Device and system for single photon detection using multiple superconducting detection elements connected in parallel

Abstract

The present invention relates to a device for single photon detection, comprising at least two superconducting detection components (1), a bias current source (2), a filter element (3) and a readout circuit (4), wherein each superconducting detection component (1) forms a detection region suitable for absorbing incident photons and is connected in parallel, and each superconducting detection component (1) is maintained at a temperature below its critical temperature (T C ) and is provided at a temperature close to and below its critical current (I C ) bias current (I B ), such as to be normally maintained in a non-resistive superconducting state and adapted to transition from said non-resistive superconducting state to a resistive state upon photon absorption, due to an increase in current density within the superconducting detection component (1) to a critical current (I C ) above, the readout circuit (4) is adapted to sense a voltage change corresponding to the transition of the superconducting detection elements (1) to their resistive state, such as to allow an event signal to be generated for each absorption of an incident photon by any one of the superconducting detection elements (1). The device is distinguished in that it also comprises at least one current redistribution element (5) adapted to at least partially redistribute the current generated after absorption of an incident photon by any one of the superconducting detection elements (1) into the current redistribution device (5), such as to avoid that any one of the superconducting detection elements (1) that has not absorbed an incident photon is subjected to an increase in current density to its critical current (I C The present invention also relates to a system for single photon detection comprising at least two such devices.

Description

Technical Field

[0001] The present invention relates to a device for single photon detection, which includes at least two superconducting detection elements and a bias current source, a filter element and a readout circuit, wherein each superconducting detection element forms a detection area suitable for absorbing incident photons and is connected in parallel to the bias current source and the readout circuit through the middle of the filter element, each superconducting detection element is maintained at a temperature below its critical temperature, the bias current source provides each superconducting detection element with a bias current close to and below the critical current of the superconducting detection element, such as to normally maintain each superconducting detection element in a non-resistive superconducting state, each superconducting detection element is suitable for transitioning from the non-resistive superconducting state to its resistive state when absorbing an incident photon, and the readout circuit is suitable for sensing a voltage change corresponding to the transition of the superconducting detection element to its resistive state, such as to allow an event signal to be generated for each absorption of an incident photon by any of the superconducting detection elements. Background Art

[0002] In general, the present invention relates to techniques and devices for single-photon detection. Many current applications, such as quantum key distribution, optical free-space communications, or optical time-of-flight (TOF) measurement techniques like optical time-domain reflectometry (OTDR) or light detection and ranging (LIDAR), require single-photon detectors with high efficiency, high detectivity, low timing jitter, and low noise. Superconducting nanowire single-photon detectors (SNSPDs) can achieve excellent performance in all of these applications.

[0003] In this context, it is well known that the simplest implementation of an SNSPD is based on a superconducting nanowire forming a single meander that is connected to a bias current source and corresponding readout electronics. The detectivity of such a conventional single-meander SNSPD is limited by its recovery time (i.e., the time required for the detector to become sensitive to single photon detection again after a photon detection or false count). As is clear to those skilled in the art, a short recovery time means that the detector can detect more photons in a given time period, provided that the detector is disabled for photon detection during its hardware-defined recovery time.

[0004] Those skilled in the art also know that the recovery time of a single-meander SNSPD is directly related to its kinetic inductance, which increases monotonically with the length of the nanowire. Therefore, reducing the kinetic inductance of a single-meander SNSPD reduces its recovery time and allows its detection rate to be improved. This is feasible before the so-called latch-up effect occurs, which prevents further reduction in the recovery time. The latch-up effect is caused by an electro-thermal feedback mechanism that causes the nanowire to enter and become stuck in a resistive state if the recovery time of the nanowire is too short compared to the rate at which the nanowire cools through thermal contact with the surrounding material.

[0005] The recovery time of the SNSPD can be further reduced by splitting the single meander nanowire into smaller nanowire segments and connecting each of them in parallel to the bias current source and the readout electronics. In fact, if the total nanowire detection area remains the same, each nanowire segment of such an SNSPD with nanowire meander segments connected in parallel is shorter than the corresponding single meander SNSPD nanowire and, therefore, each of said nanowire segments has a smaller recovery time. By connecting these segments in parallel, a single readout electronics circuit allows to determine whether one of the segments has been hit by a photon, i.e., whether the segment has become resistive due to the absorption of a photon. During the recovery time of a given segment, each of the other segments can still be used to detect another photon, so that the entire device is still ready to detect photons. This also allows to reduce the effective recovery time of the entire device compared to a single meander SNSPD with the same total nanowire detection area.

[0006] However, such SNSPDs with parallel-connected nanowire segments present the problem of current crosstalk between the connected segments. Indeed, whenever a photon absorption occurs in one of the nanowire segments, the current initially passing through this segment is of course partially redistributed into the readout electronics, which allows the automatic and unintentional creation of detection signals also in other segments. At high detection rates, the redistribution of the current generated after photon absorption in other segments can become problematic, in particular if several nanowire segments are hit by photons quasi-simultaneously, i.e., within their respective recovery times, since this can generate current pile-up effects in other segments. If the current in a given segment is close to or greater than its own local critical current, this current pile-up effect leads to an increased probability that other nanowire segments themselves become resistive (i.e., do not absorb photons). This further exacerbates the pile-up effect in the remaining nanowire segments and can eventually produce cascades, which results in a completely disabled detector in a latch-up state, i.e., a state in which all segments are resistive and in which no segment can recover to its superconducting state unless the total current is electronically reset to zero and then returned to its nominal value, a slow operation. Thus, the potential for achieving high detectivity in parallel-connected SNSPDs is severely limited by current crosstalk and the corresponding current pile-up and cascade effects.

[0007] In general, various solutions are known in the prior art for implementing SNSPDs that allow for a high detection rate to a certain extent. For example, detectors with a multi-pixel design use several independent SNSPDs integrated next to each other on a chip. Instead of connecting several nanowire segments in parallel, this solution uses separate coaxial lines and readout circuits for each detector pixel, such as to enable them to operate independently of each other. Due to the requirement for dedicated coaxial lines that must be integrated into the cryostat and dedicated readout circuits for each nanowire segment, this solution is costly and may also be impractical, for example due to the relatively large volume occupied.

[0008] Russian patent RU 2 327 253 discloses an SNSPD having several nanowire segments connected in parallel and, for each of the segments, a resistor connected in series with the corresponding segment. The current crosstalk mentioned above and the corresponding current pile-up and cascade effects are partially limited by the addition of the resistors. The recovery time of each nanowire segment can also be shortened by increasing the value of the resistor connected in series with the segment, up to a certain limit dictated by the cascade effect, which temporarily disables the entire detector. While this solution allows for individual control of the recovery time of each segment, it is not suitable for completely solving the problem of current crosstalk, especially at high detection rates, since the device will latch up at high count rates.

