Distributed microwave quantum computing system

Abstract

The present application provides a quantum node comprising: one or more communication qubits; one or more internal qubits coupled to the one or more communication qubits through an internal tunable coupler; a communication tunable coupler coupled to each of the one or more communication qubits; and a communication resonator coupled to each of the communication tunable couplers. In addition, the invention also provides a distributed quantum computing system. The distributed quantum computing system comprises two or more quantum nodes; and one or more coaxial cables or coplanar waveguides connecting the two or more quantum nodes together through at least one communication resonator of the two or more quantum nodes. The invention further provides a method for manufacturing the quantum node entanglement.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 333,225 filed on April 21, 2022, and the entire contents of that provisional patent application are incorporated herein by reference in their entirety. Technical Field

[0003] The present invention relates to semiconductor processing and computer processors, and in particular to a distributed microwave quantum computing system. Background Art

[0004] Previous experimental work has only demonstrated the generation of entanglement between two superconducting quantum processors (quantum nodes), but cannot be extended to multi-node entanglement between more than two quantum processors (references #1-4 below).

[0005] Therefore, there is a need for a quantum computing system that provides entanglement for more than two quantum processors. Summary of the invention

[0006] The various embodiments described herein are scalable to more than two quantum nodes because the architecture is self-similar and can generate high-fidelity entanglement by connecting in a large multi-node entangled network. These methods also do not require the use of single-photon detectors in between to generate predictions. These methods only require prediction detection within the computational quantum node. This further improves scalability and entanglement fidelity not seen in any previous work.

[0007] In one aspect, the present invention provides a quantum node, comprising: one or more communication qubits; one or more internal qubits, which are coupled to the one or more communication qubits via internal tunable couplers; a communication tunable coupler, which is coupled to each of the one or more communication qubits; and a communication resonator, which is coupled to each of the communication tunable couplers.

[0008] In one embodiment, the one or more internal qubits include a group of qubits connected in series, a group of qubits connected in parallel, or a group of interconnected qubit arrays. In another embodiment, a readout resonator is coupled to each of the one or more communication qubits and the one or more internal qubits. In another embodiment, the readout resonator is used for projection measurement to implement prediction-based entanglement. In another embodiment, a control connector is coupled to each of the internal tunable couplers and the communication tunable coupler. In another embodiment, an alternating current or radio frequency (AC / RF) signal is applied to the internal tunable coupler or the communication tunable coupler via the control connector to cause parametric photon exchange. In another embodiment, a controller is coupled to the control connector, wherein the controller can generate the AC / RF signal. In another embodiment, a drive connector is coupled to each of the one or more communication qubits and the one or more internal qubits. In another embodiment, the communication resonator allows the definition of a communication channel for efficient photon exchange between the quantum node and other quantum nodes. In another embodiment, the communication resonator increases the parametric photon release rate by resonantly enhancing and modifying the electromagnetic state density of the communication channel. In another embodiment, the one or more communication qubits are released simultaneously into the frequency band of the communication channel. In another embodiment, the communication resonator can limit the propagation of noise from the coaxial cable or coplanar waveguide to the quantum node. In another embodiment, a dark mode can be used to reduce the effective loss of photon transmission to and from the quantum node. In another embodiment, the communication resonator can suppress unwanted parametric sidebands. In another embodiment, the quantum node does not require any RF single photon detector nodes or RF beam splitters.

[0009] The second aspect of the present invention provides a distributed quantum computing system, comprising: two or more quantum nodes, wherein each of the quantum nodes comprises: one or more communication qubits; one or more internal qubits, which are coupled to the one or more communication qubits through an internal tunable coupler; a communication tunable coupler, which is coupled to each of the one or more communication qubits; and a communication resonator, which is coupled to each of the communication tunable couplers. One or more coaxial cables or coplanar waveguides connect the two or more quantum nodes together using at least one communication resonator in the two or more quantum nodes.

