitation light source 10 to the photon detectors 9 and 11, an optical fiber is used except for the non-polarizing beam splitter 12. In FIG. 5, the excitation light source 10 is installed on the right side (B side) of the correlated photon pair generating apparatus 1, and two photon pairs are separated by the non-polarizing beam splitter 12 installed on the left side (A side). The photon detectors 9 and 11 measure the single count rate (SA, IA) and the coincidence rate (CA).
In order to obtain the quantum efficiency of the photon detector, at the time of measurement, after obtaining predetermined measurement data in the circuit configuration of FIG. The connection point of the apparatus 1 to the non-polarizing beam splitter 12 is reconnected by changing the connection direction of the correlated photon pair generating apparatus 1 as shown in FIG. 6, and similarly, predetermined measurement data is obtained.
図６は、図５の相関光子対発生装置において、測定手段を切り替えた量子効率測定装置の構成図である。
図６では、図５の相関光子対発生装置１のＡ側とＢ側に、Ａ側とＢ側のそれぞれに接続されている構成を逆に接続する。このように、相関光子対発生装置１、すなわち、非線形導波路２を固定配置し、この相関光子対発生装置１、すなわち、非線形導波路２のＡ側とＢ側に接続される回路構成を逆にして接続し、相関光子対発生装置１をブラックボックスとした場合のＡ側からの入出力特性と、Ｂ側からの入出力特性を求めて、ブラックボックスとしての相関光子対発生装置１、すなわち、非線形導波路２の特性を求める。この場合の接続の切換は、スイッチやコネクタ等で光ファイバの接続を切り替えるようにして行うことができる。
FIG. 6 is a configuration diagram of a quantum efficiency measurement apparatus in which the measurement means is switched in the correlated photon pair generation apparatus of FIG.
In FIG. 6, the configurations connected to the A side and the B side of the correlated photon pair generating apparatus 1 of FIG. In this manner, the correlated photon pair generating device 1, that is, the nonlinear waveguide 2 is fixedly arranged, and the circuit configuration connected to the A side and the B side of the correlated photon pair generating device 1, that is, the nonlinear waveguide 2 is reversed. When the correlated photon pair generating device 1 is a black box, the input / output characteristics from the A side and the input / output characteristics from the B side are obtained, and the correlated photon pair generating device 1 as a black box, that is, The characteristics of the nonlinear waveguide 2 are obtained. In this case, the connection can be switched by switching the optical fiber connection with a switch or a connector.
図５と図６の逆接続構成における測定結果から、それぞれの単計数率（ＳＡ、ＩＡ、ＳＢ、ＩＢ）と同時計数率（ＣＡ、ＣＢ）を求めることができる。
すなわち、図５を参照すると、相関光子対発生装置１の右側（Ｂ側）に励起光源１０があり、左側（Ａ側）に無偏光ビームスプリッタ１２があり、更に、二台の光子検出器９，１１もＡ側に移動し、無偏光ビームスプリッタ１２で分離された光子対に対して、単計数率（ＳＡ、ＩＡ）と同時計数率（ＣＡ）を測定する。一方、図６を参照すると、相関光子対発生装置１の左側（Ａ側）に励起光源１０があり、右側（Ｂ側）に無偏光ビームスプリッタ１２があり、更に、二台の光子検出器９，１１もＢ側に移動し、無偏光ビームスプリッタ１２で分離された光子対に対して、単計数率（ＳＢ、ＩＢ）と同時計数率（ＣＢ）を測定する。但し、シグナル光子（透過側）の測定に対しては、光子検出器９がＡ側に設置される場合であっても、Ｂ側に設置される場合であっても、光子検出器９が用いられ、アイドラ光子（反射側）の検出では、光子検出器１１が、Ａ側に設置される場合であっても、Ｂ側に設置される場合であっても、シグナル光子の検出と異なる光子検出器１１が用いられる。便宜上、無偏光ビームスプリッタ１２を透過した光子をシグナル光子、反射した光子をアイドラ光子と記述する。
Each single count rate (SA, IA, SB, IB) and coincidence rate (CA, CB) can be obtained from the measurement results in the reverse connection configuration of FIGS.
That is, referring to FIG. 5, the excitation light source 10 is on the right side (B side) of the correlated photon pair generating apparatus 1, the non-polarizing beam splitter 12 is on the left side (A side), and two photon detectors 9 are further provided. , 11 also move to the A side and measure the single count rate (SA, IA) and coincidence rate (CA) for the photon pair separated by the non-polarizing beam splitter 12. On the other hand, referring to FIG. 6, there is an excitation light source 10 on the left side (A side) of the correlated photon pair generating apparatus 1, an unpolarized beam splitter 12 on the right side (B side), and two photon detectors 9. , 11 also move to the B side, and measure the single count rate (SB, IB) and coincidence rate (CB) for the photon pair separated by the non-polarizing beam splitter 12. However, for measurement of signal photons (transmission side), the photon detector 9 is used regardless of whether the photon detector 9 is installed on the A side or the B side. In the detection of idler photons (reflection side), photon detection different from the detection of signal photons, whether the photon detector 11 is installed on the A side or the B side. A vessel 11 is used. For convenience, a photon transmitted through the non-polarizing beam splitter 12 is described as a signal photon, and a reflected photon is described as an idler photon.
