KR20230148592A - Cryogenic Chillers for Evaluation of Quantum Devices - Google Patents

Abstract

Provided is a cryogenic chiller for quantum device evaluation, which can easily establish a cryogenic environment for testing the dedicated characteristics of semiconductors for driving quantum devices. The cryogenic chiller for quantum device evaluation according to the present invention comprises: a chamber having formed therein an accommodation space in a vacuum atmosphere; a cooling module provided long in the vertical direction so as to be exposed within the accommodation space, and having formed therein a closed hollow where an object to be tested is placed for cryogenic environmental testing for quantum device evaluation; a heat conductor connected to first and second cooling points of the cooling module; a cryogenic freezer provided in the accommodation space and performing heat exchange with the heat conductor to cool the cooling module to a cryogenic temperature; and a superconducting magnet wound around the perimeter of a region where the object to be tested is located, to form a magnetic field.

Description

Cryogenic Chillers for Evaluation of Quantum Devices}

The present invention relates to a cryogenic cooling device for evaluating quantum devices, and more specifically, to a cryogenic cooling device for evaluating quantum devices that can easily establish a cryogenic environment for testing the dedicated characteristics of semiconductors for driving quantum devices. will be. In addition, this invention was derived from research conducted as part of the Gumi City Core Component Material Technology Development Project of Gumi City (Project Management Agency: Gyeongbuk Science and Technology Promotion Center) [Project Management Number: AG3739211, Project Name: Detachable Cryogenic Temperature for Quantum Information Technology Cooling module technology development].

A quantum computer refers to a computer that can perform calculations using effects such as quantum entanglement, superposition, and teleportation in quantum mechanics. While conventional computers can only distinguish between 0 and 1 data, quantum computers are expected to be able to allow 0 and 1 data to coexist at the same time, enabling a dramatic increase in computational speed.

However, in order to maintain the qubit for as long as possible, the processor of the quantum annealing computer is made mainly of superconductors whose electrical resistance becomes 0 at extremely low temperatures and vacuum conditions close to absolute zero. This causes the manufacturing cost to increase exponentially. Of course, since it must maintain a superconducting state during operation, a vacuum cooling device capable of creating a space environment is required, so the operating cost is very expensive.

For this reason, in order to perform tests for mass production of quantum annealing computer processors, an environment of extremely low temperature and vacuum must be established. However, cooling systems such as conventional closed-circuit refrigerators (Closed Cycle Refrigerators) alone are used to conduct tests for the mass production of processors of quantum annealing computers. There is a problem that it is impossible to establish an appropriate cryogenic environment.

Therefore, a method to solve these problems is required.

Korean Patent Publication No. 10-2003-0077639

The present invention is an invention made to solve the problems of the prior art described above, and provides a cryogenic cooling device for evaluating quantum devices that can easily establish a cryogenic environment for testing the dedicated characteristics of semiconductors for driving quantum devices. It has the purpose of doing so.

The problems of the present invention are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

In order to achieve the above object, the cryogenic cooling device for evaluating quantum devices of the present invention includes a chamber with an accommodating space in a vacuum atmosphere formed inside, a chamber elongated in the vertical direction so as to be exposed within the accommodating space, and a cryogenic cooling device for evaluating quantum devices therein. A cooling module with a closed hollow in which a test object for environmental testing is placed, a heat conductor connected to a first cooling point and a second cooling point of the cooling module, provided in the accommodation space, and the cooling module at a cryogenic temperature. It includes a cryogenic refrigerator that performs heat exchange with the heat conductor to cool the test object and a superconducting magnet that is wound around the perimeter of the area where the test object is located to form a magnetic field.

At this time, the superconducting magnet may be formed to have a constant diameter from top to bottom.

Alternatively, the superconducting magnet may be formed in a shape whose diameter gradually decreases from top to bottom.

Alternatively, the superconducting magnet may be formed in a shape where the diameter gradually decreases from the top and bottom to the middle point.

Meanwhile, the test object may be provided at a position lower than the first cooling point and the second cooling point.

And the cooling module extends upward from the first cooling point, includes a first unit member made of stainless steel, is joined to a lower end of the first unit member to extend downward from the first cooling point, and is made of copper. A second unit member, joined to the lower end of the second unit member, the second cooling point is formed, a third unit member made of stainless steel and joined to the lower end of the third unit member, and the test object is inside. It is mounted and may include a fourth unit member made of copper.

