JP2023061076A - Superconducting transition edge sensor device and photon number identifier - Google Patents

Abstract

To provide a superconducting transition edge sensor device with a simple configuration for realizing a high response speed and a high counting rate by the speed.SOLUTION: A superconducting transition edge sensor device 1 includes: a superconducting transition edge sensor 2 where a bias voltage is applied to both ends and which changes a resistance value R in response to an input of heat energy from an outside; a sensor signal amplifier circuit 3 for detecting a change of a sensor current of the superconducting transition edge sensor 2 based on the change of the resistance value R; and a kinetic electric heat feedback circuit 4 for reducing the bias voltage in response to a decrease of the sensor current each time when the sensor signal amplifier circuit 3 detects the decrease of the sensor current.SELECTED DRAWING: Figure 1

Description

The present invention relates to a superconducting transition edge sensor device and a photon number discriminator using the same.

Patent Literature 1 discloses a calorimeter that converts the energy of radiation into heat and reads the accompanying temperature change as an electrical signal. This calorimeter has a thermal conductance between an absorber that absorbs radiation energy and converts it into heat, a temperature converter that measures the temperature of the absorber, and a heat bath that is kept at a constant temperature. and a resistor for controlling the temperature of the absorber.

Patent Literature 2 discloses a superconducting radiation analyzer capable of correcting fluctuations in output signal crest value due to external radiant heat or magnetic field while measuring samples. This superconducting radiation analyzer consists of a microcalorimeter that detects radiation energy as a change in temperature, a shunt resistor that has a lower resistance than the microcalorimeter, a bias power supply that applies a constant voltage to the microcalorimeter, and a constant amount of heat applied to the microcalorimeter. A heat addition device for adding heat, a signal detection mechanism for detecting the current flowing through the microcalorimeter, and a wave corresponding to the added heat amount among the output signals from the signal detection mechanism in synchronization with the heat addition from the heat addition device. A peak value monitor for measuring a peak value and an energy correction device for correcting the peak value so as to correspond to the amount of heat from the heat adding device based on the output from the peak value monitor are provided.

Japanese Patent No. 4667614 Japanese Patent No. 5026006

For example, in a configuration that counts thermal energy input using a calorimeter (superconducting transition edge sensor), it is desired to increase the sensor response speed in order to improve the counting rate even for thermal energy with short input intervals. The configuration of Patent Document 1 controls the temperature of the sensor to improve the counting rate and reduces the time constant of the sensor operation. However, in the configuration of the document, since it is necessary to have a complicated configuration in which an additional resistor and its wiring are added to the calorimeter element itself, the manufacturing process is complicated and a complicated configuration is adopted. However, there are problems such as that this is not preferable in terms of an increase in response speed. Moreover, the configuration of Patent Document 2 corrects the energy applied to the calorimeter according to the crest value of the output signal of the signal detection mechanism, so it cannot contribute to the improvement of the counting rate.

In view of the above, no technique has yet been proposed for increasing the sensor response speed with respect to input of thermal energy with a simple configuration, thereby improving the counting rate with respect to input of thermal energy with a higher frequency.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a superconducting transition edge sensor device with a simple configuration that achieves a high response speed and thus a high count rate.

