CN117213647A - Superconducting photon acquisition array, superconducting photon number resolution detector and reading method - Google Patents
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Abstract
The application provides a superconducting photon acquisition array, a superconducting photon number resolution detector and a reading method, comprising the following steps: a bias current generating unit and N subunits; n is an integer greater than or equal to 2; each subunit is sequentially connected in series to form a series structure; the bias circuit generating unit is used for generating bias current and is loaded at one end of the series structure; each subunit comprises at least one hot spot regulating structure; each hot spot regulating structure comprises a narrow nanowire part and two wide nanowires on two sides; the narrow nanowire part is used for converting the absorbed photon number into a thermal resistance value under the action of bias current; the wide nanowires are used for limiting the diffusion of the thermal resistor so as to ensure that the total thermal resistance value of each hot spot regulating structure is linearly related to photons. According to the application, by arranging the hot spot regulating structure, the photon number can be obtained based on the linear relation between the thermal resistance value and the photon number, and the photon resolution and the fidelity are effectively improved.
Description
Technical Field
The application relates to the field of superconducting application, in particular to a superconducting photon acquisition array, a superconducting photon number resolution detector and a reading method.
Background
Single photon detectors are a key technology widely used in quantum information science. The performance evaluation of the single photon detector is mainly in the aspects of detection efficiency, dark count rate, detection speed, time jitter, photon number resolution and the like. Detectors can be classified into binary detectors (which can only determine the presence or absence of a photon) and photon number resolution detectors, depending on whether they have the ability to discriminate the number of incident photons. The photon number resolution detector is mainly used for monitoring quantum states in a quantum system, is a key component of various light quantum computing frameworks and quantum random number generators, and can also improve the safety of quantum cryptography; while the fidelity of photon number resolution fundamentally affects the accuracy of the operation of these quantum systems.
A variety of photon number resolution detectors have been proposed in the semiconductor arts including visible light counters (VLPC), quantum dot gated field effect transistors (qdoffet), self-differential avalanche diodes (SD-APD) and avalanche diode (APD) arrays, but these detectors are often limited in fidelity due to low detection efficiency, high dark count rate and large read-out overlap. Therefore, the photon number resolution detector with high fidelity is still quite rare, and only the superconducting conversion edge sensor (TES) meets the application requirement of the photon quantum information at present, but the contradiction between the photon number resolution capability and the recovery time can limit the detection number rate; moreover, the deep low temperature working environment (-100 mK) is a great challenge which cannot be avoided by practical application.
Currently, with the application of superconducting materials, a Superconducting Nanowire Single Photon Detector (SNSPD) is one of the single photon detection technologies with the current most performance advantages, has detection efficiency of nearly 100%, negligible dark count rate, recovery time of nanosecond magnitude and time jitter of picosecond magnitude, and has been widely applied to quantum information technologies, such as quantum computing superiority, quantum key distribution and quantum random number. However, unlike TES, SNSPD was originally developed, and researchers generally thought that superconducting nanowire single-photon detectors were strictly binary detectors, and only the existence of photons could be resolved, and the number of photons could not be resolved at all, because the device produced extremely nonlinear resistive amplification after responding to one photon.
To overcome this problem, since 2008, a great deal of research has focused on dispersing incident photons onto a plurality of pixels using an on-chip spatial multiplexing array, the number of photons being represented by the number of responsive pixels. However, these structures encode information responsive to the number of pixels onto the amplitude of the readout pulse, i.e. the same pulse reflects multiple photon values, but the signal-to-noise ratio of the readout pulse is limited, so that resolution of photons by this device structure has a problem of low fidelity. In 2022, cheng et al, university of us, utilized time multiplexed delay lines to achieve waveguide integrated 100 pixel parallel readout; however, the detection efficiency of the structure is low, and even under ideal conditions, the fidelity of distinguishing 1 photon from 2 photons is still low, and the pixel scale needs to be further improved.
Based on this, a new superconducting photon number resolution detector is needed to resolve the photon number while maintaining high fidelity.
It should be noted that the foregoing description of the background art is only for the purpose of providing a clear and complete description of the technical solution of the present application and is presented for the convenience of understanding by those skilled in the art. The above-described solutions are not considered to be known to the person skilled in the art simply because they are set forth in the background of the application section.
Disclosure of Invention
In view of the above-mentioned drawbacks of the prior art, an object of the present application is to provide a superconducting photon collection array, a superconducting photon number resolution detector and a reading method, which are used for solving the problems of low fidelity of photon number resolution and incapability of resolving more photons in the prior art.
