Sapphire or diamond heat switch

Abstract

The invention relates to heat switches, i.e. devices that can alternate between functioning as effective thermal conductors and thermal insulators. The heat switch relies primarily on the variable thermal conductivity of sapphire or diamond to provide the heat switching functionality. The heat switch further includes a flexible connector for providing a mechanically flexible thermal connection along with the sapphire or diamond component.

Description

[0001] SAPPHIRE OR DIAMOND HEAT SWITCH

[0002] Technical Field

[0003] The invention relates to heat switches, i.e. devices that can alternate between functioning as effective thermal conductors and thermal insulators.

[0004] Background

[0005] Dilution refrigerators, such as those used to cool superconducting quantum computers, use heat switches to minimize heat transfer to the coldest stage of the refrigerator by disconnecting components when cooling is unnecessary.

[0006] During the cooling process when the temperature gradient is inverse to normal cryogenic operation, i.e. when the lower stages of the refrigerator are warmer than the upper stages of the refrigerator, the heat switches are in a thermally conductive state that facilitates cooling of the lower states by transfer of heat from the warmer lower stages to the cooler upper stages. Once the temperature gradient is reversed, the heat switches are used in a thermally insulating state, which inhibits the transfer of heat from warmer upper stages to the cooler lower stages.

[0007] There are several types of heat switches used in dilution refrigerators. For example, in gas-gap heat switches, a small gap exists between two thermally conductive components. When gas is present in the gap, thermal energy is readily transferred between the conductive components. When gas is removed from the gap, the thermally conductive components are essentially thermally disconnected. Such gas-gap heat switches are technically difficult to implement. Other types of heat switches rely for example on the contraction of a thermally conductive material to engage or disengage the heat switch’s thermal connection. In the context of dilution refrigerator there is a need to improve the thermal conductivity of heat switches in the “on” state to facilitate the transfer of heat from the warmer lower stages to the upper stages and therefore speed up the cooling process while maintaining very low thermal conductivity in the “off’ state to prevent the transfer of heat from the warmer upper stages once the lower stages have been cooled.Cooling down a superconducting quantum computer in a dilution refrigerator is a slow process taking many days, during which the system is non-functional. The time required to cool the computer only increases as the quantum computer gets larger and the cryogenic payload increases in mass. Reducing the time required to cool the lower stages of the dilution fridge is essential for improving the uptime of a superconducting quantum computer and for increasing throughput in cryogenic testing systems.

[0008] Summary of the Invention

[0009] A first aspect of the invention relates to a heat switch for a cryogenic system. The heat switch comprises a first connector for thermally coupling the heat switch to a first stage of the cryogenic system, a second connector for thermally coupling the heat switch to a second stage of the cryogenic system, a sapphire or diamond component; and a flexible connector. The sapphire or diamond component and the flexible connector form a thermal connection between the first connector and the second connector. The thermal conductivity of the thermal connection varies based on the temperature of the sapphire or diamond component. A heat switch according to the invention comprises a simple technological implementation as well as a flexible design compared to the heat switch of the prior art.

[0010] A second aspect of the invention relates to a cryogenic system comprising the heat switch described above, a first stage and a second stage, such that the heat switch connects the first stage and the second stage of the cryogenic system. Such cryogenic system can be cooled down in a more effective way compared to the prior art.

[0011] Further advantageous features of the invention are set out in the dependent claims.

[0012] Brief Description of the Drawings

[0013] Figures 1 to 5 show exemplary configurations of heat switches according to the present invention.