The present invention includes the following aspects.
[Aspect 1]
A superconducting transition edge sensor device (1),
a superconducting transition edge sensor (2) to which a bias voltage is applied across both ends thereof and whose resistance value changes according to the input of heat energy from the outside;
a sensor signal amplifier circuit (3) for detecting a change in the sensor current of the superconducting transition edge sensor based on the change in the resistance value;
a dynamic electrothermal feedback circuit (4) for reducing the bias voltage in response to a decrease in the sensor current each time a decrease in the sensor current is detected by the sensor signal amplifier circuit;
The superconducting transition edge sensor device comprising:
[Aspect 2]
The superconducting transition edge sensor (2) has a first electrode (21) and a second electrode (22), a constant voltage is applied to the first electrode, and thermal energy is input from the outside. configured to change the resistance value between the first electrode and the second electrode according to
The sensor signal amplifier circuit (3) includes a coil (31) that detects the sensor current flowing from the second electrode, and a SQUID amplifier (32) that inverts and amplifies changes in the current of the coil and outputs the result,
A superconducting transition edge sensor device according to aspect 1, wherein the dynamic electrothermal feedback circuit (4) is configured to increase the voltage of the second electrode in response to an increase in the output of the SQUID amplifier.
[Aspect 3]
The superconducting transition edge sensor (2) is electrically connected between a substrate (20), a pair of electrodes (21, 22) formed on the substrate, and the pair of electrodes, and is electrically connected to the sensor from the outside. A TES thin film portion (23) that converts the temperature resulting from the absorption of heat energy into the resistance value,
The superconducting transition edge sensor device according to aspect 1, wherein the TES thin film portion has at least one opening (23s, 23h) in plan view.
[Aspect 4]
said opening is a slit (23s),
The TES thin film portion is composed of a plurality of TES thin film regions (23t) arranged in the extending direction of the electrode,
A superconducting transition edge sensor device according to aspect 3, wherein said plurality of TES thin film regions are spaced apart from each other via said slits (23s).
[Aspect 5]
a superconducting transition edge sensor device according to any one of aspects 1 to 4;
a counter section (5) for counting changes in the output voltage of the sensor signal amplifier circuit;
with
A photon number discriminator (10), wherein the superconducting transition edge sensor (2) is configured to receive photons as an input of thermal energy from the outside.
[Aspect 6]
A superconducting transition edge sensor (2) to which a bias voltage is applied across both ends and whose resistance value changes according to the input of heat energy from the outside,
a substrate (20);
a pair of electrodes (21, 22) formed on the substrate;
a TES thin film portion (23) that is electrically connected between the pair of electrodes and converts temperature resulting from absorption of heat energy from the outside into the resistance value,
The superconducting transition edge sensor, wherein the TES thin film portion has at least one opening (23s, 23h) in plan view.
[Aspect 7]
said opening is a slit (23s),
The TES thin film portion is composed of a plurality of TES thin film regions (23t) arranged in the extending direction of the electrode,
7. The superconducting transition edge sensor of aspect 6, wherein said plurality of TES thin film regions are spaced apart from each other via said slits (23s).

INDUSTRIAL APPLICABILITY According to the present invention, a superconducting transition edge sensor device with a simple configuration that achieves a high response speed and thus a high count rate, and a photon number discriminator using the same are realized.

1 is a circuit diagram showing a superconducting transition edge sensor device according to a first embodiment of the present invention; FIG. It is a figure explaining the principle of operation of a superconducting transition edge sensor. FIG. 10 shows simulation results for a superconducting transition edge sensor device; FIG. 6 is a schematic plan view showing the structure of a superconducting transition edge sensor according to a second embodiment of the present invention;

[First embodiment]
FIG. 1 shows a configuration diagram of a superconducting transition edge sensor device 1 according to a first embodiment of the present invention. The superconducting transition edge sensor device 1 includes a superconducting transition edge sensor 2 (hereinafter also referred to as “sensor 2 ”), a sensor signal amplifier circuit 3 and a dynamic electrothermal feedback circuit 4 . For example, the superconducting transition edge sensor device 1 of the present embodiment constitutes, together with the counter section 5, a photon number discriminator 10 that counts the number of photons incident on the sensor 2 in units of photons.

The sensor 2 is a so-called calorimeter. Sensor 2 has electrodes 21 and 22 , electrode 21 being connected to constant voltage source 6 and electrode 22 being connected between the input of sensor signal amplifier circuit 3 and one end of dynamic electrothermal feedback circuit 4 .

The sensor 2 may be made of any material as long as it exhibits superconducting properties, and is preferably thin film (thickness: several nanometers to several hundred micrometers) in order to reduce heat capacity. Materials of the sensor 2 include, for example, superconducting elements such as iridium, titanium, tungsten, niobium, molybdenum, cadmium, zinc, aluminum, tin, lead, mercury, or thallium, niobium titanium alloys, niobium tin, and magnesium diboride. , or copper oxide high temperature superconductors, etc., but are not limited to these. Further, depending on the material of the sensor 2, the superconducting transition edge sensor device 1 may be provided with a cooling mechanism (not shown) for cooling to near the superconducting transition temperature.