To achieve the above and other related objects, the present application provides a superconducting photon collection array comprising: a bias current generating unit and N subunits; n is an integer greater than or equal to 2;
each subunit is sequentially connected in series to form a series structure;
the bias circuit generating unit is used for generating bias current and is loaded at one end of the series structure;
each subunit comprises at least one hot spot regulating structure; when more than two hot spot regulating structures are arranged in each subunit, the hot spot regulating structures are sequentially connected in series;
each hot spot regulating structure comprises a narrow nanowire part and two wide nanowires; each wide nanowire is respectively arranged at two sides of the narrow nanowire part and is connected with the narrow nanowire part in series;
the aspect ratio of the narrow nanowire part is less than or equal to 10, and the narrow nanowire part is used for converting the number of absorbed photons into a thermal resistance value under the action of bias current; the width of each wide nanowire is 1.2 times or more and 10 times or less of the width of the narrow nanowire part, and the width of each wide nanowire is used for limiting the diffusion of thermal resistors so as to ensure that the thermal resistance value of each hot spot regulating structure is linearly related to photons;
wherein the bias current has a current value less than a critical current value of the narrow nanowire portion.
Alternatively, the subunits are arranged in sequence along a direction or each subunit is arranged in a meandering manner.
Optionally, the widths of the two wide nanowires in each hotspot regulating structure are equal.
Optionally, the superconducting photon collection array further comprises N detection nanowires; each detection nanowire is connected with each subunit in parallel in a one-to-one correspondence manner; the detection nanowires are used for absorbing photon numbers, and each subunit converts the photon numbers absorbed by the corresponding detection nanowires into thermal resistance values.
Optionally, each detection nanowire has an aspect ratio greater than 10.
Optionally, each subunit is connected in series by a matching nanowire; the linewidth of the matching nanowire is greater than the linewidth of the detecting nanowire.
Optionally, the narrow nanowire portion includes M narrow nanowires, M being an integer greater than or equal to 1 and less than or equal to 5; when M is more than or equal to 2, each narrow nanowire is arranged in parallel; the width of the narrow nanowire part is equal to the sum of the line widths of M narrow nanowires arranged in parallel.
Optionally, corners at the junction of the narrow nanowire part and the two wide nanowires in each hot spot regulating structure are provided with chamfers; the chamfer is a chamfer angle or a round angle.
To achieve the above and other related objects, the present application provides a superconducting photon number resolution detector comprising: the superconducting photon number resolution detector comprises a readout circuit and the superconducting photon collection array; the readout circuit is connected with the output end of the superconducting photon collection array so as to collect pulses of output current of the superconducting photon collection array.
Optionally, the superconducting photon number resolution detector further comprises a calculation unit; the calculation unit is connected with the output end of the readout circuit, and calculates the photon number based on the linear relation between the pulse rising edge slope of the output current of the superconducting photon acquisition array and the photon number, or calculates the photon number based on the inverse relation between the pulse rising edge time and the photon number.
To achieve the above and other related objects, the present application provides a method for reading a superconducting photon number resolution detector, which is implemented based on the superconducting photon number resolution detector, including:
s1, enabling the bias current to flow through each subunit;
s2, incident light is incident to the superconducting photon collection array and absorbed through the corresponding subunit; each subunit converts the absorbed photon number into a thermal resistance value under the action of bias current, and the thermal resistance value of each hot spot regulating structure is linearly related to photons; and acquiring thermal resistance information of each subunit in the superconducting photon acquisition array.
Optionally, the method for reading the superconducting photon number resolution detector further comprises step S3;
and S3, calculating to obtain the photon number based on the linear relation between the rising edge slope of the output current pulse of the superconducting photon collection array and the photon number or the inverse relation between the rising edge time of the pulse and the photon number.
Optionally, the rising edge time of the output current pulse of the superconducting photon collection array and the number of photons satisfy the following conditions:
τ＝L k /nR hs
wherein τ is the rising edge time of the output current pulse of the superconducting photon acquisition array; lk is the total inductance of the superconducting photon number resolution detector; n is the number of photons collected; rhs is the resistance of each subunit that converts photons into thermal resistance.
As described above, the superconducting photon collection array, the superconducting photon number resolution detector and the reading method of the present application have the following
The beneficial effects are that:
1. according to the superconducting photon collection array, the superconducting photon number resolution detector and the reading method, through the arrangement of the hot spot regulating structures, the thermal resistance of each hot spot regulating structure is guaranteed to be linearly related to photons, and then the photon number can be obtained through the linear relation between the thermal resistance and the photon number, so that the high fidelity of the photon number resolution detector when a plurality of photon numbers are read is effectively improved.
