Packaging and Thermal Balancing of Cryogenic Dispersive-Resistive Hybrid Attenuators for Quantum Microwave Circuits

Abstract

A hybrid microwave attenuator is constructed by forming a circuit and a housing. The circuit has two ports, a resistive component configured to attenuate certain frequencies of an input signal (transmission signal), and a dispersive component configured to attenuate certain frequencies within a frequency range. The resistive component and the dispersive component are arranged in a series configuration relative to each other between the two ports of the circuit. The housing includes a closable structure within which the circuit is disposed, the structure being formed from a material exhibiting at least a threshold thermal conductivity level, which is achieved in the cryogenic temperature range in which quantum computing circuits operate. The housing further includes a pair of microwave connectors, the pair of connectors thermally coupled to the housing.

Description

[Technical field]

[0001] The present invention relates generally to devices, housing design methods and systems for construction of microwave frequency attenuator housings usable with superconducting qubits in quantum computing. More particularly, the present invention relates to devices, methods and systems for packaging and thermalization of cryogenic dispersive-resistive hybrid attenuators for quantum microwave circuits. [Background technology]

[0002] Unless otherwise distinguished where used, hereinafter in this specification the prefix "Q" in a word or phrase indicates that the word or phrase is being referred to in the context of quantum computing.

[0003] Molecules and subatomic particles are subject to the laws of quantum mechanics, a branch of physics that explores how the physical world works at the most fundamental level. At this level, particles exhibit strange behavior, can exist in two or more states simultaneously, and can interact with other particles at great distances. Quantum computing exploits these quantum phenomena to process information.

[0004] The computers we use today are known as classical computers (also referred to herein as "conventional" computers or conventional nodes, or "CNs"). Conventional computers use conventional processors fabricated using semiconductor materials and technology, semiconductor memory, and magnetic or solid-state storage devices, in an architecture known as the von Neumann architecture. Specifically, the processors of conventional computers are binary processors, i.e., processors that perform operations on binary data represented by 1s and 0s.

[0005] Quantum processors (q-processors) use the exotic properties of entangled qubit devices (referred to herein for brevity as "qubits" (plural "qubits")) to perform computational tasks. In the particular domain where quantum mechanics operates, particles of matter can exist in many states, e.g., "on" states, "off" states, and states that are both "on" and "off" simultaneously. While binary computing using semiconductor processors is limited to using only on and off states (equivalent to 1s and 0s in the binary code), quantum processors exploit these quantum states of matter to output signals that can be used in data computing.

[0006] Classical computers encode information as bits, each of which can take on a value of 1 or 0. These 1s and 0s act as on / off switches that ultimately drive computer functions. Quantum computers, on the other hand, are based on qubits, which operate according to two key principles of quantum physics: superposition and entanglement.

[0007] Superposition means that each qubit can simultaneously represent both a 1 and a 0. Entanglement means that qubits in a superposition can be correlated with each other in non-classical ways -- one state (whether it's a 1 or a 0 or both) can depend on the state of the other -- and that there is more information that can be ascertained about two qubits when they are entangled than when they are treated individually.

[0008] Using these two principles, qubits act as more sophisticated information processors that allow quantum computers to function in a manner that allows them to solve difficult problems that cannot be addressed using classical computers. IBM® has successfully built and demonstrated the operability of a quantum processor that uses superconducting qubits (IBM is a registered trademark of International Business Machines, Inc. in the United States and other countries).

[0009] Superconducting qubits include Josephson junctions. Josephson junctions are formed by separating two thin-film superconducting metal layers by a non-superconducting material. When the metals in these superconducting layers are made superconducting, for example by lowering the temperature of the metal to a specified cryogenic temperature, electron pairs can tunnel from one superconducting layer to the other through the non-superconducting layer. In a qubit, a Josephson junction, acting as a distributed nonlinear inductor, is electrically coupled in parallel with one or more capacitive devices to form a nonlinear microwave oscillator. The oscillator has a resonance / transition frequency determined by the inductance and capacitance values ​​of the qubit circuit. Unless otherwise distinguished where used, references to the term "qubit" are references to a superconducting qubit circuit using a Josephson junction.

[0010] The information processed by the qubits is carried or transmitted in the form of microwave signals / photons in the microwave frequency range. Those microwave signals are captured, processed and analyzed to decode the quantum information encoded in the signal. Readout circuits are circuits coupled to the qubits for capturing, reading and measuring the quantum state of the qubits. The output of the readout circuits is information that can be used by the q-processor to perform calculations.

[0011] A superconducting qubit has two quantum states, namely |0> and |1>. These two states can be the two energy states of an atom, for example the ground state (|g>) and the first excited state (|e>) of a superconducting artificial atom (superconducting qubit). Other examples include the spin-up and spin-down of nuclear or electron spins, the two positions of a crystal defect, and the two states of a quantum dot. Because of the quantum nature of the system, any combination of these two states is allowed and valid.

[0012] For quantum computing using qubits to be reliable, quantum circuits (q-circuits), e.g., the qubits themselves, readout circuits associated with the qubits, and other parts of the quantum processor, must not significantly change the energy state of the qubits, such as by injecting or dissipating energy, or affect the relative phase between the |0> and |1> states of the qubits. This operational constraint on circuits that operate with quantum information requires special consideration in fabricating the semiconductor and superconducting structures used in such circuits.

[0013] Currently available superconducting quantum circuits are built using materials that become superconducting at cryogenic temperatures, for example at temperatures of about 10-100 millikelvin (mK), or about 4 K. The electronic circuits used to control, operate, and measure the quantum circuits are typically located outside the dilution fridge that houses the superconducting quantum circuit. The temperature outside the fridge is typically around 300 K (room temperature).

[0014] Currently available superconducting quantum circuits usually operate in the microwave frequency range. Microwave signals / pulses are used to initialize, operate, control and measure the superconducting qubits in the superconducting q-circuits. Microwave transmission lines are used inside the dilution refrigerator to carry these microwave signals between the external electronic circuitry outside the refrigerator and the superconducting quantum circuitry inside the refrigerator. Coaxial lines are one example of a transmission line that can carry these microwave signals.

[0015] Currently available dilution refrigerators are cryogenic devices that can be used to cool samples / devices down to millikelvin temperatures. However, the transition from room temperature to the millikelvin temperature inside the refrigerator is not sudden or rapid. To facilitate temperature transitions and cooling operations, dilution refrigerators consist of multiple thermally isolated stages (referred to herein for brevity as “stages”) maintained at different ambient temperatures. For example, a typical commercial dilution refrigerator has five temperature stages inside the refrigerator: 40K, 4K, 0.7K, 0.1K, and 0.01K (also known as the base stage). For simplicity, the following will focus on the input line inside the refrigerator. It is common practice to use lossy transmission lines to connect two successive stages and incorporate resistive attenuators and filters on the path of these lines of the different stages in order to maintain a temperature difference between different stages inside the refrigerator and to protect the quantum circuit from noise coming through the input lines originating from room temperature electronics, or blackbody radiation of higher stages, or other electromagnetic noise sources. In general, the components serve multiple purposes: they attenuate / reduce noise coming through these input lines, they attenuate / reduce microwave signals propagating in these lines, they provide thermal isolation between the stages, and they cool the microwave signals propagating in the components.