（量子効率計算方法）
以下に、シグナル光子とアイドラ光子の測定値である単計数率（ＳＡ、ＩＡ）と同時計数率（ＣＡ）、単計数率（ＳＢ、ＩＢ）と同時計数率（ＣＢ）、及び、相関光子対発生装置１のＡ端からＢ端までの透過率（Ｚ＝ｐｑ）を用いて光子検出器９，１１の量子効率（α、β）を求めるための計算方法を示す。但し、シグナル光子用（無偏光ビームスプリッタ１２に対して透過側）の光子検出器９の量子効率をα、アイドラ光子用（無偏光ビームスプリッタ１２に対して反射側）の光子検出器１１の量子効率をβとし、相関光子対発生装置１の光子対発生率をμと記述する。
右側（Ｂ側）に励起光源１０を設置し、左側（Ａ側）に設置された無偏光ビームスプリッタ１２により分離される光子対に対して、単計数率が、ＳＡ＝ｐαμＢ、ＩＡ＝ｐβμＢで与えられ、同時計数率が、ＣＡ＝０．５ｐ２αβμＢで与えられ、ｐは非線形導波路２とＡ側で接続している光ファイバ３に関する透過率である（図２参照）。但し、Ｓはシグナル光子、Ｉはアイドラ光子を意味する。また、右側（Ｂ側）に励起光源１０を設置した場合に得られる相関光子対発生装置１の光子対発生率をμＢと記述する。また、同じ経路なので同時計数率ＣＡはｐ×ｐに比例する。尚、係数０．５は無偏光ビームスプリッタによる光子対の分離成功確率が５０％であることを示す。
左側（Ａ側）に励起光源１０を移動し、右側（Ｂ側）に移動した無偏光ビームスプリッタ１２により分離された光子対に対して、単計数率が、それぞれ、ＳＢ＝ｑαμＡ、ＩＢ＝ｑβμＡで与えられ、同時計数率が、ＣＢ＝０．５ｑ２αβμＡで与えられ、ｑは非線形導波路２と右側（Ｂ側）で接続している光ファイバ４に関する透過率である。但し、Ａ側に励起光源１０を設置した場合に得られる光子対発生率をμＡと記述する。また、同じ経路なので同時計数率ＣＡはｑ×ｑに比例する。尚、係数０．５は無偏光ビームスプリッタによる光子対の分離成功確率が５０％であることを示す。
(Quantum efficiency calculation method)
Below, the single count rate (SA, IA) and coincidence rate (CA), the single count rate (SB, IB) and the coincidence rate (CB), which are measured values of the signal photon and idler photon, and the correlated photon pair A calculation method for obtaining the quantum efficiencies (α, β) of the photon detectors 9 and 11 using the transmittance (Z = pq) from the A end to the B end of the generator 1 will be described. However, the quantum efficiency of the photon detector 9 for signal photons (transmission side with respect to the non-polarization beam splitter 12) is α, and the quantum efficiency of the photon detector 11 for idler photons (reflection side with respect to the non-polarization beam splitter 12). The efficiency is β, and the photon pair generation rate of the correlated photon pair generator 1 is described as μ.
For the photon pairs separated by the non-polarizing beam splitter 12 installed on the right side (B side) and the non-polarizing beam splitter 12 installed on the left side (A side), the single count rate is SA = pαμ B , IA = pβμ The coincidence rate is given by B = CA = 0.5p 2 αβμ B , where p is the transmittance for the optical fiber 3 connected to the nonlinear waveguide 2 on the A side (see FIG. 2). However, S means a signal photon and I means an idler photon. Further, the photon pair generation rate of the correlated photon pair generation apparatus 1 obtained when the excitation light source 10 is installed on the right side (B side) is described as μ B. Since the same route is used, the coincidence rate CA is proportional to p × p. A coefficient of 0.5 indicates that the probability of successful separation of photon pairs by the non-polarizing beam splitter is 50%.
For the photon pairs separated by the non-polarizing beam splitter 12 that has moved the excitation light source 10 to the left side (A side) and moved to the right side (B side), the single count rates are SB = qαμ A and IB =, respectively. given Qbetamyu a, coincidence rate is given by CB = 0.5q 2 αβμ a, q is the transmittance to an optical fiber 4 that is connected with the non-linear waveguide 2 and the right (B side). However, describing the photon pair generation rate obtained when installed excitation light source 10 to the A side and mu A. Since the same route is used, the coincidence counting rate CA is proportional to q × q. A coefficient of 0.5 indicates that the probability of successful separation of photon pairs by the non-polarizing beam splitter is 50%.