[0009] Chinese patent application CN 106 289 515 discloses a single-meander SNSPD with a self-gain structure. To this end, the SNSPD includes a second nanowire, unexposed to photons, alongside a single-meander nanowire exposed to photons, with the two nanowires connected in parallel. The single-meander nanowire is used to detect photons, while the unexposed nanowire is used to amplify the pulse signal caused by photons hitting the single-meander nanowire, such as to increase the amplitude of the output signal. More specifically, the unexposed nanowire is used to provide an internal gain mechanism for a so-called SNAP-SNSPD device, which is intended to improve the signal-to-noise ratio of a single-meander SNSPD. Despite the use of an unexposed nanowire alongside the single-meander nanowire exposed to photons, the device according to CN 106 289 515 must still be considered a single-meander SNSPD. Its additional structure only allows for an improvement in the signal-to-noise ratio and thus amplification of the SNSPD's single-meander pulse signal, while the device otherwise suffers from the same drawbacks as other known single-meander SNSPDs, particularly with regard to the aforementioned issues associated with current crosstalk. In fact, in order to perform the amplification of the pulse signal, the additional structure of the device according to CN 106289515 must be designed so that it cannot support the increase in current caused by the detection of photons in the nanowires exposed to the photons. This is achieved by selecting the width of the unexposed nanowires (such as strictly equal to N times the width of the nanowires exposed to the photons) and having 1 / N times the inductance and resistance values of the nanowires exposed to the photons. Therefore, the unexposed nanowires of the device according to CN 106289515 are specifically designed so that the current density in the unexposed nanowires generated after the detection of photons in the nanowires exposed to the photons will rise above the critical current density that it can support, thus causing the unexposed nanowires to become resistive and ultimately contribute to increasing the amplitude of the output signal. However, for the same reason, by construction principle, the device according to CN 106289515 is not suitable for solving, but rather leads to, the above-mentioned problems associated with current crosstalk. Summary of the Invention

[0010] Purpose of the present invention

[0011] Therefore, the solution of single photon detection by using superconducting nanowire single photon detectors according to the prior art is still affected by several drawbacks. The object of the present invention is to at least partially overcome the difficulties mentioned above and to realize a device for single photon detection with high efficiency, high detectivity, low timing jitter and low noise. The device should be particularly suitable for high detectivity by avoiding the disadvantages of the prior art devices due to current crosstalk and the corresponding current pile-up and cascade effects, while maintaining high efficiency. In addition, the device should be suitable for applications in the field of quantum key distribution, optical free space communication and time of flight (TOF) measurements, such as optical time domain reflectometry (OTDR), light detection and ranging (LiDAR), positron emission tomography (PET) scanners and TOF cameras. At the same time, the device should occupy a relatively small volume and be possible to produce at a sustainable cost without unnecessary or expensive components.

[0012] Solution according to the invention

[0013] To this end, the present invention proposes a device characterized by the fact that the device includes at least two superconducting detection elements as well as a bias current source, a filter element and a readout circuit, wherein each superconducting detection element forms a detection area suitable for absorbing incident photons and is connected in parallel to the bias current source and the readout circuit through the filter element as an intermediate, each superconducting detection element is maintained at a temperature below its critical temperature, the bias current source provides each superconducting detection element with a bias current located close to and below the critical current of the superconducting detection element so as to maintain each superconducting detection element in a non-resistive superconducting state under normal circumstances, each superconducting detection element is suitable for transitioning from the non-resistive superconducting state to a resistive state when absorbing an incident photon, and the readout circuit is suitable for sensing the voltage change corresponding to the transition of the superconducting detection element to its resistive state so as to allow the generation of an event signal for each absorption of an incident photon by any one of the superconducting detection elements. In particular, the device according to the invention is characterized by the fact that it also comprises at least one current redistribution component adapted to at least partially redistribute the current generated after absorption of an incident photon by any of said superconducting detection components into said current redistribution components, such as to avoid that any superconducting detection component which has not absorbed an incident photon is subjected to an increase in current density above its critical current.

[0014] These features allow achieving the objectives identified above, in particular by adding to the prior art devices a complementary structure implemented by the current redistribution element. Indeed, by distributing the currents generated after the crosstalk between the superconducting detection elements to the current redistribution element located within the device, it is possible to reduce or (respectively) avoid the current crosstalk and the corresponding current pile-up and cascade effects. Thus, compared to the prior art, the device can operate with a higher detection rate while maintaining a high efficiency of the device.

[0015] In a particularly preferred embodiment of the invention, the current redistribution components are adapted to support sufficient current to maintain superconductivity even if all superconducting detection components are in their resistive state. Furthermore, the dimensions of the current redistribution components may be selected, such as to select their respective kinetic inductances. The current redistribution components may be arranged within the device, such as to be not exposed to incident photons or to have a geometry, in particular a width and / or thickness, that prevents them from being photodetected even when exposed to photons. The device according to the invention further comprises at least one control element, each of which is connected in series to the superconducting detection components or (respectively) to the current redistribution components to allow the bias current to be divided into different parts of the device in a controlled manner.

[0016] Further features and advantages of the invention are mentioned in the following description which discloses the invention in more detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings illustrate exemplarily and schematically some known prior art devices as well as the principles and several embodiments of the present invention.

[0018] Figures 1a to 1f illustrate the prior art related to the present invention; in particular, Figure 1a schematically illustrates the simplest embodiment of the prior art according to the SNSPD based on a superconducting nanowire, which forms a single meander line connected to a bias current source and corresponding readout electronic devices; Figure 1b schematically illustrates an electronic circuit equivalent to the embodiment of the SNSPD of Figure 1a; Figure 1c schematically illustrates an electronic circuit equivalent to the embodiment of the SNSPD, which SNSPD includes several nanowire segments connected in parallel to the bias current source and the corresponding readout electronic devices; Figure 1d schematically illustrates an embodiment of a single photon detector with a multi-pixel design using several independent SNSPDs; Figure 1e schematically illustrates an embodiment of the SNSPD including several nanowire segments connected in parallel to the bias current source and the corresponding readout electronic devices, for each of the segments, the SNSPD also including a resistor connected in series with the corresponding nanowire segment; Figure 1f shows a numerical simulation of the behavior of the device of Figure 1e upon photon absorption.