[0016] The signals propagating on the lines passing through the stages may contain noise, particularly electromagnetic noise. This noise may be in the microwave frequency spectrum or in the infrared spectrum. When the lines and signals are involved in quantum computing using q circuits, electronic, microwave and infrared noise are undesirable for reasons described herein.

[0017] Attenuating a signal is the process of reducing the power of a particular frequency or range of frequencies in that signal. An attenuator is an electronic circuit with two ports that is configured to attenuate a particular frequency or range of frequencies of the input signal / noise.

[0018] A resistive attenuator attenuates the transmitted signal (hereafter referred to as the transmission signal) and / or noise by dissipating the energy of the signal and / or noise in the resistive components of the attenuator. A dispersive attenuator attenuates the transmission signal / noise passing through its two ports by reflecting a portion of the energy / power of the transmission signal / noise away from the port where the transmission signal / noise entered.

[0019] Exemplary embodiments recognize that standard commercially available microwave attenuators are either resistive or dispersive attenuators, but not both. Additionally, exemplary embodiments recognize certain disadvantages of currently available resistive microwave attenuators. For example, in most cases, currently available resistive attenuators are formed such that the metal case surrounding the substrate is stainless steel, which has a poor thermal conductivity coefficient. Additionally, the connector pins located at both ports of the resistive attenuator are mechanically pressed against conductors on the substrate, which provides poor thermal contact. The substrate is mechanically pressed against the body of the metal case, which also provides poor thermal contact. Additionally, the substrate material used for these attenuators has a thermal conductivity coefficient that is far from ideal.

[0020] Exemplary embodiments further recognize that, unfortunately, the lower the attenuation of currently available resistive attenuators, the greater the thermal and electrical resistance between the attenuator's center conductor and the attenuator's corresponding outer conductor (e.g., ground) formed by the attenuator's metal case. Exemplary embodiments recognize that currently available resistive attenuators currently provide fixed attenuation over a wide frequency band, and do not allow the attenuation level of the attenuator to be frequency dependent (i.e., the attenuation level is fixed with respect to frequency). Additionally, currently available resistive attenuators dissipate microwave power within the attenuator itself. Such absorptive attenuation can have several undesirable consequences: (1) absorptive attenuation can increase the temperature of the attenuator, especially if the attenuator is poorly thermally balanced to the stage, which leads to reduced cooling of the microwave signal passing through the attenuator. (2) absorptive attenuation can increase the temperature of the stage, especially with many attenuators and limited cooling capacity. (3) absorptive attenuation can increase blackbody radiation toward the cooler stage.

[0021] Exemplary embodiments also recognize certain disadvantages of currently available distributed commercial microwave attenuators. These attenuators have similar thermal balancing issues as the resistive attenuators outlined above. Additionally, these attenuators can cause multiple reflections of the signal within the line. These reflections can cause microwave pulse / signal distortion, interference, and ripples in the signal under test.

[0022] Exemplary embodiments recognize that for an attenuator to be effective and usable in cryogenic environments, and particularly with quantum computing devices, it must be shielded from microwave interference. While microwave interference can come from a variety of sources, exemplary embodiments recognize that a poorly formed housing of an attenuator can result in significant microwave interference with a signal being propagated through the attenuator. For example, connections within a line contribute to microwave interference by causing signal reflections within the lines that connect through the connections. The greater the number of connections, the greater the number of reflection points and other disturbances introduced by the connections.

[0023] Exemplary embodiments recognize that this microwave shielding should be performed with robust thermal balancing so that the temperature difference between the attenuator and the corresponding refrigeration stage is minimized. Thermal balancing of one structure to another is the process of constructing and bonding two structures in such a way that the bond achieves, at a minimum, a threshold level of thermal conductivity between the two structures. Good thermal balancing is one in which the thermal conductivity between the thermally bonded structures exceeds a required threshold level of thermal conductivity.

[0024] Exemplary embodiments recognize that currently available cryogenic attenuators are suitable for operation at cryogenic temperatures up to about 77 Kelvin (K), but are not suitable for use with quantum computing circuits operating at temperatures below 1 Kelvin, up to 2 milli-K. In the temperature range in which quantum computing circuits operate, currently available cryogenic attenuators exhibit insufficient thermal conductivity of the substrate, housing, and microwave connectors. Additionally, currently available cryogenic attenuators use microwave connectors of different genders, which creates the need for a gender-changing adapter. This adapter increases the number of reflection points on the microwave line and adds additional thermal mass that must be cooled down to milli-K.

[0025] Exemplary embodiments recognize that in order to use the attenuators for the control lines of the quantum processor, the attenuators must be embedded in specially designed housings that are thermally fixed to various parts of the dilution refrigerator stages. This thermal fixing of currently available cryogenic attenuators still fails to achieve the desired thermal balancing level, and also increases the cost and work involved in fixing. There is a need for packaging and thermal balancing of cryogenic distributed-resistive hybrid attenuators for quantum microwave circuits that provides the desired thermal balancing level at temperatures at which quantum processors currently operate, while at the same time providing improved microwave hygiene by minimizing reflections in the microwave line.

[0026] Therefore, there is a need in the art to address the above-mentioned problems. Summary of the Invention

[0027] Viewed from a first aspect, the present invention provides a hybrid microwave attenuator comprising a circuit having two ports, the circuit comprising a resistive component configured to attenuate a plurality of frequencies of an input signal (transmission signal), and a dispersive component configured to attenuate a second plurality of frequencies within a frequency range, the resistive component and the dispersive component being arranged in a series configuration with respect to each other between the two ports of the circuit, the hybrid microwave attenuator further comprising a housing, the housing being a closable structure within which the circuit is disposed, the structure being formed from a material exhibiting at least a threshold thermal conductivity level, the threshold thermal conductivity level being achieved in the cryogenic temperature range in which quantum computing circuits operate, and a pair of microwave connectors thermally coupled to the housing.

