阅读说明：本技术 一种光子数分辨探测器及其系统 (Photon number resolution detector and system thereof ) 是由 胡小龙 邹锴 许亮 王昭 孟赟 胡南 于 2020-06-28 设计创作，主要内容包括：本发明公开了一种光子数分辨探测器及其系统,探测器包括：超导纳米线多光子探测器由多根光敏纳米线与1根电流库并联构成,多根光敏纳米线探测光子后,溢出的电流存储在电流库中,电流库中的超导电流的大小与探测光子数形成对应关系；确定光敏纳米线和电流库之间线宽的比值、以及二者之间的动能电感的比值；在电流库结构上集成一个y型读出臂,实现非侵入式的测量电流库中的电流I<Sub>R</Sub>。系统包括：探测器,以及对应的电路器件。本发明保留了SNSPD的高探测效率等主要优点,同时利用SNSPD的本征光子数分辨能力,实现高保真度的多光子探测；本发明使用单个偏置电路与读出电路,旨在简化多光子探测系统的复杂度,且赋予器件可分辨光子数n的扩展性。(The invention discloses a photon number resolution detector and a system thereof, wherein the detector comprises: the superconducting nanowire multi-photon detector is formed by connecting a plurality of photosensitive nanowires and 1 current bank in parallel, overflowing current is stored in the current bank after the photosensitive nanowires detect photons, and the magnitude of superconducting current in the current bank and the number of detected photons form a corresponding relation; determining the ratio of the line width between the photosensitive nanowire and the current bank and the ratio of the kinetic energy inductance between the photosensitive nanowire and the current bank; a y-type read-out arm is integrated on the current bank structure to realize non-invasive measurement of current I in the current bank R . The system comprises: a detector, and corresponding circuit components. The invention retains the main advantages of high detection efficiency of SNSPD, and realizes high-fidelity multi-photon detection by utilizing the intrinsic photon number resolution capability of SNSPD; the invention uses a single bias circuit and a read-out circuit, aims to simplify the complexity of a multi-photon detection system and endows the device with the expansibility of distinguishing the photon number n.)

1. A photon number resolving detector, characterized in that it comprises: a superconducting nanowire multi-photon detector is provided,

the superconducting nanowire multi-photon detector is formed by connecting a plurality of photosensitive nanowires and 1 current bank in parallel, overflowing current is stored in the current bank after the photosensitive nanowires detect photons, and the magnitude of superconducting current in the current bank and the number of detected photons form a corresponding relation;

determining the ratio of the line width between the photosensitive nanowire and the current bank and the ratio of the kinetic energy inductance between the photosensitive nanowire and the current bank; a y-type read-out arm is integrated on the current bank structure to realize non-invasive measurement of current I in the current bank_R。

2. The photon number resolving detector of claim 1, wherein said integrating a y-type read arm on the current bank structure provides non-invasive measurement of the current I in the current bank_RThe method specifically comprises the following steps:

current I in the current bank to be monitored_RA y-type read arm into which a read current flows; an included angle exists between the reading arm and the current bank, and the superconducting current in the current bank is deduced by measuring the critical current of the reading arm, so that the reading of the number of the detection photons is realized.

3. A photon number-resolving detection system, the system comprising: the photon number resolving detector of claim 1,

the photon number resolution detector is arranged in the refrigerator, the light source adopts a pulse laser, and the light source is coupled to the photon number resolution detector after passing through the polarization controller and the optical attenuator;

the random waveform generator generates two paths of current pulse signals, the current pulse signals are attenuated by the radio frequency attenuator and then are respectively used as a bias current signal and a read current signal of the photon number resolution detector, the read current signal is amplified by the amplifier and then is led into the oscilloscope, the critical current of the read current signal is observed, and finally the current I in the current library is realized_RIs read out.

