Patent Description:
An additional approach to the use of processors and related components, based on CMOS technology, is the use of superconducting logic-based components and devices. Superconducting logic-based components and devices can also be used to process quantum information, such as qubits. But, even superconducting logic-based devices, such as superconducting memories, consume significant amount of power because of the need to operate at cryogenic temperatures (e.g., <NUM> or below).

<CIT> discloses a computing system with superconducting components operating at cryogenic temperatures. <CIT> discloses a superconductor electronic computer immersed in liquid helium. <CIT> discloses a cooler for low temperature functional equipment.

In one aspect of the present disclosure, a superconducting computing system including a housing, arranged inside a liquid hydrogen environment, where a lower pressure is maintained inside the housing than a pressure outside the housing. The superconducting computing system may further include a substrate, arranged inside the housing, having a surface, where a plurality of components attached to the surface is configured to provide at least one of a computing or a storage functionality, and where the substrate further comprises a plurality of circuit traces for interconnecting at least a subset of the plurality of the components, where the housing is configured such that each of the plurality of components is configured to operate at a first temperature, where the first temperature is below <NUM> Kelvin, despite the liquid hydrogen environment having a second temperature greater than <NUM> Kelvin.

In another aspect of the present disclosure, a superconducting computing system including a housing, arranged inside a liquid hydrogen environment, where a lower pressure is maintained inside the housing than a pressure outside the housing, is provided. The superconducting computing system may further include a first substrate, inside the housing, arranged in a first plane having a first surface parallel to the first plane, where a first plurality of components, attached to the first surface, is configured to provide at least one of a computing or a storage functionality. The superconducting computing system may further include a second substrate, inside the housing, arranged in a second plane, parallel to the first plane, the second substrate having a second surface parallel to the second plane, where a second plurality of components, attached to the second surface, is configured to provide at least one of the computing functionality or the storage functionality, and where the first substrate further comprises a first plurality of circuit traces for interconnecting at least a subset of the first plurality of the components, and where the second substrate further comprises a second plurality of circuit traces for interconnecting at least a subset of the second plurality of the components, where liquid helium inside the housing is configured to cool the environment inside the housing such that each of the first plurality of components and the second plurality of components is configured to operate at a first temperature, where the first temperature is below <NUM> Kelvin, despite the liquid hydrogen environment having a second temperature greater than <NUM> Kelvin.

In yet another aspect, the present disclosure relates to a superconducting computing system including a first storage tank. The superconducting computing system may further include a second storage tank containing hydrogen in a liquified state, where the second storage tank is arranged inside the first storage tank. The superconducting computing system may further include a cryostat wall, arranged inside the second storage tank, where a vacuum is maintained inside a space enclosed by the cryostat wall. The superconducting computing system may further include a substrate, inside the cryostat wall, where a plurality of components, coupled to the substrate, is configured to provide at least one of a computing or a storage functionality. The superconducting computing system may further include a cooling system configured to maintain a temperature inside the housing below <NUM> Kelvin.

Examples described in this disclosure relate to computing systems that include superconducting components and devices. Certain examples of the present disclosure relate to a computing system comprising components operating at cryogenic temperatures (e.g., at or below <NUM> Kelvin). In one example, the superconducting system is housed in a vacuum assembly, which is enclosed in a liquid hydrogen environment. In this example, the superconducting system may include one or more superconducting components formed on a substrate. The superconducting component may include integrated circuit chips mounted on the substrate. Superconducting components and devices may use Josephson junctions to implement the functionality associated with a circuit. An exemplary Josephson junction may include two superconductors coupled via a region that impedes current. The region that impedes current may be a physical narrowing of the superconductor itself, a metal region, or a thin insulating barrier. As an example, the Superconductor-Insulator-Superconductor (SIS) type of Josephson junctions may be implemented as part of the superconducting circuits. As an example, superconductors are materials that can carry a direct electrical current (DC) in the absence of an electric field. Superconductors have a critical temperature (Tc) below which they have zero resistance. Niobium, one such superconductor, has a critical temperature (Tc) of <NUM> Kelvin degrees. At temperatures below Tc, niobium is superconductive; however, at temperatures above Tc, it behaves as a normal metal with electrical resistance. Thus, in the SIS type of Josephson junction superconductors may be niobium superconductors and insulators may be Al<NUM>O<NUM> barriers. In SIS type of junctions, the superconducting electrons are described by a quantum mechanical wave-function. A changing phase difference in time of the phase of the superconducting electron wave-function between the two superconductors corresponds to a potential difference between the two superconductors.

