1 kelvin and 300 millikelvin hot stage for cryogenic environments

Abstract

Techniques are provided that facilitate efficient heat distribution management within a cryogenic environment. In one example, a cryostat can include a plurality of thermal stages between 4 Kelvin (K) stages and cold plate stages. The plurality of thermal stages can include a stationary stage and an intermediate thermal stage that provides additional cooling capacity for the cryostat. The intermediate thermal stage can be directly mechanically coupled to the stationary stage via a support post.

Description

Background Art

[0001] The present invention relates to cryogenic environments and, more particularly, to techniques that facilitate efficient heat distribution management within cryogenic environments.

[0002] A cryostat can maintain a sample or device positioned on a sample mounting surface within the cryostat at a temperature close to absolute zero to facilitate evaluation of such samples or devices under cryogenic conditions. A cryostat typically provides such low temperatures using five heat stages mechanically coupled to a room temperature plate of an outer vacuum chamber surrounding the five heat stages. The five heat stages of the cryostat comprise a thermal profile in which each subsequent heat stage has a progressively lower temperature than the temperature present at the preceding heat stage.

[0003] In addition to having progressively lower temperatures, each subsequent thermal stage typically has progressively lower available cooling power than the cooling power available at the preceding thermal stage. For example, while a 50 Kelvin (50-K) stage may have 30 watts (W) of available cooling power at a temperature of 50 K, a 4 Kelvin (4-K) stage may have 1.5 W of available cooling power at a temperature of 4 K, and a mixing chamber stage, typically associated with the lowest temperature within a cryostat, may have 20 microwatts (μW) of available cooling power at a temperature of 20 milliKelvin (mK). Consequently, effectively managing available cooling power may become increasingly important at lower temperature regions within the cryostat's thermal profile. Summary of the Invention

[0004] The following is an overview presented to provide a basic understanding of one or more embodiments of the present invention. This overview is not intended to identify key or critical elements, or to delineate any scope of a particular embodiment or any scope of the claims. Its sole purpose is to present the concepts in a simplified form as a prelude to the more detailed description presented later. In one or more embodiments described herein, systems, devices, and / or methods are described that facilitate efficient heat distribution management within a low-temperature environment.

[0005] According to an embodiment, a cryostat may include a plurality of hot stages between a 4 Kelvin (K) stage and a cold plate stage. The plurality of hot stages may include a stationary stage and an intermediate hot stage, the intermediate hot stage providing additional cooling capacity for the cryostat. The intermediate hot stage may be directly mechanically coupled to the stationary stage via support rods. One aspect of such a cryostat is that the cryostat may facilitate efficient heat distribution management within a low temperature environment.

[0006] In one embodiment, the intermediate hot stage can operate at a temperature of about 1 Kelvin (K). One aspect of such a cryostat is that the cryostat can facilitate increasing the cooling capacity of the stationary stage, cold plate stage, and / or mixing chamber stage by exposing these stages to 1 K blackbody radiation instead of 4 K blackbody radiation.

[0007] According to another embodiment, a cryostat can include a stationary stage mechanically coupled directly to an intermediate hot stage via support rods. The intermediate hot stage can provide additional cooling capacity for the cryostat. The stationary stage and the intermediate hot stage can be included in a plurality of hot stages between the 4-K stage and the cold plate stage. One aspect of such a cryostat is that it can facilitate efficient heat distribution management within a low-temperature environment.

[0008] In one embodiment, the intermediate hot stage can operate at a temperature of approximately 300 millikelvin (mK). One aspect of such a cryostat is that the cryostat can facilitate increasing the cooling power of the cold plate stage and / or mixing chamber stage by exposing these stages to 300 mK blackbody radiation instead of 700 mK blackbody radiation.

[0009] According to another embodiment, the cryostat can include a sealed canister that facilitates evaporative cooling of the helium medium. The sealed canister can be coupled to an intermediate hot stage that provides additional cooling capacity for the cryostat. The intermediate hot stage can be directly mechanically coupled to the stationary stage via support rods. The stationary stage and the intermediate hot stage can be included in a plurality of hot stages between the 4-K stage and the cold plate stage. One aspect of such a cryostat is that it can facilitate efficient heat distribution management within the cryogenic environment.