2. The superconducting photon collection array, the superconducting photon number resolution detector and the reading method convert photon number information into thermal resistance information, and collect the thermal resistance information through bias current, so that the photoelectric conversion process is realized, photon number resolution is more efficient and simple, and large-scale popularization and use can be performed.
Drawings
Fig. 1 is a schematic diagram of a superconducting photon collection array according to the present application.
Fig. 2 is a schematic structural diagram of a hot spot control structure.
Fig. 3 is a schematic structural diagram of another hot spot control structure.
Fig. 4 is a schematic diagram of another superconducting photon collection array according to the present application.
Fig. 5 shows a statistical distribution of rising edge slopes of output pulses of the superconducting photon acquisition array of the present application.
Description of element reference numerals
1. Superconductive photon collection array
11. Subunit
11a first subunit
11b second subunit
111. Narrow nanowire portion
111a narrow nanowires
112. First wide nanowire
113. Second wide nanowire
2. Superconductive photon collection array
21. Detecting nanowires
22. Matching nanowires
Detailed Description
Other advantages and effects of the present application will become apparent to those skilled in the art from the following disclosure, which describes the embodiments of the present application with reference to specific examples. The application may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present application.
Please refer to fig. 1-5. It should be noted that, the illustrations provided in the present embodiment merely illustrate the basic concept of the present application by way of illustration, and only the components related to the present application are shown in the drawings and are not drawn according to the number, shape and size of the components in actual implementation, and the form, number and proportion of the components in actual implementation may be arbitrarily changed, and the layout of the components may be more complex.
Example 1
As shown in fig. 1, the present embodiment provides a superconducting photon collection array 1, including: a bias current generating unit (not shown in the figure) and N sub-units 11; n is an integer greater than or equal to 1.
As shown in fig. 1, the sub-units 11 are sequentially connected in series to form a series structure, and one end of the series structure is loaded with a preset bias current.
Specifically, the sub-units 11 are arranged in order in one direction or the sub-units 11 are arranged in a meandering manner. In this embodiment, as shown in fig. 1, each sub-unit 11 is meandered to form a two-dimensional planar structure, upon which incident light is incident. In another example, if the incident light is coupled to each subunit 11 by optical waveguide transmission, each subunit 11 may be arranged sequentially in a direction to facilitate the coupling of the incident light. It should be noted that the coupling manner of photons and each subunit 11 may be set in various ways, for example: any way of coupling photons to the corresponding subunits, such as free space coupling, optical fiber coupling, or waveguide coupling, is within the scope of this embodiment. In addition, in order to further improve the efficiency of optical coupling, the shapes of the arrangement of the subunits 11 may be set based on different coupling modes, so as to ensure that photons are absorbed by each subunit 11.
Further, as shown in fig. 1 to 3, each subunit 11 includes at least one hot spot control structure; when more than two hot spot regulating structures are arranged in each subunit, the hot spot regulating structures are sequentially connected in series. In the present embodiment, each subunit 11 is provided with a hot spot regulating structure.
As an example, each hotspot regulation structure comprises at least a narrow nanowire portion 111 and two wide nanowires. Each wide nanowire is respectively arranged at two sides of the narrow nanowire part 111 and is connected with the narrow nanowire part 111 in series; the aspect ratio of the narrow nanowire portion 111 is less than or equal to 10, and is used for converting the number of absorbed photons into a thermal resistance value under the action of bias current; the width of each wide nanowire is 1.2 times or more and 10 times or less of the width of the narrow nanowire part, and the width is used for limiting the diffusion of thermal resistance so as to ensure that the thermal resistance value of each hot spot regulating structure is linearly related to photons.
In the present embodiment, for convenience of description, the wide nanowires on both sides of the narrow nanowire portion 111 are denoted as a first wide nanowire 112 and a second wide nanowire 113. In the present embodiment, in order to facilitate industrial production, the widths of the two wide nanowires (the first wide nanowire 112 and the second wide nanowire 113) are set to be equal. In practice, the widths of the first wide nanowire 112 and the second wide nanowire 113 may be set to be unequal, so long as the widths of the first wide nanowire 112 and the second wide nanowire 113 are 1.2 times or more and 10 times or less of the narrow nanowire portion 111, which are both the protection scope of the present embodiment.