[0014] Figure 6 shows an exemplary configuration of a cryogenic system according to the present invention.Detailed Description of the Invention

[0015] The heat switch of the present invention relies primarily on the variable thermal conductivity of sapphire or diamond to provide the heat switching functionality. In other words, the thermal conductivity of the sapphire or diamond within the heat switch is the dominant factor in the overall thermal conductivity of the heat switch. Sapphire is particularly advantageous because it has relatively high thermal conductivity at typical temperatures within a cryostat during the cooling phase, e.g. 10K - 100K, but relatively low thermal conductivity at temperatures within the coldest stages of the cryostat during normal operation phase, e.g. less than 5K and less than 1K. Until now, Sapphire has been used primarily for its mechanical properties, for example its hardness of 9 on the Mohs scale. Diamond may be even more advantageous, because it has even higher transition temperature for passive switching than sapphire at typical temperatures within a cryostat during the cooling phase. Diamonds used in this invention may be natural or artificial, i.e. lab-grown.

[0016] The heat switches of the present invention may be passive heat switches, i.e. the thermal conductivity of the heat switch changes only in response to the change in temperature of the heat switch. The heat switch of the present invention is dependent on the operating temperature and relies on a temperature change. In other words, the heat switch may be a self-switching device. In contrast, an active heat switch is one in which the thermal conductivity of the heat switch changed in response to some stimulus applied to the heat switch primarily for the purpose of changing the thermal conductivity, e.g. applying an electrical signal to cause two parts to move apart and break a thermally conductive connection between them, or applying a mechanical motion. The heat switches of the present invention may also be used as part of or in combination with an active heat switch.

[0017] Furthermore, the heat switch according to the invention may change its thermal conductivity but its thermal conductivity is not broken as for example in the prior art gas-gap heat switch where a mechanical stress results in a loss of the thermal conductivity of the heat switch. Accordingly, the heat switch according to the invention may be used several times, repetitively.Figures 1 to 5 depict four different examples 100, 200, 300, 400, 500 of heat switches according to the present invention. The examples depicted in Figures 1 to 5 are not exhaustive. Other arrangements of components are possible within the scope of the invention, as defined in the claims. The essential features of the heat switch of the present invention are at least one sapphire or diamond component and at least one flexible connector.

[0018] The term “sapphire component” refers to a component of the heat switch that includes one or more sapphire elements that are rigidly connected together, either directly or via an intermediate rigid member, e.g. multiple sapphire elements fixed to the same stage of a cryogenic device, or sapphire elements connected to one another via a rigid connector. In other words, a “sapphire component” in this context may refer to either a single sapphire element or to multiple sapphire elements that are directly connected to one another, or to multiple sapphire elements connected to a common rigid component.

[0019] The term “diamond component” refers to a component of the heat switch that includes one or more diamond elements that are rigidly connected together, either directly or via an intermediate rigid member, e.g. multiple diamond elements fixed to the same stage of a cryogenic device, or diamond elements connected to one another via a rigid connector. In other words, a “diamond component” in this context may refer to either a single diamond element or to multiple diamond elements that are directly connected to one another, or to multiple diamond elements connected to a common rigid component.

[0020] The term “sapphire or diamond component” refers to a sapphire component or a diamond component as described above. The sapphire or diamond component may thus comprise either sapphire element(s) or diamond element(s). Terms such as “one or more sapphire or diamond elements” or “multiple sapphire or diamond elements” refer to number of elements where each element is made of sapphire or where each element is made of diamond. In general, the sapphire or diamond component or components are indicated by reference number 101 in Figure 1, 201a-b in Figure 2, 301a-b in Figure 3, 401a-d in Figure 4, and 501a-b in Figure 5. As discussed above, the function of the sapphire or diamond component or components is to provide the variable thermal conductivity needed for operation of the heat switch. The sapphire or diamond component orcomponents contribute the majority, i.e. > 50%, or even > 90%, of the thermal conductivity or resistance to the heat switch.