[0010] In an embodiment, the seal can may comprise a sintered material.One aspect of such a cryostat is that the cryostat may facilitate thermal budget optimization. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 An exemplary, non-limiting cryostat is shown according to one or more embodiments described herein.

[0012] Figure 2 A circuit schematic of an exemplary, non-limiting cryostat is shown according to one or more embodiments described herein.

[0013] Figure 3 An exemplary, non-limiting cryostat is shown with an intermediate hot stage providing additional cooling capabilities according to one or more embodiments described herein.

[0014] Figure 4Another exemplary, non-limiting cryostat is shown with an intermediate hot stage providing additional cooling capabilities according to one or more embodiments described herein.

[0015] Figure 5 An exemplary, non-limiting cryostat is shown having multiple intermediate hot stages each providing additional cooling capacity according to one or more embodiments described herein. DETAILED DESCRIPTION

[0016] The following detailed description is illustrative only and is not intended to limit the embodiments and / or the application or uses of the embodiments. In addition, it is not intended to be bound by any express or implied information presented in the preceding background or summary or detailed description.

[0017] One or more embodiments will now be described with reference to the accompanying drawings, wherein like reference numerals are used throughout to refer to like elements. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a more thorough understanding of one or more embodiments. However, it will be apparent that in various circumstances, one or more embodiments may be practiced without these specific details.

[0018] Figure 1 An exemplary, non-limiting cryostat 100 is shown according to one or more embodiments described herein. Figure 1 As shown, the cryostat 100 includes an outer vacuum chamber 110 formed by a sidewall 120 between a top plate 130 and a bottom plate 140. In operation, the outer vacuum chamber 110 can maintain a pressure differential between an ambient environment 150 of the outer vacuum chamber 110 and an interior 160 of the outer vacuum chamber 110. The cryostat 100 also includes a plurality of heat stages (or stages) 170 disposed within the interior 160, each of the plurality of heat stages being mechanically coupled to the top plate 130. The plurality of stages 170 include a stage 171, a stage 173, a stage 175, a stage 177, and a stage 179. Each of the plurality of stages 170 can be associated with a different temperature. For example, stage 171 may be a 50 Kelvin (50-K) stage associated with a temperature of 50 Kelvin (K), stage 173 may be a 4 Kelvin (4-K) stage associated with a temperature of 4 K, stage 175 may be associated with a temperature of 700 milliKelvin (mK), stage 177 may be associated with a temperature of 100 mK, and stage 179 may be associated with a temperature of 10 mK. Each stage in the plurality of stages 170 is spatially isolated from the other stages in the plurality of stages 170 by a plurality of support rods (e.g., support rods 172 and 174). In an embodiment, stage 175 may be a stationary stage, stage 177 may be a cold plate stage, and stage 179 may be a mixing chamber stage.

[0019] Figure 2 A circuit schematic diagram of an exemplary, non-limiting cryostat 200 is shown according to one or more embodiments described herein. As discussed above, a cryostat can maintain a sample or device positioned on a sample mounting surface within the cryostat at a temperature near absolute zero to facilitate evaluation of such a sample or device under cryogenic conditions. Evaluating a sample or device under cryogenic conditions typically involves interacting with such a sample or device using one or more devices located external to the cryostat at room temperature. To this end, a cryostat can include input / output (I / O) lines that facilitate the propagation of electrical signals between a sample positioned within the cryostat and a device external to the cryostat.

[0020] By way of example, a superconducting qubit can be positioned on a sample mounting surface 260 of a cryostat 200. Coupling the superconducting qubit positioned on the sample mounting surface 260 to one or more devices external to the cryostat 200 are four I / O lines: a drive line 271; a flux line 273; a pump line 275; and an output (or readout) line 277. Those skilled in the art will appreciate that these four I / O lines can contribute to the heat load placed on the cryostat 200 in a number of ways. One way in which the four I / O lines can contribute to the heat load is that each I / O line can provide a thermal path along which heat can be conducted from a higher temperature hot stage to a lower temperature hot stage. For example, in Figure 2 , drive line 271 is routed from the 50-K stage 210 of the cryostat 200 to the mixing chamber stage 250. Along the routing path through the cryostat 200, the drive line 271 can provide a thermal path through which heat can be conducted from a higher temperature thermal stage to a lower temperature thermal stage, for example, from the 50-K stage 210 to the 4-K stage 220.