Various superconducting circuits including transmission lines can be formed by coupling multiple Josephson junctions by inductors or other components, as needed. Microwave pulses can travel via these transmission lines under the control of at least one clock. The microwave pulses can be positive or negative, or a combination thereof. The microwave pulses may have a frequency of up to <NUM> or higher. Any circuit board or other type of structure, such as an interposer with such superconducting circuits may be required to support not only the, high-frequency microwave signals but also direct current (DC) signals.

Although there are several benefits of superconductivity, including lower resistance and better bandwidth characteristics, superconducting materials need to be operated at cryogenic temperatures (e.g., <NUM>). In a large-scale computing system that is data processing intensive, hundreds of megawatts of power may be required for the <NUM> environment. The present disclosure describes a computing system that may advantageously consume less power by limiting thermal parasitic effects by enclosing the cryo-computing environment inside a liquid hydrogen environment maintained at a temperature of approximately <NUM> Kelvin. In addition, the use of additional features that lower the thermal parasitic effects may further enhance the operational efficiency of such a system. The cryo-computing environment may be formed using conduction, convection, or immersion.

<FIG> is a view <NUM> of a superconducting computing system <NUM> inside a liquid hydrogen environment in accordance with one example. In this example, the liquid hydrogen environment may include a storage tank <NUM> that may include a liquid hydrogen container <NUM>. Liquid hydrogen container <NUM> may include liquified hydrogen, which may be at a temperature between <NUM> Kelvin to <NUM> Kelvin. Additional details concerning an example liquid hydrogen environment are provided with respect to <FIG>. Liquid hydrogen container <NUM> may include superconducting computing system <NUM>. Superconducting computing system <NUM> may include a housing <NUM>. Housing <NUM> may be configured to maintain a vacuum inside the housing. Components (e.g., processors and memory) corresponding to superconducting computing system <NUM> are located inside housing <NUM> that maintains vacuum. Housing <NUM> may include a thermal shield <NUM>, which may further enclose superconducting components that may be arranged as part of two sets of superconducting components: a first superconducting component set <NUM> and a second superconducting component set <NUM>. The superconducting components may be included in just one set or more sets. The superconducting components may be configured to operate in a cryogenic environment (e.g., in a vacuum and at a temperature below <NUM> Kelvin).

With continued reference to <FIG>, in this example, housing <NUM> may be configured as a cylindrical container arranged inside liquid hydrogen container <NUM> towards the bottom of liquid hydrogen container <NUM>. In this example, housing <NUM> may be arranged inside liquid hydrogen container <NUM> on supports <NUM> and <NUM>. Supports <NUM> and <NUM> may be configured to minimize contact with liquid hydrogen container <NUM> and thus minimize any thermal conduction through the supports. In the operating mode, liquid hydrogen would surround the cryogenic computing environment, with only the supports touching the inner surface of liquid hydrogen container <NUM>. A retractable ring may drop out of housing <NUM> to seal off an "airlock" from the outside environment through which parts, robotics, new equipment, or the like could be passed for installation into housing <NUM>. Airlock <NUM> could be either a full ring or it could be reduced to a smaller size to save cost and liquid Helium. In this example, airlock <NUM> is shown in an open position. The combination of the retractable ring and the airlock may function as a transfer system to allow access to housing <NUM>. <FIG> shows the same superconducting computing system <NUM> as described with respect to <FIG>, and shows the liquid hydrogen environment described earlier. In <FIG>, however, airlock <NUM> is shown in its closed position <NUM>. Although <FIG> and <FIG> show superconducting computing system <NUM> as having a certain form and arrangement, superconducting computing system <NUM> may have a different form and arrangement. Similarly, although <FIG> and <FIG> show the liquid hydrogen environment including a spherical storage container, liquid hydrogen container <NUM> may be of a different shape, including a cylindrical shape.