[0028] Viewed from another aspect, the present invention provides a method comprising forming a hybrid microwave attenuator by assembling a circuit having two ports, the circuit comprising a resistive component configured to attenuate a plurality of frequencies of an input signal (transmission signal) and a dispersive component configured to attenuate a second plurality of frequencies within a frequency range, the resistive component and the dispersive component being arranged in a series configuration with respect to each other between two ports of the circuit, the method further comprising forming a housing, the housing being a closable structure within which the circuit is disposed, the structure being formed from a material exhibiting at least a threshold thermal conductivity level, the threshold thermal conductivity level being achieved in the cryogenic temperature range in which the quantum computing circuit operates, and a pair of microwave connectors thermally coupled to the housing.

[0029] Viewed from another aspect, the present invention provides a manufacturing system performing operations including forming a hybrid microwave attenuator by assembling a circuit having two ports, the circuit comprising a resistive component configured to attenuate a plurality of frequencies of an input signal (transmission signal) and a dispersive component configured to attenuate a second plurality of frequencies within a frequency range, the resistive component and the dispersive component being arranged in a series configuration with respect to each other between two ports of the circuit, the operations further including forming a housing, the housing being a closable structure within which the circuit is disposed, the structure being formed from a material exhibiting at least a threshold thermal conductivity level, the threshold thermal conductivity level being achieved in a cryogenic temperature range in which the quantum computing circuit operates, and a pair of microwave connectors thermally coupled to the housing.

[0030] An exemplary embodiment provides an electronic attenuation device. In one embodiment, the hybrid microwave attenuator includes a circuit having two ports, the circuit comprising a resistive component configured to attenuate a plurality of frequencies of an input signal (transmission signal) and a dispersive component configured to attenuate a second plurality of frequencies within a frequency range, the resistive component and the dispersive component being arranged in a series configuration with respect to each other between the two ports of the circuit. The attenuator of this embodiment further includes a housing, the housing being a closable structure within which the circuit is disposed, the structure being formed from a material exhibiting at least a threshold thermal conductivity level, the threshold thermal conductivity level being achieved in the cryogenic range in which the quantum computing circuit operates, and a pair of microwave connectors physically and thermally coupled to the housing.

[0031] In another embodiment, the hybrid microwave attenuator is configured to operate in a temperature range of one refrigeration stage, and the dispersive component further comprises an inductive element formed from a material that exhibits less than a threshold thermal energy absorption when operating in the temperature range and exhibits greater than a required threshold electrical conductivity when operating in the temperature range. In another embodiment, the boundaries of the temperature range are 300 Kelvin (K) and 2K.

[0032] In another embodiment, the temperature range boundaries are 2K and 0.000001K.

[0033] In another embodiment, the hybrid microwave attenuator is configured to operate in the temperature range of a single refrigeration stage, and the dispersive component further includes a capacitive element including a dielectric of a material that exhibits less than a threshold thermal energy absorption when operating in the temperature range, and a pair of plates having an electrical conductivity greater than a threshold electrical conductivity when operating in the temperature range.

[0034] In another embodiment, the hybrid microwave attenuator is configured to operate in the temperature range of a single refrigeration stage, and the dispersive component further comprises a substrate formed from a material that exhibits a thermal conductivity greater than a threshold thermal conductivity when operating in the temperature range.

[0035] In another embodiment, the sexes of each connector in the pair of connectors are identical.

[0036] In another embodiment, each connector of the pair of connectors is coupled to one of two ports of a circuit.

[0037] In another embodiment, the hybrid microwave attenuator is configured to operate over a temperature range of one of the refrigeration stages, and the pair of connectors are formed from a material that exhibits a thermal conductivity greater than a required threshold thermal conductivity while operating over the temperature range.

[0038] In another embodiment, the hybrid microwave attenuator is configured to operate in the temperature range of one of the refrigeration stages, and the closeable structure is formed from a material that exhibits a thermal conductivity greater than a required threshold thermal conductivity when operating in this temperature range.

[0039] One embodiment includes a fabrication method for producing a well thermally balanced, low noise hybrid microwave attenuator.

[0040] One embodiment includes a system for fabricating a well-thermally balanced, low-noise hybrid microwave attenuator.

[0041] The appended claims set forth the novel features which are believed to be characteristic of the invention, however the invention itself, as well as its preferred modes of use, together with its objects and advantages, will best be understood by reference to the following detailed description of illustrative embodiments when read in conjunction with the accompanying drawings. [Brief description of the drawings]

[0042] [Figure 1] FIG. 1 is a block diagram of an exemplary configuration for input line conditioning of a quantum computing device, in accordance with an exemplary embodiment. [Diagram 2] 1A-1C show examples of currently available resistive microwave attenuators that can be used as components of a hybrid attenuator in accordance with exemplary embodiments. [Diagram 3] FIG. 2 illustrates an example configuration of a hybrid attenuator in accordance with an example embodiment. [Figure 4] FIG. 2 illustrates an example circuit for implementing a hybrid attenuator in accordance with an example embodiment. [Diagram 5] FIG. 13 illustrates microwave simulation results of scattering parameters of an example hybrid attenuator. [Figure 6] FIG. 13 illustrates another exemplary configuration of a hybrid attenuator in accordance with an exemplary embodiment. [Figure 7] FIG. 2 illustrates an example circuit for implementing a hybrid attenuator in accordance with an example embodiment. [Figure 8] FIG. 13 illustrates microwave simulation results of scattering parameters of an example hybrid attenuator. [Figure 9] 1 illustrates a rendering of an example packaging or housing for a hybrid attenuator in accordance with an example embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0043] Quantum computing involves reliably reading microwave radiation on the order of a single photon. A low microwave noise environment limits microwave noise to a threshold level that allows for reliable reading of microwave radiation on the order of a single photon. The exemplary embodiments used to describe the present invention generally address and solve the above-mentioned need for a low microwave noise, well thermally balanced packaging or housing, primarily for attenuating certain microwave signals on input lines that connect to q-circuits. The exemplary embodiments provide such packaging and thermal balancing of a cryogenic distributed-resistive hybrid attenuator for quantum microwave circuits that addresses the above-mentioned need or problem.

[0044] Exemplary embodiments recognize that the performance of superconducting-based quantum architectures depends heavily on the quality of the superconducting qubits themselves, which can be directly characterized by measuring the coherence time. The coherence time strongly depends on the performance of the microwave hardware in the temperature range in which the quantum computing circuit operates. The microwave hardware includes not only the qubits themselves, but also the attenuators and attenuator housings used in the microwave lines. To increase the coherence time, and therefore improve the functionality of the quantum processor, the microwave components, control lines, components and packaging are all designed to minimize microwave noise and are thermally equilibrated to a quantum computing-acceptable thermal equilibration level.