As an example, the narrow nanowire portion includes M narrow nanowires, M being set to an integer of 1 or more and 5 or less; when M is 2 or more, each narrow nanowire 111a is arranged in parallel; the width of the narrow nanowire portion 111 is equal to the sum of line widths of M narrow nanowires 111a arranged in parallel. That is, the width of the first wide nanowire 112 and the width of the second wide nanowire 113 are equal to or greater than the sum of the line widths of the M narrow nanowires 111a arranged in parallel.
As a first example, as shown in fig. 2, the narrow nanowire portion 111 in the first subunit 11a includes 1 narrow nanowire 111a. The bias current flows in from the second wide nanowire 113 and the first wide nanowire 112 flows out. When the narrow nanowire 111a receives a photon and responds, the narrow nanowire 111a quenches itself to a resistive state. The narrow nanowire 111a that becomes the resistive state generates joule heat during this transformation process, and the joule heat is continuously diffused by the bias current, thereby causing the resistive portion to be diffused, which is called a thermal resistance diffusion process. Since the line width of the nanowire is related to the bias current density, the wider the nanowire is, the lower the bias current density is, and the thermal resistor is not easy to expand; therefore, after the narrow nanowire 111a in this example is converted into the thermal resistor, since both ends are connected with wide nanowires (the line width is greater than 1.2 times of the narrow nanowire 111 a), the thermal resistor can be prevented from further expanding, so that the thermal resistor is only generated on the narrow nanowire 111a. The desired thermal resistance can be adjusted by the length of the narrow nanowire 111a according to the linear relationship between the resistance value in the normal conductor and the conductor length. Because the resistance value obtained by photon conversion is in a linear relation with photons through the narrow nanowire 111a, the thermal resistance values respectively converted by the subunits 11 in the superconducting photon collection array 1 are summed to obtain the total resistance, and the number of photons absorbed by each subunit 11 is further obtained.
As a second example, as shown in fig. 3, the narrow nanowire portion 111 in the second subunit 11b includes 2 narrow nanowires 111a arranged in parallel. When photons are collected by the superconducting photon collection array 1, the process of absorbing photons by the second subunit 11b includes: of the two narrow nanowires 111a in the narrow nanowire portion 111 of the second subunit 11b, any one of the narrow nanowires 111a receives photons and turns into a thermal resistor, and since bias current flows to the other narrow nanowire 111a connected in parallel, the thermal resistor is diffused and transmitted to the other narrow nanowire, so that both the two narrow nanowires 111a turn into thermal resistors. Therefore, if any one of the narrow nanowires 111a of the narrow nanowire portion 111 absorbs photons, both of the two parallel narrow nanowires 111a are converted into a resistive state, and since both ends are connected to be wide nanowires (the sum of line widths of the narrow nanowires 111a each having a width of 2 or more arranged in parallel), the thermal resistance is not allowed to continue to expand, and is generated only on the two narrow nanowires 111a. At this time, the resistance value obtained by photon conversion absorbed by the narrow nanowire 111a is still in a linear relationship with photons, and the total resistance can be obtained based on the superconducting photon collection array 1, so as to obtain the number of photons absorbed by each subunit 11. Compared with the first example, the method has the advantages that the plurality of narrow nanowires 111a are arranged in parallel, so that the magnitude of the input bias current is improved, the signal-to-noise ratio of the final response pulse is improved, and the accuracy and the fidelity of photon number resolution are improved.
In the present embodiment, each narrow nanowire 111a is set to a width of 30nm to 1 μm, including but not limited to: 50nm, 120nm, 500nm, 750nm, with lengths set at 30nm to 20 μm, including but not limited to: 60nm, 500nm, 1 μm, 5 μm, 10 μm, with a thickness set to 2nm to 20nm, including but not limited to: 5nm, 10nm, 15nm; the width of the wide nanowire is set to 50nm to 20 μm, including but not limited to, greater than the sum of the line widths of the narrow nanowires 111a connected in parallel in each sub-unit 11: 500nm, 1 μm, 5 μm, 10 μm, with a thickness set to 2nm to 20nm, including but not limited to: 5nm and 10nm.
In this embodiment, the materials of the narrow nanowires and the wide nanowires may be any material such as NbN, nbTiN, moSi, WSi, taNd, and any material suitable for the superconducting photon number resolution detector may be used, which is not limited to this embodiment.