<FIG> shows a superconducting computing system <NUM> inside a liquid hydrogen environment <NUM>, in accordance with one example. Superconducting computing system <NUM> may include a housing <NUM>. Housing <NUM> may be configured to maintain a vacuum inside the housing. Thus, components (e.g., processors and memory) corresponding to superconducting computing system <NUM> are located inside housing <NUM> that maintains vacuum. Housing <NUM> may include one or more substrates (e.g., substrate <NUM>, <NUM>, and <NUM>). Each of these substrates may be formed using glass or other suitable materials; for example, various types of polymers. In one example, the glass material may be borosilicate glass. Housing <NUM> may further include a thermal shield <NUM> that may be configured to thermally isolate portions of each of the substrates located inside thermal shield <NUM>. Although not shown, thermal shield <NUM> may be cooled via liquid helium (or other appropriate coolant) flowing through pipes or tubes coupled to thermal shield <NUM>. In one example, thermal shield <NUM> may be formed using a nickel-iron alloy (e.g., Mu-metal). Thermal shield <NUM> may further be wrapped into a multi-layer insulation (not shown). This way thermal shield <NUM> may provide thermal isolation between the <NUM> space and the <NUM> liquid hydrogen environment surrounding housing <NUM>. In one example, superconducting components (e.g., Central-Processing Units (CPUs), Graphics-Processing Units (GPUs), Artificial Intelligence Processors, Field-Programmable Gate Arrays (FPGAs), Application-Specific Integrated Circuits (ASICs), Application-Specific Standard Products (ASSPs), System-on-a-Chip systems (SOCs), Complex Programmable Logic Devices (CPLDs)) may be located on substrates (e.g., <NUM>, <NUM>, and <NUM>). The superconducting components may be configured to provide any functionality that is required to implement a computing function or a storage function. As an example, without limitation, the computing functionality may include at least one of (or any appropriate combination of) a central-processing functionality, a graphics-processing functionality, an artificial-intelligence functionality, a gate-array functionality, a memory functionality, or a bus-interface-management functionality. Superconducting components may also provide storage functionality and may comprise memory components, including any of non-volatile or volatile memory components. Volatile memory components may include any of the various types of random-access memory components, including dynamic random-access memory (DRAM) components. Non-volatile memory components may include any of various types of memory components that can store information even when they are not powered, including flash-memory components. Superconducting components may further include Field-Programmable Gate Arrays (FPGAs), Application-Specific Integrated Circuits (ASICs), Application-Specific Standard Products (ASSPs), System-on-a-Chip systems (SOCs), Complex Programmable Logic Devices (CPLDs).

With continued reference to <FIG>, thermal shield <NUM> may help maintain a temperature that is suitable for allowing the superconducting devices to operate consistent with the superconductivity principles. Thus, superconducting components may be maintained at cryogenic temperatures (e.g., a few milli Kelvins to <NUM> Kelvin). This may be accomplished via the combination of thermal isolation and cooling via liquid helium or other such coolants. As an example, copper sidewalls <NUM> may be mounted adjacent to superconducting components. Copper sidewalls <NUM> may also be cooled via liquid helium flowing through pipes (e.g., pipes <NUM>, <NUM>, <NUM>, and <NUM>) as shown in <FIG>. In one example, a system operating in a cryogenic environment may require a vacuum to operate properly. In one example, a vacuum may relate to a pressure in a range of <NUM>-<NUM> Torr to <NUM>-<NUM> Torr. It is to be recognized that the temperature ranges referred to herein relate to the temperature of the environment in which these components are operating and not the temperature of the components themselves. Thus, references such as "operating at" or "maintained at" refer to the temperature of the environment in which these components are operating or are being maintained inside.