[0019] Figures 2a to 2c The structure of the device and system for single photon detection according to the present invention is shown; in particular, Figure 2a schematically illustrates a first embodiment of a device for single photon detection according to the present invention; Figure 2b schematically illustrates a second embodiment of a device for single photon detection according to the present invention; Figure 2c The structure of a system for single photon detection according to the present invention comprising several devices is schematically illustrated.

[0020] Figures 3a to 3c The advantages of the device for single photon detection according to the present invention are illustrated, in part, compared with prior art devices; in particular, Figure 3a shows the results of a numerical simulation of current crosstalk in a device according to the invention after an incident photon has been absorbed by one of its photosensitive sections; Figure 3b shows a comparison of the detection rate related to the number of detected photons per second of a device for single photon detection according to the present invention and a conventional single-meant SNSPD, both covering almost the same photosensitive area; Figure 3c A comparison of the average detection efficiency per photon with respect to the number of detected photons per second of a device for single photon detection according to the present invention and a conventional single-meander SNSPD is shown, both covering almost the same photosensitive area. DETAILED DESCRIPTION

[0021] The present invention will be described in detail below with reference to the above-mentioned drawings.

[0022] The present invention relates to a device for single photon detection based on superconducting material, the superconducting material forming a superconducting detection component having an absorption region for incident photons. Therefore, the remainder of the present description will mainly deal with the case where the superconducting detection component is realized by a superconducting nanowire, without limiting the scope of the corresponding interpretation, which extends by analogy to any type of superconducting detection component suitable for this purpose, for example, any kind of superconducting tape of suitable material and / or a superconducting film or coating of suitable shape and thickness known to those skilled in the art. Therefore, and for reasons of simplicity of the language used, the following description will make extensive use of the terms "superconducting detection component", "superconducting nanowire" and "superconducting nanowire segment", again without limiting the scope of the corresponding interpretation, which extends by analogy to any kind of suitable superconducting material.

[0023] In this context, in order to better understand the technical problems briefly mentioned in the introduction and the basis of the present invention, the following description will briefly review the structure and working principles of several prior art devices as well as the corresponding difficulties and shortcomings, especially with the help of the schematic diagrams shown in Figures 1a to 1f.

[0024] Figure 1a schematically illustrates the simplest embodiment of a prior art SNSPD based on superconducting nanowires. The nanowire 1 forms a single meander connected to a bias current source 2 and corresponding readout electronics 4. The bias current source 2 provides a DC bias current I B , which is close to and lower than the critical current I of the superconducting nanowire 1 C And flows through the single meandering superconducting nanowire 1 through the middle of the bias tee 3. The bias tee 3 can be implemented as having an inductance L B The inductor and the capacitor C B 1a as an example, but it can also consist of any other equivalent duplexer or filter element 3, allowing the realization of a bias tee in order to combine or separate the DC and AC components of the electrical signal. The single meandering nanowire 1 forms the detection region, which is exposed to incident light (i.e., incident photons) and is cooled to its critical temperature T C Below, the current flowing through the single meander nanowire 1 is usually kept below its critical current I C In the case of absorption of incident photons by the superconducting nanowire 1, the superconducting nanowire 1 transitions from its non-resistive superconducting state to a resistive state due to the appearance of local resistive hot spots, which produces a reduction in the effective width of the superconducting nanowire and thus leads to an increase in the current density within the remaining width of the superconducting nanowire 1 to the critical current I C The readout electronics 4 typically consists of an amplifier and a comparator capable of sensing the voltage change after the amplifier, so that the transition of the single meander superconducting nanowire 1 from its non-resistive superconducting state to the resistive state caused by photon absorption will result in the generation of an output voltage pulse, thereby allowing single photon detection. This configuration can be illustrated in a simplified and schematic manner by an electronic circuit system equivalent to the single meander SNSPD of FIG1a, such as that shown in FIG1b. Therein, the single meander nanowire forming the detector 1 consists of a kinetic inductance L K , provide the resistor R of normal resistance state N and a physical representation of the switch SW controlled by photon absorption. For the schematic diagram of Figure 1b, the operating principle of the above single-meant SNSPD can be simplified as follows. When the detector 1 is in its superconducting state, the switch SW is closed and the bias current I provided by the bias current source 2 is B flows through the detector 1. When photon absorption occurs, the switch SW opens, i.e. the detector 1 enters its resistive state, the probability of this happening being dependent on the bias current I B value and the temperature of detector 1, and current begins to flow through resistor R N This dissipates the heat by Joule heating and strengthens the resistive state of the detector, which keeps the switch SW open. Because the resistor R, which typically has a resistance of about 1 kOhm NTypically much larger than the impedance of the readout circuitry, which typically has a resistance of about 50 Ohms, the current flowing after photon absorption is instantaneously redirected to the readout circuitry 4. This means that heat is no longer dissipated through R N dissipation, thereby allowing the detector 1 to cool down again to its critical temperature T C Below, this is equivalent to closing the switch SW and setting the bias current I B Pulled back into the detector 1, the latter is ready for photon detection again. However, as mentioned in the introduction, the detectivity of such a conventional single-meander SNSPD is greatly limited by its recovery time, especially as the detection area increases, that is, as the length of the superconducting nanowire 1 increases, because the recovery time is proportional to the kinetic inductance L of the single-meander. K is directly related to the η, which increases monotonically with the length of the nanowire.

[0025] FIG1c schematically illustrates, in a simplified manner similar to FIG1b, an electronic circuit equivalent to an embodiment of a SNSPD comprising several nanowire segments 1 connected in parallel to a bias current source 2 and corresponding readout electronics 4 via an intermediate bias tee, which is a filter element 3. Each nanowire segment 1 has a kinetic inductance L K and resistor R N , they usually each have the same or similar values, and the bias current I B is usually divided equally into each nanowire segment 1, that is, for the example of a SNSPD comprising three nanowire segments shown in FIG1c , each segment 1 is biased with a current of ˜0.33*I B The operating principle of such an SNSPD with several parallel-connected nanowire segments 1 generally corresponds to what was explained above for the single-meander SNSPD, with the difference that, when a photon absorption occurs in one of the nanowire segments 1, the current generated after the photon absorption is not only redirected towards the readout electronics 4 to generate a signal pulse, which allows photon detection, but also automatically enters the other nanowire segments 1, where, due to this current crosstalk between some or all of the nanowire segments 1, the local current thus temporarily increases to exceed the bias current I B As long as the increased current in any nanowire segment 1 associated with current crosstalk remains below the local critical current I C , the principle of using several nanowire segments 1 connected in parallel to increase the detectivity works. However, this current crosstalk mentioned in the introduction and the corresponding current pile-up and cascade effects can lead to partially or completely disabled detectors, i.e., a state in which part or all of the nanowire segments 1 are in a resistive state, causing most or the entire detector to be in a blocked state. This can occur in particular at high detectivities, where several nanowire segments 1 can contribute to the generation of current crosstalk because they are hit by photons at the same time.