It should be further noted that, when the subunit 11 of the present embodiment is configured as a plurality of hot spot control structures connected in series, for example: two hot spot regulating structures connected in series are arranged in the same subunit 11, and the working principle at this time is basically identical to that of using one hot spot regulating structure, except that the thermal resistance value of the subunit 11 is the sum of two series-connected thermal resistors. In practice, no matter how many hot spot regulating structures are arranged, as long as at least one hot spot regulating structure is arranged in the subunit 11, the photon number can be converted into the corresponding hot spot regulating structure which is linearly related to the photon through the hot spot regulating structure which always keeps the thermal resistance value, so as to obtain the absorbed photon number.
As an example, corners at the junction of the narrow nanowire portion 111 and the two wide nanowires in each hotspot regulation structure are provided with chamfers; the chamfer is a chamfer angle or a rounding angle, so that the current crowding effect when current flows through the corner is avoided.
As shown in fig. 1, the bias circuit generating unit is configured to generate a bias current, and make the bias current load one end of a serial structure formed by each subunit; wherein the bias current has a current value smaller than a critical current value of the narrow nanowire section 111 in each subunit 11.
The working mechanism of the superconducting photon collection array 1 of the present embodiment is explained below with reference to fig. 1:
when a certain narrow nanowire 111a in the subunit 11 absorbs a photon and responds, it changes from a superconducting state to a resistive state. In this embodiment, when the narrow nanowire is changed to a resistive state, the size of the single thermal resistor Rhs is designed according to actual needs, and is set to be 50Ω -10kΩ, such as 500Ω, 5kΩ, 8kΩ. The two-dimensional plane where the superconducting photon collection array 1 is arranged is large enough to ensure that the more the number of the subunits 11 is, the better the incident light energy is absorbed. In the present embodiment, the number of the setting subunits 11 is 10000 or more. If less than 100 photons are simultaneously incident on the superconducting photon collection array 1, the photons are absorbed and responded by different subunits 11; the superconducting photon collection array 1 responds to n photons to generate n thermal resistors correspondingly, and the size of the single thermal resistor Rhs is limited in a set range, so that thermal resistor diffusion cannot be continuously carried out, and the number of photons can be known after the size nRhs of the total thermal resistor is read. When the thermal resistance information is collected outside the superconducting photon collection array 1 through the current, the photon number can be calculated based on the linear relation between the output current and the thermal resistance.
The present embodiment also provides a superconducting photon number resolution detector, including: a readout circuit and the above-described superconducting photon collection array 1; the readout circuit is connected with the output end of the superconducting photon collection array 1 to collect the pulse of the output current of the superconducting photon collection array 1, and the information of photon number can be obtained by observing the pulse waveform information of the output current.
Specifically, the superconducting photon number resolution detector further comprises a calculation unit; the calculating unit is connected with the output end of the readout circuit, and calculates the photon number based on the linear relation between the pulse rising edge slope of the output current of the superconducting photon collection array 1 and the photon number, or calculates the photon number based on the inverse relation between the pulse rising edge time of the output current of the superconducting photon collection array 1 and the photon number.
The embodiment also provides a reading method of the superconducting photon number resolution detector, which is realized based on the superconducting photon number resolution detector and comprises the following steps:
s1, the bias current flows through each subunit 11.
Specifically, a bias current is input to one end of a series structure formed by the series connection of the respective subcells 11.
S2, incident light is incident to the superconducting photon collection array 1 and absorbed by the corresponding subunit 11; each subunit 11 converts the absorbed photon number into a thermal resistance value under the action of bias current, and the thermal resistance value of each hot spot regulating structure is linearly related to photons; thermal resistance information of each subunit 11 in the superconducting photon acquisition array 1 is acquired.
Specifically, a plurality of photons in the incident light are emitted to each subunit 11, the subunits 11 receiving the photons are converted into a resistance state, the current flowing through each subunit collects the thermal resistance information of each subunit 11 in the superconducting photon collection array 1, and the thermal resistance information is output as output current, and photon number information can be obtained based on the pulse information of the output current.
Specifically, the method for reading the superconducting photon number resolution detector of the present embodiment further includes step S3:
and S3, calculating to obtain the photon number based on the linear relation between the rising edge slope (1/tau) of the output current pulse of the superconducting photon collection array 1 and the photon number n or the inverse relation between the rising edge time tau of the output current pulse of the superconducting photon collection array 1 and the photon number n.