[0021] Another way that the four I / O lines can contribute to thermal loads involves heat generated due to dissipation of signals propagating along a given I / O line or via intervening electrical components (e.g., Joule heating). For example, a microwave flux signal propagating along flux line 273 toward a SQUID loop associated with a superconducting qubit positioned on sample mounting surface 260 can introduce heat on stationary stage 230 of cryostat 200 via thermal coupling 274. As another example, a microwave pump signal propagating along flux line 273 for operation of traveling-wave parametric amplifier (TWPA) 283 can introduce heat on cold stage 240 via attenuator 285 coupled to flux line 273 and cold stage 240.

[0022] Another way that the four I / O lines can contribute to thermal loading is that a higher temperature hot stage represents a radiation load to a lower temperature hot stage. For example, a direct current (DC) signal can introduce heat to the 4-K stage 220, which biases the high electron mobility transistor (HEMT) amplifier 285 to facilitate measurement of a superconducting qubit positioned on the sample mounting surface 260 via output line 277. Such heat introduced to the 4-K stage 220 can expose a low temperature hot stage (e.g., stationary stage 230) to a radiation load from the 4-K stage 220 that appears as 4K blackbody radiation to the low temperature hot stage.

[0023] As discussed above, each subsequent hot stage of a cryostat typically has progressively lower available cooling power than the cooling power available at the preceding hot stage. Consequently, effectively managing the available cooling power can become increasingly important at lower temperature regions within the cryostat's thermal profile. The embodiments described herein facilitate efficient thermal profile management within a cryogenic environment by implementing intermediate hot stages that can provide additional cooling capacity. For example, according to various embodiments, the additional cooling capacity provided by the intermediate hot stages can improve thermal profile management efficiency by reducing the amount of heat that can be conducted from the higher temperature hot stage to the lower temperature hot stage via I / O lines. As another example, according to various embodiments, the intermediate hot stages can improve thermal profile management efficiency by exposing the low temperature hot stage to a radiation load having a lower level of blackbody radiation.

[0024] Figure 3 An exemplary, non-limiting cryostat 300 is shown with an intermediate hot stage providing additional cooling capability according to one or more embodiments described herein. Figure 3 As shown, the cryostat 300 includes a 50-K stage 310 that can be coupled to a room temperature plate (e.g., Figure 1 on the top plate 130). Figure 3 The cryostat 300 is also shown to include multiple hot stages between the 4-K stage 320 and the cold plate stage 340. The multiple hot stages include a stationary stage 340 and an intermediate hot stage 330. The intermediate hot stage 330 is directly mechanically coupled to the 4-K stage 320 via support rods 322 and directly mechanically coupled to the stationary stage 340 via support rods 332. The intermediate hot stage 330 is indirectly mechanically coupled to the 50-K stage 310 via support rods 312, indirectly mechanically coupled to the cold plate stage 350 via support rods 342, and indirectly mechanically coupled to the mixing chamber stage 360 ​​via support rods 352. The surface 331 of the intermediate hot stage 330 can be implemented in various shapes. For example, the surface 331 can be implemented as a circle, a quarter circle, a triangle, a quadrilateral, etc. As another example, the surface 331 can be implemented as an amorphous shape.

[0025] The intermediate hot stage 330 may include a feedthrough element 334 interposed with a wiring structure 390 that facilitates the propagation of electrical signals between the 4-K stage 320 and the cold plate stage 350. The wiring structure 390 may include I / O lines that couple a sample positioned within the cryostat 300 to one or more devices external to the cryostat 300. For example, the wiring structure 390 may include I / O lines such as Figure 2 The drive line 271, the flux line 273, the pump line 275 and / or the output (or readout) line 277. In an embodiment, the intermediate hot stage 330 may include copper, gold, silver, brass, platinum or a combination thereof.