[0045] Exemplary embodiments enable better and faster thermal balancing of microwave components and cleaner microwave signal throughput by utilizing the attenuator design, packaging design, attenuator manufacturing materials, and high thermal conductivity materials in packaging manufacturing described herein. First, several embodiments are presented with reference to several figures that illustrate various designs of the proposed hybrid attenuator. Then, several embodiments are presented that illustrate a well-thermally balanced, low-noise packaging of an embodiment hybrid attenuator.

[0046] Operations described herein as being performed with respect to one or more frequencies should be construed as being performed with respect to signals of that frequency or frequencies. Unless expressly distinguished when used, all references to "signals" are references to microwave signals.

[0047] One embodiment provides a hybrid microwave attenuator (also referred to interchangeably herein as a "hybrid attenuator") construction that exhibits both resistive and dispersive characteristics. Another embodiment provides a method for designing and constructing a hybrid attenuator that may be implemented as a software application. This application implementing an embodiment of the design and construction method may be configured to function with existing circuit manufacturing systems, such as circuit assembly systems.

[0048] For clarity of explanation, and without any implication of limitation thereto, the exemplary embodiments are described using several exemplary configurations. From this disclosure, one skilled in the art may devise numerous modifications, adaptations and variations of the described configurations to achieve the described objectives, which are contemplated within the scope of the exemplary embodiments.

[0049] Additionally, simplified diagrams of example resistors, inductors, capacitors and other circuit components are used in the figures and exemplary embodiments. An actual circuit may have additional structures or components not shown or described herein, or structures or components that differ from those shown but have similar functionality to those described herein, without departing from the scope of the exemplary embodiments.

[0050] Moreover, the exemplary embodiments are described with respect to actual or hypothetical specific components by way of example only: the steps described by the various exemplary embodiments may be adapted to fabricate circuits using various components that may be intended to provide or may be repurposed to provide the described functionality in a hybrid attenuator, and such adaptations are contemplated to fall within the scope of the exemplary embodiments.

[0051] The exemplary embodiments are described by way of example only with respect to certain types of materials, electrical properties, steps, numbers, frequencies, circuits, components, and applications. The specific manifestations of these and other similar artifacts are not intended to limit the invention. Any suitable manifestations of these and other similar artifacts may be selected within the scope of the exemplary embodiments.

[0052] The examples in the present disclosure are used only for clarity of explanation and are not intended to limit the exemplary embodiments. The advantages listed herein are merely examples, and are not intended to limit the exemplary embodiments. Additional or different advantages may be realized by certain exemplary embodiments. Furthermore, certain exemplary embodiments may have some, all, or none of the advantages listed above.

[0053] Referring to FIG. 1, this figure shows a block diagram of an exemplary configuration of input line conditioning of a quantum computing device, according to an exemplary embodiment. The configuration 100 comprises a set of one or more dilution refrigerator stages 102, 104, ... 106. An input line 108 connects an external circuit to a q-circuit 110. Assuming that the line 108 conveys a microwave signal to the q-circuit 110, the signal S1 is a signal that includes microwave noise that is attenuated along with the signal S1. The signal S n is the attenuated signal arriving at the q circuit 110.

[0054] One embodiment configures a hybrid attenuator that includes some but not all of stages 102-106. Another embodiment configures a hybrid attenuator that includes each of stages 102-106, as shown in FIG. 1. For example, hybrid attenuator 112 is configured to operate with stage 102. Hybrid attenuator 112 receives an input signal S1 and a reflected signal S from a subsequent stage in the series of stages. R2 The hybrid attenuator 112 receives (S1+S R2 ) attenuating one frequency or frequency band of the signal to generate signal S2.

[0055] The hybrid attenuator 114 is configured to operate in conjunction with the stage 104. The hybrid attenuator 114 receives the input signal S2 and the reflected signal S from a subsequent stage in the series of stages. R3 The hybrid attenuator 114 receives (S2+S R3 ) signal to generate signal S3. After operating in this manner, stage 106 (Stage n) has a hybrid attenuator 116 configured with stage 106 (Stage n). Hybrid attenuator 116 attenuates different frequencies or frequency bands of the input signal S from the previous stage in the series of stages. n-1(and possibly a reflected signal, not shown, if circuit 110 is configured to reflect any signal frequencies). Hybrid attenuator 116 receives (S n-1 + reflected frequency) signal to form the input to the signal S n Generate.

[0056] Referring to FIG. 2, this diagram illustrates examples of currently available resistive microwave attenuators that can be used as components of a hybrid attenuator in accordance with an exemplary embodiment. Circuit 200 implements an exemplary 10 dB lumped-element resistive attenuator (i.e., two equal series resistors connected in the middle by one resistor to ground) formed between port 1 and port 2 using a T-configuration. In microwave engineering terminology, the S 12 represents the scattering parameters of the signal entering port 2 and leaving port 1 (i.e., transmission from port 2 to port 1). Similarly, S 21 represents the scattering parameter of the signal entering port 1 and exiting port 2. 11 and S 22 represent the reflection parameters of the signal entering port 1 and the signal entering port 2, respectively.

[0057] Graph 202 shows microwave simulation results for the scattering parameters of resistive attenuator 200. As can be seen in graph 202, the transmitted signal (scattering parameters S 21 and S 12 The reflection parameter S 11 and S 22 This device is well matched to 50 ohms on both ports, as shown by the negligible amplitude of . This means that there is almost no reflection from the device ports. The lost energy of the transmitted signal is dissipated as heat in the resistors of circuit 200.

[0058] Referring to FIG. 3, this figure shows one exemplary configuration of a hybrid attenuator according to an exemplary embodiment. This exemplary configuration of this figure of a hybrid attenuator 300, i.e., variation 1, comprises a resistive attenuator 302, a low-pass filter 304, and a high-pass filter 306. These components can be arranged in various sequences within the scope of the exemplary embodiment. For example, one sequence can be 304-302-306 in the order shown (i.e., low-pass filter 304, followed by resistive attenuator 302, followed by high-pass filter 306). Other sequences can be 302-304-306, 304-306-302, 306-302-304, 306-304-302, and other possible sequences in a similar manner.

[0059] The hybrid attenuator 300 is a distributed-resistive attenuator and can be implemented as a two-port integrated circuit. The low-pass filter 304 is a distributed filter that filters out frequencies above a threshold frequency (passes frequencies below the threshold frequency). The resistive attenuator 302 is a resistive or absorptive filter that operates in the manner of the resistive attenuator 200 of FIG. 2. The high-pass filter 306 is a distributed filter that filters out frequencies below a threshold frequency (passes frequencies above the threshold frequency). According to one embodiment, a circuit fabrication system forms and connects these three components 302, 304 and 306 on the same chip or printed circuit board.

[0060] Referring to Figure 4, this figure shows an example circuit for implementing a hybrid attenuator according to an example embodiment. Component 402 is a resistive attenuator, i.e., a resistive element implementing component 302 of Figure 3. Component 404 is a distributed element implementing a low pass filter, i.e., component 304 of Figure 3. Component 406 is a distributed element implementing a high pass filter, i.e., component 306 of Figure 3.