At this time, the fourth unit member may be formed to have a constant diameter from top to bottom.

Alternatively, the fourth unit member may be formed in a shape where the diameter gradually decreases from the top to the bottom.

Alternatively, the fourth unit member may be formed in a shape where the diameter gradually decreases from the top and bottom to the middle point.

Additionally, the present invention may further include a cover member formed to surround the fourth unit member and made of stainless steel.

In addition, in the present invention, an auxiliary pipe member made of copper coated with a coating metal may be provided inside the fourth unit member and has a diameter smaller than the diameter of the fourth unit member.

Meanwhile, the cavity of the cooling module is filled with helium, and in this case, the present invention further includes an auxiliary refrigerator that lowers the temperature in the cavity by adjusting the density of helium filled in the cavity of the cooling module from outside the chamber. You can.

The cryogenic cooling device for quantum device evaluation of the present invention to solve the above problems includes a cooling module formed with a closed hollow in which a test object for cryogenic environmental testing for quantum device evaluation is placed, and a cooling module connected to this cooling module. By utilizing a cryogenic refrigerator that can cool the cooling module to extremely low temperatures by performing heat exchange with the heat conductor, it has the advantage of easily establishing a cryogenic environment to test the dedicated characteristics of semiconductors for driving quantum devices. .

In particular, according to an embodiment of the present invention, an auxiliary refrigerator capable of additionally lowering the internal temperature of the cooling module using the Joule-Thomson Effect is further included, providing a stable test environment and maintaining it for a long time. there is.

The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims.

1 is a diagram showing the structure of a cryogenic cooling device for evaluating quantum devices according to an embodiment of the present invention;
2 and 3 are diagrams showing the structure of a cooling module in a cryogenic cooling device for evaluating quantum devices according to an embodiment of the present invention;
Figure 4 is a view showing various forms of the fourth unit member provided in the cooling module in the cryogenic cooling device for evaluating quantum devices according to an embodiment of the present invention;
Figure 5 is a graph showing the temperature change trend of the cooling module according to the shape of the fourth unit member in the cryogenic cooling device for evaluating quantum devices according to an embodiment of the present invention;
Figure 6 is a diagram showing the results of heat transfer model analysis of the cooling module using finite element analysis in the cryogenic cooling device for evaluating quantum devices according to an embodiment of the present invention;
Figure 7 is a graph showing the results of analysis of the characteristics of the cooling module using finite element analysis in the cryogenic cooling device for evaluating quantum devices according to an embodiment of the present invention;
Figure 8 is a graph showing the change in heat transfer characteristics of the cooling module according to the convective heat transfer coefficient in the cryogenic cooling device for evaluating quantum devices according to an embodiment of the present invention;
Figure 9 is a diagram showing various forms of superconducting magnets in the cryogenic cooling device for evaluating quantum devices according to an embodiment of the present invention;
10 and 11 are diagrams showing magnetic field change characteristics according to the shape of a superconducting magnet in a cryogenic cooling device for evaluating quantum devices according to an embodiment of the present invention;
Figure 12 is a diagram showing the structure of a fourth unit member in a cryogenic cooling device for evaluating quantum devices according to another embodiment of the present invention; and
Figure 13 is a diagram showing magnetic field distribution characteristics according to the coating material of the auxiliary pipe member provided inside the fourth unit member in the cryogenic cooling device for evaluating quantum devices according to another embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention, in which the object of the present invention can be realized in detail, will be described with reference to the attached drawings. In describing this embodiment, the same names and the same symbols are used for the same components, and additional description accordingly will be omitted.

Figure 1 is a diagram showing the structure of a cryogenic cooling device for evaluating quantum devices according to an embodiment of the present invention.

As shown in FIG. 1, the cryogenic cooling device for evaluating quantum devices according to an embodiment of the present invention includes a chamber 5, a cooling module 100, a heat conductor 30, a cryogenic refrigerator 10, and an auxiliary refrigerator. (20) and a superconducting magnet (200).

The chamber 5 has an accommodating space 6 formed inside it, and is equipped to discharge the air within the accommodating space 6 to the outside, so that the accommodating space 6 can be formed into a vacuum atmosphere.