A sensor portion between the electrodes 21 and 22 is composed of a TES (Transition Edge Sensor), and for convenience of explanation, it may be equivalently described as a variable resistor. The resistance value R of this variable resistor monotonically increases with temperature rise. That is, when a photon is incident on the sensor 2, it becomes a thermal input, causing the resistance value R to rise sharply. Therefore, assuming that the bias voltage between both electrodes of the sensor 2 is constant, the sensor current flowing through the sensor 2 decreases due to the increase in the resistance value R associated with the incidence of photons.

Sensor signal amplifier circuit 3 includes coil 31 , SQUID element 32 and amplifier 33 . The SQUID element 32 and the amplifier 33 are also collectively referred to as "SQUID amplifier". The coil 31 is connected between the electrode 22 of the sensor 2 and the constant voltage source 6 (negative pole), that is, connected in series with the sensor 2 . The SQUID element 32 is electromagnetically coupled to the coil 31 and consists of, for example, a ring containing two Josephson couplings, and generates a current when a current (magnetic field) is generated in the coil 31 . Both ends of the SQUID element 32 are connected to input terminals of an amplifier 33 (op-amp). The amplifier 33 amplifies the voltage generated in the SQUID element 32 and outputs it. Specifically, when the current (sensor current) of the coil 31 decreases, the output voltage of the amplifier 33 increases (that is, the entire SQUID amplifier constitutes an inverting amplifier circuit).

The dynamic electrothermal feedback circuit 4 includes a series circuit of resistors 41 , 43 and a capacitor 42 and forms a negative feedback circuit in relation to the sensor signal amplifier circuit 3 . One end of the resistor 43 is connected to ground. This series circuit is between the output end of the sensor signal amplifier circuit 3 (output terminal of the amplifier 33) and the connection node between the output end of the sensor 2 (electrode 22) and the input end of the sensor signal amplifier circuit 3 (coil 31). connected to For convenience of explanation, the connection node of the sensor 2 (electrode 22), the sensor signal amplifier circuit 3 (coil 31) and the dynamic electrothermal feedback circuit 4 is referred to as node Nfb. Also, the resistor 43 may be omitted.

A dynamic electrothermal feedback circuit 4 regulates the feedback current flowing between the input and output of the sensor signal amplifier circuit 3 . Specifically, when the current in the coil 31 in the sensor signal amplifier circuit 3 decreases, the output voltage of the amplifier 33 increases, and the dynamic electrothermal feedback circuit 4 increases the voltage of the node Nfb. Note that the values of the resistor 41 and the capacitor 42 are appropriately determined in consideration of the response characteristics of this dynamic feedback system. Also, the dynamic electrothermal feedback circuit 4 may be an impedance circuit having desired response characteristics, and may be, for example, a resistor only, a capacitor only, or a parallel circuit of a resistor and a capacitor.

The counter unit 5 is connected to the output terminal of the sensor signal amplifier circuit 3 (the output terminal of the amplifier 33), and detects and counts changes in the output of the amplifier 33. FIG. The counter unit 5 counts the increase in the output voltage of the amplifier 33 when photons are incident on the sensor 2 and the current (sensor current) of the coil 31 decreases. Therefore, this count value corresponds to the number of incident times or the number of incident photons.

The operating principle of the sensor 2 will now be described with reference to FIG. FIG. 2 shows sensor temperature T (upper row : temperature), the relationship between sensor temperature T and resistance value R (middle: bias point), and the relationship between elapsed time t and sensor current I (lower: signal (current)).

Note that the sensor temperature T, sensor current I, and resistance value R in this description refer to the average temperature, average current, and average resistance value of the TES that constitutes the sensor 2, respectively. Regarding the sensor temperature T shown in the upper part of each figure, the darker the color, the higher the temperature. Regarding the relationship between the sensor temperature T and the resistance value R shown in the middle of each figure, the resistance value R is low in the superconducting region on the low temperature side of the critical temperature Tc, and the resistance value R is high in the normal conducting region on the high temperature side of the critical temperature Tc. The change in the resistance value R becomes steep near the critical temperature Tc. A specific configuration of the sensor 2 will be described later.