[0021] In the embodiments described below, sapphire components comprising one or more sapphire elements are used as examples. However, in alternative embodiments, diamond can be used instead of sapphire. Unless expressly stated otherwise, any embodiment described herein as comprising sapphire components and sapphire elements is also intended to encompass corresponding embodiments comprising diamond components and diamond elements, with the term “sapphire” replaced by “diamond”. In cases where the heat switch comprises more than one component, said components can be of the same or of a different type, i.e., some or all components may be sapphire components and / or some or all components may be diamond components. For example, when the heat switch comprises a first component and a second component, both components may be sapphire components or both components may be diamond components, or the first component may be a sapphire component, and the second component may be a diamond component or vice versa.

[0022] Each sapphire component may include a single sapphire element, as shown in Figures 1 to 3, or multiple sapphire elements arranged in parallel, as shown in Figure 4, or in series, as shown in Figure 5. Each sapphire element may be a single sapphire crystal of high purity, for example of purity of around 99.997. Each sapphire element may also be made of multiple crystals. Each sapphire element has a generally elongated shape, such as a rod, bar, shaft, dowel, pipe or beam.

[0023] A heat switch according to the present invention includes at least one flexible connector. A flexible connector may connect a sapphire component to a stage of a cryostat, as shown in Figures 1 and 5. Alternatively, a flexible connector may connect one sapphire component to another sapphire component, as shown in Figures 2 to 4.

[0024] In general, the flexible connector is indicated by reference number 102 in Figures 1, 202 in Figure 2, 302 in Figure 3, 402 in Figure 4, and 502 in Figure 5. The flexible connector provides a mechanically flexible connection between the stages (indicated by reference numbers 111, 211, 311, 411, 511 and 112, 212, 312, 412, 512 in Figures 1 to 5) of the cryogenic system in which the heat switchis to be used and the sapphire component or components to account for different rates of thermal expansion and contraction of the sapphire component and the cryogenic system. Figures 1-5 show a single flexible connector 102, 202, 302, 402, 502. However, an arbitrary number of flexible connectors may be used between the sapphire component(s) and the stage(s) of the cryogenic system, e.g. cryogenic system 600. The flexible connector or flexible connectors may be made of a material that also exhibits a good thermal conductivity over the range where sapphire is a good conductor. For example, each flexible connector may include one or more of a copper braid, a graphite braid, a silver braid, or a silver wire. If multiple flexible connectors are used, they may be formed of the same material or different materials.

[0025] In addition to the sapphire component(s) and flexible connector(s), in practice, further connectors for thermally coupling the heat switch between the stages of a cryogenic system in which it is to be used may also be required. These further connectors are indicated by reference numbers 103 and 104 in Figure 1, 203 and 204 in Figure 2, 303 and 304 in Figure 3, 403a-b and 404a-b in Figure 4, and 503 and 504 in Figure 5. However, it will be appreciated that the invention lies primarily in the use of sapphire as a heat switch material, as discussed above, rather than in the precise manner of connection of the heat switch to the cryostat stages. These further connectors may be fixed connectors that mechanically hold the sapphire component(s) and / or flexible connector(s) in a fixed position relative to the stages of the cryogenic system. The further connectors may be formed of copper or any other material with suitable mechanical and thermal properties. Additional intermediate connectors may also be required for connections between sapphire elements within a sapphire component, or between a sapphire component and a flexible connector. These additional intermediate connectors are indicated by reference numbers 105 in Figure 1, 205a-b in Figure 2, 305a-b in Figure 3, 405a-d in Figure 4, 505a-b in Figure 5. Again, it will be appreciated that the invention lies primarily in the use of sapphire or diamond as a heat switch material, as discussed above, rather than in the precise manner of the intermediate connections within the heat switch. The intermediate connectors may be formed of copper or any other material with suitable mechanical and thermal properties.Figure 1 shows a first heat switch 100. The heat switch 100 includes a sapphire component 101 and a flexible connector 102. The sapphire component 101 is a single piece, namely an integral component. The heat switch is intended to be connected between a first stage 111 of a cryogenic system, e.g. the cryogenic system 600 shown in Figure 6, such as a dilution refrigerator, and a second stage 112 of the cryogenic system. That is, when installed in a cryogenic system, the heat switch 100 provides a thermal connection between a first stage 111 of the cryogenic system and a second stage 112 of the cryogenic system. The heat switch 100 is connected to the first stage 111 by a first connector 103 and to the second stage 112 by a second connector 104. The first connector 103 connects the sapphire component 101 to the first stage 111 such that the sapphire component 101 is mechanically fixed to the first stage 111 at one end of the sapphire component. The sapphire component 101 is connected to the second stage 112 at its second end via the flexible connector 102 and the second connector 104. The flexible connector 102 is fixed at a first end to the sapphire component 101, e.g. via an intermediate connector 105, and fixed at a second end to the second stage 112. The flexible connector 102 therefore provides a mechanically flexible thermal connection between the sapphire component 101 and the second stage 112, which accommodates different rates of thermal expansion and contraction of the sapphire component 101 and the cryogenic system without creating stress or strain on the sapphire component 101 and the cryogenic system, which may lead to damage to one or both of the sapphire component 101 and the cryogenic system.