[0026] Figure 1d schematically illustrates an embodiment of a single-photon detector with a multi-pixel design. In this case, several independent superconducting nanowire segments 1 are connected to corresponding readout circuits 4 via separate coaxial lines. That is, the nanowire segments 1 are not connected in parallel, so that each nanowire segment 1 is incorporated into a separate SNSPD. As mentioned in the introduction, this solution is costly, occupies a relatively large volume, and generally represents a different approach compared to SNSPDs comprising several nanowire segments connected in parallel.

[0027] FIG1e schematically illustrates an embodiment of an SNSPD according to Russian patent RU 2 327 253, comprising several nanowire segments 1 connected in parallel to a bias current source 2 and corresponding readout electronics 4, respectively, via the intermediate of a bias tee of a filter element 3. For each of the segments, the SNSPD further comprises a resistor R connected in series with the corresponding nanowire segment 1. S . Although adding the resistor R S This allows to control the recovery time of each segment to a certain extent and partially limit the current crosstalk mentioned above and the corresponding current accumulation and cascade effects, but this measure is not suitable for completely solving the current crosstalk problem at high detection rates, because the crosstalk is caused by the resistor R S The resistance of the device decreases with the increase of the resistance. This resistance is limited to a maximum value, above which the device will latch up. To understand the reason for the latter, Figure 1f shows a numerical simulation of the behavior of the device of Figure 1e caused by current crosstalk when one of the nanowire segments 1 absorbs a photon. The flash in the inset in the upper right corner of Figure 1f symbolizes that a photon hits the leftmost nanowire segment 1. The current generated after this photon absorption in one of the other segments that was not hit by the photon is shown in the main figure of Figure 1f. Before the photon absorption, the current in the non-hit segment is stable at a bias current of about 20 μA. When the leftmost segment is hit by a photon, the current in the non-hit segment rises to slightly above 27 μA at time 100 ns in Figure 1f, and then slowly returns to the value of the bias current, which is due to the temporal dynamics of the electronic circuit. However, the superconducting nanowire segment 1 should be as close to and below its critical current I as possible. C operation in order to maximize its detection efficiency. Therefore, if the critical current I CIf the bias current is greater than 20 μA but less than 27 μA, the situation shown in Figure 1f will result in all nanowire segments 1 being in a resistive state, causing the entire device to latch up and thus be disabled. Therefore, it is not possible to operate this device near its maximum detection efficiency, and it is necessary to reduce the bias current, which in turn reduces efficiency. Furthermore, it is likely that the latch-up state of the device will still occur at high detection rates, making the device unsuitable for photon detection at high count rates.

[0028] Turning now to the apparatus for single photon detection according to the present invention, it should be noted that the present invention proposes an anti-cascade design for parallel-connected SNSPDs. The anti-cascade parallel-connected SNSPDs according to the present invention, hereinafter referred to as ACPC-SNSPDs, are primarily designed to address the aforementioned current crosstalk issues at high count rates and the corresponding current pile-up and cascade effects, such as to unleash the potential of parallel-connected SNSPDs to achieve high detection rates.

[0029] Generally speaking, the device for single photon detection according to the present invention comprises at least two, usually several, superconducting detection components 1 as well as a bias current source 2, a filter element 3 and a readout circuit 4, such as Figure 2a Schematically shown in FIG. Preferably, each superconducting detection component 1 is realized by a superconducting nanowire segment, which generally has a meandering geometry and is well known to those skilled in the art. Each superconducting detection component 1 (i.e., each meandering superconducting nanowire segment 1) is exposed to light, forms a detection region suitable for absorbing incident photons and is connected in parallel to the bias current source 2 and the readout circuit 4 through the intermediate body of the filter element 3. Each superconducting detection component 1 is maintained below its critical temperature T C The bias current source 2 provides each superconducting detection component 1 with a critical current I close to and lower than the critical current I of the superconducting detection component 1. C Bias current I B , such as to generally maintain each superconducting detection component 1 in a non-resistive superconducting state. Moreover, in the event of absorption of an incident photon, each superconducting detection component 1 is adapted to transition from said non-resistive superconducting state to a resistive state. In fact, the absorption of the incident photon generates a disturbed region in the superconducting detection component 1. The disturbed region, which is passed through by the bias current IB like the rest of the superconducting detection component 1, leads to the appearance of a local resistive hot spot, which produces a reduction in the effective volume of the superconducting detection component 1 and thus leads to an increase in the current density within the remaining superconducting volume of the superconducting detection component 1 above the critical current I C In turn, the readout circuit 4 is adapted to sense the voltage change corresponding to said transition of the superconducting detection elements 1 to their resistive state and thus allows to generate an event signal for each absorption of an incident photon by any one of said superconducting detection elements 1 .

[0030] Although the superconducting detection components 1 are preferably each realized by a meandering superconducting nanowire segment, these detection components may also be formed by superconducting tapes of any kind of suitable material and / or by superconducting films or coatings of suitable shape and thickness, which are generally known to those skilled in the art and are therefore not described in more detail here. In addition, each superconducting detection component 1 can have any suitable geometric shape, for example, it can be a meandering, circular, straight-line form, a staggered geometric shape, a combination of these geometric shapes or any other shape suitable for a specific application. In any case, at least two superconducting detection components 1 (i.e., for many applications, all meandering superconducting nanowire segments 1) are preferably produced simultaneously and integrally by using known manufacturing methods. The bias current I is provided to each superconducting detection component 1. B The bias source 2 can be selected by a person skilled in the art from among all known components suitable for that purpose and is therefore not described in more detail here. The filter element 3 is also known per se and can be implemented as comprising an inductor L B An inductor and a bias tee 3 of a capacitor with capacitance CB, such as Figure 2a , but it may also include a duplexer or any other equivalent component allowing the implementation of a filter in order to combine or separate the DC and AC components of the electrical signal. The readout circuit 4 generally comprises an amplifier and a comparator capable of sensing the voltage change after the amplifier, but may also include any other equivalent readout device known to those skilled in the art, provided that the invention is not located in these components of the device.