[0026] The intermediate hot stage 330 can provide additional cooling capacity for the cryostat 300 via a sealed tank 370 connected to the intermediate hot stage 330. To this end, the sealed tank 370 facilitates evaporative cooling of the helium medium (helium-4). The condenser line 372 can connect the outlet port 382 of the pump 380 to the sealed tank 370 via the 4-K stage 320. In one embodiment, the pump 380 can be a vacuum pump for circulating the helium medium through the sealed tank 370. In an embodiment, the pump 380 is located outside the cryostat 300. In one embodiment, the pump 380 is located inside the cryostat 300. In this embodiment, the pump 380 can be implemented as an adsorption pump. The condenser line 372 can provide a return path for the helium medium to the sealed tank 370. The pumping line 374 may couple the inlet port 384 of the pump 380 to the seal pot 370 via the 4-K stage 320. The 4-K stage 320 may provide access for the condenser line 372 and / or the pumping line 374 via a feed-through element (eg, feed-through element 323).

[0027] In operation, helium-4 can flow in a gaseous state from outlet port 382 toward sealed tank 370. Feedthrough element 323 can thermally anchor condenser line 372 to 4-K stage 320. When helium-4 flows through feedthrough element 323, helium-4 can be converted from a gaseous state to a liquid state. The helium-4 in the liquid state can be collected in sealed tank 370. Inlet port 384 of pump 380 can reduce the pressure above the liquefied helium-4 collected in sealed tank 370. Helium-4 in a gaseous state can be formed above the liquefied helium-4 collected in sealed tank 370 by evaporation and flow to the inlet port 384 of pump 380 via pumping line 374. The heat carried by the gaseous helium-4 flowing through pumping line 374 can reduce the temperature of the liquefied helium-4 maintained in sealed tank 370. Such evaporative cooling of the liquefied helium-4 in the sealed tank 370 can reduce the temperature of the intermediate hot stage 330, allowing the intermediate hot stage 330 to operate at a temperature of approximately 1 K. In one embodiment, the sealed tank 370 can be vacuum-sealed or cryogenically sealed. In one embodiment, the sealed tank 370 can include a sintered material that facilitates thermal budget optimization. The sintered material can include silver, gold, copper, platinum, etc.

[0028] Figure 4 Another exemplary, non-limiting cryostat 400 is shown having an intermediate hot stage providing additional cooling capability according to one or more embodiments described herein. Figure 4 As shown, the cryostat 400 includes a 50-K stage 410 that can be coupled to a room temperature plate (e.g., Figure 1 on the top plate 130). Figure 4 The cryostat 400 is also shown to include multiple hot stages between the 4-K stage 420 and the cold plate stage 450. These multiple hot stages include a stationary stage 430 and an intermediate hot stage 440. The intermediate hot stage 440 is directly mechanically coupled to the stationary stage 430 via support rods 432, and directly mechanically coupled to the cold plate stage 450 via support rods 442. The intermediate hot stage 440 is indirectly mechanically coupled to the 50-K stage 410 via support rods 412, indirectly mechanically coupled to the 4-K stage 420 via support rods 422, and indirectly mechanically coupled to the mixing chamber stage 460 via support rods 452. The surface 441 of the intermediate hot stage 440 can be implemented in various shapes. For example, the surface 441 can be implemented in a circular shape, a quarter circle, a triangle, a quadrilateral, etc. As another example, the surface 441 can be implemented in an amorphous shape.

[0029] The intermediate hot stage 440 may include a feedthrough element 444 interposed with a wiring structure 490 that facilitates propagation of electrical signals between the 4-K stage 420 and the cold plate stage 450. The stationary stage 430 may also include a feedthrough element 434 interposed with the wiring structure 490. The wiring structure 490 may include I / O lines that couple a sample positioned within the cryostat 400 to one or more devices external to the cryostat 400. For example, the wiring structure 490 may include I / O lines such as Figure 2 The drive line 271, the flux line 273, the pump line 275 and / or the output (or readout) line 277. In one embodiment, the intermediate hot stage 440 can include copper, gold, silver, brass, platinum or a combination thereof.