[0026] Figure 2 shows a second heat switch 200. The heat switch 200 includes a first sapphire component 201a, a second sapphire component 201b, and a flexible connector 202. The heat switch 200 comprises a sapphire component which is made of two parts, namely a first sapphire component and a second sapphire component. Like the heat switch 100 of the first embodiment, the heat switch 200 is intended to be connected between a first stage 111 of a cryogenic system, e.g. a dilution refrigerator, and a second stage 112 of the cryogenic system. That is, when installed in a cryogenic system, the heat switch 200 provides a thermal connection between a first stage 211 of the cryogenic system and a second stage 212 of the cryogenic system. The heat switch 200 is connected to the first stage 211 by a first connector 203 and to the second stage 212 by a second connector 204. The first connector 203 connects the first sapphire component 201a to thefirst stage 211 such that the first sapphire component 201a is mechanically fixed to the first stage 211. The second sapphire component 201b is connected to the second stage 212 by the second connector 104 such that the second sapphire component 201b is mechanically fixed to the second stage 212. The flexible connector 202 is fixed at a first end to the first sapphire component 201a, e.g. via a first intermediate connector 205a, and fixed at a second end to the second sapphire component 201b, e.g. via a second intermediate connector 205b. The flexible connector 102 therefore provides a mechanically flexible thermal connection between the first sapphire component 201a and the second sapphire component 201b, which accommodates different rates of thermal expansion and contraction of the sapphire components 201a-b and the cryogenic system without creating stress or strain on the sapphire components and the cryogenic system, which may lead to damage to one or both of the sapphire component and the cryogenic system.

[0027] In Figure 2, both components 201a, 201b of the heat switch 200 have the same size in terms of length and diameter. However, the sapphire components 201a, 201b may also have a different size, i.e. one of the components may be longer than the other one.

[0028] Figure 3 shows a third heat switch 300. The heat switch 300 is arranged in the same manner as described above with respect to Figure 2. However, while in heat switch 200 of Figure 2 the combined length of the sapphire components 201a, 201b is less than 100% of the distance between the first stage 211 and the second stage 212, in heat switch 300 of Figure 3, the combined length of the sapphire components 301a, 301b, is greater than 100% of the distance between the first stage 311 and the second stage 312. This demonstrates that the flexible connector 202, 302, in combination with the use of two sapphire components, 201 a-b or 301 a-b, allows the same heat switch to be used with different cryogenic systems or between different stages of cryogenic systems having different separations between the stages. The use of a flexible connector further allows the positions on each stage at which the heat switch is connected to not be vertically aligned, i.e. aligned along an axis perpendicular to the surfaces of the stages. This allows for more flexible positioning within the cryogenic system and increases the number of available positions within the cryogenic system atwhich the heat switches may be placed, thereby increasing the total number of installable heat switches in a given cryogenic system.