As an example, the output current pulse rising edge time τ of the superconducting photon collection array 1 and the photon number satisfy:
τ＝L k /nR hs (1)
wherein τ is the rising edge time of the output current pulse of the superconducting photon acquisition array; lk is the total inductance of the superconducting photon number resolution detector; n is the number of photons collected; rhs is the resistance value of the thermal resistor converted from each subunit 11 after receiving photons. As shown in fig. 5, each waveform diagram shows a venation diagram in which 1 photon number to 11 photon numbers are absorbed, and the photon numbers of the response are calculated according to the time τ of the rising edge of the response pulse or the slope (1/τ) of the rising edge; the smaller the pulse rise time of the output current, or the larger the rise slope, the more photons absorbed by the superconducting photon collection array.
The superconductive photon collection array 1 of the embodiment absorbs photons through the narrow nanowire portions 111 in the hot spot regulation structure, and limits thermal resistance diffusion of the narrow nanowire portions 111 through the wide nanowires on two sides of the narrow nanowire portions 111, so that thermal resistance generation is guaranteed to be only represented at the narrow nanowire portions 111, and finally, a linear relation between thermal resistance values and photon numbers is kept, and further, the photon numbers are accurately read through output currents.
Example two
In the first embodiment, the light absorption rate through the hot spot adjusting structure is relatively low, because photons are coupled to each subunit 11, and since the wide nanowire position of each subunit 11 absorbs photons and then does not change the thermal resistance diffusion, only the narrow nanowire absorbs photons, there is a possibility that photons are incident on the wide nanowire, resulting in inaccurate reading.
Based on this, in order to further improve the accuracy of the light absorption rate and the photon number resolution of the first embodiment, as shown in fig. 4, the present embodiment provides a superconducting photon collection array 2. The present embodiment is basically the same as the superconducting photon collection array 1 of the first embodiment, except that the present embodiment further provides a detection nanowire 21 for improving the light absorption rate and the photon number resolution accuracy.
Specifically, the superconducting photon collection array 2 of the present embodiment further includes N detection nanowires 21; each detection nanowire 21 is in one-to-one correspondence with each subunit 11 in the present embodiment, and each detection nanowire 21 is used for absorbing the photon number, and each subunit 11 converts the photon number absorbed by the corresponding detection nanowire 21 into a thermal resistance value. The detection nanowires 21 are connected in parallel with each subunit 11, so that the detection nanowires are used as the positions of the superconductive photon collection array 2 for absorbing photons in the embodiment (as shown in fig. 4, each detection nanowire 21 is arranged at the left side of each subunit 11, and the incidence of incident light is limited at the position of each detection nanowire 21 in actual use, so that the detection nanowires can be absorbed when each photon is incident on any position of the detection nanowire 21 and then converted into a resistance state, and meanwhile, the detection nanowires 21 are separated from the wide nanowires of the hot spot regulation structure in each subunit 11 in the embodiment, and the wide nanowires can not influence the detection nanowires 21 to absorb photons.
As an example, in order to facilitate the improvement of the light absorption rate, the aspect ratio of the detection nanowires 21 is set to be greater than 10, so that each detection nanowire 21 can effectively absorb photons. However, when the aspect ratio of the detection nanowire 21 is greater than 10, if the detection nanowire 21 absorbs photons and changes to a resistive state, the thermal resistance thereof will be continuously expanded along with the length, and finally, the linear relationship between the thermal resistance value and the photon number generated by each subunit absorbing photons cannot be maintained. Thus, reading the thermal resistance value directly through the detection nanowire 21 may result in inaccurate numbers of photons finally read. In this embodiment, when the detecting nanowire 21 absorbs photons and changes to a resistive state, the loaded current information will change accordingly, and after the current information transmits the thermal resistance information to each subunit 11 connected in parallel, the wide nanowire in the hot spot adjusting structure in each subunit 11 maintains the superconducting state, but the narrow nanowire portion 111 will quench due to the current signal carrying the thermal resistance information and change to the resistive state. Meanwhile, when each detection nanowire 21 is arranged in parallel with each subunit 11 and each subunit 11 is read through a current signal, the difference of the resistance between each detection nanowire 21 and each subunit 11 is large, and when the current signal collects the thermal resistance information, the thermal resistance information of each subunit 11 can be regarded as only reactive, so that the thermal resistance of each detection nanowire 21 can not influence the thermal resistance reading of each subunit 11. The thermal resistance of each subunit 11 is linearly related to the number of photons. Further, the reading method according to the first embodiment is continued, and the resistance value of the narrow nanowire portion 11 is read, thereby obtaining the photon count.