As shown in FIG. 2(a), just before a photon enters the sensor 2, the sensor 2 is in a steady state (low temperature), the resistance value R is low, and the sensor current I is i0. As shown in FIG. 2(b), immediately after a photon is incident on the sensor 2 (central portion), Joule heat is generated according to the energy of the incident photon, thereby increasing the sensor temperature T. As shown in FIG. As the sensor temperature T rises, the resistance value R sharply rises, and the sensor current I sharply decreases to i1. As shown in FIG. 2(c), when the Joule heat is released and decreases, the sensor temperature T decreases, the resistance value R decreases, and the sensor current I begins to increase. As shown in FIG. 2(d), when the release of Joule heat is substantially completed, the sensor temperature T returns to the steady state shown in FIG. Return to i0.

Here, in a configuration in which the bias voltage applied to the TES is constant without using the dynamic electrothermal feedback circuit 4 (referred to as static electrothermal feedback), the process in FIG. It relies on the effect of current reduction due to changes in resistance R under constant bias voltage. Therefore, with such static electrothermal feedback, the time to reach the state of FIG. 2(b) from the state of FIG.

On the other hand, in the superconducting transition edge sensor device 1 of the present embodiment, the bias voltage can be controlled by the dynamic electrothermal feedback circuit 4, and the process of FIGS. can be controlled. Specifically, immediately after the photon incidence in FIG. 2(b), the dynamic electrothermal feedback circuit 4 raises the potential of the node Nfb by its feedback operation, thereby lowering the bias voltage applied to the sensor 2. FIG. Since the amount of Joule heat generated by the TES is proportional to the square of the bias voltage, the rise in the potential of the node Nfb causes the falling value i1 of the sensor current I to be reduced by the static electrothermal feedback (that is, the configuration without the dynamic electrothermal feedback circuit 4). will be even lower than in the case of Due to this lower sensor current I, the release of Joule heat in FIG. 2(c) is enhanced. That is, the decrease in Joule heat due to active or dynamic control greatly hinders the Joule heat increase factor due to the increase in sensor current I (due to the decrease in sensor temperature T and resistance value R accompanying the decrease in Joule heat). recovery to steady state proceeds. Therefore, the time to reach the state of FIG. 2(d) from the state of FIG. 2(b) is reduced compared to static electrothermal feedback.

Thus, in the superconducting transition edge sensor device 1 of the present embodiment, dynamic electrothermal feedback using the dynamic electrothermal feedback circuit 4 increases the response speed of the sensor 2 (TES).

[Verification by simulation]
Numerical simulations were conducted to verify the increase in response speed due to the dynamic electrothermal feedback mechanism of the superconducting transition edge sensor device 1 of the present embodiment. This simulation is an example, and the superconducting transition edge sensor device 1 of the present embodiment is not limited to the configuration used in this simulation.

In this numerical simulation, thermoelectric coupling calculation was performed using the finite difference method. In this calculation, the calculation was performed by simulating the sensor 2 (TES) composed of an 8 μm square iridium thin film optimized for light detection. The calculation was performed by dividing the 8 μm square TES into 40×40 meshes. At each time step of the simulation, (1) the current density distribution was first calculated, then (2) the temperature change of the TES was calculated by thermal calculation, and then (3) the physical property values were updated.

For each mesh, the calculation of current density in (1) was first performed. In order to calculate the current density, it is necessary to obtain the potential distribution in the TES. As boundary conditions, potentials of φ=5 μV and 0 μV were set at both ends (electrode portions) of the iridium thin film. According to Kirchhoff's current law, the sum of the currents flowing into one point (i, j) of the mesh in the TES is zero. Therefore, since the sum of the current inflows from the four surrounding points (i+1, j), (i-1, j), (i, j+1), and (i, j-1) is 0, the following equation is It holds.

where each φ represents the potential at that mesh point. R1 is the average resistance value of points (i+1, j) and (i, j), R2 is the average resistance value of points (i−1, j) and (i, j), and R3 is the point (i, j+1). and (i,j), and R4 represents the average resistance of points (i,j-1) and (i,j). If the mesh division number of the TES is N (in this case, N=40×40=1600), the above equation holds for N points, so it is possible to formulate N-dimensional simultaneous equations. This simultaneous equation was solved by an iterative solution method, and the converged value was taken as the potential distribution of the TES. Once the potential distribution is determined, the current flowing through each point of the mesh can be determined by dividing the potential difference at each mesh point by the average resistance value between each mesh. That is, this allows the current density distribution to be calculated.