以上より、同時計数率ＣＡとＣＢの積が、
ＣＡ・ＣＢ＝０．２５ｐ２ｑ２α２β２μＡμＢ
で与えられ、Ｚ＝ｐｑから
ＪＣ≡ＣＡ・ＣＢ＝０．２５Ｚ２α２β２μＡμＢ
となり、単計数率ＳＡとＳＢの積が、
ＪＳ≡ＳＡ・ＳＢ＝ｐｑα２μＡμＢ＝Ｚα２μＡμＢ
となり、ＪＣとＪＳの比が
ＪＣ／ＪＳ＝０．２５Ｚβ２
となり、光子検出器１１の量子効率βが
β＝２√（ＪＣ／ＪＳ／Ｚ）
で求められる。
From the above, the product of the coincidence rate CA and CB is
CA · CB = 0.25p 2 q 2 α 2 β 2 μ A μ B
Given, Z = JC≡CA · from pq CB = 0.25Z 2 α 2 β 2 μ A μ B with
The product of the single count rate SA and SB is
JS≡SA · SB = pqα 2 μ A μ B = Zα 2 μ A μ B
And the ratio of JC to JS is JC / JS = 0.25Zβ 2
And the quantum efficiency β of the photon detector 11 is β = 2√ (JC / JS / Z)
Is required.
また、同時計数率ＣＡとＣＢの積が、
ＣＡ・ＣＢ＝０．２５ｐ２ｑ２α２β２μＡμＢ
で与えられ、Ｚ＝ｐｑから
ＪＣ≡ＣＡ・ＣＢ＝０．２５Ｚ２α２β２μＡμＢ
となり、単計数率ＩＡとＩＢの積が、
ＪＩ≡ＩＡ・ＩＢ＝ｐｑβ２μＡμＢ＝Ｚβ２μＡμＢ
となり、ＪＣとＪＩの比が
ＪＣ／ＪＩ＝０．２５Ｚα２
となり、光子検出器９の量子効率αが
α＝２√（ＪＣ／ＪＩ／Ｚ）
で求められる。
Also, the product of the coincidence rate CA and CB is
CA · CB = 0.25p 2 q 2 α 2 β 2 μ A μ B
Given, Z = JC≡CA · from pq CB = 0.25Z 2 α 2 β 2 μ A μ B with
The product of the single count rate IA and IB is
JI≡IA · IB = pqβ 2 μ A μ B = Zβ 2 μ A μ B
And the ratio of JC to JI is JC / JI = 0.25Zα 2
The quantum efficiency α of the photon detector 9 is α = 2√ (JC / JI / Z)
Is required.
以上より、光子検出器９、１１の量子効率を知ることができる。
以上のとおりであるから、特許文献１、非特許文献１ともに極微弱コヒーレント光を量子効率測定に使用しているが、本発明では、相関光子対を量子効率測定に使用するため、測定原理が全く異なる。
非特許文献２は、後記する本発明と同様に相関光子対を利用して二台の光子検出器の量子効率を測定している。しかし、本発明は、非線形結晶から各光子検出器までの間で発生する伝搬損失を考慮しているので、従来のものではできない正確な測定ができる。
From the above, the quantum efficiency of the photon detectors 9 and 11 can be known.
As described above, both of Patent Document 1 and Non-Patent Document 1 use extremely weak coherent light for quantum efficiency measurement. However, in the present invention, a correlation photon pair is used for quantum efficiency measurement. Completely different.
Non-Patent Document 2 measures the quantum efficiency of two photon detectors using correlated photon pairs as in the present invention described later. However, since the present invention takes into account the propagation loss that occurs between the nonlinear crystal and each photon detector, accurate measurements that cannot be made with conventional devices can be made.