[0030] The intermediate hot stage 440 can provide additional cooling capacity for the cryostat 400 via a sealed tank 470 connected to the intermediate hot stage 440. To this end, the sealed tank 470 facilitates evaporative cooling of the helium medium (helium-3). The condenser line 472 can connect the outlet port 482 of the pump 480 to the sealed tank 470 via the 4-K stage 420. In one embodiment, the pump 480 is located outside the cryostat 400. In one embodiment, the pump 480 can be a vacuum pump for circulating the helium medium through the sealed tank 470. In one embodiment, the pump 480 is located inside the cryostat 400. In this embodiment, the pump 480 can be implemented as an adsorption pump. The condenser line 472 can provide a return path for the helium medium to the sealed tank 470. The pumping line 474 may couple the inlet port 484 of the pump 480 to the seal pot 470 via the 4-K stage 420. The 4-K stage 420 may provide access to the condenser line 472 and / or the pumping line 474 via a feed-through element, such as the feed-through element 423. The stationary stage 430 may provide access to the condenser line 472 and / or the pumping line 474 via a feed-through element, such as the feed-through element 433.

[0031] In operation, helium-3 can flow in a gaseous state from outlet port 482 toward sealed tank 470. Feedthrough elements 423 and / or 433 can thermally anchor condenser line 472 to 4-K stage 420 and / or stationary stage 430, respectively. When helium-3 flows through feedthrough elements 423 and / or 433, the helium-3 can be converted from a gaseous state to a liquid state. The helium-3 in the liquid state can be collected in sealed tank 470. The inlet port 484 of pump 480 can reduce the pressure above the liquefied helium-3 collected in sealed tank 470. Gaseous helium-3 can be formed above the liquefied helium-3 collected in sealed tank 470 by evaporation and flow to the inlet port 484 of pump 480 via pumping line 474. The heat carried by the gaseous helium-3 flowing through pumping line 474 can reduce the temperature of the liquefied helium-3 maintained in sealed tank 470. This evaporative cooling of the liquefied helium-3 in the sealed tank 470 can reduce the temperature of the intermediate hot plate 440, allowing the intermediate hot plate 440 to operate at a temperature of approximately 300 mK. In one embodiment, the sealed tank 470 can be vacuum-sealed or cryogenically sealed. In one embodiment, the sealed tank 470 can include a sintered material that facilitates thermal budget optimization. The sintered material can include silver, gold, copper, platinum, etc.

[0032] Figure 5 An exemplary, non-limiting cryostat is shown having multiple intermediate heat stages each providing additional cooling capacity according to one or more embodiments described herein. Figure 5 As shown, the cryostat 500 includes a 50-K stage 505 that can be coupled to a room temperature plate (e.g., Figure 1 on the top plate 130). Figure 5 The cryostat 500 is also shown to include a plurality of hot stages between the 4-K stage 510 and the cold plate stage 530. The plurality of hot stages include a stationary stage 520 and a plurality of intermediate hot stages (eg, an intermediate hot stage 515 and an intermediate hot stage 525).

[0033] The intermediate hot stage 515 is mechanically coupled directly to the 4-K stage 510 via support rods 512, and directly to the stationary stage 520 via support rods 516. The intermediate hot stage 515 is mechanically coupled indirectly to the 50-K stage 505 via support rods 506, indirectly to the intermediate hot stage 525 via support rods 522, indirectly to the cold plate stage 530 via support rods 526, and indirectly to the mixing chamber stage 535 via support rods 532. The intermediate hot stage 525 is mechanically coupled directly to the stationary stage 520 via support rods 522, and directly to the cold plate stage 530 via support rods 526. The intermediate hot stage 525 is indirectly mechanically coupled to the 50-K stage 505 via support rods 506, indirectly mechanically coupled to the 4-K stage 510 via support rods 512, indirectly mechanically coupled to the intermediate hot stage 515 via support rods 516, and indirectly mechanically coupled to the mixing chamber stage 535 via support rods 532. The intermediate hot stages 515 and 525 are directly mechanically coupled to opposite sides of the stationary stage 520 via support rods 516 and 522, respectively. Surfaces 519 and / or 529 of the intermediate hot stages 515 and 525, respectively, can be implemented in various shapes. For example, the surfaces 519 and / or 529 can be implemented as a circle, a quarter circle, a triangle, a quadrilateral, etc. As another example, the surfaces 519 and / or 529 can be implemented as an amorphous shape.