After the current density distribution calculation, (2) temperature change was calculated by thermal calculation. In the heat calculation, heat conduction in the TES, heat transfer from the TES to the silicon wafer, which is a heat bath, and Joule heating due to the bias current (sensor current) flowing through the TES were calculated. This can be represented by the following heat equation:

Here, α is the thermal diffusivity, K is the heat transfer parameter from the TES to the heat bath, C is the heat capacity, P is the Joule heating, and n is the exponent of the power law of heat transfer, and n=5 was used in this calculation. represents This equation was differentiated and calculated for each point of the mesh to calculate the temperature change per unit time.

From the results of the current density distribution calculation and heat calculation described above, the temperature distribution within the TES is obtained for each time step. Using this temperature distribution, (3) updating of physical property values was performed. Here, first, by comparing the superconducting transition temperature of the iridium thin film at each point of the mesh, the determination of superconductivity or normal conductivity at each point of the mesh was performed. Based on the results, various physical properties (electrical resistivity, heat capacity, thermal conductivity) were updated at each point of the mesh.

From the initial state, when (1) current density distribution calculation, (2) temperature distribution calculation by thermal calculation, and (3) physical property update calculation are repeatedly performed for each time step, the TES reaches a steady state after a certain time step. A converged state is reached. After that, energy due to photon incidence was applied to the center of the TES, and the change in the bias current over time was measured as a signal value.

Numerical simulations similar to those described above were also performed for conventional static electrothermal feedback. Comparative results of numerical simulations for static electrothermal feedback and dynamic electrothermal feedback are shown in FIG. In FIG. 3, the horizontal axis indicates time, and the vertical axis indicates bias current (sensor current).

Line 301 shows the calculated results for the static electrothermal feedback (comparative example) and lines 302 and 303 show the calculated results for the dynamic electrothermal feedback (inventive example). Lines 302 (feedback factor=2.0) and 303 (feedback factor=3.0) are the results for different feedback factors (parameters such as SQUID element 32, resistor 41, capacitor 42). The input external energy is 1.0 eV.

As shown in FIG. 3, in the static electrothermal feedback of line 301, the sensor current decreases from 1.10 μA to about 1.06 μA at the time of energy input (photon incidence (at 1.0 μs on the horizontal axis)), and then It took about 1.0 μs to return to 1.10 μA. On the other hand, the dynamic electrothermal feedback of line 302 required only about 0.4 μs for the sensor current to decrease from 1.10 μA to about 1.03 μA at photon incidence and then return to 1.10 μA. That is, the recovery time in this case was reduced by about 60% compared to line 301 . Furthermore, the dynamic electrothermal feedback of line 303 required only about 0.3 μs for the sensor current to decrease from 1.10 μA to about 0.995 μA at photon incidence and then return to 1.10 μA. That is, the recovery time in this case was reduced by about 70% compared to line 301 .

As can be seen from the above results, the conventional static electrothermal feedback operates with a constant voltage bias (fixed potential at the edge boundary condition). On the other hand, in the calculation of the dynamic electrothermal feedback of this embodiment, the voltage change corresponding to the signal output of the TES is fed back to the bias electrode to dynamically change the bias voltage of the TES. That is, when a signal is generated by optical input, the bias voltage applied across the TES is rapidly and dynamically lowered in accordance with the signal value. As a result, the bias current flowing through the TES is further reduced and the Joule heating is rapidly reduced. This provides both an increase in the peak value of the output signal and a fast decay. This increase in crest value contributes to an improvement in the signal-to-noise ratio (S/N ratio), and fast attenuation contributes to an increase in response speed and counting rate.