[0029] In Figure 3, both elements 301a, 301b of the heat switch 300 have the same size in terms of length and diameter. However, the elements 301a, 301b may also have a different size, i.e. one of the elements may be longer than the other one. Figure 4 shows a fourth heat switch 400. Figure 4 demonstrates that each sapphire component of a heat switch of the invention may be made up of an arbitrary number of sapphire elements arranged in parallel, bearing in mind the physical limits of available space within the cryogenic system in which the heat switch is used. By varying the number of sapphire elements arranged in parallel, the thermal conductivity of the connection may be adjusted, with a higher number of sapphire elements arranged in parallel providing a higher thermal conductivity between the stages 411 and 412. As shown in Figure 4, the heat switch 400 is arranged in the same manner as described above with respect to Figure 2.

[0030] However, each first sapphire component 401a is made up of two sapphire elements 406a-b arranged in parallel, and second sapphire component 401b is made up of two sapphire elements 407a-b arranged in parallel.

[0031] A single flexible connector 402 may be connected to both sapphire elements 406a-b, 407a-b of each sapphire component 401a-b, as shown in Figure 4. In this case, each sapphire element 406a-b and 407a-b may be connected to the flexible connector 403 by a different intermediate connector 405a-d as shown in Figure 4. Alternatively, sapphire elements of the same sapphire component may be connected to the flexible connector 402 by a single common intermediate connector, i.e. sapphire element 406a-b may be connected by a single common intermediate connector to the flexible connector 402, and / or sapphire elements 407a-b may be connected by a different single common intermediate connector to the flexible connector 402. Alternatively, sapphire element 406a may be connected to sapphire element 407a by a different flexible connector to that flexible connector connecting sapphire element 406b to sapphire element 407b. In general, any suitable arrangement and manner of connecting sapphire elements 406a-b and 407a-b may be used.

[0032] Sapphire elements 406a, 406b may be connected to the first stage 411 by different connectors 403a, 403b as shown in Figure 4, or by a single common connector (not shown). Similarly, sapphire elements 407a, 407b may beconnected to the second stage by different connectors 404a, 404b, as shown in Figure 4, or by a single common connector (not shown).

[0033] While Figure 4 shows a heat switch 400 including two sapphire components 401a, 401b, each of which includes two sapphire elements 406a-b and 407a-b respectively, it will be appreciated that the technique of using multiple sapphire elements arranged in parallel within a sapphire component may be used with any number of sapphire components, and within all or only some of the sapphire components of a heat switch of the present invention.

[0034] While Figure 4 also shows sapphire elements 406a-b and 407a-b which have the same size, the sapphire elements 406a-b and 407a-b may also have a different size.

[0035] Figure 5 shows a fifth heat switch 500. Figure 5 demonstrates that each sapphire component of a heat switch of the invention may be made up of an arbitrary number of sapphire elements arranged in series. In Figure 5, the sapphire component 501 is made up of two sapphire elements 506a, 506b arranged in series. The first sapphire element 506a is connected to the first stage 511 of the cryogenic system by a first connector 503. Sapphire elements 506a, 506b are connected to one another via an intermediate connector 505b. The second sapphire element 506b is connected to a first end of the flexible connector 502 by an intermediate connector 505a. The flexible connector 502 is connected at its second end to the second stage 512 by a second connector 504. While Figure 5 shows sapphire elements 506a-b having the same size, the sapphire elements 506a-b may also have a different size.

[0036] Arranging multiple sapphire elements in series within a single sapphire component enables greater distances between stages of the cryogenic system to be spanned by sapphire with a given maximum size of a single sapphire element. Other arrangements that those shown in Figures 1 to 5 may be envisaged for heat switches according to the present invention. For example:

[0037] - A heat switch with a single sapphire component that includes multiple sapphire elements arranged in parallel.

[0038] - A heat switch with a single sapphire component that includes multiple sapphire elements arranged both in series and in parallel.- A heat switch with two sapphire components, one of which includes multiple sapphire elements arranged in parallel.