The cooling module 100 is provided long in the vertical direction so as to be exposed within the accommodation space 6, and has a closed hollow space (S, see FIG. 3) inside which a test object (S, see FIG. 3) for cryogenic environmental testing for quantum device evaluation is mounted. 105, see FIG. 3) is formed. Additionally, the hollow 105 may be filled with helium gas, which will be described later.

A pair of heat conductors 30 may be provided and connected to the first cooling point and the second cooling point of the cooling module 100, respectively. In particular, the heat conductor 30 connected to the second cooling point may be connected to the cooling module 100 at a predetermined point. It is formed in a branched form and can also be connected to the superconducting magnet 200. However, of course, the heat conductor 30 connected to the superconducting magnet 200 may also be independently provided and connected to the second cooling point.

The heat conductor 30 may be formed of a material with high thermal conductivity, such as copper.

The cryogenic refrigerator 10 is provided so that at least a portion of the receiving space 6 is exposed, and performs heat exchange with the heat conductor 30 to cool the cooling module 100 to a cryogenic temperature.

At this time, the cryogenic freezer 10 may have a two-stage structure in which the first freezer and the second freezer are arranged up and down along the longitudinal direction, and the first freezer and the second freezer may each be connected to the heat conductor 30. there is.

In particular, in the case of the first freezer located at the top, the cooling module 100 can be cooled to a temperature below about 65K, and the second freezer can cool the cooling module 100 to a temperature below 4.2K, which is a higher temperature than the first freezer. (100) can be cooled. In particular, in the case of the superconducting magnet 200, the resistance is very low at a temperature below 6K, and at temperatures above 6K, the resistance is high and it is difficult to form a high magnetic field, so the second freezer and the heat conductor 30 are used. It can be connected to so that it can be cooled down to a temperature of 4.2K or lower.

However, this is presented as an example, and the cooling temperatures of the first freezer and the second freezer are not limited to this embodiment.

The auxiliary refrigerator 20 is additionally provided to cool the cooling module 100 together with the cryogenic refrigerator 10. To this end, the hollow 105 of the cooling module 100 is filled with helium, and the auxiliary refrigerator 20 adjusts the density of the helium filled in the hollow 105 of the cooling module 100 from outside the chamber 5. The temperature within the hollow 105 can be lowered through the Joule-Thomson Effect.

The superconducting magnet 200 is wound to surround the area where the test object (S) is located and forms a magnetic field, thereby causing the area where the test object (S) is located to have superconducting characteristics. Various forms of the superconducting magnet 200 will be described later.

Figures 2 and 3 are diagrams showing the structure of the cooling module 100 in the cryogenic cooling device for evaluating quantum devices according to an embodiment of the present invention.

As shown in Figures 2 and 3, the cooling module 100 is provided long in the vertical direction, and a first cooling point and a second cooling point where a pair of heat conductors 30 are connected are respectively set.

In addition, the first cooling point and the second cooling point are each provided with a ring member 160 for connecting the heat conductor 30 and transmitting cold air transmitted from the heat conductor 30 to the cooling module 100. It can be. This ring member 160 may be made of stainless steel, and this is to prevent the heat being transferred from being quickly lost as the ring member 160 is made of a material with high thermal conductivity.

At this time, a test object (S), such as a semiconductor memory for driving a quantum device, may be provided at a position lower than the first cooling point and the second cooling point.

In particular, in this embodiment, the cooling module 100 is divided into a plurality of unit members 110 to 140, and these are joined to each other in the vertical direction.

Specifically, the cooling module 100 of this embodiment includes a first unit member 110 that extends upward from the first cooling point and is made of stainless steel, and a first unit member 110 that extends downward from the first cooling point. A second unit member 120 made of copper, joined to the bottom of the second unit member 120, a second cooling point is formed, a third unit member 130 made of stainless steel, and a third unit member 130 made of stainless steel. It is joined to the lower end of the third unit member 130, the test object S is mounted on the inside, and includes a fourth unit member 140 made of copper.

The reason why the cooling module 100 has a form in which different materials are alternately bonded in this way is because the heat loss rate in the cooling module 100 is high when a single material is used, so as to minimize heat loss through bonding of different materials. will be.

Additionally, a sealing cap 141 may be provided at the bottom of the fourth unit member 140 to shield the hollow portion of the cooling module 100.

Additionally, in the case of this embodiment, a cover member 150 formed to surround the fourth unit member 140 and made of stainless steel may be further included. This cover member 150 serves to surround and protect the outside of the fourth unit member 140.