As described above, the superconducting transition edge sensor device 1 of the present embodiment includes a superconducting transition edge sensor 2 that has a bias voltage applied to both ends thereof and changes the resistance value R according to the input of heat energy from the outside. , a sensor signal amplifier circuit 3 for detecting changes in the sensor current of the superconducting transition edge sensor 2 based on changes in the resistance value R, and a decrease in the sensor current each time a decrease in the sensor current is detected by the sensor signal amplifier circuit 3. a dynamic electrothermal feedback circuit 4 for instantaneously lowering the bias voltage in response to .

Thus, the dynamic electrothermal feedback circuit 4 is biased each time a decrease in sensor current is detected by the sensor signal amplifier circuit 3 due to the input of thermal energy from the outside (in this embodiment, incident photons). Instantly reduce the voltage. Therefore, the release of Joule heat from the sensor 2 immediately after the thermal energy is input is promoted, and the time required for the release is shortened. That is, simply by adding the dynamic electrothermal feedback circuit 4 between the sensor 2 and the sensor signal amplifier circuit 3, the response speed to the input of heat energy from the outside is improved, and the heat input interval (incident interval) is short. The counting rate improves with respect to energy input. Therefore, a superconducting transition edge sensor device 1 having a simple configuration that achieves a high response speed and thus a high count rate is realized. Moreover, at the same time, since the range of decrease in the sensor current increases when thermal energy is input, an effect of improving the signal-to-noise ratio of the sensor signal is obtained.

Here, the superconducting transition edge sensor 2 has an electrode 21 (first electrode) and an electrode 22 (second electrode). It is configured to change the resistance value R between the electrodes 21 and 22 accordingly. The sensor signal amplifier circuit 3 includes a coil 31 for detecting a sensor current flowing from the electrode 22 and a SQUID amplifier (32, 33) for inverting and amplifying changes in the current of the coil 31 and outputting the result. The dynamic electrothermal feedback circuit 4 is configured to instantaneously increase the voltage of the electrode 22 in response to an increase in the output of the SQUID amplifier. In this way, the bias voltage is controlled by changing the potential of the electrode 22 on the downstream side (high impedance side) of the sensor 2 instead of the potential of the electrode 21 on the side of the constant voltage source 6 (low impedance side). and responsiveness are guaranteed.

Further, the photon number discriminator of this embodiment includes a superconducting transition edge sensor device 1 and a counter section 5 for counting changes in the output voltage of the sensor signal amplifier circuit 3. The superconducting transition edge sensor 2 is external Photons are configured to be incident as input of thermal energy from. Thereby, a photon number discriminator having the above effect is realized.

[Second embodiment]
In the above-described first embodiment, the structure for speeding up the release of Joule heat is shown by the structure of the dynamic electric heat feedback. In addition, in this embodiment, the same code|symbol is attached|subjected to the same component as the component of 1st Embodiment, and the overlapping description is abbreviate|omitted.

FIG. 4A shows a schematic plan view of the structure of the sensor 2 of the superconducting transition edge sensor device 1 according to the second embodiment.

The sensor 2 comprises electrodes 21 and 22 and a TES thin film portion 23 which are formed on the substrate 20 . Substrate 20 is, for example, a silicon wafer that acts as a heat bath. Wiring from the electrode 21 to the constant voltage source 6 and wiring from the electrode 22 to the node Nfb are not shown.

The TES thin film portion 23 is electrically connected to the electrodes 21 and 22 and has the above resistance value R therebetween. The material of the TES thin film portion 23 is, for example, a material having superconducting properties such as iridium, tungsten, or titanium, but is not limited thereto. In order to reduce the heat capacity, the TES thin film portion 23 is preferably a thin film having a thickness of several nanometers to several hundred micrometers, preferably several tens of nanometers to several hundred micrometers. The electrodes 21 and 22 and the TES thin film portion 23 can be formed using photolithography, for example.

The TES thin film portion 23 is composed of a plurality of TES thin film regions 23t, and slits 23s are interposed between the plurality of TES thin film regions 23t. In this embodiment, a slit configuration in which the TES thin film portion 23 is divided and separated is adopted. The slit 23s may be a space (air), or may be filled with an insulating material (synthetic resin such as polyolefin, glass, silicon oxide film, or the like).