[0061] Component 402 comprises a T-configuration of resistive elements R1, R2 and R3, as in Figure 2. Note that this depiction of component 402 and resistors R1, R2 and R3 is a lumped realization, i.e., a representation of the effective function of component 402 as a resistive attenuator in the microwave frequency range. An equivalent π-configuration of this component also exists, which configurations are interchangeable with this non-limiting exemplary configuration shown.

[0062] Component 404 comprises a π-arrangement of capacitive elements C1 and C2, with one side coupled to ground, i.e., the outer conductor of the hybrid attenuator, and the other side coupled to inductive element L1 via the central conductor of the hybrid attenuator, as shown. This depiction of component 404 and elements C1, C2 and L1 is a representation of the effective function of component 404 as a lumped element realization, i.e., a low-pass filter in the microwave frequency range. This example shows a simple one-unit cell low-pass filter. This design also covers the case where, instead of the simple low-pass filter shown in FIG. 4, a more advanced low-pass filter is used, consisting of several unit cells, and whose attenuation, transmission, bandwidth, cut-off frequency and ripple characteristics are further or differently optimized.

[0063] Component 406 comprises a π-arrangement of inductive elements L2 and L3, with one side coupled to ground, i.e., the outer conductor of the hybrid attenuator, and the other side coupled to capacitive element C3 via the central conductor of the hybrid attenuator, as shown. This depiction of component 406 and elements L2, L3 and C3 is a representation of the effective function of component 406 as a lumped element realization, i.e., a high pass filter in the microwave frequency range. This example shows a simple one-unit cell high pass filter. This design also covers the case where, instead of the simple high pass filter shown in FIG. 4, a more advanced high pass filter is used, consisting of several unit cells, and whose attenuation, transmission, bandwidth, cut-off frequency and ripple characteristics are further or differently optimized.

[0064] In component 406, the capacitive element C3 on the center conductor of the hybrid attenuator acts as a direct current (DC) block that can be used to eliminate the formation of ground loops in the refrigerator. Such ground loops are undesirable because they can generate electronic noise. Additionally, the inductive elements L2 and L3 provide a negligible resistance path between the center conductor and the outer conductor of the hybrid attenuator. Such a low resistance electrical-thermal path can significantly improve the thermal balancing of the center conductor of the hybrid attenuator compared to a resistive attenuator alone, where the center conductor is thermally isolated from ground (the attenuator housing) by a significant electrical-thermal resistance.

[0065] To promote low microwave noise, high thermal balancing, or both, various embodiments accomplish the fabrication of hybrid attenuator 400 in various ways using lumped elements as shown and described herein. One embodiment fabricates components 402, 404, and 406 on a single chip using semiconductor fabrication methods on a wafer substrate. Another embodiment fabricates components 402, 404, and 406 on a printed circuit board (PCB) using circuit assembly methods for integrating electrical and electronic devices to form components 402, 404, and 406 on the same PCB.

[0066] To form the lumped element realization of components 402, 404, and 406, one embodiment fabricates the inductors, e.g., inductive elements L1, L2, or L3, or combinations thereof, using metals that exhibit a Residual Resistance Ratio (RRR) of at least 100 and a thermal conductivity higher than the threshold thermal conductivity level of 1 W / (cm×K) at 4 Kelvin. RRR is the ratio of a material's resistivity at room temperature to its resistivity at 0 K. Since 0 K cannot be reached in practice, an approximation at 4 K is used. Furthermore, since different stages operate in different temperature ranges, the choice of materials for the inductive elements also varies from lumped element realization to lumped element realization depending on the stage and thermal range in which the lumped element realization is operating. For operation in the temperature range from 300 K to 2 K, some non-limiting examples of metals that can be used for the inductive elements include aluminum and brass. For operation in the temperature range of 2K to 0.000001K, some non-limiting examples of metals that can be used for the inductive element include oxygen-free high conductivity copper, electrolytic copper, gold, platinum or silver.

[0067] To form a lumped element realization of components 402, 404, and 406, one embodiment fabricates a capacitor, such as capacitive element C1, C2, or C3, or a combination thereof, using a dielectric material exhibiting an RRR of at least 100 and plates having a thermal conductivity greater than the threshold thermal conductivity level of 1 W / (cm×K) at 4 Kelvin. Some non-limiting examples of materials that can be used for the dielectric of the capacitive elements include silicon nitride (SiN), crystalline silicon, and amorphous silicon.

[0068] To form a lumped element implementation of components 402, 404, and 406, one embodiment uses a thin film of a resistive metal to fabricate resistors, such as resistive elements R1, R2, or R3, or combinations thereof. In one embodiment, the thickness of the thin film is less than a threshold thickness, such as 100 nm, and some non-limiting examples of metals that can be used to form thin film resistive elements are NiCr, TaN, and CrN. x (nickel-chromium, tantalum nitrate).

[0069] To fabricate the hybrid attenuator 400 in one or more of the above manners, one embodiment uses a substrate material that exhibits high thermal conductivity at low temperatures. In one embodiment, the thermal conductivity of the substrate is at least equal to or above a threshold thermal conductivity level in a temperature range, such as a temperature range of 4-300K, such as 0.1 W / (cm×K) at 4 Kelvin. Some non-limiting examples of materials that can be used to form the substrate include silicon, gallium arsenide (GaAs), sapphire, quartz, and fused silica.

[0070] These lumped implementations of components 402, 404, and 406 are not intended to be limiting: from this disclosure, one skilled in the art will be able to devise many other implementations to the illustrated lumped implementations, e.g., using additional or different elements to achieve functionality similar to that of the lumped implementations shown herein, and such implementations are contemplated within the scope of the exemplary embodiments.

[0071] Referring to Figure 5, this figure shows microwave simulation results of scattering parameters of an example hybrid attenuator. The hybrid attenuator circuit, whose scattering parameters are shown in Figure 5, is based on the lumped element circuit 400 shown in Figure 4. Specifically, in this non-limiting exemplary implementation, R1 and R2 were each set to 27 ohms, R3 was set to 36 ohms, L1 was set to 3.18 nanohenries (nH), C1 and C2 were each set to 0.64 picofarads (pF), L2 and L3 were each set to 2.65 nH, and C3 was set to 0.53 pF.

[0072] In FIG. 5, a graph 502 shows the transmission parameter S 21 and S 12 , and graphs 506 and 504 respectively represent the reflection parameter S 11 and S 22Graph 502 illustrates significant attenuation (e.g., 20 dB at 7 GHz) for transmitted signals at frequencies above the superconducting qubit frequency range (e.g., 3-5 GHz) and significant attenuation (e.g., 20 dB at 2 GHz) for transmitted signals at frequencies below the superconducting qubit frequency range, while signals in the qubit signal range can pass with moderate attenuation (i.e., about 10 dB attenuation).