[0031] In fact, the device for single photon detection according to the present invention differs from the prior art in two main aspects. Firstly, in order to reduce the electrical crosstalk between the superconducting detection components 1 connected in parallel (i.e. between the meandering superconducting nanowire segments 1), at least one additional segment 5, also connected in parallel, is integrated into the device, such as in Figure 2a. These additional parallel sections 5 are engineered so that they do not become resistive even when light is incident on the device, i.e., these sections are preferably not exposed to incident light and / or have a geometry that prevents them from being detected by light even when exposed to light, in particular, due to their width and / or thickness, these additional sections 5 are not suitable for photon detection. In the following, the superconducting detection component 1 suitable for detecting photons when light is incident on the device (i.e., in general, the meandering superconducting nanowire section 1) is also referred to as the "photosensitive section", and the additional parallel section 5 that is not exposed to light and / or has a geometry that does not allow detection of photons even when light is incident on the device is referred to as the "current redistribution section", "current redistribution path" or "current redistribution component" 5. It should also be noted that the term "integrated" is used here to mean that the current redistribution component 5 is preferably manufactured in one piece and at the same time as the photosensitive section, i.e., typically using the same nanofabrication technology used to produce all the meandering superconducting nanowire sections 1. Typically, a chip comprising all components of the entire ACPC-SNSPD is manufactured in one piece using the same nanofabrication technology. The addition of additional segments such as the current redistribution element 5 is suitable for solving problems associated with current crosstalk and the corresponding current pile-up and cascading effects, since the current crosstalk between the photosensitive segments has become disabled and the amount of current increase in any other segment (i.e., the amount of current increase in a given segment) decreases with the total number of segments. The latter is valid to a certain extent for both cases: the total number of segments consists only of photosensitive segments, as in prior art devices, and the total number of segments consists of photosensitive segments used for photon detection and additional segments used only as current redistribution elements, as in devices for single photon detection according to the present invention. However, the latter configuration according to the present invention is particularly advantageous, especially at high detection rates, provided that the current redistribution element 5 does not contribute to the generation or increase of current crosstalk, but only reabsorbs current generated by crosstalk originating from the photosensitive segment 1. Due to this design, only a limited number of segments (i.e., the photoactive segments 1) can become resistive simultaneously by absorbing incoming light, while the current redistribution paths 5 cannot become resistive by absorption of incident light due to the construction of the device. Secondly, the additional segments (i.e., the current redistribution paths 5) are designed to support sufficient current to remain superconducting, i.e., remain available to carry current in their superconducting state, even if all photoactive segments 1 of the device are in their resistive state after multiple simultaneous absorption of photons. This is accomplished by selecting the superconducting material, number, geometry, width and / or thickness of the current redistribution paths 5 in such a way that even if the entire bias current flows into the current redistribution paths 5 (which would occur if all photoactive segments 1 were in a non-superconducting state), the current density in each redistribution path 5 is still below the critical current density of the superconducting material used.For this purpose, the superconducting material used for the current redistribution path 5 may be, for example, different from the superconducting material used for the photosensitive nanowires. For the same purpose, the width W for a given superconducting material is used. S And the thickness is d S A given number N S The photosensitive nanowires 1 and all have the same resistance value R R Terminate (assuming for this example that it is equal to R S ) and (for this example also assume) the number of superconducting materials produced is N R The minimum width W required for the current redistribution path 5 is R The formula W R >W S *[1+(N S / N R )] to calculate. It should be noted that W R must be above this value, which forms the minimum width W of the current redistribution path 5 R In particular, W R The lower limit of the value is based on the critical current density and the cross section d*W of the redistribution path 5 R The proportionality assumption is made, but in practice there may be reasons why the requirements for the redistribution paths obtained from this assumption are insufficient, although still necessary, such as limitations of superconducting materials or constraints due to nanofabrication methods. For these reasons, the minimum width W required for the current redistribution path 5 is R It is generally fixed at a value greater than the minimum width required according to the formula mentioned above. It should also be emphasized that this is only mentioned as a specific example, but the formula mentioned above does not represent the minimum width W. R The most general expression of the lower limit of , provided that this formula is in principle valid only when the photosensitive nanowire 1 and the current redistribution path 5 are made of the same material and thickness and the resistance R S With R R If the thickness d of the photosensitive nanowire 1 and the current redistribution path 5 is the same as S with d R are different and if the resistance R S It is not necessarily the same as RR, so a more general expression is formula W R >W S *(d S / d R )*[(R S / R R )+(N S / N R)]. For the case where the materials of the photosensitive nanowire 1 and the current redistribution path 5 are also different, it is possible to also indicate the minimum width W R For simplicity, this is not described further here, but can be obtained by a person skilled in the art based on the present disclosure and its technical teachings. In this context, it is noted that the device according to Chinese patent application CN 106 289 515 has an unexposed nanowire whose width is limited to less than the W mentioned above. R The lower limit of the value is set to allow amplification of the pulse signal, and as explained in the introduction, this unexposed nanowire cannot be used as a current redistribution path, such as proposed in the present invention. In contrast, the design of the device according to the present invention allows for a cascade of current pile-up effects that do not temporarily disable all photosensitive sections 1 and require a time-consuming device reset. This provides freedom in designing additional sections that serve as current redistribution paths 5, such as to ensure optimal performance of the overall device.

[0032] As a specific example, Figure 2a A schematic diagram of a first embodiment of a device for single photon detection according to the invention is shown, wherein the device comprises three parallel-connected photosensitive segments 1 forming a detection area, similar to the three nanowire segments of the prior art device shown in Figures 1c and 1e, and two parallel-connected current redistribution paths 5, which are not present in the prior art SNSPD using parallel-connected nanowire segments and are not exposed to the incident light. These current redistribution paths 5 allow limiting any current crosstalk that occurs between the three photosensitive segments 1 when photon absorption occurs in one or several of these photosensitive segments 1. This therefore allows avoiding the corresponding current pile-up and cascade effects observed in prior art devices. Moreover, this is also subject to the choice of the shape of the current redistribution paths 5 (such as the choice of their respective kinetic inductances L KR ), preferably depending on the kinetic inductance L of the photosensitive section 1 K in such a way as to allow for optimal cooperation with the photosensitive segment 1. In addition, as Figure 2a As shown in FIG, the device for single photon detection according to the first embodiment of the present invention preferably, but not necessarily, further includes control elements 6 and 7, which are usually implemented as resistors R S and R R , which are connected in series to the photosensitive section 1 or (respectively) the current redistribution path 5 in order to divide the DC bias current into different parts of the device in a predefined, controlled manner. R is also selected in a way that allows the current flowing into the photosensitive section 1 and the current redistribution path 5 to be selected. S and R R The value of .