[0010] In one embodiment, the two or more quantum nodes are different from or substantially the same as each other. In another embodiment, the two or more quantum nodes are superconducting quantum nodes. In another embodiment, the one or more internal qubits include a group of qubits connected in series, a group of qubits connected in parallel, or a group of interconnected qubit arrays. In another embodiment, a readout resonator is coupled to each of the one or more communication qubits and the one or more internal qubits. In another embodiment, the readout resonator is used for projection measurement to achieve prediction-based entanglement. In another embodiment, a control connector is coupled to each of the internal tunable couplers and the communication tunable coupler. In another embodiment, an AC / RF signal is applied to the internal tunable coupler or the communication tunable coupler via the control connector to cause parametric photon exchange. In another embodiment, a controller is coupled to the control connector, wherein the controller can generate the AC / RF signal. In another embodiment, a drive connector is coupled to each of the one or more communication qubits and the one or more internal qubits. In another embodiment, the communication resonator allows the definition of a communication channel for efficient photon exchange between the quantum node and other quantum nodes. In another embodiment, the communication resonator increases the parametric photon release rate by resonantly enhancing and modifying the electromagnetic density of states of the communication channel. In another embodiment, the one or more communication qubits are released simultaneously into the frequency band of the communication channel. In another embodiment, the communication resonator is capable of limiting the propagation of noise from the coaxial cable or coplanar waveguide to the quantum node. In another embodiment, a dark mode can be used to reduce the effective loss of photon transmission in and out of the quantum node. In another embodiment, the communication resonator can reject unwanted parametric sidebands. In another embodiment, the quantum node does not require any RF single photon detector nodes or RF beam splitters. In another embodiment, the system is scalable.

[0011] The third aspect of the present invention provides a method for manufacturing a quantum node, comprising: depositing a first metal on the top of a substrate; coating the first metal with a first photoresist; selectively removing the first photoresist to leave a first pattern; etching the first metal to transfer the first pattern to the first metal to form a ground plane, the ground plane comprising one or more communication qubits, one or more internal qubits, one or more internal tunable couplers, one or more communication tunable couplers, one or more communication resonators, and control lines; removing the first photoresist; depositing a second metal in a second pattern; oxidizing the outside of the second metal; and depositing a third metal in a third pattern. The combination of the first metal, the second metal, the oxidized outer portion of the second metal, and the third metal forms one or more communication qubits, the one or more internal qubits are coupled to the one or more communication qubits through the one or more internal tunable couplers, and the communication tunable coupler is coupled to each of the one or more communication qubits and each of the one or more communication resonators.

[0012] In one embodiment, the first metal comprises aluminum, niobium or tantalum, and the second metal and the third metal comprise aluminum. In another embodiment, the method further comprises manufacturing a wiring wafer containing control lines and coplanar waves, and bonding the wiring wafer to the quantum node. In another embodiment, the method further comprises bonding the wiring wafer to a printed circuit board.