[0073] Referring to FIG. 6, this figure shows another exemplary configuration of a hybrid attenuator according to an exemplary embodiment. This exemplary configuration of this figure of a hybrid attenuator 600, i.e., variant configuration 2, comprises a resistive attenuator 602 and a bandpass (or bandstop) filter 604. These components can be arranged in various arrangements within the scope of the exemplary embodiment. For example, one arrangement can be 604-602 in the order shown (i.e., bandpass filter 604 followed by resistive attenuator 602). Other arrangements can be 602-604, 604-602-604, and other possible arrangements in a similar manner for different frequency bands.

[0074] The hybrid attenuator 600 is a distributed-resistive attenuator and can be implemented as a two-port integrated circuit. The bandpass filter 604 is a distributed filter that passes a frequency band between two threshold frequencies (attenuating / blocking frequencies outside this passband). The resistive attenuator 602 is a resistive or absorptive filter that operates in the manner of the resistive attenuator 302 of Figure 3. According to one embodiment, a circuit fabrication system forms and connects these two components 602 and 604 together on the same chip or printed circuit board.

[0075] Referring to Figure 7, this figure shows an example circuit for implementing a hybrid attenuator according to an example embodiment. Component 702 is a resistive element implementing a resistive attenuator in a manner similar to component 302 of Figure 3. Component 704 is a dispersive element implementing a bandpass filter that replaces components 304 and 306 of Figure 3 and performs a similar role.

[0076] Component 702 comprises a T-configuration of resistive elements R4, R5 and R6, as in Figure 2. It should be noted that this depiction of component 702 and resistors R4, R5 and R6 is a lumped element realization, i.e., a representation of the effective function of component 702 as a resistive attenuator in the microwave frequency range.

[0077] Component 704 comprises an arrangement of parallel capacitive elements L6 and C6, one side of which is coupled to ground, i.e., the outer conductor of the hybrid attenuator. L6-C6 is coupled on the other side to series elements L4-C4 and L5-C5 through the inner conductor of the hybrid attenuator, as shown. This depiction of component 704 and elements L4-L6 and C4-C6 is a representation of the effective function of component 704 as a lumped element realization, i.e., a bandpass filter in the microwave frequency range. This example shows a simple one-unit cell bandpass filter. This design also covers the case where, instead of the simple bandpass filter shown in FIG. 7, a more advanced bandpass filter is used, consisting of several unit cells, and whose attenuation, transmission, bandwidth, cutoff frequency and ripple characteristics are further or differently optimized.

[0078] In component 704, capacitive elements C4 and C5 on the inner conductor of the hybrid attenuator provide a DC block that can be used to eliminate the formation of ground loops in the refrigerator. Such ground loops are undesirable because they can generate electronic noise. Inductive element L6 connecting the center and outer conductors of the hybrid attenuator provides a negligible resistance path between the center and outer conductors of the hybrid attenuator. Such a low resistance electrical-thermal path can significantly improve the thermal balancing of the center conductor of the hybrid attenuator compared to a resistive attenuator alone, where the center conductor is thermally isolated from ground (the attenuator case) by a significant electrical-thermal resistance.

[0079] To promote low microwave noise, high thermal balancing, or both, various embodiments accomplish fabrication of hybrid attenuator 700 in a manner similar to the embodiment described with respect to hybrid attenuator 400 of Figure 4. One embodiment fabricates components 702 and 704 on a single chip using semiconductor fabrication methods on a wafer substrate. Another embodiment fabricates components 702 and 704 on a printed circuit board (PCB) using circuit assembly methods for integrating electrical and electronic devices to form components 702 and 704 on the same PCB.

[0080] To form the lumped element realizations of components 702 and 704, an embodiment uses the materials and techniques described with respect to inductive elements L1, L2, or L3 of FIG. 4 to fabricate inductors, e.g., inductive elements L4, L5, or L6, or combinations thereof. Similarly, an embodiment uses the materials and techniques described with respect to capacitive elements C1, C2, or C3 of FIG. 4 to fabricate capacitors, e.g., capacitive elements C4, C5, or C6, or combinations thereof. An embodiment uses the materials and techniques described with respect to resistive elements R1, R2, or R3 of FIG. 4 to fabricate resistors, e.g., resistive elements R4, R5, or R6, or combinations thereof. When a substrate is used to fabricate lumped element realizations 702 and 704, an embodiment uses the materials described with respect to FIG. 4 for the substrate.

[0081] These lumped implementations of components 702 and 704 are not intended to be limiting: from this disclosure, one skilled in the art will be able to devise many other implementations to the illustrated lumped implementations, e.g., using additional or different elements to achieve functionality similar to that of the lumped implementations shown herein, and such implementations are contemplated within the scope of the exemplary embodiments.

[0082] Referring to Figure 8, this figure shows microwave simulation results of scattering parameters of an example hybrid attenuator. The hybrid attenuator circuit, whose scattering parameters are shown in Figure 8, is based on the lumped element circuit 700 shown in Figure 7. Specifically, in this non-limiting exemplary implementation, R4 and R5 were each set to 27 ohms, R6 was set to 36 ohms, L4 and L5 were each set to 3.98 nH, C4 and C5 were each set to 0.398 pF, L6 was set to 0.497 nH, and C6 was set to 3.18 pF.

[0083] Graphs 804A and 804B respectively show the reflection parameters S 11 and S 22 Graph 804A shows significant reflection outside the frequency range of the qubit signal, which is approximately 3 to 5 GHz, while graph 804B shows good matching of the qubit frequency range to 50 ohms (i.e., the characteristic impedance of the external port of the hybrid attenuator).

[0084] Graph 806 illustrates the transmission parameter S of the exemplary hybrid attenuator shown in FIG. 21 and S 12 Graph 806 shows significant attenuation at frequencies above and below the qubit frequency range. The configuration of component 702 with bandpass filter 704 produced a low level of attenuation of about -10 to -12 decibels (dB) within the qubit signal range of about 3 to 5 GHz of the input signal, thus passing the qubit signal with relatively little attenuation, while suppressing noise and signals outside the qubit range. Such modest attenuation of the qubit signal may be useful when the quantum gate duration decreases as the qubit pulse power increases (e.g., cross-resonance gates).