[0034] The intermediate hot stage 515 and the intermediate hot stage 525 may include feedthrough elements 518 and 528, respectively, interposed with a wiring structure 580 that facilitates propagation of electrical signals between the 4-K stage 510 and the cold plate stage 530. The stationary stage 520 may also include a feedthrough element 524 interposed with the wiring structure 580. The wiring structure 580 may include I / O lines that couple a sample positioned within the cryostat 500 to one or more devices external to the cryostat 500. For example, the wiring structure 580 may include, for example, Figure 2 The I / O lines of the drive line 271, the flux line 273, the pump line 275 and / or the output (or readout) line 277 are shown. In one embodiment, the intermediate heat stage 515 and / or 525 may include copper, gold, silver, brass, platinum or a combination thereof.

[0035] The intermediate hot stage 515 can provide additional cooling capacity for the cryostat 500 via a sealed tank 540 coupled to the intermediate hot stage 515. To this end, the sealed tank 540 facilitates evaporative cooling of the helium medium (helium-4). A condenser line 542 can couple an outlet port 552 of a pump 550 to the sealed tank 540 via the 4-K stage 510. The condenser line 542 can provide a return path for the helium medium to the sealed tank 540. A pumping line 544 can couple an inlet port 554 of the pump 540 to the sealed tank 540 via the 4-K stage 510. The 4-K stage 510 can provide a passage for the condenser line 542 and / or the pumping line 544 via a feedthrough element (such as the feedthrough element 513).

[0036] In operation, helium-4 can flow in a gaseous state from the outlet port 552 toward the sealed tank 540. The feed-through element 513 can thermally anchor the condenser line 542 to the 4-K stage 510. When the helium-4 flows through the feed-through element 513, the helium-4 can be converted from a gaseous state to a liquid state. The helium-4 in the liquid state can be collected in the sealed tank 540. The inlet port 554 of the pump 550 can reduce the pressure above the liquefied helium-4 collected in the sealed tank 540. The helium-4 in the gaseous state can be formed on the liquefied helium-4 collected in the sealed tank 540 by evaporation and flow to the inlet port 554 of the pump 550 via the pumping line 554. The heat carried by the gaseous helium-4 flowing through the pumping line 554 can reduce the temperature of the liquefied helium-4 maintained in the sealed tank 540. Such evaporative cooling of the helium-4 liquefied in the sealed tank 540 can lower the temperature of the intermediate hot stage 515 so that the intermediate hot stage 515 can be operated at a temperature of about 1K.

[0037] The intermediate thermal stage 525 can provide additional cooling capacity for the cryostat 500 via a sealed tank 560 coupled to the intermediate thermal stage 525. To this end, the sealed tank 560 facilitates evaporative cooling of a helium medium (helium-3). A condenser line 562 can couple an outlet port 572 of a pump 570 to the sealed tank 560 via the 4-K stage 510. In one embodiment, the pumps 550 and / or 570 can be vacuum pumps for circulating the corresponding helium medium through the sealed tanks 540 and / or 560, respectively. In one embodiment, the pump 570 and / or 550 can be located outside of the cryostat 500. In one embodiment, the pump 570 and / or 550 can be located within the cryostat 500. In this embodiment, the pump 570 and / or 550 can be implemented as a sorption pump. The condenser line 562 can provide a return path for the helium medium to the sealed tank 560. A pumping line 564 can couple an inlet port 574 of the pump 570 to the sealed tank 560 via the 4-K stage 510. The 4-K stage 510 can provide passage for the condenser line 562 and / or the pumping line 564 via a feedthrough element, such as the feedthrough element 514. The intermediate thermal stage 515 can provide passage for the condenser line 562 and / or the pumping line 564 via a feedthrough element, such as the feedthrough element 517. The static stage 520 can provide passage for the condenser line 562 and / or the pumping line 564 via a feedthrough element, such as the feedthrough element 523.