[0033] In another embodiment of the present invention, not shown in the figure but with Figure 2a The current redistribution path 5 is exposed to light brought by the optical fiber, but no light is detected even when exposed to light, for example because of the geometry of the nanowires forming the current redistribution path 5, i.e., because of its width and / or thickness. More precisely, the geometry of the nanowires of each current redistribution path 5 can be selected, such as to obtain any desired kinetic inductance L. KR , while selecting a width and / or thickness large enough to prevent light detection even when a single photon is absorbed by the nanowires that form the current redistribution path.

[0034] In another embodiment of the present invention, not shown in the figure but with Figure 2a Similar to a device, light is directed towards the device by free space coupling, using a lens, in a manner that allows incident light to be directed either only towards the photosensitive section 1 or also towards the current redistribution path 5, but, in this case, the current redistribution path 5 is unable to detect light due to the geometry that can be chosen (such as mentioned above).

[0035] Figure 2b A second embodiment of the device according to the invention is schematically illustrated, wherein the photosensitive segments 1 connected in parallel inside the device are strategically positioned in the center of the device. Each photosensitive segment 1 is preferably terminated by a control element 6 connected in series to the corresponding photosensitive segment 1 and connected by a resistor R S Realize, in Figure 2b The top of the photosensitive section 1 is shown as a wavy line. The current redistribution path 5 connected in parallel with the photosensitive section 1 is formed by a meandering superconducting nanowire and can be arranged, for example, to form two mutually opposing arcs of a circle, with the photosensitive section 1 located near the center and between the two arcs, such as Figure 2b The device preferably further comprises control elements 7, each of which is connected in series to the current redistribution path 5, said control elements 7 being Figure 2b The resistor R shown in R To achieve this, the resistor R R exist Figure 2b In the figure, the straight lines are outside the two arcs of the circle. As in all other embodiments of the device according to the invention, the ends of the photosensitive sections 1 and the current redistribution paths 5 that are not used as parallel connections inside the device are connected to the control elements 6, 7 of these ends, respectively, and, if present, to ground, just like the bias current source 2. The latter is connected to the ground. Figure 2b The bias current I is not fully shown in the figure, but is symbolically indicated in the bottom center. BThe current flows into the device through the connecting line also located between the two arcs and is then divided into the photosensitive segment 1 and the current redistribution path 5. In this embodiment, the photosensitive segment 1 is preferably exposed to incident light brought into the interior of the device by an optical fiber having a core diameter similar to or smaller than the detection area formed by all the photosensitive segments 1 together.

[0036] In general, as already stated above, the superconducting material, the number, geometry, width and / or thickness of the current redistribution paths 5 of the device according to the invention are chosen so that the current density in each redistribution path 5 is always lower than the critical current density of the superconducting material for the corresponding redistribution path 5, even if the entire bias current flows into the redistribution path 5 (which would be the case if all photoactive segments 1 were in a non-superconducting state). However, due to the large number of potential applications of the device according to the invention and the large number of parameters of the device that are suitable for being modified in order to meet the corresponding constraints, it is difficult to indicate strict mathematical rules for the selection of the number and dimensions of the different components of the device (in particular the number and dimensions of the photoactive segments 1 and the current redistribution paths 5), but working values can be found within certain ranges (such as will be explained below). In fact, the number N of photoactive segments 1 is S is the detection rate to be achieved (requiring a large number of photosensitive segments 1) and the desired output signal amplitude (which increases with the number N of photosensitive segments 1 S The reduced signal amplitude also increases the timing jitter of the SNSPD, which constitutes the trade-off between the number N of photosensitive segments 1 selected. S Another trade-off to consider when . S Typical values of preferably lie in the range of 2 to 100, and more preferably between 4 and 40, and even more preferably between 6 and 15.

[0037] The number N of redistribution paths 5 is preferably selected R So that the ratio N S / (N R +N S ) is in the range between 5% and 50%, more preferably between 10% and 25%. The redistribution paths 5 can also be at least partially grouped so that the paths with a given inductance L KR and the resistor R corresponding to the control element 7 R The initial expected number N of redistribution paths 5 R can be reallocated by a single equivalent path or by reducing (or increasing) the number N RE The equivalent redistribution path 5 is replaced with a properly chosen inductor L KRE and the resistance R of the corresponding control element(s) RE, to obtain the same physical behavior of the entire device. For example, a single equivalent redistribution path 5 (i.e., N RE =1) can be compared with the initial expected number N R The parallel redistribution path 5 works in the same way (here N R >1), provided that the geometry of the single redistribution path 5 is chosen so that its inductance L KRE Equal to L KR / (N R / N RE ) and its corresponding control element 7 resistance R RE Equal to R R / (N R / N RE ). The geometry (i.e. mainly the width and thickness) of the equivalent redistribution path 5 must also be modified to support sufficient current to maintain superconductivity even if all photosensitive sections 1 are in their resistive state. This can be achieved by choosing the width W of the equivalent redistribution path RE Equal to or greater than W R *N R / N RE In this case, L KRE It may also be chosen to have a slightly larger value (preferably twice) or a slightly smaller value (preferably down to half) if this allows improving the AC behavior of the equivalent redistribution paths 5 and if it does not affect the normal operation of the device. RE The value can be between 1 and N R In practice, choose N RE = 1, i.e., a single equivalent redistribution path 5 replaces the initially expected number N R redistribution path, but it will cause difficulties in nanofabrication because the resistance R RE may be too small to be manufactured with sufficiently high precision. Therefore, in practice, the number N of equivalent redistribution paths 5 is RE The values are preferably chosen such as between 2 and N R More preferably, it is in the range of 4 to N R / 2, and even more preferably between 8 and N R / 4.

[0038] In a preferred embodiment, the control element 7 of the redistribution path 5 and its resistance and / or inductance (R R and L KR ) has a resistance and / or inductance (R R and L KR ) of the same value. This ensures that the current is evenly split among the different components of the device. Redistribute the kinetic inductance L of path 5KR The value of is preferably chosen to be equal to the kinetic inductance L of the photosensitive section 1 K , but can also be different in order to modify the AC behavior of the redistribution path 5. The resistance Rs of the control element 6 is preferably chosen to have as high a value as possible, since a high value shortens the recovery time of the photosensitive section, but it must also be kept under maximum limits, preferably between 2 and 500 Ohms, more preferably between 5 and 150 Ohms, even more preferably between 10 and 100 Ohms, depending on the materials used and the kinetic inductance L K The value of , because otherwise the device will show latching behavior. Kinetic inductance L of photosensitive section 1 K It is also determined by the geometry of the superconducting material and the nanowires (ie, the length, width, and thickness of each photosensitive segment 1). K Must be minimized to improve recovery time for each individual segment. K and L KR The value of preferably lies in the range of 20 to 10000 nH, more preferably 50 to 1000 nH, even more preferably 100 to 500 nH.