[0085] Referring to FIG. 9, this figure shows a rendering of an exemplary packaging or housing for a hybrid attenuator according to an exemplary embodiment. Housing 900 is a non-limiting exemplary configuration of a housing for a cryogenic resistive-dispersive hybrid attenuator. Housing 900 exhibits high thermal equilibration with associated stages, minimizes the generation and introduction of microwave reflections in the connecting lines passing through the hybrid attenuator (not visible) contained within the housing, and is usable in one or more temperature ranges in which the quantum processing circuit or portions of the quantum processing circuit operate. Housing 900 is formed from a material that exhibits high thermal conductivity, for example, a thermal conductivity that meets or exceeds a threshold thermal conductivity level of 1 Watt / Kelvin-centimeter.

[0086] The housing 900 comprises a base 902 that includes a space in which a hybrid attenuator may be manufactured, positioned, or otherwise installed. The housing 900 further comprises a cover 904. The cover 904 is configured to completely cover an opening (not shown) in the base 902 that can be used to install the attenuator within the base 902. The cover 904 is thermally fixed, fastened, or otherwise thermally coupled to the base 902 in such a manner that the base 902 and cover 904 are well thermally balanced with respect to each other, i.e., such that when bonded together, the combination of the base 902 and cover 904 is at the same thermal temperature.

[0087] One non-limiting, exemplary approach to fastening the cover 904 to the base 902 for acceptable thermal equilibration in the quantum computing temperature range is shown in FIG. 9. To thermally equilibrate the cover 904 to the base 902, one or more screws 906 made from a material exhibiting a thermal conductivity higher than a threshold thermal conductivity level are in thermal contact with the cover 904 and the base 902. Brass is one non-limiting example of a material that can be used to manufacture the screws 906. This example of fastening for thermal equilibration is not intended to be limiting. From this disclosure, one skilled in the art can devise many other fastening methods for good thermal equilibration, which are contemplated within the scope of the exemplary embodiment. For example, instead of the screws 906, a thermally conductive bonding agent exhibiting a thermal conductivity higher than a threshold thermal conductivity level can be used to bond the cover 904 to the base 902.

[0088] Housing 900 further comprises connectors 908 and 910. Connectors 908 and 910 are specifically configured for use with signals in the microwave frequency range. According to an exemplary embodiment, connectors 908 and 910 are selected to be identical in type and gender. For example, connectors 908 and 910 may both be female SubMiniature version A (SMA) type connectors such that a gender-matching adapter is not required to connect a microwave cable to housing 900 (and thereby to connect the microwave cable to hybrid attenuator 400 or 700 within housing 900). Thus, the use of identical in type and gender connectors 908 and 910 minimizes microwave signal reflections that would otherwise result from a gender-matching adapter.

[0089] Additionally, the material or combination of materials used for connectors 908 and 910 should exhibit high thermal conductivity (above a threshold) and high electrical conductivity (above a threshold electrical conductivity or below a threshold resistance). One such non-limiting combination of materials for forming connectors 908 and 910 is brass with gold plating. In one non-limiting embodiment, this threshold electrical conductivity is comparable to the electrical conductivity, measured at room temperature, of copper or copper alloys used in the fabricated electrical wiring.

[0090] These examples of types, genders, and material combinations of connectors 908 and 910 are not intended to be limiting. Given this disclosure, one of ordinary skill in the art can devise many other types, genders, and material combinations of microwave connectors that are contemplated within the scope of the exemplary embodiments. For example, miniature coaxial (MCX) or micro-miniature coaxial (MMCX) connectors, or many other types of microwave and radio frequency connectors of the same gender and suitable materials or material combinations, can be formed and used as connectors 908 and 910 within the scope of the exemplary embodiments.

[0091] Additionally, connectors 908 and 910 may be secured to the microwave cable using any suitable fastening technique. The illustrated non-limiting example shows threaded screw connectors 908 and 910 into which a corresponding male end of a microwave cable may be screwed. Press-fit or friction coupling type connectors may be used for connectors 908 and 910 without departing from the scope of the exemplary embodiments, so long as the connectors are of the same gender and are formed to meet the thermal and electrical conductivity requirements described herein.

[0092] Various embodiments of the present invention are described herein with reference to the associated figures. Alternative embodiments may be devised without departing from the scope of the present invention. Although the following description and drawings describe various connections and relationships between elements (e.g., above, below, next to, etc.), those skilled in the art will appreciate that many of the relationships described herein are orientation independent, as long as the described functionality is maintained even when the orientation is changed. These connections and / or relationships can be direct or indirect, unless otherwise specified, and the present invention is not intended to be limited in this respect. Thus, the connection of entities can be direct or indirect, and the relationship between entities can be direct or indirect. As an example of an indirect relationship, when the description herein describes a layer "A" being formed on a layer "B," it includes the situation where there are one or more intermediate layers between layers "A" and "B," so long as the relevant properties and functions of layers "A" and "B" are not substantially altered by the intermediate layers (e.g., layer "C").

[0093] The following definitions and abbreviations are used for the interpretation of the claims and the specification. As used herein, the terms "comprises," "comprising," "includes," "including," "has," "having," "contains," or "containing," or other variations of these terms, are intended to cover non-exclusive inclusion. For example, a composition, mixture, process, method, article, or device that includes a list of elements is not necessarily limited to only those elements, but may include other elements not expressly listed or inherent to such composition, mixture, process, method, article, or device.

[0094] Moreover, the term "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment or design described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments or designs. The terms "at least one" and "one or more" are understood to include any integer number greater than or equal to one, i.e., 1, 2, 3, 4, etc. The term "plurality" is understood to include any integer number greater than or equal to two, i.e., 2, 3, 4, 5, etc. The term "connected" can include an indirect "connected" and a direct "connected."

[0095] When reference is made herein to "one embodiment," "an embodiment," "an exemplary embodiment," or the like, it indicates that the embodiment being described may include a particular feature, structure, or characteristic, but that all embodiments may or may not include that particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Moreover, when a particular feature, structure, or characteristic is described with respect to one embodiment, it is within the knowledge of one of ordinary skill in the art to affect such feature, structure, or characteristic with respect to other embodiments, whether or not expressly described.

[0096] The terms "about," "substantially," "approximately," and variations of these terms are intended to include the degree of error associated with the magnitude of the particular quantity, based on the equipment available at the time of filing this application. For example, "about" can include a range of ±8%, 5%, or 2% of a given value.

[0097] The above description of various embodiments of the present invention has been provided for illustrative purposes, and is not intended to be exhaustive or to limit the above description to only the disclosed embodiments. Many modifications and variations that do not depart from the scope of the described embodiments will be apparent to those skilled in the art. The terms used in this specification have been selected to best explain the principles of the embodiments, practical applications, or technical improvements over commercially available technology, or to enable those skilled in the art to understand the embodiments disclosed herein.