[0038] In operation, helium-3 can flow from the outlet port 572 toward the sealed tank 560 in a gaseous state. The feedthrough elements 514, 517, and / or 523 can thermally anchor the condenser line 562 to the 4-K stage 510, the intermediate thermal stage 515, and / or the static stage 520, respectively. As the helium-3 flows through the feedthrough elements 515, 517, and / or 523, the helium-3 can transition from a gaseous state to a liquid state. The helium-3 in the liquid state can be collected in the sealed tank 560. The inlet port 574 of the pump 570 can lower the pressure above the liquefied helium-3 collected in the sealed tank 560. The helium-3 in the gaseous state can form above the liquefied helium-3 collected in the sealed tank 560 by evaporation and flow to the inlet port 574 of the pump 570 via the pumping line 564. The heat carried by the helium-3 in the gaseous state flowing through the pumping line 564 can lower the temperature of the liquefied helium-3 maintained in the sealed tank 560. Such evaporative cooling of the helium-3 liquefied in the sealed tank 560 can lower the temperature of the intermediate thermal stage 525, such that the intermediate thermal stage 525 can operate at a temperature of about 300 mK. In one embodiment, the sealed tanks 540 and / or 560 can be vacuum sealed or cryogenically sealed. In one embodiment, the sealed tanks 540 and / or 560 can include a sintered material that facilitates thermal budget optimization. The sintered material can include silver, gold, copper, platinum, and the like.

[0039] Embodiments of the present invention may be systems, methods and / or apparatus at any possible level of integrated technical detail. What has been described above includes only examples of systems, methods and apparatus. Of course, for the purposes of describing the present disclosure, it is not possible to describe every conceivable combination of components or computer-implemented method, but one of ordinary skill in the art will recognize that many further combinations and permutations of the present disclosure are possible. Furthermore, to the extent that the terms "include," "have," and "have" are used in the detailed description, claims, appendices, and drawings, these terms are intended to be inclusive in a manner similar to how the term "comprising" is understood when employed as a transitional word in a claim.

[0040] In addition, the term "or" is intended to mean an inclusive "or" rather than an exclusive "or". That is, unless otherwise specified or clear from the context, "X employs A or B" is intended to mean any natural inclusive arrangement. That is, if X employs A; X employs B; or X employs both A and B, then "X employs A or B" is satisfied in any of the foregoing cases. In addition, the articles "a" and "an" used in this specification and the drawings should generally be interpreted to mean "one or more" unless otherwise specified or clear from the context to point to the singular form. As used herein, the terms "example" and / or "exemplary" are used to indicate use as an example, instance, or illustration. For the avoidance of doubt, the subject matter disclosed herein is not limited to these examples. In addition, any aspect or design described herein as "example" and / or "exemplary" is not necessarily to be construed as preferred or advantageous over other aspects or designs, nor is it meant to exclude equivalent exemplary structures and techniques known to those of ordinary skill in the art.

[0041] The description of various embodiments has been given for the purpose of illustration, but is not intended to be exhaustive or limited to the embodiments of the present disclosure. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is selected to best explain the principles of the embodiments, the practical application of or improvement to technology found in the marketplace, or to enable those of ordinary skill in the art to understand the embodiments of the present disclosure.

[0042] Although certain example embodiments have been described, these embodiments are presented as examples only and are not intended to limit the scope of the present disclosure. Thus, nothing in the foregoing description is intended to suggest that any particular feature, characteristic, step, module, or block is required or indispensable. In fact, the novel methods and systems described herein may be implemented in a variety of other forms; furthermore, various omissions, substitutions, and changes in the form of the methods and systems described herein may be made without departing from the spirit of the present disclosure. The accompanying claims and their equivalents are intended to cover such forms or modifications that fall within the scope and spirit of certain disclosures.

Claims

1. A cryostat comprising: a plurality of hot stages between a 4 Kelvin (4-K) stage and a cold plate stage, the plurality of hot stages comprising a stationary stage and an intermediate hot stage providing additional cooling capacity for the cryostat, wherein the intermediate hot stage is directly mechanically coupled to the stationary stage and additionally coupled to the 4-K stage or the cold plate stage via corresponding support rods, and wherein a pump coupled to the intermediate hot stage circulates a helium medium through a sealed tank coupled to the intermediate hot stage to maintain the temperature of the intermediate hot stage below a preset threshold.

2. The cryostat of claim 1 , wherein the intermediate hot stage operates at a temperature of approximately 1 Kelvin.

3. The cryostat of claim 1 , wherein the intermediate hot stage operates at a temperature of approximately 300 millikelvin (mK).