１ 相関光子対発生装置
２ 非線形導波路
３ 光ファイバ（Ａ側、左側）
４ 光ファイバ（Ｂ側、右側）
５ レンズ（Ａ側、左側）
６ レンズ（Ｂ側、右側）
７ 参照光源
８ 光減衰器
９ 光子検出器
１０ 励起光源
１１ 光子検出器
１２ 無偏光ビームスプリッタ
１３ 計数器
１４ 計数器
１５ 同時計数器
1 Correlated Photon Pair Generator 2 Nonlinear Waveguide 3 Optical Fiber (A Side, Left Side)
4 Optical fiber (B side, right side)
5 Lens (A side, left side)
6 Lens (B side, right side)
7 Reference light source 8 Optical attenuator 9 Photon detector 10 Excitation light source 11 Photon detector 12 Non-polarizing beam splitter 13 Counter 14 Counter 15 Simultaneous counter
Claims (16)
前記励起光源に前記光ファイバの一方を着脱自在に接続すると共に前記無偏光ビームスプリッタに前記光ファイバの他方を着脱自在に接続し、
前記無偏光ビームスプリッタの前記それぞれの光子の出力側をそれぞれ前記光子検出器に接続し、前記相関光子対発生装置で発生した前記シグナル光子とアイドラ光子を前記それぞれの光子検出器で検出し、その検出したデータをそれぞれの光子検出器に個別に接続した計数器により計数して単計数率を求め、前記両計数器の同時に出力される出力信号を取り込んで所定の処理を行う同時計数器により計数して同時計数率を求め、
前記光ファイバの一方を前記励起光源から切り離して前記無偏光ビームスプリッタへ繋ぎ直し、前記光ファイバの他方を前記無偏光ビームスプリッタから切り離して前記励起光源へ繋ぎ直した状態で
前記相関光子対発生装置で発生した前記シグナル光子とアイドラ光子を前記それぞれの光子検出器で検出し、その検出したデータをそれぞれの光子検出器に個別に接続した計数器により計数して単計数率を求め、前記両計数器の同時に出力される出力信号を取り込んで所定の処理を行う同時計数器により計数して同時計数率を求めて、前記それぞれの単計数率と前記同時計数率との関係から前記シグナル光子とアイドラ光子を検出し前記それぞれの光子検出器の量子効率を求めることを特徴とする量子効率測定方法。 A correlated photon pair generating device comprising a nonlinear waveguide for generating a correlated photon pair and a pair of optical fibers disposed on both sides thereof, an excitation light source for exciting the nonlinear waveguide, and the correlated photon pair as a signal photon and an idler An unpolarized beam splitter that separates the photons into different photon detectors, two photon detectors that individually detect the signal photons and idler photons, and the detection outputs of the respective photon detectors individually In an apparatus having two counters for counting and a simultaneous counter that takes in output signals output simultaneously from both counters and performs predetermined processing,
Removably connecting one of the optical fibers to the excitation light source and removably connecting the other optical fiber to the non-polarizing beam splitter,
The output side of each photon of the non-polarizing beam splitter is connected to the photon detector, and the signal photon and idler photon generated by the correlated photon pair generator are detected by the respective photon detector, The detected data is counted by a counter individually connected to each photon detector to obtain a single count rate, and the output is simultaneously output from both counters. To calculate the coincidence rate,
One of the optical fibers is disconnected from the excitation light source and reconnected to the non-polarization beam splitter, and the other of the optical fibers is disconnected from the non-polarization beam splitter and reconnected to the excitation light source, the correlated photon pair generation device The signal photons and idler photons generated in step 1 are detected by the respective photon detectors, and the detected data is counted by a counter individually connected to the respective photon detectors to obtain a single count rate. The simultaneous counting rate is obtained by taking in the output signal output simultaneously from the counter and performing a predetermined process, and the signal photon and idler are calculated from the relationship between the single counting rate and the simultaneous counting rate. A quantum efficiency measurement method, comprising: detecting a photon and obtaining a quantum efficiency of each photon detector.
ｐ、ｑがｐ≠１、ｑ≠１であることを特徴とする請求項１記載の量子効率測定方法。 2. The quantum efficiency measurement method according to claim 1, wherein transmittances p and q between the nonlinear waveguide and each of the pair of optical fibers arranged on both sides thereof are p ≠ 1 and q ≠ 1. .
率をβとし、相関光子対発生装置の光子対発生率をμとし、上記励起光源と無偏光ビームスプリッタに対して相関光子対発生装置を一定の接続状態としたとき、前記無偏光ビームスプリッタにより分離される光子対に対して、光子対発生率をμＢとし、各単計数率を、それぞれＳＡ＝ｐαμＢ、ＩＡ＝ｐβμＢで与え、分離成功確率を５０％とし、同時計数率をＣＡ＝０．５ｐ２αβμＢで与え、ｐを非線形導波路と前記一定の接続状態で接続している光ファイバに関する透過率で与え、前記一定の接続状態と逆の接続状態にしたとき、無偏光ビームスプリッタにより分離された光子対に対して、光子対発生率をμＡとし、各単計数率を、それぞれＳＢ＝ｑαμＡ、ＩＢ＝ｑβμＡで与え、分離成功確率を５０％とし、同時計数率をＣＢ＝０．５ｑ２αβμＡで与え、ｑを非線形導波路と前記一定の接続状態と逆の接続状態で接続している光ファイバに関する透過率で与えるとき、同時計数率ＣＡとＣＢの積が、
ＣＡ・ＣＢ＝０．２５ｐ２ｑ２α２β２μＡμＢ
で与えられ、Ｚ＝ｐｑとすれば
ＪＣ≡ＣＡ・ＣＢ＝０．２５Ｚ２α２β２μＡμＢ
となり、単計数率ＳＡとＳＢの積が、
ＪＳ≡ＳＡ・ＳＢ＝ｐｑα２μＡμＢ＝Ｚα２μＡμＢ
となり、ＪＣとＪＳの比が
ＪＣ／ＪＳ＝０．２５Ｚβ２