[0013] In another embodiment of the present invention, a loss-proof entanglement protocol for three or more quantum nodes includes: (a) providing three or more quantum nodes, each quantum node including: a first quantum node connected to a second quantum node via a first coaxial cable or a first coplanar waveguide, the second quantum node connected to a third quantum node via a second coaxial cable or a second coplanar waveguide, wherein each of the first quantum node, the second quantum node, and the third quantum node includes: a first qubit, a second qubit, a third qubit, a first internal tunable coupler connected between the first qubit and the second qubit, a second internal tunable coupler connected between the second qubit and the third qubit, and a first tunable coupler connected between the first qubit and the second qubit. (a) providing a first communication tunable coupler for a first quantum bit, a second communication tunable coupler connected to the third quantum bit, a first communication resonator coupled to the first communication tunable coupler, and a second communication resonator coupled to the second communication tunable coupler; (b) setting the third quantum bit of the first quantum node, the first communication channel mode, the third quantum bit of the second quantum node, and the second communication channel mode to a 0 state, and setting the second quantum bit of the first quantum node, the first quantum bit of the second quantum node, the second quantum bit of the second quantum node, and the first quantum bit of the third quantum node to a 1 state; and (c) performing one half of a two-qubit swap between: (1) the second quantum bit of the first quantum node and the first quantum node (d) performing half of a two-qubit swap between: (1) the third qubit of the first quantum node and the first coaxial cable or the first coplanar waveguide, and (2) the third qubit of the second quantum node and the second coaxial cable or the second coplanar waveguide; (e) measuring the third qubit of the first quantum node and the third qubit of the second quantum node; and (f) if the third qubit of the first quantum node is measured to be in the 1 state, swapping the third qubit of the first quantum node and the first communication cable. The channel mode is set to the 0 state. If the third qubit of the second quantum node is measured to be in the 1 state, the third qubit of the second quantum node and the second communication channel mode are set to the 0 state; (g) (1) if the second qubit of the first quantum node is detected to be in the 1 state, the state of the third qubit of the first quantum node is reversed, (2) if the state of the first coaxial cable or the first coplanar waveguide is detected, the first qubit of the second quantum node is reversed to be in the 1 state (3) if the second qubit of the second quantum node is detected to be in the 1 state, the third qubit of the second quantum node is reversed to be in the 1 state, and (4) if the first qubit of the third quantum node is detected to be in the 1 state, the second coaxial cable or the second coplanar waveguide is reversed;(h) performing one half of a two qubit exchange between: (1) a third qubit of a first quantum node and a first coaxial cable or a first coplanar waveguide, and (2) a third qubit of a second quantum node and a second coaxial cable or a second coplanar waveguide; (i) measuring the third qubit of the first quantum node and the third qubit of the second quantum node; (j) wherein if the third qubit of the first quantum node is detected to be in a 1 state, a first entanglement is established between the second qubit of the first quantum node and the first qubit of the second quantum node, and if the third qubit of the second quantum node is detected to be in a 1 state, a second entanglement is established between the second qubit of the second quantum node and the first qubit of the third quantum node; (k) performing a Bell measurement on the first qubit of the second quantum node and the second qubit of the second quantum node; (1) wherein a third entanglement is established between the second qubit of the first quantum node and the first qubit of the third quantum node. ;

[0014] In one embodiment, (f) further comprises repeating (b), (c), (d), and (e) until the third qubit of the first quantum node and the third qubit of the second quantum node are detected in the 1 state in (e). In another embodiment, (j) further comprises repeating (b), (c), (d), (e), (f), (g), (h), and (i) until the third qubit of the first quantum node and the third qubit of the second quantum node are detected in the 1 state in (e) and (i).

[0015] In another embodiment of the present invention, a loss-preventing entanglement protocol package for two quantum nodes includes: (a) providing two quantum nodes, the two quantum nodes including: a first quantum node connected to a second quantum node via a coaxial cable or a coplanar waveguide, and wherein the first quantum node and the second quantum node both include: a first qubit, a second qubit, a third qubit, a first internal tunable coupler connected between the first qubit and the second qubit, a second internal tunable coupler connected between the second qubit and the third qubit, a first communication tunable coupler connected to the first qubit, a second communication tunable coupler connected to the third qubit, a first communication resonator coupled to the first communication tunable coupler, and a second communication resonator coupled to the second communication tunable coupler; (b) setting the third qubit and the communication channel mode of the first quantum node to a 0 state, and setting the second qubit of the first quantum node and the first qubit of the second quantum node to a 1 state; (c) performing half of a two-qubit swap between: (1) the second qubit of the first quantum node and the first qubit of the first quantum node are swapped; (d) performing half of a two-qubit exchange between the third qubit of the first quantum node and the coaxial cable or the coplanar waveguide; (e) measuring the third qubit of the first quantum node; (f) if the third qubit of the first quantum node is detected to be in the 1 state, setting the third qubit of the first quantum node and the communication channel mode to the 0 state; (g) if the second qubit of the first quantum node is detected to be in the 1 state, reversing The invention relates to a method for detecting a state of a third qubit of the first quantum node, and (2) if the first qubit of the second quantum node is detected to be in the 1 state, reversing the state of the coaxial cable or the coplanar waveguide; (h) performing one half of a two-qubit swap between the third qubit of the first quantum node and the coaxial cable or the coplanar waveguide; (i) measuring the third qubit of the first quantum node; and (j) wherein if the third qubit of the first quantum node is detected to be in the 1 state, establishing entanglement between the second qubit of the first quantum node and the first qubit of the second quantum node.