In this embodiment, the width of the detection nanowire is set to 30nm to 1 μm, including but not limited to: 50nm, 500nm, 750nm, with lengths set at 30nm to 100 μm, including but not limited to: 50nm, 75nm, the thickness is set as: 2nm to 20nm, including but not limited to: 10nm and 15nm. In fact, the length of the detection nanowire is not limited to this embodiment.
It should be noted that, the specific shape of the detection nanowire in the embodiment is not limited to the embodiment, and any detection nanowire setting that can absorb photons and convert them into thermal resistors so as to change bias current is the protection scope of the embodiment. Through the arrangement of the embodiment, the detection nanowire is arranged at a preset position, so that photon absorptivity is ensured.
As an example, each subunit 11 is connected in series by a matching nanowire 22; the linewidth of the matching nanowire 22 is larger than the linewidth of the detecting nanowire 21; on the one hand, the matched nano wire 22 can separate the detection nano wire 21 from the hot spot regulating structure in each subunit 11, so that the diffusion of the hot resistance is further limited, and the accuracy of the hot resistance value in the hot spot regulating structure is ensured; on the other hand, since the matching nanowire 22 is larger than the line width of the detecting nanowire 21, the current value of the bias current can be improved, so that the signal-to-noise ratio of the final response pulse is improved, and the accuracy and the fidelity of photon number resolution are improved.
In this embodiment, the width of the matching nanowire 22 is set to 30nm to 10 μm, including but not limited to: 550nm, 1 μm, 10 μm, length set to 30nm to 500 μm, including but not limited to: 100 μm, 200 μm, 300 μm, with a thickness set to 2nm to 20nm, including but not limited to: 500nm, 1 μm, 10 μm, 15 μm. In fact, the value of the matching nanowire 22 is not limited to the embodiment, and any setting larger than the detecting nanowire 21 is the protection scope of the embodiment.
The present embodiment also provides a superconducting photon number resolution detector, which is implemented based on the superconducting photon collection array 2 of the present embodiment, and the setting of the superconducting photon number resolution detector of the present embodiment is basically the same as that of the first embodiment, and is not described in detail herein.
The embodiment also provides a reading method of the superconducting photon number resolution detector, which is realized based on the superconducting photon number resolution detector provided by the embodiment. The method for reading the superconducting photon number resolution detector in this embodiment is basically the same as that in the first embodiment, and will not be described in detail here.
The application realizes a superconducting photon number resolution detector based on a superconducting photon collection array, and photon number information can be read by utilizing the rising edge of response pulse, and more than 10 photon numbers can be resolved; the number of pixels in the superconducting photon collection array can be more than 1000 and is far greater than the number of incident photons, so that the problem of reading failure caused by reflecting a plurality of photon values by the same pulse can be effectively avoided. The detector efficiency of the application can reach 100%, so the photon number resolution effect has fidelity close to 100%.
In summary, the present application provides a superconducting photon collection array, a superconducting photon number resolution detector and a reading method, including: a bias current generating unit and N subunits; n is an integer greater than or equal to 2; each subunit is sequentially connected in series to form a series structure; the bias circuit generating unit is used for generating bias current and is loaded at one end of the series structure; each subunit comprises at least one hot spot regulating structure; each hot spot regulating structure comprises a narrow nanowire part and two wide nanowires; the narrow nanowire part is used for converting the absorbed photon number into a thermal resistance value under the action of bias current; the wide nanowires are used for limiting diffusion of thermal resistance so as to ensure that the thermal resistance of each hot spot regulating structure is linearly related to photons. According to the application, by arranging the hot spot regulating structure, the photon number can be obtained based on the linear relation between the thermal resistance value and the photon number, and the photon resolution and the fidelity are effectively improved. Therefore, the application effectively overcomes various defects in the prior art and has high industrial utilization value.
The above embodiments are merely illustrative of the principles of the present application and its effectiveness, and are not intended to limit the application. Modifications and variations may be made to the above-described embodiments by those skilled in the art without departing from the spirit and scope of the application. Accordingly, it is intended that all equivalent modifications and variations of the application be covered by the claims, which are within the ordinary skill of the art, be within the spirit and scope of the present disclosure.