となり、光子検出器の量子効率βが
β＝２√（ＪＣ／ＪＳ／Ｚ）
で求められることを特徴とする請求項１乃至４のいずれか１項記載の量子効率測定方法。 The quantum efficiency of the photon detector for the signal photon is α, the quantum efficiency of the single photon detector for the idler photon is β, the photon pair generation rate of the correlated photon pair generator is μ, the excitation light source and the unpolarized beam When the correlation photon pair generating device is in a fixed connection state with respect to the splitter, the photon pair generation rate is μ B for each photon pair separated by the non-polarizing beam splitter, and each single count rate is SA. = Pαμ B , IA = pβμ B , separation success probability is 50%, coincidence rate is given by CA = 0.5p 2 αβμ B , and p is connected to the nonlinear waveguide in the constant connection state given by the transmittance to an optical fiber, when the connection state of the constant connection state opposite, with respect to the photon pairs separated by non-polarizing beam splitter, the photon pair generation rate and mu a, each single count rate SB = Arufamyu A, given by IB = qβμ A, the separation success probability of 50% the coincidence ratio CB = 0.5Q given by 2 αβμ A, q at the constant connection state opposite to the connection state and the non-linear waveguide The product of coincidence rates CA and CB, given by the transmittance for the connected optical fiber, is
CA · CB = 0.25p 2 q 2 α 2 β 2 μ A μ B
Given, Z = if pq JC≡CA · CB = 0.25Z 2 α 2 β 2 μ A μ B with
The product of the single count rate SA and SB is
JS≡SA · SB = pqα 2 μ A μ B = Zα 2 μ A μ B
And the ratio of JC to JS is JC / JS = 0.25Zβ 2
The quantum efficiency β of the photon detector is β = 2√ (JC / JS / Z)
The quantum efficiency measurement method according to claim 1, wherein the quantum efficiency measurement method is obtained by:
率をβとし、相関光子対発生装置の光子対発生率をμとし、両側の励起光源と無偏光ビームスプリッタに対して相関光子対発生装置を一定の接続状態としたとき、前記無偏光ビームスプリッタにより分離される光子対に対して、光子対発生率をμＢとし、各単計数率を、それぞれＳＡ＝ｐαμＢ、ＩＡ＝ｐβμＢで与え、分離成功確率を５０％とし、同時計数率をＣＡ＝０．５ｐ２αβμＢで与え、ｐを非線形導波路と前記一定の接続状態で接続している光ファイバに関する透過率で与え、前記一定の接続状態と逆の接続状態にしたとき、無偏光ビームスプリッタにより分離された光子対に対して、光子対発生率をμＡとし、各単計数率を、それぞれＳＢ＝ｑαμＡ、ＩＢ＝ｑβμＡで与え、分離成功確率を５０％とし、同時計数率をＣＢ＝０．５ｑ２αβμＡで与え、ｑを非線形導波路と前記一定の接続状態と逆の接続状態で接続している光ファイバに関する透過率で与えるとき、同時計数率ＣＡとＣＢの積が、
ＣＡ・ＣＢ＝０．２５ｐ２ｑ２α２β２μＡμＢ
で与えられ、Ｚ＝ｐｑとすれば
ＪＣ≡ＣＡ・ＣＢ＝０．２５Ｚ２α２β２μＡμＢ
となり、単計数率ＩＡとＩＢの積が、
ＪＩ≡ＩＡ・ＩＢ＝ｐｑβ２μＡμＢ＝Ｚβ２μＡμＢ
となり、ＪＣとＪＩの比が
ＪＣ／ＪＩ＝０．２５Ｚα２
となり、光子検出器の量子効率αが
α＝２√（ＪＣ／ＪＩ／Ｚ）
で求められることを特徴とする請求項１乃至５のいずれか１項記載の量子効率測定方法。 The quantum efficiency of the photon detector for the signal photon is α, the quantum efficiency of the single photon detector for the idler photon is β, the photon pair generation rate of the correlated photon pair generator is μ, and the excitation light source on both sides and unpolarized light when the correlated photon pair generating device and constant attachment state with respect to the beam splitter, the relative photon pairs are separated by an polarizing beam splitter, the photon pair generation rate and mu B, each single counting rate, respectively SA = pαμ B , IA = pβμ B , separation success probability is 50%, coincidence rate is given by CA = 0.5p 2 αβμ B , p is connected to the nonlinear waveguide in the constant connection state given by the transmittance to an optical fiber which are, when the connection state of the constant connection state opposite, with respect to the photon pairs separated by non-polarizing beam splitter, the photon pair generation rate and mu a, the single count rate SB respectively Qarufamyu A, given by IB = qβμ A, the separation success probability of 50% the coincidence ratio CB = 0.5Q given by 2 αβμ A, q at the constant connection state opposite to the connection state and the non-linear waveguide The product of coincidence rates CA and CB, given by the transmittance for the connected optical fiber, is
CA · CB = 0.25p 2 q 2 α 2 β 2 μ A μ B
Given, Z = if pq JC≡CA · CB = 0.25Z 2 α 2 β 2 μ A μ B with
The product of the single count rate IA and IB is
JI≡IA · IB = pqβ 2 μ A μ B = Zβ 2 μ A μ B
And the ratio of JC to JI is JC / JI = 0.25Zα 2
The quantum efficiency α of the photon detector is α = 2√ (JC / JI / Z)
The quantum efficiency measurement method according to claim 1, wherein the quantum efficiency measurement method is obtained by:
を持つ参照光源と前記二台の光子検出器の一方を接続し、単計数率Ｘ＝ανを測定し、参照光源と前記光子検出器の間に前記相関光子対発生装置を設置して、導波路透過後の単計数率Ｙ＝ｐｑανを測定し、前記相関光子対発生装置の透過率Ｚ＝ｐｑを求めることを特徴とする請求項１乃至６のいずれか１項記載の量子効率測定方法。 When the light intensity of the reference light source is expressed by the number of photons ν per unit gate, the reference light source having the same wavelength as the correlated photon pair is connected to one of the two photon detectors, and the single count rate X = αν is measured. Then, the correlated photon pair generating device is installed between a reference light source and the photon detector, and the single count rate Y = pqαν after transmission through the waveguide is measured, and the transmittance Z = pq of the correlated photon pair generating device. The quantum efficiency measurement method according to claim 1, wherein the quantum efficiency measurement method is obtained.
度を調整することを特徴とする請求項１乃至７のいずれか１項記載の量子効率測定方法。 8. The light intensity of the reference light source according to claim 7, wherein the light intensity of the reference light source is adjusted so that the single count rate satisfies X << 1 and Y << 1. 9. Quantum efficiency measurement method.
る相関光子対発生装置と、前記非線形導波路を励起する励起光源と、前記相関光子対をシグナル光子とアイドラ光子に分離し、それぞれ異なる光子検出器に入射させる無偏光ビームスプリッタと、前記シグナル光子とアイドラ光子をそれぞれ個別に検出する２つの光子検出器と、前記それぞれの光子検出器の検出出力を個別に計数する２つの計数器と、前記両計数器の同時に出力される出力信号を取り込んで所定の処理を行う同時計数器を有する装置において、
前記励起光源に前記光ファイバの一方を着脱自在に接続すると共に前記無偏光ビームスプリッタに前記光ファイバの他方を着脱自在に接続し、
前記無偏光ビームスプリッタの前記それぞれの光子の出力側をそれぞれ前記光子検出器に接続し、前記相関光子対発生装置で発生した前記シグナル光子とアイドラ光子を前記それぞれの光子検出器で検出し、その検出したデータをそれぞれの光子検出器に個別に接続した計数器により計数して単計数率を求め、前記両計数器の同時に出力される出力信号を取り込んで所定の処理を行う同時計数器により計数して同時計数率を求め、
前記光ファイバの一方を前記励起光源から切り離して前記無偏光ビームスプリッタへ繋ぎ直し、前記光ファイバの他方を前記無偏光ビームスプリッタから切り離して前記励起光源へ繋ぎ直した状態で前記相関光子対発生装置で発生した前記シグナル光子とアイドラ光子を前記それぞれの光子検出器で検出し、その検出したデータをそれぞれの光子検出器に個別に接続した計数器により計数して単計数率を求め、前記両計数器の同時に出力される出力信号を取り込んで所定の処理を行う同時計数器により計数して同時計数率を求めて、前記それぞれの単計数率と前記同時計数率との関係から前記シグナル光子とアイドラ光子を検出し前記それぞれの光子検出器における量子効率を求めることを特徴とする量子効率測定装置。 A correlated photon pair generating device comprising a nonlinear waveguide for generating a correlated photon pair and a pair of optical fibers disposed on both sides thereof, an excitation light source for exciting the nonlinear waveguide, and the correlated photon pair as a signal photon and an idler An unpolarized beam splitter that separates the photons into different photon detectors, two photon detectors that individually detect the signal photons and idler photons, and the detection outputs of the respective photon detectors individually In an apparatus having two counters for counting and a simultaneous counter that takes in output signals output simultaneously from both counters and performs predetermined processing,
Removably connecting one of the optical fibers to the excitation light source and removably connecting the other optical fiber to the non-polarizing beam splitter,
The output side of each photon of the non-polarizing beam splitter is connected to the photon detector, and the signal photon and idler photon generated by the correlated photon pair generator are detected by the respective photon detector, The detected data is counted by a counter individually connected to each photon detector to obtain a single count rate, and the output is simultaneously output from both counters. To calculate the coincidence rate,
One of the optical fibers is disconnected from the excitation light source and reconnected to the non-polarization beam splitter, and the other of the optical fibers is disconnected from the non-polarization beam splitter and reconnected to the excitation light source, the correlated photon pair generation device The signal photons and idler photons generated in step 1 are detected by the respective photon detectors, and the detected data is counted by a counter individually connected to the respective photon detectors to obtain a single count rate. The simultaneous counting rate is obtained by taking in the output signal output simultaneously from the counter and performing a predetermined process, and the signal photon and idler are calculated from the relationship between the single counting rate and the simultaneous counting rate. quantum efficiency measurement apparatus and obtains quantum efficiency of detecting said respective photon detector photons.