[0016] In one embodiment, (f) further includes repeating (b), (c), (d), and (e) until the third qubit of the first quantum node is detected in (e) to be in the 1 state. In another embodiment, (j) further includes repeating (b), (c), (d), (e), (f), (g), (h), and (i) until the third qubit of the first quantum node is detected in (e) and (i) to be in the 1 state. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] For a more complete understanding of the features and advantages of the present invention, please refer to the detailed description and accompanying drawings of the present invention, in which:

[0018] Figure 1 is a block diagram of a quantum node in one embodiment of the present invention;

[0019] FIG. 2A to FIG. 2C is a block diagram of one or more internal qubits configured together in various non-limiting configurations in accordance with an embodiment of the present invention;

[0020] Figure 3 is a device mask and microscopic image for a three-qubit quantum node in one embodiment of the present invention;

[0021] Figure 4 is a loss-preventing entanglement protocol between node 1 and node 3 in one embodiment of the present invention;

[0022] FIG. 5A to FIG. 5C is a flow chart of an anti-loss entanglement protocol between node 1 and node 3 in one embodiment of the present invention;

[0023] Fig. 6A is a protocol diagram of a loss-preventing entanglement protocol between node 1 and node 2 in one embodiment of the present invention;

[0024] FIG6B is a diagram of click probability and entanglement fidelity of a loss-proof entanglement protocol between node 1 and node 2 according to an embodiment of the present invention;

[0025] Figure 6C is a qubit decoherence finite fidelity diagram of a loss-proof entanglement protocol between node 1 and node 2 in one embodiment of the present invention;

[0026] FIG. 7A to FIG. 7B is a flow chart of an anti-loss entanglement protocol between node 1 and node 2 in one embodiment of the present invention;

[0027] Figure 8 It is a parametric photon exchange (SWAP) between the communication qubit of a quantum node and the communication resonators of two quantum nodes and the coaxial cable / coplanar waveguide in one embodiment of the present invention;

[0028] Fig. 9 is a method for manufacturing a quantum node in one embodiment of the present invention;

[0029] Fig.10 is a manufacturing process of an embodiment of the present invention; and

[0030] FIG. 11A to FIG. 11C The invention relates to a method for manufacturing a flip chip quantum cluster on a wafer in one embodiment of the present invention. DETAILED DESCRIPTION

[0031] The following describes an example embodiment of the system of the present application. For the sake of clarity, this specification does not describe all features of the actual implementation process. Of course, it should be understood that when developing any actual implementation, a large number of specific implementation-related decisions must be made to achieve the developer's specific goals, such as meeting system-related or business-related constraints, which vary from one implementation to another. In addition, it should be understood that such development work may be complex and time-consuming, but it is still routine work for a person of ordinary skill in the art with the disclosure provided by this application.

[0032] It is hoped that an experimental testbed will be built for multi-node entangled network protocols. Users can see the effectiveness of these error-proof protocols for multi-node entangled network protocols on actual quantum hardware in the near future. The testbed should be universal, meaning that it can be easily reconfigured and expanded in a co-designed way according to the needs of users by combining the scalability of superconducting quantum processors and the extensibility of entangled networks. This provides a unique opportunity for the distributed quantum information processing community.