4. A photon number resolving detection system according to claim 3, wherein the system operates in 3 phases:

in the pre-bias stage, a negative current pulse is input into an arbitrary waveform generator at the y-type reading arm end, so that most of current in a current bank is transferred into the photosensitive nanowire;

in the photon detection stage, after light pulse incidence, a triangular wave signal is input by a y-type reading arm end by adopting an arbitrary waveform generator, and the triangular wave signal is used for scanning and measuring the current value in a current library to obtain photon number distribution information in each pulse;

and in the device resetting stage, after each triangular wave signal, a large bias current pulse signal is input to enable the whole device to be in a resistive state, and then the input of the bias current is stopped to enable the device to be recovered to a superconducting state.

5. A photon number resolving detection system according to claim 3 or 4, further comprising:

the distribution of the actual photon number in each pulse under different incident photon numbers is measured by adjusting the attenuation value of the optical attenuator, and compared with the Poisson distribution predicted by theory, the reliability of photon resolution detection is verified.

Technical Field

The invention relates to the field of photoelectronic devices, in particular to a photon number resolution detector and a system thereof.

Background

With the development of quantum optics and classical optics, multi-photon cooperative detection needs to be realized in a near infrared band, and a detector capable of realizing photon number resolution is needed. The photon number resolution detector means that when 0 to n photons are incident, the detector can output corresponding n +1 states in real time to resolve the incident photon number. At present, photon number resolution detection is widely applied to the aspects of quantum communication, laser radar and the like.

In order to realize high-fidelity multi-photon detection, the conventional method for realizing photon number resolution adopts M (M is greater than or equal to n) independent high-performance single photon detectors, for example, a Superconducting nanowire single-photon detector (SNSPD) array is used to cooperatively detect a plurality of photons, thereby realizing resolution of the number of incident photons. Although individual SNSPDs have good performance, each requires operation in the liquid helium temperature region and separate biasing and readout circuitry.

Therefore, with the increase of the number n of detected photons, the complexity of the whole multi-photon detection system also increases, so that the expansion of the photon resolution number n is limited, and on the other hand, when the number of detectors is fixed, the detection fidelity of the number of photons is sharply reduced with the increase of the number of incident photons. Another multiphoton detection scheme is to use detectors with intrinsic photon number resolving power, such as: SNSPD, superconducting transition edge detector (TES), etc. The fidelity of this approach is 1, but there is a limit to the maximum number of resolvable photons, typically less than 10 photons, for example: the maximum number of resolvable photons of SNSPD is only 4.

Disclosure of Invention

The invention provides a photon number resolution detector and a system thereof, the invention improves the traditional single photon detector into the photon number resolution detector, retains the main advantages of high detection efficiency of SNSPD and the like, and simultaneously realizes high-fidelity multi-photon detection by utilizing the intrinsic photon number resolution capability of the SNSPD; the present invention uses a single bias circuit and readout circuit to simplify the complexity of the multi-photon detection system and to give the device the scalability of the distinguishable photon number n, as described in detail below:

a photon number resolving detector, comprising: a superconducting nanowire multi-photon detector is provided,

the superconducting nanowire multi-photon detector is formed by connecting a plurality of photosensitive nanowires and 1 current bank in parallel, overflowing current is stored in the current bank after the photosensitive nanowires detect photons, and the magnitude of superconducting current in the current bank and the number of detected photons form a corresponding relation;

determining the ratio of the line width between the photosensitive nanowire and the current bank and the ratio of the kinetic energy inductance between the photosensitive nanowire and the current bank; a y-type read-out arm is integrated on the current bank structure to realize non-invasive measurement of current I in the current bank_R。

Wherein, said integrating a y-type reading arm on the current bank structure realizes the non-invasive measurement of the current I in the current bank_RThe method specifically comprises the following steps:

current I in the current bank to be monitored_RA y-type read arm into which a read current flows; an included angle exists between the reading arm and the current bank, and the superconducting current in the current bank is deduced by measuring the critical current of the reading arm, so that the reading of the number of the detection photons is realized.