ｐ、ｑがｐ≠１、ｑ≠１であることを特徴とする請求項９記載の量子効率測定装置。 10. The quantum efficiency measuring apparatus according to claim 9, wherein transmittances p and q between the nonlinear waveguide and each of the pair of optical fibers arranged on both sides thereof are p ≠ 1 and q ≠ 1. .
率をβとし、相関光子対発生装置の光子対発生率をμとし、上記励起光源と無偏光ビームスプリッタに対して相関光子対発生装置を一定の接続状態としたとき、前記無偏光ビームスプリッタにより分離される光子対に対して、光子対発生率をμＢとし、各単計数率を、それぞれＳＡ＝ｐαμＢ、ＩＡ＝ｐβμＢで与え、分離成功確率を５０％とし、同時計数率をＣＡ＝０．５ｐ２αβμＢで与え、ｐを非線形導波路と前記一定の接続状態で接続している光ファイバに関する透過率で与え、前記一定の接続状態と逆の接続状態にしたとき、無偏光ビームスプリッタにより分離された光子対に対して、光子対発生率をμＡとし、各単計数率を、それぞれＳＢ＝ｑαμＡ、ＩＢ＝ｑβμＡで与え、分離成功確率を５０％とし、同時計数率をＣＢ＝０．５ｑ２αβμＡで与え、ｑを非線形導波路と前記一定の接続状態と逆の接続状態で接続している光ファイバに関する透過率で与えるとき、同時計数率ＣＡとＣＢの積が、
ＣＡ・ＣＢ＝０．２５ｐ２ｑ２α２β２μＡμＢ
で与えられ、Ｚ＝ｐｑとすれば
ＪＣ≡ＣＡ・ＣＢ＝０．２５Ｚ２α２β２μＡμＢ
となり、単計数率ＳＡとＳＢの積が、
ＪＳ≡ＳＡ・ＳＢ＝ｐｑα２μＡμＢ＝Ｚα２μＡμＢ
となり、ＪＣとＪＳの比が
ＪＣ／ＪＳ＝０．２５Ｚβ２
となり、光子検出器の量子効率βが
β＝２√（ＪＣ／ＪＳ／Ｚ）
で求められることを特徴とする請求項９乃至１２のいずれか１項記載の量子効率測定装置
。 The quantum efficiency of the photon detector for the signal photon is α, the quantum efficiency of the single photon detector for the idler photon is β, the photon pair generation rate of the correlated photon pair generator is μ, the excitation light source and the unpolarized beam When the correlation photon pair generating device is in a fixed connection state with respect to the splitter, the photon pair generation rate is μ B for each photon pair separated by the non-polarizing beam splitter, and each single count rate is SA. = Pαμ B , IA = pβμ B , separation success probability is 50%, coincidence rate is given by CA = 0.5p 2 αβμ B , and p is connected to the nonlinear waveguide in the constant connection state given by the transmittance to an optical fiber, when the connection state of the constant connection state opposite, with respect to the photon pairs separated by non-polarizing beam splitter, the photon pair generation rate and mu a, each single count rate SB = Arufamyu A, given by IB = qβμ A, the separation success probability of 50% the coincidence ratio CB = 0.5Q given by 2 αβμ A, q at the constant connection state opposite to the connection state and the non-linear waveguide The product of coincidence rates CA and CB, given by the transmittance for the connected optical fiber, is
CA · CB = 0.25p 2 q 2 α 2 β 2 μ A μ B
Given, Z = if pq JC≡CA · CB = 0.25Z 2 α 2 β 2 μ A μ B with
The product of the single count rate SA and SB is
JS≡SA · SB = pqα 2 μ A μ B = Zα 2 μ A μ B
And the ratio of JC to JS is JC / JS = 0.25Zβ 2
The quantum efficiency β of the photon detector is β = 2√ (JC / JS / Z)
The quantum efficiency measuring device according to claim 9, wherein the quantum efficiency measuring device is obtained by:
率をβとし、相関光子対発生装置の光子対発生率をμとし、
両側の励起光源と無偏光ビームスプリッタに対して相関光子対発生装置を一定の接続状態としたとき、前記無偏光ビームスプリッタにより分離される光子対に対して、光子対発生率をμＢとし、各単計数率を、それぞれＳＡ＝ｐαμＢ、ＩＡ＝ｐβμＢで与え、分離成功確率を５０％とし、同時計数率をＣＡ＝０．５ｐ２αβμＢで与え、ｐを非線形導波路と前記一定の接続状態で接続している光ファイバに関する透過率で与え、
前記一定の接続状態と逆の接続状態にしたとき、無偏光ビームスプリッタにより分離された光子対に対して、光子対発生率をμＡとし、各単計数率を、それぞれＳＢ＝ｑαμＡ、ＩＢ＝ｑβμＡで与え、分離成功確率を５０％とし、同時計数率をＣＢ＝０．５ｑ２αβμＡで与え、ｑを非線形導波路と前記一定の接続状態と逆の接続状態で接続している光ファイバに関する透過率で与えるとき、
同時計数率ＣＡとＣＢの積が、
ＣＡ・ＣＢ＝０．２５ｐ２ｑ２α２β２μＡμＢ
で与えられ、Ｚ＝ｐｑから
ＪＣ≡ＣＡ・ＣＢ＝０．２５Ｚ２α２β２μＡμＢ
となり、単計数率ＩＡとＩＢの積が、