[0033] In addition to serving as a testbed for advanced entanglement network link protocols, the combination of advanced superconducting quantum processors and high-fidelity entanglement networks enables the development of scalable distributed quantum computing architectures to power the next evolution of superconducting quantum computers. As with classical high-performance computing (HPC), processors cannot be arbitrarily scaled up by increasing the area of ​​silicon because uniformity and yield rapidly decrease with area. This is especially true for quantum processors because qubit quality can be adversely affected by small defects, and the sub-millimeter size of superconducting qubits is determined by the achievable inductance and capacitance density, which does not allow for miniaturization as per Moore's Law according to fundamental microwave superconducting physics. Since the number of qubits added per standard-sized chip is ultimately limited, and there is no such limit for cryogenic temperatures, the future development path for superconducting quantum computing will rely on distributed quantum computing in a cryogenic space, just as HPC relies on distributed computing using a network of standard-sized CPUs. In addition, specialized devices dedicated to high-fidelity logic, long-duration quantum memory, and future novel superconducting quantum computing platforms can be engineered as modular components and connected together through local entanglement networks.

[0034] In addition, quantum devices may have incompatible manufacturing processes and even incompatible operating environments. However, incompatible devices can often provide unique capabilities that cannot be obtained using compatible technologies. For example, quantum microwave-optical transducers require procedures involving materials that are relatively lossy in microwaves and operate with strong optical inputs that are harmful to the coherence of superconducting quantum bits. However, such transducers provide the ability to generate entanglement in microwave quantum computing devices over long distances through optical fibers, making quantum Internet with powerful superconducting quantum computers possible in the future. Local quantum entanglement networks can allow high-fidelity transmission of quantum states between incompatible devices, and integrate such transducers into superconducting quantum computers as quantum network cards.

[0035] In addition, the embodiments described herein have the following features:

[0036] 1. Parametric photon release, which allows fast, high-fidelity, and controllable deterministic release and capture of microwave photons, thereby generating loss-proof entanglement through prediction.

[0037] 2. In addition, when photon release is not required, this is all done using full microwave control, without noise-sensitive DC control and without high-loss attenuation. This microwave-activated photon release allows the release time and photon waveform to be programmed by room-temperature electronics.

[0038] 3. In addition, parametric photon release allows photons to be released into desired frequency bands that are determined and influenced by manufacturing and randomness. This makes the system manufacturing yield stable because precise cross-wafer device manufacturing uniformity is not required.

[0039] 4. The incorporation of wide bandwidth photon release filters (communication resonators) allows the definition of communication channels for efficient photon exchange between quantum nodes. The photon release filters: (1) limit the propagation of noise from the lossy RF cables connecting the quantum nodes into the high coherence nodes; (2) increase the parametric photon release rate by resonantly enhancing and modifying the electromagnetic density of states of the communication channel; (3) reject undesirable parametric sidebands, since if the channel does not have a photon release filter to define a communication band, the qubit can be released into two bands simultaneously. This restriction significantly improves the fidelity of the photon release.

[0040] 5. Scalable to more than two nodes, as the architecture is self-similar and can generate high-fidelity entanglement in large multi-node entanglement networks through connections.

[0041] 6. These methods use predictions for generating loss-proof entanglement between nodes connected by lossy RF cables or coplanar waveguides. Unlike reference #3 below, the prediction protocol is designed and implemented entirely within the quantum processing unit (quantum node) without using separate RF single-photon detector nodes and lossy RF beam splitters. This simplification and innovation improves the efficiency of entanglement generation by more than an order of magnitude and eliminates the strict limitations in manufacturing parameter-matched narrowband quantum processor nodes and single-photon detector node detection.

[0042] 7. This approach is the only one that combines the scalability of 2D (planar) quantum processor architectures (references 1 and 4) with prophetic-based loss-proof microwave entanglement generation (reference 3).

[0043] This architecture is the inevitable enabling technology to enable superconducting quantum computing technology to expand beyond the near-term stage to large-scale quantum computing clusters, which can generate critical quantum computing capabilities to solve and accelerate challenging computing tasks in designing new drugs, new materials, new chemicals and cutting-edge quantum-enabled artificial intelligence, which will significantly change the future of the computing industry and the many industries that rely on it. This technology can be used to build cutting-edge industry-leading quantum computers that will disrupt the computing industry in the coming years.