Figure 4 is a diagram showing various forms of the fourth unit member 140 provided in the cooling module 100 in the cryogenic cooling device for evaluating quantum devices according to an embodiment of the present invention. As shown in FIG. 4, the fourth unit member 140 may be implemented in various forms.

First, as shown on the left side of FIG. 4, the fourth unit member 140A may be formed in the shape of an empty cylinder with a constant diameter from top to bottom.

And, as shown in the center of FIG. 4, the fourth unit member 140B may be formed in an hourglass shape whose diameter gradually decreases from the top and bottom to the middle point, and as shown on the right side of FIG. 4. Likewise, the fourth unit member 140C may be formed in a cone shape whose diameter gradually decreases from the top to the bottom.

As such, the fourth unit member 140 can be implemented in various forms, and has different heat transfer characteristics depending on the form.

FIG. 5 shows a graph showing a temperature change trend of the cooling module according to the shape of the fourth unit member 140 in the cryogenic cooling device for evaluating quantum devices according to an embodiment of the present invention.

Referring to this, it can be confirmed that the cylindrical fourth unit member 140 has the best cooling efficiency.

Next, Figure 6 is a diagram showing the results of heat transfer model analysis of the cooling module 100 using the finite element analysis method in the cryogenic cooling device for evaluating quantum devices according to an embodiment of the present invention, and Figure 7 is a diagram showing the results of the analysis of the heat transfer model of the cooling module 100 using the finite element analysis method. This is a graph showing the results of analyzing the characteristics of the cooling module 100 using finite element analysis in a cryogenic cooling device for evaluating quantum devices according to an embodiment of .

As shown in FIG. 6, it can be confirmed that the cooling module 100 is cooled from the third unit member 130 to the fourth unit member 140 over time, and this characteristic is shown in FIG. 7 It can be interpreted as a graph of linear scale and log scale.

And Figure 8 is a graph showing the change in heat transfer characteristics of the cooling module 100 according to the convective heat transfer coefficient in the cryogenic cooling device for evaluating quantum devices according to an embodiment of the present invention.

As shown in Figure 8, analysis was attempted when the convection heat transfer coefficient was 0W/(㎡K), 1W/(㎡K), 5W/(㎡K), and 10W/(㎡K), and the convection It was confirmed that the cooling efficiency was the best when the heat transfer coefficient was 0W/(㎡K).

Figure 9 is a diagram showing various forms of superconducting magnets in a cryogenic cooling device for evaluating quantum devices according to an embodiment of the present invention.

As described above, the superconducting magnet 200 is wound to surround the area where the test object (S) is located to form a magnetic field, so that the area where the test object (S) is located has superconducting characteristics, It can be implemented in various forms.

First, as shown on the left side of FIG. 9, the superconducting magnet 200A may be formed in a cone shape whose diameter gradually decreases from the top to the bottom.

And, as shown in the center of FIG. 9, the superconducting magnet 200B can be formed in the shape of a cylinder with a constant diameter from top to bottom, and as shown on the right side of FIG. 9, the superconducting magnet 200C has It can be formed in an hourglass shape with the diameter gradually decreasing from the top and bottom to the middle point.

10 and 11 are diagrams showing magnetic field change characteristics depending on the shape of the superconducting magnet in the cryogenic cooling device for evaluating quantum devices according to an embodiment of the present invention.

As shown in Figures 10 and 11, the cylindrical superconducting magnet 200B has an overall uniform field area, but the cone-shaped superconducting magnet 200A or the hourglass-shaped superconducting magnet 200C has better flux. It is confirmed to have density.

Considering this comprehensively, it is desirable to apply a cone-shaped superconducting magnet (200A).

Figure 12 is a diagram showing the structure of the fourth unit member 140 in a cryogenic cooling device for evaluating quantum devices according to another embodiment of the present invention.

As shown in FIG. 12, another embodiment of the present invention has a diameter smaller than the diameter of the fourth unit member 140 on the inside of the fourth unit member 140 and is made of copper coated with a coating metal. It has the characteristic of being additionally provided with a pipe member 142.

The reason why the auxiliary pipe member 142 is provided in this way is because the magnetic field density on the lower surface of the fourth unit member 140 increases significantly when a member made of copper coated with a metal with excellent permeability is additionally provided.