ＪＩ≡ＩＡ・ＩＢ＝ｐｑβ２μＡμＢ＝Ｚβ２μＡμＢ
となり、ＪＣとＪＩの比が
ＪＣ／ＪＩ＝０．２５Ｚα２
となり、光子検出器の量子効率αが
α＝２√（ＪＣ／ＪＩ／Ｚ）
で求められることを特徴とする請求項９乃至１３のいずれか１項記載の量子効率測定装置。 The quantum efficiency of the photon detector for signal photons is α, the quantum efficiency of the single photon detector for idler photons is β, the photon pair generation rate of the correlated photon pair generator is μ,
When the correlated photon pair generation device is in a fixed connection state with respect to the excitation light source and the non-polarizing beam splitter on both sides, the photon pair generation rate is μ B for the photon pair separated by the non-polarizing beam splitter, Each single count rate is given by SA = pαμ B and IA = pβμ B , the separation success probability is 50%, the coincidence rate is given by CA = 0.5p 2 αβμ B , and p is the above-mentioned constant with the nonlinear waveguide It is given by the transmittance for the optical fiber connected in the connection state of
When the connection state is opposite to the constant connection state, the photon pair generation rate is μ A for the photon pairs separated by the non-polarizing beam splitter, and the single count rates are SB = qαμ A and IB, respectively. = Qβμ A , separation success probability is 50%, coincidence rate is given by CB = 0.5q 2 αβμ A , and q is connected to the non-linear waveguide in a connection state opposite to the fixed connection state. When given by the transmittance for an optical fiber,
The product of coincidence rate CA and CB is
CA · CB = 0.25p 2 q 2 α 2 β 2 μ A μ B
Given, Z = JC≡CA · from pq CB = 0.25Z 2 α 2 β 2 μ A μ B with
The product of the single count rate IA and IB is
JI≡IA · IB = pqβ 2 μ A μ B = Zβ 2 μ A μ B
And the ratio of JC to JI is JC / JI = 0.25Zα 2
The quantum efficiency α of the photon detector is α = 2√ (JC / JI / Z)
The quantum efficiency measuring apparatus according to claim 9, wherein the quantum efficiency measuring apparatus is obtained by:
を持つ参照光源と前記二台の光子検出器の一方を接続し、単計数率Ｘ＝ανを測定し、参照光源と前記光子検出器の間に前記相関光子対発生装置を設置して、導波路透過後の単計数率Ｙ＝ｐｑανを測定し、前記相関光子対発生装置の透過率Ｚ＝ｐｑを求めることを特徴とする請求項９乃至１４のいずれか１項記載の量子効率測定装置。 When the light intensity of the reference light source is expressed by the number of photons ν per unit gate, the reference light source having the same wavelength as the correlated photon pair is connected to one of the two photon detectors, and the single count rate X = αν is measured. Then, the correlated photon pair generating device is installed between a reference light source and the photon detector, and the single count rate Y = pqαν after transmission through the waveguide is measured, and the transmittance Z = pq of the correlated photon pair generating device. The quantum efficiency measuring device according to claim 9, wherein the quantum efficiency measuring device is obtained.
強度を調整することを特徴とする請求項８乃至１５のいずれか１項記載の量子効率測定装
置。
16. The light intensity of the reference light source according to claim 15, wherein the light intensity of the reference light source is adjusted so that the single count rate satisfies X << 1 and Y << 1. Quantum efficiency measuring device.
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