[0044] The embodiments described herein have many advantages, including but not limited to: (1) being a "mature" and scalable technology for advanced quantum logic; (2) being rapidly manufactured and tested based on established micro / nano manufacturing infrastructure; (3) being easily understood and highly efficient programmable qubit-photon parameter conversions tailored to the requirements of various protocols; and / or (4) being accessible (in the cloud) to user-accessible protocol testbeds and directly applicable in distributed microwave quantum computing. Some embodiments may be confined to cryogenic space and use quantum optical-microwave transducers interconnected with fiber optic networks.

[0045] Various non-limiting embodiments will now be described in more detail.

[0046] Reference Figure 1, shows a block diagram of a quantum node 100 according to an embodiment of the present invention. In this example, the quantum node 100 includes: two or more communication qubits 102, 106; one or more internal qubits 104, which are coupled between the two or more communication qubits 102, 106 through an internal tunable coupler 108; a communication tunable coupler 110, which is coupled to each of the one or more communication qubits 102, 106; and a communication resonator 112, which is coupled to each of the communication tunable couplers 110. The two or more communication qubits 102, 106 and the one or more internal qubits 104 can be (but are not required to be) identical to each other. Similarly, the internal tunable coupler 108 and the communication tunable coupler 110 can be (but are not required to be) identical to each other. These names simply represent the placement of the components within the quantum node. In addition, as indicated by the label "N" in the block diagram, the internal qubits 104 can be any number. One or more internal qubits 104 can be arranged together in any desired structure, such as (but not limited to) a group of qubits connected in series ( Figure 2A ), a set of qubits connected in parallel ( Figure 2B ), an array of interconnected qubits ( Figure 2C) etc. In addition, any of the internal qubits 104 may be connected to a communication tunable coupler 110, which is connected to a communication resonator 112. In this case, the internal qubit 104 is essentially a communication qubit 102, 106. Thus, the quantum node 100 is configurable and scalable to meet any desired operating characteristics. In other embodiments, the quantum node includes one or more communication qubits and one or more internal qubits 104 coupled to the one or more communication qubits. In addition, a readout resonator 114 is coupled to each of the one or more communication qubits 102, 106 and the one or more internal qubits 104. The readout resonator 114 may be used for projection measurement to implement prediction-based entanglement. A control connector 116 is coupled to each of the internal tunable couplers 108 and the communication tunable coupler 110. An alternating current or radio frequency (AC / RF) signal may be applied to the internal tunable coupler 108 or the communication tunable coupler 110 via the control connector 116 to induce parametric photon exchange. A controller 118 may be coupled to the control connector 116, wherein the controller 118 may operate at room temperature and generate AC / RF signals. A drive connector 120 is coupled to each of the one or more communication qubits 102, 106 and the one or more internal qubits 104. It should be noted that the drive connection 120 applies a single qubit operation to each qubit. For example, changing the state of the qubit from 0 to 1 or from 1 to 0 or from 0 to a superposition state such as (|1>+|0>) / sqrt(2). The communication resonator 112 (coupled with a coaxial cable or coplanar waveguide mode) allows the definition of a communication channel for efficient photon exchange between the quantum node 100 and other quantum nodes (not shown). In addition, the communication resonator 112 enhances the parametric photon release rate by resonantly enhancing and modifying the electromagnetic state density of the communication channel. Two or more communication qubits 102, 106 and the one or more internal qubits 104 can be released simultaneously into the frequency band of the communication channel. In addition, the communication resonator 112 can limit the propagation of noise into the quantum node 100 from the coaxial cable, coplanar waveguide or other type of suitable connector or waveguide (not shown) connected to the communication resonator 112. Dark modes can be used to reduce the effective loss of photon transmission in and out of the quantum node 100. The dark mode is a resonance or communication mode formed by the mixture of two communication resonators and the coaxial cable / coplanar waveguide or other connector / waveguide coupled to the two communication resonators. It is "dark" because it participates in the lossy coaxial cable / coplanar waveguide region with minimal energy. The communication resonator 112 can also reject undesirable parametric sidebands during the exchange of photons between the qubit and the communication resonator. Finally, the quantum node 100 does not require any RF single photon detector nodes or RF beam splitters.