A photon number-resolving detection system, the system comprising: a photon number-resolving detector for detecting the number of photons,

the photon number resolution detector is arranged in the refrigerator, the light source adopts a pulse laser, and the light source is coupled to the photon number resolution detector after passing through the polarization controller and the optical attenuator;

the random waveform generator generates two paths of current pulse signals, the current pulse signals are attenuated by the radio frequency attenuator and then are respectively used as a bias current signal and a read current signal of the photon number resolution detector, the read current signal is amplified by the amplifier and then is led into the oscilloscope, the critical current of the read current signal is observed, and finally the current I in the current library is realized_RIs read out.

Further, the system works in 3 phases:

in the pre-bias stage, a negative current pulse is input into an arbitrary waveform generator at the y-type reading arm end, so that most of current in a current bank is transferred into the photosensitive nanowire;

in the photon detection stage, after light pulse incidence, a triangular wave signal is input by a y-type reading arm end by adopting an arbitrary waveform generator, and the triangular wave signal is used for scanning and measuring the current value in a current library to obtain photon number distribution information in each pulse;

and in the device resetting stage, after each triangular wave signal, a large bias current pulse signal is input to enable the whole device to be in a resistive state, and then the input of the bias current is stopped to enable the device to be recovered to a superconducting state.

Wherein the system further comprises:

the distribution of the actual photon number in each pulse under different incident photon numbers is measured by adjusting the attenuation value of the optical attenuator, and compared with the Poisson distribution predicted by theory, the reliability of photon resolution detection is verified.

The technical scheme provided by the invention has the beneficial effects that:

1. the invention improves on the basis of SNSPD with high detection efficiency, and realizes real-time photon number resolution detection by using single-path reading of a single detector;

2. the invention uses a single bias circuit and a read-out circuit, aims to simplify the complexity of a multi-photon detection system and endows the device with the expansibility of distinguishing the photon number n;

3. the photon number resolution detector provided by the invention is expected to be applied to scenes with large photon number resolution requirements.

Drawings

Fig. 1 is a schematic diagram of a device structure, a schematic diagram of an electrical structure and a simulation diagram of photon number response of the photon number resolution detector when M is 2;

wherein, (a) is a superconducting nanowire multi-photon detector structure under the condition that M is 2: n is a radical of₁，N ₂2 photosensitive nanowire structures; r is a current bank structure for storing current. The yTron structure reads current I through_readSense current in the current bankI_biasBiasing current for the device as a whole; (b) an equivalent circuit model of the superconducting nanowire multi-photon detector structure under the condition that M is 2; (c) the method is used for simulating the evolution diagram of the superconducting current in the current library with time under different incident photons through a thermoelectric model.

Fig. 2 is a schematic diagram of a device structure of the photon number resolving detector when M is 20, a simulation diagram of a steady-state current of a current bank, and a simulation diagram of a minimum difference value of the steady-state current;

wherein, (a) is a superconducting nanowire multi-photon detector structure under the condition that M is 20: n is a radical of₁To N₂₀The structure is 20 photosensitive nano wires; r is a current bank structure for storing current. The yTron structure reads current I through_readCritical value ofSensing the current I in the current bank_R，I_biasBiasing current for the device as a whole; (b) the steady state value distribution diagram of the current in the current bank under the condition of different incident photon numbers n; (c) is the minimum difference between the steady state currents in the current bank for different incident photon numbers n.

FIG. 3 is a diagram of a yTron structure diagram and simulation results of yTron current sensing;

wherein, (a) is a yTron structure schematic diagram, and a certain included angle exists between the current library and the reading arm; (b) for currents I in the current bank_RCritical current of read armThe relationship of (A) is simulated, and the simulation result shows the critical current of the read-out armWith the current I in the current bank_RThere is a linear relationship between the current levels in the current bank, which can be sensed based on the critical current of the sensing arm.

FIG. 4 is a diagram of a photon number-resolved detection system and expected experimental results.

Wherein, (a) is a schematic diagram of a photon number resolution detection system; (b) for the expected experimental results: the first row is the time-sequential distribution of the incident light pulses, and the second and third rows represent the readout currents I generated by an Arbitrary Waveform Generator (AWG), respectively_readWith a global bias current I_biasThe last row represents the superconducting current I in the current bank_RAnd the number of incident photons.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention are described in further detail below.