Claims (13)
1. A superconducting photon collection array, the superconducting photon collection array comprising: a bias current generating unit and N subunits; n is an integer greater than or equal to 2;
each subunit is sequentially connected in series to form a series structure;
the bias circuit generating unit is used for generating bias current and is loaded at one end of the series structure;
each subunit comprises at least one hot spot regulating structure; when more than two hot spot regulating structures are arranged in each subunit, the hot spot regulating structures are sequentially connected in series;
each hot spot regulating structure comprises a narrow nanowire part and two wide nanowires; each wide nanowire is respectively arranged at two sides of the narrow nanowire part and is connected with the narrow nanowire part in series;
the aspect ratio of the narrow nanowire part is less than or equal to 10, and the narrow nanowire part is used for converting the number of absorbed photons into a thermal resistance value under the action of bias current; the width of each wide nanowire is 1.2 times or more and 10 times or less of the width of the narrow nanowire part, and the width of each wide nanowire is used for limiting the diffusion of thermal resistors so as to ensure that the thermal resistance value of each hot spot regulating structure is linearly related to photons;
wherein the bias current has a current value less than a critical current value of the narrow nanowire portion.
2. The superconducting photon collection array of claim 1, wherein: each subunit is sequentially arranged along a direction or each subunit is arranged in a winding way.
3. The superconducting photon collection array of claim 1, wherein: the widths of the two wide nanowires in each hot spot regulating structure are equal.
4. The superconducting photon collection array of claim 1, wherein: the superconducting photon collection array also comprises N detection nanowires; each detection nanowire is connected with each subunit in parallel in a one-to-one correspondence manner; the detection nanowires are used for absorbing photon numbers, and each subunit converts the photon numbers absorbed by the corresponding detection nanowires into thermal resistance values.
5. The superconducting photon collection array of claim 4, wherein: the aspect ratio of each detection nanowire is greater than 10.
6. The superconducting photon collection array of claim 4, wherein: each subunit is connected in series through a matching nanowire;
the linewidth of the matching nanowire is greater than the linewidth of the detecting nanowire.
7. The superconducting photon collection array according to any one of claims 1-6, wherein: the narrow nanowire part comprises M narrow nanowires, M is an integer which is more than or equal to 1 and less than or equal to 5; when M is more than or equal to 2, each narrow nanowire is arranged in parallel; the width of the narrow nanowire part is equal to the sum of the line widths of M narrow nanowires arranged in parallel.
8. The superconducting photon collection array of claim 7, wherein: chamfer angles are arranged at corners of junctions of the narrow nanowire parts and the two wide nanowires in each hot spot regulating structure; the chamfer is a chamfer angle or a round angle.
9. A superconducting photon number resolution detector, characterized in that the superconducting photon number resolution detector comprises a readout circuit and a superconducting photon collection array according to any one of claims 1-8; the readout circuit is connected with the output end of the superconducting photon collection array so as to collect pulses of output current of the superconducting photon collection array.
10. The superconducting photon number resolution detector of claim 9, wherein: the superconducting photon number resolution detector also comprises a calculation unit; the calculation unit is connected with the output end of the readout circuit, and calculates the photon number based on the linear relation between the pulse rising edge slope of the output current of the superconducting photon acquisition array and the photon number, or calculates the photon number based on the inverse relation between the pulse rising edge time and the photon number.
11. A method for reading a superconducting photon number resolution detector, based on the implementation of the superconducting photon number resolution detector as claimed in any one of claims 9 to 10, characterized in that the method for reading a superconducting photon number resolution detector comprises:
s1, enabling the bias current to flow through each subunit;
s2, incident light is incident to the superconducting photon collection array and absorbed through the corresponding subunit; each subunit converts the absorbed photon number into a thermal resistance value under the action of bias current, and the thermal resistance value of each hot spot regulating structure is linearly related to the photon number; and acquiring thermal resistance information of each subunit in the superconducting photon acquisition array.
12. The method of reading a superconducting photon number resolution detector according to claim 11, wherein: the reading method of the superconducting photon number resolution detector further comprises the step S3;
and S3, calculating to obtain the photon number based on the linear relation between the rising edge slope of the output current pulse of the superconducting photon collection array and the photon number or the inverse relation between the rising edge time of the pulse and the photon number.
13. The method of reading a superconducting photon number resolution detector according to claim 12, wherein: the rising edge time of the output current pulse of the superconducting photon collection array and the number of photons satisfy the following conditions:
τ＝L k /nR hs
wherein τ is the rising edge time of the output current pulse of the superconducting photon acquisition array; l (L) k Resolving the total inductance of the detector for the number of superconducting photons; n is the number of photons collected; r is R hs The photon is received by each subunit and then converted into the resistance value of the thermal resistor.
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