[0047] Reference FIG. 2A to FIG. 2C, shows a block diagram of one or more internal qubits 104 configured together in various non-limiting configurations. Figure 2A is a set of quantum bits 104a, 104b, ..., 104n connected in series. Figure 2B It is a group of qubits 104a, 104b, 104c, ..., 104n and 104d, 104e, 104f, ..., 104m connected in parallel. Figure 2C It is the interconnected quantum bit arrays 10411, 10412, 10413, ..., 1041n and 10421, 10422, 10423, ..., 104in and 104i1, 104i2, 104i3, ..., 104in.

[0048] Reference Figure 3 , showing a three-qubit quantum node (such as Figure 1 300 and microscopic image 302 of a quantum node 100 in FIG. 300. The quantum node comprises three qubits 304, 306, 308 coupled in series with tunable couplers 310. A communication resonator 312 is coupled to each tunable coupler 310 connected to an external qubit 304, 308. The qubits 304, 306, 308 are identical to each other. Likewise, the tunable couplers 310 are identical to each other. A readout resonator (qubit-readout) 314 is coupled to each qubit 304, 306, 308 and is used to perform projection measurements to implement prediction-based loss-proof quantum entanglement generation as described below. A control connector (coupler Z) 316 is coupled to each tunable coupler 310 and is used to control the tunable coupler 310 between qubits (for a two-qubit gate) or between a qubit and a communication resonator (for parametric photon release or capture). A drive connector (XY drive) 318 is coupled to each qubit 304, 306, 308 and is used to perform single-qubit gates on the connected superconducting charge qubits.

[0049] Reference Figure 4 , shows the loss-proof entanglement protocol between node 1 and node 3 in one embodiment of the present invention. This illustration focuses only on the prediction-based loss-proof entanglement generation and high-fidelity entanglement exchange in a linear quantum network of three quantum nodes (node ​​1, node 2, node 3). The three superconducting quantum nodes (node ​​1, node 2, node 3) are substantially identical and each contains three superconducting charge qubits Q ij , where i represents the number of nodes and j represents the number of qubits. It should be noted that in other embodiments, the quantum nodes may be different from each other. The three quantum nodes (node ​​1, node 2, node 3) are connected to each other by coaxial cable 402 (shown as a red cylinder). Coaxial cable 402 is composed of T ij, where the transmission line mode connects node i and node j. A coplanar waveguide can be used instead of the coaxial cable 402.

[0050] The three qubits in each node are indicated with a light blue letter Q, and there are four tunable couplers 404 for generating two-qubit gates on demand. There is also on-chip coupling to a coaxial transmission line 402 (also known as a coaxial cable) through a communication resonator 406. The qubit readout resonator is used to perform the projection measurements required for prediction-based entanglement creation.

[0051] This example is called a baseline because it is designed to demonstrate the basic functionality needed to build a scalable entangled network using advanced quantum nodes and encoding. More complex quantum processor nodes can be designed by adding more superconducting charge qubits, because each node only needs three qubits to generate prediction-based entanglement through lossy cables. More nodes can be added because entanglement generation and exchange can be linked together to build large multi-node entangled networks.

[0052] Please also refer to Figure 4 The protocol diagram 408 and FIG. 5A to FIG. 5C Flowchart 500 of describes a loss-proof entanglement protocol between node 1 and node 3 in one embodiment of the present invention. Three or more quantum nodes are provided in 502. The three or more quantum nodes include: a first quantum node, which is connected to a second quantum node by a first coaxial cable or a first coplanar waveguide; the second quantum node is connected to a third quantum node by a second coaxial cable or a second coplanar waveguide, and wherein the first quantum node, the second quantum node and the third quantum node all include: a first qubit, a second qubit, a third qubit, a first internal tunable coupler connected between the first qubit and the second qubit, a second internal tunable coupler connected between the second qubit and the third qubit, a first communication tunable coupler connected to the first qubit, a second communication tunable coupler connected to the third qubit, a first communication resonator coupled to the first communication tunable coupler, and a second communication resonator coupled to the second communication tunable coupler. As used herein, coaxial cable or coplanar waveguide may also refer to other types of suitable connectors or waveguides.