[0039] - A heat switch with two sapphire components, one of which includes multiple sapphire elements arranged in series.

[0040] - A heat switch with two sapphire components, one which includes multiple sapphire components arranged in series and the other includes multiple sapphire components arranged in parallel.

[0041] - A heat switch with two sapphire components, one of which includes multiple sapphire elements arranged in parallel and in series.

[0042] - A heat switch with two sapphire components, both of which include multiple sapphire elements arranged in parallel and in series.

[0043] The present invention also extends to a cryogenic system including one or more heat switches as described above. Figure 6 depicts a cryogenic system 600 including heat switches 601, 602, 603 according to the invention. The cryogenic system 660 comprises four different stages, namely a first stage 611 , a second stage 612, a third stage 613 and a fourth stage 614. The stages correspond to different temperature stages within the cryogenic system.

[0044] Heat switch 601 provides a thermal connection between a first stage 611 and a second stage 612. Heat switch 601 corresponds to the heat switch 200 shown in Figure 2 with two sapphire elements in each sapphire component.

[0045] Heat switch 602 provides a thermal connection between the second stage 612 and a third stage 613. Heat switch 602 corresponds to the heat switch 300 shown in Figure 3 with two sapphire elements arranged in series in each sapphire component. Furthermore, the components of heat switch 602 are the same size as the components of heat switch 601, but due to a smaller vertical separation between the second stage 612 and the third stage 613, the total length (measured vertically) of the sapphire components of heat switch 602 is greater than 100% of the separation between the stages 612 and 613. However, the components of the heat switch 602 do not have to be of the same size and could have different sizes. As described above, the flexible connector in combination with the use of two sapphire components allows the same heat switch to be used between different stages of cryogenic systems having different separations between the stages. As shown on Figure 6, the heat switch can be provided at each level of the dilution fridge, namely on each stage of the dilution fridge. In avariant, the heat switch can also be provided to only some of the stages within the dilution fridge.

[0046] Heat switch 603 provides a thermal connection between the third stage 613 and a fourth stage 614. Heat switch 603 corresponds to the heat switch 400 shown in Figure 4, demonstrating that different configurations of heat switches may be used within the same cryogenic system in order to provide different or tailored thermal conductivity between stages as appropriate.

[0047] The heat switches may be integrated within a support structure of the cryogenic system, e.g. a support structure used to maintain the relative positions of the first and second stages within the cryogenic system. By integrating the heat switch or heat switches within the support structure, space may be saved within the cryogenic system. Alternatively, the heat switches may be connected at arbitrary positions on the first stage and second stage of the cryogenic system. The use of a flexible connector as described above further allows the positions on each stage at which the heat switch is connected to not be vertically aligned, i.e. aligned along an axis perpendicular to the surfaces of the stages. This allows for more flexible positioning within the cryogenic system and increases the number of available positions within the cryogenic system at which the heat switches may be placed, thereby increasing the total number of installable heat switches in a given cryogenic system. Furthermore, heat switches according to the present invention can be reused across multiple heating / cooling cycles, e.g. due to maintenance of the cryogenic system or replacement of parts, such as quantum processing units, within the cryogenic system. The same heat switch can also be removed from a first system and re-used in a second cryogenic system, even if the second cryogenic system has a different distance between stages, for example.

Claims

Claims1. A heat switch (100, 200, 300, 400, 500, 601 , 602, 603) for a cryogenic system, the heat switch comprising:a first connector (103, 203, 303, 403a, 503) for thermally coupling the heat switch to a first stage (111, 211, 311, 411, 511) of the cryogenic system;a second connector (104, 204, 304, 404a, 504) for thermally coupling the heat switch to a second stage (112, 212, 312, 412, 512) of the cryogenic system;a sapphire or diamond component (101, 201a, 301a, 401a, 501); and a flexible connector (102, 202, 302, 402, 502);wherein the sapphire or diamond component and the flexible connector form a thermal connection between the first connector and the second connector, andwherein the thermal conductivity of the thermal connection varies based on the temperature of the sapphire or diamond component.