With continued reference to <FIG>, superconducting components may communicate with each other using circuit traces formed on the top or the bottom surface of each of the common substrates (e.g., <NUM>, <NUM>, and <NUM>). The circuit traces may be formed using a suitable manufacturing process, including, but not limited to, selective laser sintering, fused deposition modeling, direct metal laser sintering, stereolithography, cladding, electron beam melting, electron beam direct manufacturing, aerosol jetting, ink jetting, semi-solid freeform fabrication, digital light processing, laminated object manufacturing, 3D printing, or other similar manufacturing processes. In one example, the circuit traces may be made of niobium (or another suitable superconducting material) in a region of the substrate that includes superconducting components. Although <FIG> shows a certain arrangement of components, substrates, and other component, these could be arranged in a different manner. In addition, fewer or additional components, substrates, and other components may be present.

<FIG> shows a detailed view of a portion <NUM> of the superconducting computing system of <FIG> in accordance with one example. Portion <NUM> may include a cryostat wall <NUM> enclosing a cryo-computing environment (CCE) <NUM>. Cryostat wall <NUM> may be used to isolate CCE <NUM> from the liquid hydrogen environment. In this example, CCE <NUM> may include superconducting components arranged inside a vacuum. CCE <NUM> may include a superconducting substrate <NUM>, qubit wafer <NUM>, a liquid helium heat transfer <NUM>, and a <NUM> mK cold plate <NUM>. AC/DC power supply cables <NUM> may be used to provide AC and/or DC power to the superconducting components. Data cables <NUM> may be used to allow communication of microwave signals or other signals to/from the superconducting components in CCE <NUM>.

Still referring to <FIG>, in this example, the chips <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> may be arranged as a <NUM>-D array on (or near) the top face of a single monolithic wafer (e.g., qubit wafer <NUM>) of silicon or sapphire. The <NUM> mK cold plate <NUM> may be thermally strapped to the mixing chamber (e.g., the hermetic helium (He) heat transfer bath) of a dilution refrigerator. Although not shown in <FIG>, the thermal hierarchy may be maintained using the dilution refrigerator and cold plates or other thermal couplings. The dilution refrigerator may be a wet dilution refrigerator or a dry dilution refrigerator. As an example, a wet dilution refrigerator may use a combination of pumps and heat exchangers to generate different levels of temperature from <NUM> to <NUM> mK. A circulating pump (not shown) may pump via a return line to circulate liquid Helium through the various stage of the dilution refrigerator. The liquid Helium may be a mixture of two isotopes (He-<NUM> and He-<NUM>). Another pump may access liquid Helium from a reservoir and may collect any condensation formed as a result of the heat exchange with the circulating liquid Helium. Additional heat exchangers may be used to cool the circulating Helium to a temperature at which the liquid Helium may undergo a phase separation generating a concentrated phase and a diluted phase of the Helium. As these two phases may enter a mixing chamber (not shown), the concentrated phase may be diluted, creating additional cooling. As the cooled diluted Helium is circulated from the mixing chamber to a still, the cooled diluted Helium may be used to cool the downward (towards the mixing chamber) flowing Helium until it reaches the still. As the liquid Helium continues to be circulated the thermally coupled cold plates may be used to maintain the superconducting components and the qubit wafer at the desired cryogenic temperatures.