According to this slit configuration, the actual size of the TES thin film portion 23, that is, The benefit of faster Joule heat release due to reduced heat capacity outweighs. In other words, the area of each TES thin film region 23 is reduced while the light receiving sensitivity is maintained at the same level as compared to the TES thin film having the same area.

As an example, in the present embodiment, each TES thin film region 23t has a length L of 2 μm in the arrangement direction along the extending direction of the electrodes 21 and 22 (vertical direction toward the paper surface of FIG. 4). The interval G between 23t (the length of each slit 23s in the arrangement direction) is 500 nm. Therefore, the aperture ratio (=total area of slits 23s/(total area of TES thin film region 23t+total area of slits 23s)) is 20%. Note that, in the present embodiment, the aperture ratio may be defined as G/(L+G). In this embodiment, the distance D between the electrodes 21 and 22 is 12 μm as an example.

Note that the planar shape of the TES thin film portion 23 is not limited to that shown in FIG. For example, two TES thin film regions 23t and one slit 23s therebetween also constitute the present embodiment. Also, as shown in FIG. 4B, the TES thin film portion 23 may be provided with a large number of holes 23h instead of the slits. The hole 23h has the same function as the slit 23s.

The shape of each hole 23h is, for example, circular, rectangular, or polygonal. In the present disclosure, these slits and holes are collectively referred to as openings. It is preferable that the openings (slits 23 s or holes 23 h ) are uniformly distributed in the TES thin film portion 23 in order to reduce variations in the resistance value R with respect to the incident positions of photons. In addition, in order to increase the contact area between the TES thin film portion 23 and the electrodes 21 and 22 and increase the heat radiation through the electrodes 21 and 22, openings are provided in the overlapping regions of the TES thin film portion 23 and the electrodes 21 and 22. may not be provided.

From the viewpoint of ensuring a photon-receivable area, the aperture ratio of the TES thin film portion 23 is preferably 30% or less, 25% or less, or 20% or less in plan view. Moreover, from the viewpoint of securing high-speed release of Joule heat, the aperture ratio of the TES thin film portion 23 is preferably 1% or more, 5% or more, 10% or more, or 15% or more in plan view. That is, the aperture ratio of the TES thin film portion 23 is 1 to 30%, 1 to 25%, 1 to 20%, 5 to 30%, 5 to 25%, 5 to 20%, 10 to 30%, 10 to 25%, Preferably 10-20%, 15-30%, 15-25% or 15-20%. As a result, it is possible to secure both a photon-receivable area and high-speed release of Joule heat.

As described above, in the superconducting transition edge sensor device 1 of the present embodiment, the superconducting transition edge sensor 2 includes the substrate 20, the pair of electrodes 21 and 22 formed on the substrate 20, and the electrodes 21 and 22. The TES thin film portion 23 is electrically connected between and converts the temperature resulting from the absorption of heat energy from the outside into a resistance value R. The TES thin film portion 23 has at least one opening in plan view. As a result, the heat capacity of the TES thin film portion 23 can be reduced, and the release of Joule heat after incident photons can be accelerated. That is, in the superconducting transition edge sensor device 1, a high response speed and a high counting rate are thereby realized.

Here, the TES thin film portion 23 includes a plurality of TES thin film regions 23t arranged in the extending direction of the electrodes 21 and 22, and the plurality of TES thin film regions 23t are spaced apart from each other via slits 23s to form at least one of the TES thin film regions 23t. It is preferred to form an aperture. Thereby, the TES thin film portion 23 can be produced by a simple process.

[Other embodiments]
Although the preferred embodiments of the present invention have been shown above, the present invention can be modified in various forms, for example, as shown below.

For example, in each of the above-described embodiments, the superconducting transition edge sensor device 1 is used as a photon number discriminator, but the application is not limited to a superconducting X-ray detector or a superconducting γ-ray detector. etc. is also applicable. Also, the superconducting transition edge sensor device 1 and the photon number discriminator of the present invention are widely used in quantum technology, and can be applied to quantum computers, for example. Also, the superconducting transition edge sensor device 1 and the photon number discriminator of the present invention are applicable to error-tolerant quantum computers that can perform calculations while correcting errors in quantum units. That is, the photon number discriminator of the present invention can be suitably applied to optical quantum computing based on continuous quantum information processing of light.