[0039] The device according to the present invention (i.e., ACPC-SNSPD using meandering superconducting nanowires in most practical applications) can be integrated into more complex systems if desired or required. For example, it is possible to implement a large multi-pixel array single photon detection system 10 comprising multiple independent ACPC-SNSPDs with a dedicated coaxial line and readout for each pixel (i.e., for each ACPC-SNSPD), such as in Figure 2c 1d . Although the photosensitive section 1 and the current redistribution path 5 are connected in parallel within each ACPC-SNSPD integrated into the multi-pixel array single-photon detection system 10, the ACPC-SNSPDs are integrated into the system 10 such that each has a separate readout 4. Therefore, it can be considered that this configuration has broad similarities with the existing device shown in FIG1d . Of course, the number of ACPC-SNSPDs integrated into such a multi-pixel array single-photon detection system 10 can vary, and the integrated ACPC-SNSPDs can have the same different detection areas, components, and layouts, etc., all of which are selected depending on the specific application of the multi-pixel array single-photon detection system 10. The multi-pixel array single-photon detection system 10 can be implemented by a chip or any type of integrated circuit and can also be used as part of another larger single-photon detection structure.

[0040] In general, the different parts of the device or system according to the invention (ie, the photosensitive section 1, the current redistribution path 5, its kinetic inductance L, respectively) must be carefully optimized. Kand L KR ) number and size, control elements 6, 7 (ie, resistors R S and R R ) and the length, thickness and width of the nanowires (if the photosensitive section 1 is realized in this way) or, in general, the geometry of the superconducting detection element 1. As a general rule, crosstalk is reduced by increasing the number of current redistribution elements 5, by the kinetic inductance L K and L KR The small value of the resistor R S and R R The large resistance of the resistor is minimized. It will be clear to those skilled in the art how to apply this rule to specific layouts and applications, and it is impossible to describe all possible configurations covered by the present invention in this article. However, applying this general rule may also result in reducing the amplitude of the output signal, which may reduce the jitter of the detector and the kinetic inductance L K and L KR The small value of the resistor R S and R R The large capacitance of may also result in an increase in the speed of the device in terms of a reduction in its recovery time, which may again lead to a latch-up of the entire device in certain situations. For these reasons, a careful optimization of the number and dimensions of the different parts of the device is required for each specific layout and application. For these reasons, a precise control of the dimensions of the different parts of the device according to the invention is important, and the current redistribution path 5 is preferably integrated into the device by using the nanofabrication processes used for the production of the photosensitive section 1 of the device, as already mentioned above. Although this is not mandatory, due to the presence of parasitic capacitances, resistances and inductances and due to a correct control of the inductance L of the current redistribution path 5 KR and resistor R R The difficulty of integrating these components without using the same nanofabrication process may impair the proper implementation of the present invention.

[0041] The advantages of the ACPC-SNSPD of the multi-pixel array single photon detection system 10 according to the present invention are as follows: Figure 3a 1 and 2 are explained with the aid of numerical simulations showing how current crosstalk between photoactive segments 1 of a device according to the invention is reduced after one of its photoactive segments absorbs an incident photon. Figure 3a The flash in the inset at the upper right corner symbolizes a photon hitting the leftmost photosensitive segment 1. The current generated after the absorption of this photon in one of the other segments that was not hit by the photon is Figure 3a Before photon absorption, the current in the non-hit segment is stable at a bias current of about 20 μA. When the photosensitive segment 1 on the far left is hit by a photon, Figure 3aAt the time 100 ns, the current in the missed section rises only minimally to about 20.65 μA due to the mitigation of the current due to crosstalk caused by the current redistribution means 5, and then slowly recovers to the value of the bias current due to the temporal dynamics of the electronic circuit. The current crosstalk inside the device according to the present invention or inside the system 10 is therefore much smaller than in the case of prior art devices (such as discussed by way of example in the context of FIG. 1 f). This allows approaching their critical current I C The photosensitive section 1 of such a device or such a system 10 is thus operated at maximum efficiency. Furthermore, due to the mitigation of current crosstalk caused by the current redistribution component 5, the device or system 10 does not become disabled even at high photon detection rates.

[0042] exist Figure 3b In this paper, the measured detectivity as a function of the number of incident photons is compared for two devices, one based on the conventional single-meant SNSPD of Figure 1a and the other based on the Figure 2b The similar ACPC-SNSPD shown in . Figure 2b The ACPC-SNSPD shown in Figure 1 is used to establish Figure 3b The ACPC-SNSPD consists of 6 photosensitive sections and 14 current redistribution paths, and light to which the photosensitive sections are exposed but not to which the current redistribution paths are exposed is brought into the device by an optical fiber. Figure 3b The total area covered by the photoactive segment of the ACPC-SNSPD is approximately 16 μm x 16 μm. Figure 3b The comparison shown in

[15] demonstrates that the ACPC-SNSPD according to the present invention can operate in a high detection range that is not possible with conventional single-bend SNSPDs. In fact, although efficiency losses were also observed with the ACPC-SNSPD according to the present invention, these losses were much lower than those suffered by conventional single-bend SNSPDs and prohibited their use at high detection rates.

[0043] Figure 3c The average detection efficiency per incident photon is shown as a function of the number of incident photons for a conventional single-meant SNSPD and for an ACPC-SNSPD according to the present invention, where a continuous wave (CW) light source is used to illuminate the device. The comparison shows that the detection efficiency of the conventional single-meant SNSPD and the ACPC-SNSPD similar to FIG1a is essentially constant when the photon count rate is below 1 MHz. Figure 3cIn the example shown, for a photon count rate range below 1 MHz, the average detection efficiency per incident photon for the single-meander is approximately 77%, while the average detection efficiency per incident photon for the ACPC-SNSPD is approximately 66%. As the photon count rate (i.e., the photon detection rate) increases, the average efficiency of both devices begins to decline. However, the photon count rate at which the efficiency drops to half the nominal efficiency (i.e., the 3 dB efficiency drop line) is already around 6 MHz for the conventional single-meander SNSPD, while it is only around 70 MHz for the ACPC-SNSPD. This means that the ACPC-SNSPD according to the present invention can be used in a particularly advantageous manner at high detection rates.