With continued reference to <FIG>, some basic interface circuitry may reside on the qubit wafer itself; more complex interface circuitry may reside on chips <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>, which are flip-chip bonded (circuit face down) to qubit wafer <NUM>. Cables (e.g., cable <NUM>) may be routed through radiation shields to chips <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> mounted on superconducting substrate <NUM>. In this example, chips <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> may operate at approximately <NUM> Kelvin. Cables (e.g., cable <NUM>) may be thermally clamped, as needed, to maintain a thermal hierarchy. Although <FIG> shows a certain number of components arranged in a certain manner, there could be more or fewer number of components arranged differently.

In one example, the superconducting components may be formed to support signals ranging from DC to signals having a frequency that is greater than <NUM>. In this example, the superconducting components may be fabricated over large silicon substrates such as <NUM> wafers, <NUM> wafers or even larger wafers, which may be separated into multiple dies. In one example, the substrate could be made from silicon or any other thermally insulating or conducting material. Also, in this example, signal traces and ground planes may be formed by sputtering niobium, or a similar superconducting material. As an example, compounds of niobium such as niobium nitride (NbN) or niobium titanium nitride (NbTiN) may also be used. Other physical vapor deposition (PVD) methods, such as molecular beam epitaxy (MBE), may also be used. Depending on the type of the material used for the traces, sputtering processes, chemical vapor deposition (CVD) processes, plasma enhanced chemical vapor deposition (PECVD) process, evaporation processes, or atomic layer deposition (ALD) processes may also be used. Thus, for example, the niobium compounds such as NbN and NbTiN may be formed using a CVD process.

<FIG> shows a superconducting computing system <NUM> inside a liquid hydrogen environment <NUM> in accordance with one example. Liquid hydrogen environment <NUM> may include a storage tank <NUM>. Storage tank <NUM> may include a liquid hydrogen container <NUM>. Liquid hydrogen container <NUM> may include superconducting computing system <NUM>, including supports <NUM> and <NUM>. Superconducting computing system <NUM> may also include an airlock <NUM>, which may further be coupled to a set of cables <NUM>. Superconducting computing system <NUM> may be like the superconducting computing systems described earlier. Liquid hydrogen supply may be provided a gas supply line <NUM>. Valves <NUM> and <NUM> may be used to control and regulate the supply. Any boil-off gas formed due to boiling of liquid hydrogen may be removed from liquid hydrogen container <NUM> via boil-off gas discharge line <NUM>. The discharge of the boil-off gas may be controlled and regulated using valves <NUM> and <NUM>. If needed, some of the boil-off gas may be processed to generate liquified hydrogen using liquefier <NUM>. The liquified hydrogen may be returned to liquid hydrogen container <NUM> via gas return line <NUM>. The returning gas may be controlled and regulated via valves <NUM> and <NUM>. Although <FIG> shows a certain shape and arrangement of the various components, they may have other shapes and they may be arranged differently.

In conclusion, in one aspect of the present disclosure, a superconducting computing system including a housing, arranged inside a liquid hydrogen environment, where a lower pressure is maintained inside the housing than a pressure outside the housing. The superconducting computing system may further include a substrate, arranged inside the housing, having a surface, where a plurality of components attached to the surface is configured to provide at least one of a computing or a storage functionality, and where the substrate further comprises a plurality of circuit traces for interconnecting at least a subset of the plurality of the components, where the housing is configured such that each of the plurality of components is configured to operate at a first temperature, where the first temperature is below <NUM> Kelvin, despite the liquid hydrogen environment having a second temperature greater than <NUM> Kelvin.

In the superconducting computing system, the lower pressure may be in range between <NUM>-<NUM> Torr to <NUM>-<NUM> Torr, and the second temperature may be in a range between <NUM> Kelvin and <NUM> Kelvin. The liquid hydrogen environment may include a structure comprising the liquid hydrogen, and the plurality of components may be cooled using at least one cold plate coupled to liquid helium.