In each of the above embodiments, the dynamic electrothermal feedback circuit 4 raises the voltage of the node Nfb in order to lower the bias voltage applied to the sensor 2 when photons are incident. This is most suitable considering the response speed of feedback control, the number of parts (cost), and the like. However, it is also possible to lower the bias voltage when photons are incident by other configurations. For example, by providing a series circuit of a switching element such as a transistor and a resistor between the node Nfb and the constant voltage source 6 and turning on the switching element when a photon is incident (when the signal of the sensor signal amplifier circuit 3 rises), the electrode A configuration in which 21 and 22 are substantially at the same potential as the constant voltage source 6 is also possible.

1 superconducting transition edge sensor device 2 superconducting transition edge sensor 3 sensor signal amplifier circuit 4 dynamic electrothermal feedback circuit 5 counter unit 6 constant voltage source 10 photon number discriminator 20 substrate 21 electrode (first electrode)
22 electrode (second electrode)
23 TES thin film portion 23t TES thin film region 23s slit (opening)
23h hole (opening)
31 coil 32 SQUID element (SQUID amplifier)
33 amplifier (SQUID amplifier)
41, 43 resistor 42 capacitor

Claims (7)

A superconducting transition edge sensor device (1),
a superconducting transition edge sensor (2) to which a bias voltage is applied across both ends thereof and whose resistance value changes according to the input of heat energy from the outside;
a sensor signal amplifier circuit (3) for detecting a change in the sensor current of the superconducting transition edge sensor based on the change in the resistance value;
a dynamic electrothermal feedback circuit (4) for reducing the bias voltage in response to a decrease in the sensor current each time a decrease in the sensor current is detected by the sensor signal amplifier circuit;
The superconducting transition edge sensor device comprising: The superconducting transition edge sensor (2) has a first electrode (21) and a second electrode (22), a constant voltage is applied to the first electrode, and thermal energy is input from the outside. configured to change the resistance value between the first electrode and the second electrode according to
The sensor signal amplifier circuit (3) includes a coil (31) that detects the sensor current flowing from the second electrode, and a SQUID amplifier (32) that inverts and amplifies changes in the current of the coil and outputs the result,
2. The superconducting transition edge sensor device of claim 1, wherein the dynamic electrothermal feedback circuit (4) is configured to increase the voltage of the second electrode in response to an increase in the output of the SQUID amplifier. . The superconducting transition edge sensor (2) is electrically connected between a substrate (20), a pair of electrodes (21, 22) formed on the substrate, and the pair of electrodes, and is electrically connected to the sensor from the outside. A TES thin film portion (23) that converts the temperature resulting from the absorption of heat energy into the resistance value,
2. The superconducting transition edge sensor device according to claim 1, wherein said TES thin film portion has at least one opening (23s, 23h) in plan view. said opening is a slit (23s),
The TES thin film portion is composed of a plurality of TES thin film regions (23t) arranged in the extending direction of the electrode,
4. The superconducting transition edge sensor device of claim 3, wherein said plurality of TES thin film regions are spaced apart from each other via said slits (23s). a superconducting transition edge sensor device according to any one of claims 1 to 4;
a counter section (5) for counting changes in the output voltage of the sensor signal amplifier circuit;
with
A photon number discriminator (10), wherein the superconducting transition edge sensor (2) is configured to receive photons as an input of thermal energy from the outside. A superconducting transition edge sensor (2) to which a bias voltage is applied across both ends thereof and whose resistance value changes according to the input of heat energy from the outside,
a substrate (20);
a pair of electrodes (21, 22) formed on the substrate;
a TES thin film portion (23) that is electrically connected between the pair of electrodes and converts temperature resulting from absorption of heat energy from the outside into the resistance value,
The superconducting transition edge sensor, wherein the TES thin film portion has at least one opening (23s, 23h) in plan view. said opening is a slit (23s),
The TES thin film portion is composed of a plurality of TES thin film regions (23t) arranged in the extending direction of the electrode,
7. The superconducting transition edge sensor of claim 6, wherein said plurality of TES thin film regions are spaced apart from each other via said slits (23s).

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