4. The cryostat according to any one of claims 1 to 3, wherein the sealed can is coupled to the intermediate hot stage to facilitate evaporative cooling of the helium medium. The cryostat according to claim 1 , wherein the sealed canister is vacuum-tight or cryogenically-tight. The cryostat of claim 1 , wherein the helium medium is helium-4 or helium-3. 7 . The cryostat of claim 1 , wherein an outlet port of a pump is coupled to the seal can to provide a return path for the helium medium to the seal can.

8. The cryostat of claim 4, wherein the seal can comprises a sintered material that facilitates thermal budget optimization, and wherein the sintered material comprises copper, gold, silver, or platinum.

9. The cryostat of any one of claims 1 to 3, wherein the intermediate hot stage comprises copper, gold, silver, brass, platinum, or a combination thereof.

10. The cryostat according to any one of claims 1 to 3, wherein the intermediate hot stage includes a feed-through element interposing a wiring structure that facilitates propagation of electrical signals between the 4-K stage and the cold plate stage.

11. The cryostat according to any one of claims 1 to 3, further comprising: A pumping line couples an inlet port of the pump to the intermediate hot stage via the 4-K stage, wherein the pump is located outside the cryostat.

12. A cryostat comprising: A stationary stage is directly mechanically coupled to an intermediate hot stage via support rods, wherein the intermediate hot stage provides additional cooling capacity for the cryostat, wherein the stationary stage and the intermediate hot stage are included in a plurality of hot stages between a 4-K stage and a cold plate stage, wherein the intermediate hot stage is directly mechanically coupled to the cold plate stage via respective support rods, and wherein a pump coupled to the intermediate hot stage circulates a helium medium through a sealed tank coupled to the intermediate hot stage to maintain a temperature of the intermediate hot stage below a preset threshold.

13. The cryostat of claim 12, wherein the stationary stage includes a feed-through element interposing a wiring structure that facilitates propagation of electrical signals between the 4-K stage and the cold plate stage via the intermediate hot stage.

14. The cryostat of claim 12 or 13, wherein the stationary stage provides access for a pumping line coupling an inlet port of the pump to the intermediate hot stage via the 4-K stage, and wherein the pump is located external to the cryostat.

15. The cryostat of claim 12 or 13, wherein the plurality of hot stages further comprises an additional intermediate hot stage that provides additional cooling capacity for the cryostat, and wherein the intermediate hot stage and the additional intermediate hot stage are directly coupled to opposite sides of the stationary stage via respective support rods.

16. The cryostat of claim 15, wherein the additional intermediate hot stage operates at a temperature of approximately 1 Kelvin.

17. The cryostat of claim 12 or 13, wherein the intermediate hot stage operates at a temperature of about 300 millikelvin (mK).

18. A cryostat comprising: a sealed tank facilitating evaporative cooling of a helium medium, wherein the sealed tank is coupled to an intermediate hot stage that provides additional cooling capacity for the cryostat, wherein the intermediate hot stage is directly mechanically coupled to a stationary stage via support rods, and wherein the stationary stage and the intermediate hot stage are included in a plurality of hot stages between a 4-K stage and a cold plate stage; and An additional seal can is coupled to an additional intermediate hot stage that provides additional cooling capacity to the cryostat, wherein the plurality of hot stages further comprises the additional intermediate hot stage.

19. The cryostat of claim 18, wherein the helium medium is helium-4 or helium-3.

20. The cryostat of claim 18 or 19, wherein the sealed can comprises a sintered material that facilitates thermal budget optimization, and wherein the sintered material comprises copper, gold, silver, or platinum.

21. The cryostat of claim 18 or 19, wherein the intermediate hot stage and the additional intermediate hot stage are mechanically coupled directly to opposite sides of the stationary stage via respective support rods.

22. The cryostat of claim 18 or 19, wherein the seal pot is coupled to a pump external to the cryostat via a pumping line, and wherein the 4-K stage provides a passage for the pumping line.

23. The cryostat of claim 18 or 19, wherein the seal pot is coupled to a pump external to the cryostat via a condenser line, and wherein the 4-K stage provides a passage for the condenser line.

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