That is, in this embodiment, the auxiliary pipe member 142 coated with an arbitrary coating metal is provided adjacent to the test object S located inside the fourth unit member 140, so that the high magnetic field in the test area is provided. formation can be induced.

And Figure 13 shows the magnetic field distribution characteristics according to the presence or absence of coating of the auxiliary pipe member 142 provided inside the fourth unit member 140 in the cryogenic cooling device for evaluating quantum devices according to another embodiment of the present invention. It is a drawing.

As shown in FIG. 13, it can be seen that when the auxiliary pipe member 142 is coated with an iron (Fe) thin film, it exhibits superior magnetic field distribution characteristics compared to the auxiliary pipe member 142 on which no coating is formed.

As described above, the preferred embodiments according to the present invention have been examined, and the fact that the present invention can be embodied in other specific forms in addition to the embodiments described above without departing from the spirit or scope thereof is recognized by those skilled in the art. It is self-evident to them. Therefore, the above-described embodiments are to be regarded as illustrative and not restrictive, and thus the present invention is not limited to the above description but may be modified within the scope of the appended claims and their equivalents.

S: test subject
5: Chamber
6: Accommodation space
10: Cryogenic freezer
20: Auxiliary freezer
30: heat conductor
100: Cooling module
105: hollow
110: First unit member
120: Second unit member
130: Third unit member
140: Fourth unit member
141: Sealing cap
142: Auxiliary pipe member
150: Cover member
160: Ring member
200 superconducting magnet

Claims (12)

A chamber having an accommodating space in a vacuum atmosphere formed therein;
A cooling module is provided to be elongated in the vertical direction so as to be exposed within the accommodation space, and has a closed hollow inside in which a test object for cryogenic environmental testing for quantum device evaluation is placed;
A heat conductor connected to a first cooling point and a second cooling point of the cooling module;
a cryogenic refrigerator provided in the accommodation space and performing heat exchange with the heat conductor to cool the cooling module to a cryogenic temperature; and
a superconducting magnet that is wound around the perimeter of the area where the test object is located to form a magnetic field;
Including,
Cryogenic cooling device for quantum device evaluation. According to paragraph 1,
The superconducting magnet is formed in a shape with a constant diameter from top to bottom,
Cryogenic cooling device for quantum device evaluation. According to paragraph 1,
The superconducting magnet is formed in a shape whose diameter gradually decreases from top to bottom,
Cryogenic cooling device for quantum device evaluation. According to paragraph 1,
The superconducting magnet is formed in a shape where the diameter gradually decreases from the top and bottom to the middle point,
Cryogenic cooling device for quantum device evaluation. According to paragraph 1,
The test object is provided at a position lower than the first cooling point and the second cooling point,
Cryogenic cooling device for quantum device evaluation. According to clause 5,
The cooling module is,
a first unit member extending upward from the first cooling point and made of stainless steel;
a second unit member made of copper and joined to the lower end of the first unit member to extend downward from the first cooling point;
a third unit member joined to the lower end of the second unit member, forming the second cooling point, and made of stainless steel; and
a fourth unit member joined to the lower end of the third unit member, inside which the test object is mounted, and made of copper;
Including,
Cryogenic cooling device for quantum device evaluation. According to clause 6,
The fourth unit member is formed in a shape with a constant diameter from top to bottom,
Cryogenic cooling device for quantum device evaluation. According to clause 6,
The fourth unit member is formed in a shape where the diameter gradually decreases from the top to the bottom,
Cryogenic cooling device for quantum device evaluation. According to clause 6,
The fourth unit member is formed in a shape where the diameter gradually decreases from the top and bottom to the middle point,
Cryogenic cooling device for quantum device evaluation. According to clause 6,
It is formed to surround the fourth unit member and further includes a cover member made of stainless steel,
Cryogenic cooling device for quantum device evaluation. According to clause 6,
Inside the fourth unit member, an auxiliary pipe member having a diameter smaller than the diameter of the fourth unit member and made of copper coated with a coating metal is provided,
Cryogenic cooling device for quantum device evaluation. According to paragraph 1,
The cavity of the cooling module is filled with helium,
Further comprising an auxiliary refrigerator that lowers the temperature in the cavity by adjusting the density of helium filled in the cavity of the cooling module outside the chamber,
Cryogenic cooling device for quantum device evaluation.