[0044] In view of the above description of the structure and mode of operation of the device and system of the present invention, its advantages are clear. Primarily and most importantly, as the main advantage of the proposed detector design, such a device allows operating an SNSPD having multiple nanowire segments connected in parallel at a high detection rate while avoiding current crosstalk and the corresponding cascade effect, which causes SNSPDs of the prior art to enter a latch-up state, especially at high count rates. Secondly, the device according to the present invention allows the creation of a larger sensitive surface for collecting light from large-core optical fibers (e.g., from multimode optical fibers) or free-space propagating beams with corresponding advantages. That is, the effective recovery time of the device according to the present invention is reduced compared to a conventional single-meander SNSPD covering the same large area, and with the design according to the present invention, the yield of the device is less affected (wherein the yield of the device decreases as the size of the photosensitive area increases, due to the greater probability of having limitations in the meander), because a defective segment (e.g., due to manufacturing problems) does not prevent the operation of other photosensitive segments. Third, the device and system according to the present invention are particularly suitable for applications in the fields of quantum key distribution, optical free-space communication and time-of-flight (TOF) measurements, such as, for example, optical time-domain reflectometry (OTDR) and light detection and ranging (LiDAR). Finally, the device occupies a relatively small volume and can be produced at a sustainable cost, provided that no dedicated readout electronics or other expensive components are required for each nanowire segment. The device thus allows achieving the objectives set out above.

Claims

1. A device for single photon detection, comprising at least two superconducting detection elements (1), a bias current source (2), a filter element (3), and a readout circuit (4), wherein each superconducting detection element (1) forms a detection region suitable for absorbing incident photons and is connected in parallel to the bias current source (2) and the readout circuit (4) via the filter element (3) as an intermediate, and each superconducting detection element (1) is maintained at a temperature below its critical temperature (T C ), the bias current source (2) provides each superconducting detection component (1) with a critical current (I C ) bias current (I B ) to maintain each superconducting detection element (1) in a non-resistive superconducting state under normal circumstances, each superconducting detection element (1) is adapted to transition from the non-resistive superconducting state to a resistive state upon absorption of an incident photon, and the readout circuit (4) is adapted to sense a voltage change corresponding to the transition of the superconducting detection element (1) to its resistive state to allow generation of an event signal for each absorption of an incident photon by any one of the superconducting detection elements (1), characterized in that The device further comprises at least one current redistribution component (5) adapted to at least partially redistribute current generated after any one of the superconducting detection components (1) absorbs incident photons into the current redistribution component (5) to prevent any one of the superconducting detection components (1) that has not absorbed incident photons from suffering a current density increase to its critical current (I C )above.

2. The device according to claim 1, characterized in that The at least two superconducting detection components (1) are each realized by a superconducting nanowire segment having a meandering geometry or any other shape covering a detection area.

3. The device according to claim 2, characterized in that All superconducting detection components (1) are manufactured in one piece.

4. The device according to claim 2 or 3, characterized in that The current redistribution means (5) are realized by superconducting nanowire segments having a meandering geometry or any other shape covering the detection area.

5. The device according to claim 4, characterized in that The current redistribution component (5) is manufactured in one piece with the superconducting nanowire section forming the superconducting detection component (1).

6. The device according to any one of claims 1 to 3, characterized in that The current redistribution component (5) is adapted to support sufficient current to maintain superconductivity even if all superconducting detection components (1) are in their resistive state to avoid disabling of the superconducting detection components (1) due to current pile-up and / or cascading effects.

7. The device according to any one of claims 1 to 3, characterized in that The current redistribution component (5) is made of a superconducting material different from the superconducting material used to make the superconducting detection component (1).

8. The device according to any one of claims 1 to 3, characterized in that The current redistribution component (5) has the formula W R >W S *[1+(N S / N R )] Determine the minimum width (W R ), N S The width is W S The number of superconducting detection components (1) and N R is the number of current redistribution components (5).

9. The device according to any one of claims 1 to 3, characterized in that Reassign the number of components (5) (N R ) is chosen so that the ratio N S / (N R +N S ) is in the range of 5% to 50%, N S is the number of superconducting detection components (1).

10. The device according to any one of claims 1 to 3, characterized in that Reassign the number of components (5) (N R ) is chosen so that the ratio N S / (N R +N S ) is in the range of 10% to 25%, N S is the number of superconducting detection components (1).

11. The device according to any one of claims 1 to 3, characterized in that The shape and / or size of the current redistribution components (5) are selected to select their respective kinetic inductances (L KR ).

12. The device according to any one of claims 1 to 3, characterized in that The shape and / or size of the current redistribution element (5) is selected to depend on the corresponding kinetic inductance (L K ) and select their respective dynamic inductance (L KR ).

13. The device according to any one of claims 1 to 3, characterized in that The current redistribution components (5) are arranged inside the device so as not to be exposed to incident photons and / or have a geometry that prevents them from being optically detected even if exposed to incident photons.

14. The device according to claim 13, characterized in that The geometry is width and / or thickness.

15. The device according to any one of claims 1 to 3, characterized in that The device further comprises at least one control element (6, 7), each control element (6, 7) being connected in series to the superconducting detection component (1) and, respectively, to the current redistribution component (5).

16. The device according to claim 15, characterized in that The control elements (6, 7) connected in series to the superconducting detection element (1) and correspondingly connected in series to the current redistribution element (5) are realized as resistors (R S , R R ).

17. The device according to any one of claims 1 to 3, characterized in that It is implemented by a chip or any type of integrated circuit.

18. The device according to any one of claims 1 to 3, characterized in that The device also includes a light source or optical fiber allowing light to be introduced into the device, or directed towards the device by free-space coupling.

19. A system (10) for single photon detection, characterized in that The system comprises at least two devices according to any one of claims 1 to 18, each device comprising a separate readout circuit (4).

20. The system (10) according to claim 19, characterized in that It forms a large multi-pixel array, with each pixel being formed by one of the devices.

21. Use of the device according to any one of claims 1 to 18 and / or the system according to any one of claims 19 to 20 for quantum key distribution, optical free space communication and time-of-flight (TOF) measurements.

22. Use of the device according to any one of claims 1 to 18 and / or the system according to any one of claims 19 to 20 for an application selected from the group consisting of optical time domain reflectometry (OTDR), light detection and ranging (LiDAR), positron emission tomography (PET) scanner, and a TOF camera.

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