2. The heat switch of claim 1 , wherein the sapphire component (401a, 501) comprises multiple sapphire elements (406a, 406b, 506a, 506b) arranged in series or in parallel or the diamond component (401a, 501) comprises multiple diamond elements (406a, 406b, 506a, 506b) arranged in series or in parallel.

3. The heat switch of claim 1 or 2, wherein the sapphire or diamond component (101, 201a, 301a) or each sapphire or diamond element (406a, 406b, 506a, 506b) is a single sapphire or diamond crystal respectively.

4. The heat switch of claim 2 or 3, wherein the sapphire or diamond component (101, 201a, 301a) or each sapphire or diamond element (406a, 406b, 506a, 506b) has an elongated shape, such as a rod, bar, shaft, dowel, pipe, or beam5. The heat switch of any preceding claim, wherein the flexible connector (102, 202, 302, 402, 502) is a copper ribbon, graphite ribbon, a silver ribbon or a silver wire.

6. The heat switch of any one of the preceding claims, wherein the sapphire or diamond component (101, 201a, 301a, 401a, 501) is directly connected to the first connector (103, 203, 303, 403a, 503) and wherein the sapphire or diamond component is connected to the second connector (104, 204, 304, 404a, 504) via the flexible connector (102, 202, 302, 402, 502).

7. The heat switch of any of claims 1 to 6, wherein the sapphire or diamond component (201a, 301a, 401a) is a first sapphire or diamond component, wherein the heat switch further comprises a second sapphire or diamond component (201b, 301b, 401b), and wherein:the first sapphire or diamond component is directly connected to the first connector (203, 303, 403a);the second sapphire or diamond component is directly connected to the second connector (204, 304, 404a); andthe first sapphire or diamond component is connected to the second sapphire or diamond component via the flexible connector (202, 302, 402).

8. The heat switch of claim 6 or 7, wherein the sapphire component (401a) comprises at least two sapphire elements (406a, 406b) or the diamond component (401a) comprises at least two diamond elements (406a, 406b), and wherein the flexible connector (402) is directly connected to all of the at least two sapphire or diamond elements of the first sapphire or diamond component.

9. The heat switch of claim 7 or 8, wherein the first sapphire or diamond component (201a, 301a, 401a) and the second sapphire or diamond component (201b, 301b, 401b) are physically separated such that they are only connected to each other via the flexible connector (202, 302, 402).

10. The heat switch of any of claims 7 to 9, wherein the second sapphire component (401b) comprises at least two sapphire elements (407a, 407b) or the second diamond component (401b) comprises at least two diamond elements (407a, 407b), and wherein the flexible connector (404) is directly connected to all of the at least two sapphire or diamond elements of the second sapphire or diamond component.

11. The heat switch of any preceding claim, wherein the heat switch is a passive heat switch.

12. The heat switch of any preceding claim, wherein the thermal conductivity of the sapphire or diamond component or sapphire or diamond components (101, 201a, 201b, 301a, 301b, 401a, 401b, 501) accounts for more than 50%, more than 60%, more than 70%, more than 80% or more than 90% of the thermal conductivity of the thermal connection.

13. A cryogenic system (600) comprising:a first stage (611);a second stage (612); andat least one heat switch (601) according to any preceding claim.

14. A cryogenic system according to claim 13, wherein the at least one heat switch is integrated with a support structure of the cryogenic system, wherein the support structure is configured to maintain the position of the first stage relative to the second stage within the cryostat.

15. A cryogenic system according to claim 13, wherein the at least one heat switch (602) is connected to the first stage (612) at a first position and connected to the second stage (613) at a second position, and wherein the first position is not aligned with the second position along an axis perpendicular to the surface of the first stage and / or second stage.

Images