The substrate may be accessible via a transfer system configured to allow access to the substrate. Each of the plurality of components may comprise at least one of a central processing unit, a graphics-processing unit, an artificial-intelligence processor, a field-programmable gate array, an application-specific integrated circuit, an application-specific standard product, a system-on-a-chip, a complex programmable logic device, a static random-access memory, a dynamic random-access memory, or a Josephson magnetic random-access memory.

The computing functionality may comprise at least one of a central-processing functionality, a graphics-processing functionality, an artificial-intelligence functionality, a gate-array functionality, a memory functionality, or a bus-interface-management functionality and where the storage functionality comprises at least one of a memory functionality, gate-array functionality, a memory controller functionality, or a bus-interface-management functionality. The substrate may include a plurality of circuit traces and each of the plurality of circuit traces may comprise a superconducting metal.

Each of the first substrate and the second substrate may be accessible via a transfer system configured to allow access to each of the first substrate and the second substrate. Each of the first plurality of components and the second plurality of components may comprise at least one of a central processing unit, a graphics-processing unit, an artificial-intelligence processor, a field-programmable gate array, an application-specific integrated circuit, an application-specific standard product, a system-on-a-chip, a complex programmable logic device, a static random-access memory, a dynamic random-access memory, or a Josephson magnetic random-access memory.

The computing functionality may comprise at least one of a central-processing functionality, a graphics-processing functionality, an artificial-intelligence functionality, a gate-array functionality, a memory functionality, or a bus-interface-management functionality and where the storage functionality comprises at least one of a memory functionality, gate-array functionality, a memory controller functionality, or a bus-interface-management functionality. Each of the first plurality of circuit traces and the second plurality of circuit traces may comprise a superconducting metal.

The vacuum may correspond to a pressure in a range between <NUM>-<NUM> Torr to <NUM>-<NUM> Torr, and the hydrogen in the liquified state may be maintained at a second temperature in a range between <NUM> Kelvin and <NUM> Kelvin.

It is to be understood that the methods, modules, and components depicted herein are merely exemplary. For example, and without limitation, illustrative types of superconducting devices may include Field-Programmable Gate Arrays (FPGAs), Application-Specific Integrated Circuits (ASICs), Application-Specific Standard Products (ASSPs), System-on-a-Chip systems (SOCs), Complex Programmable Logic Devices (CPLDs), etc..

In addition, in an abstract, but still definite sense, any arrangement of components to achieve the same functionality is effectively "associated" such that the desired functionality is achieved. Hence, any two components herein combined to achieve a particular functionality can be seen as "associated with" each other such that the desired functionality is achieved, irrespective of architectures or inter-medial components. Likewise, any two components so associated can also be viewed as being "operably connected," or "coupled," to each other to achieve the desired functionality.

Furthermore, those skilled in the art will recognize that boundaries between the functionality of the above-described operations are merely illustrative. The functionality of multiple operations may be combined into a single operation, and/or the functionality of a single operation may be distributed in additional operations. Moreover, alternative embodiments may include multiple instances of a particular operation, and the order of operations may be altered in various other embodiments.

Although the disclosure provides specific examples, various modifications and changes can be made without departing from the scope of the disclosure as set forth in the claims below. Any benefits, advantages, or solutions to problems that are described herein with regard to a specific example are not intended to be construed as a critical, required, or essential feature or element of any or all the claims.

Claim 1:
A superconducting computing system comprising:
a housing, arranged inside a liquid hydrogen environment, wherein a lower pressure is maintained inside the housing than a pressure outside the housing; and
a substrate, arranged inside the housing, having a surface, wherein a plurality of components, attached to the surface, is configured to provide at least one of a computing or a storage functionality, and wherein the substrate further comprises a plurality of circuit traces for interconnecting at least a subset of the plurality of the components, wherein the housing is configured such that each of the plurality of components is configured to operate at a first temperature, wherein the first temperature is below <NUM> Kelvin, despite the liquid hydrogen environment having a second temperature greater than <NUM> Kelvin.