Claims

1. 1. A hybrid microwave attenuator comprising: A circuit having a first port and a second port, the circuit comprising: A resistive component configured to attenuate multiple frequencies of an input signal (transmission signal); a dispersive component configured to attenuate a second plurality of frequencies within a frequency range, the resistive component and the dispersive component being arranged in a series configuration with respect to one another between the first port and the second port of the circuit; and Equipped with the hybrid microwave attenuator is configured to operate over a temperature range of one refrigeration stage; the dispersive component comprises a first inductive element, a second inductive element and a third inductive element formed from a first material that exhibits a thermal conductivity greater than a threshold thermal conductivity level when operating in the temperature range; the second inductive element and the third inductive element are configured to provide an electrical-thermal path between a center conductor of the hybrid microwave attenuator and a ground of the hybrid microwave attenuator; said threshold thermal conductivity level of thermal conductivity being achieved in a cryogenic range of operation of a quantum circuit receiving a signal passing through said hybrid microwave attenuator; said threshold thermal conductivity level for thermal conductivity being at least 1 W / (cm K) at 4 Kelvin and a residual resistance ratio of at least 100; the hybrid microwave attenuator further comprising a housing; The housing comprises: a pair of microwave connectors thermally coupled to the housing; The resistance component comprises: a first resistor and a second resistor connected in series with the first resistor; The distributed component comprises: a first capacitive element electrically connected to the first port; a second capacitive element electrically connected to the first resistor; a first inductive element having one end electrically connected to the first capacitive element and the other end electrically connected to the second capacitive element; a second inductive element electrically connected to the second resistor; a third inductive element electrically connected to the second port; a third capacitive element, one end of which is electrically connected to the second inductive element and the other end of which is electrically connected to the third inductive element; The ground and the housing are connected. Hybrid microwave attenuator.

2. 2. The hybrid microwave attenuator of claim 1, wherein the temperature range boundaries are 300 Kelvin (K) and 2K.

3. 2. The hybrid microwave attenuator of claim 1, wherein the temperature range boundaries are 2K and 0.000001K.

4. 4. A hybrid microwave attenuator as claimed in claim 1, wherein the dispersive component further comprises the first capacitive element, the second capacitive element, and the third capacitive element each including a pair of plates having a thermal conductivity above the threshold thermal conductivity level when operating in the temperature range.

5. 5. A hybrid microwave attenuator as claimed in claim 1, wherein the sexes of the respective connectors of said pair of microwave connectors are identical.

6. 6. A hybrid microwave attenuator as claimed in claim 1, wherein each connector of the pair of microwave connectors is coupled to one of the first and second ports of the circuit.

7. 1. A method comprising: forming a hybrid microwave attenuator by assembling a circuit having a first port and a second port; The circuit, A resistive component configured to attenuate multiple frequencies of an input signal (transmission signal); a dispersive component configured to attenuate a second plurality of frequencies within a frequency range, the resistive component and the dispersive component being arranged in a series configuration with respect to one another between the first port and the second port of the circuit; and Equipped with the hybrid microwave attenuator is configured to operate over a temperature range of one refrigeration stage; the dispersive component comprises a first inductive element, a second inductive element and a third inductive element formed from a first material that exhibits a thermal conductivity greater than a threshold thermal conductivity level when operating in the temperature range; the second inductive element and the third inductive element are configured to provide an electrical-thermal path between a center conductor of the hybrid microwave attenuator and a ground of the hybrid microwave attenuator; said threshold thermal conductivity level of thermal conductivity being achieved in a cryogenic range of operation of a quantum circuit receiving a signal passing through said hybrid microwave attenuator; said threshold thermal conductivity level for thermal conductivity being at least 1 W / (cm K) at 4 Kelvin and a residual resistance ratio of at least 100; The method further comprises: Forming the housing wherein the housing comprises: a pair of microwave connectors thermally coupled to the housing; The resistance component comprises: a first resistor and a second resistor connected in series with the first resistor; The distributed component comprises: a first capacitive element electrically connected to the first port; a second capacitive element electrically connected to the first resistor; a first inductive element having one end electrically connected to the first capacitive element and the other end electrically connected to the second capacitive element; a second inductive element electrically connected to the second resistor; a third inductive element electrically connected to the second port; a third capacitive element, one end of which is electrically connected to the second inductive element and the other end of which is electrically connected to the third inductive element; The ground and the housing are connected. method.

8. 8. The method of claim 7, wherein the temperature range boundaries are 300 Kelvin (K) and 2K.

9. 8. The method of claim 7, wherein the temperature range boundaries are 2K and 0.000001K.

10. 10. The method of claim 7, wherein the dispersive component further comprises the first capacitive element, the second capacitive element, and the third capacitive element including a pair of plates having a thermal conductivity above the threshold thermal conductivity level when operating in the temperature range.

11. 10. The method of claim 7, wherein the sexes of the connectors in each of said pair of microwave connectors are identical.

12. 10. The method of claim 7, wherein each connector of the pair of microwave connectors is coupled to one of the first and second ports of the circuit.

13. A manufacturing system that performs operations, the operations comprising: forming a hybrid microwave attenuator by assembling a circuit having a first port and a second port; The circuit, A resistive component configured to attenuate multiple frequencies of an input signal (transmission signal); a dispersive component configured to attenuate a second plurality of frequencies within a frequency range, the resistive component and the dispersive component being arranged in a series configuration with respect to one another between the first port and the second port of the circuit; and Equipped with the hybrid microwave attenuator is configured to operate over a temperature range of one refrigeration stage; the dispersive component comprises a first inductive element, a second inductive element and a third inductive element formed from a first material that exhibits a thermal conductivity greater than a threshold thermal conductivity level when operating in the temperature range; the second inductive element and the third inductive element are configured to provide an electrical-thermal path between a center conductor of the hybrid microwave attenuator and a ground of the hybrid microwave attenuator; said threshold thermal conductivity level of thermal conductivity being achieved in a cryogenic range of operation of a quantum circuit receiving a signal passing through said hybrid microwave attenuator; said threshold thermal conductivity level for thermal conductivity being at least 1 W / (cm K) at 4 Kelvin and a residual resistance ratio of at least 100; the operations further include forming a housing; The housing comprises: a pair of microwave connectors thermally coupled to the housing; The resistance component comprises: a first resistor and a second resistor connected in series with the first resistor; The distributed component comprises: a first capacitive element electrically connected to the first port; a second capacitive element electrically connected to the first resistor; a first inductive element having one end electrically connected to the first capacitive element and the other end electrically connected to the second capacitive element; a second inductive element electrically connected to the second resistor; a third inductive element electrically connected to the second port; a third capacitive element, one end of which is electrically connected to the second inductive element and the other end of which is electrically connected to the third inductive element; The ground and the housing are connected. Manufacturing system.

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