[0053] In 504, the third qubit of the first quantum node, the first communication channel mode (formed by mixing the second communication resonator of the first quantum node, the first communication resonator of the second quantum node and the first coaxial cable or the first coplanar waveguide), the third qubit of the second quantum node and the second communication channel mode (formed by mixing the second communication resonator of the second quantum node, the first communication resonator of the third quantum node and the second coaxial cable or the second coplanar waveguide) are set to the 0 state, and the second qubit of the first quantum node, the first qubit of the second quantum node, the second qubit of the second quantum node and the first qubit of the third quantum node are set to the 1 state.

[0054] At 506, one half of a two-qubit swap is performed between: (1) the second qubit of the first quantum node and the third qubit of the first quantum node; (2) the first coaxial cable or the first coplanar waveguide and the first qubit of the second quantum node; (3) the second qubit of the second quantum node; and (4) the second coaxial cable or the second coplanar waveguide and the first qubit of the third quantum node.

[0055] At 508, one half of a two-qubit swap is performed between: (1) the third qubit of the first quantum node and the first coaxial cable or the first coplanar waveguide; and (2) the third qubit of the second quantum node and the second coaxial cable or the second coplanar waveguide.

[0056] At 510, a third qubit of the first quantum node and a third qubit of the second quantum node are measured.

[0057] In 512, if the third qubit of the first quantum node is detected to be in the 1 state in 510, the third qubit of the first quantum node and the first communication channel mode (formed by mixing the second communication resonator of the first quantum node, the first communication resonator of the second quantum node and the first coaxial cable or the first coplanar waveguide) are set to the 0 state, and if the third qubit of the second quantum node is detected to be in the 1 state in 510, the third qubit of the second quantum node and the second communication channel mode (formed by mixing the second communication resonator of the second quantum node, the first communication resonator of the third quantum node and the second coaxial cable or the second coplanar waveguide) are set to the 0 state.

[0058] In 514, (1) if the second qubit of the first quantum node is in the 1 state, the state of the third qubit of the first quantum node is inverted; (2) if the first qubit of the second quantum node is in the 1 state, the state of the first coaxial cable or the first coplanar waveguide is inverted; (3) if the second qubit of the second quantum node is in the 1 state, the state of the third qubit of the second quantum node is inverted; and (4) if the first qubit of the third quantum node is in the 1 state, the state of the second coaxial cable or the second coplanar waveguide is inverted. It should be noted that these are actually quantum controlled NOT gates (CNOTs), which are blind (i.e., the qubit state should not be observed to determine whether the inversion (NOT) operation occurs). The quantum nature of the gate means that it occurs as a natural, intrinsic quantum process that does not require observation.

[0059] At 516, one half of a two-qubit swap is performed between: (1) the third qubit of the first quantum node and the first coaxial cable or the first coplanar waveguide; and (2) the third qubit of the second quantum node and the second coaxial cable or the second coplanar waveguide.

[0060] At 518, a third qubit of the first quantum node and a third qubit of the second quantum node are measured.

[0061] In 520, if the third qubit of the first quantum node is detected to be in the 1 state in 510 and 518, a first entanglement is established between the second qubit of the first quantum node and the first qubit of the second quantum node, and if the third qubit of the second quantum node is detected to be in the 1 state in 510 and 518, a second entanglement is established between the second qubit of the second quantum node and the first qubit of the third quantum node.

[0062] At 522, a Bell measurement is performed on the first qubit of the second quantum node and the second qubit of the second quantum node.

[0063] At 524, a third entanglement is established between the second qubit of the first quantum node and the first qubit of the third quantum node.

[0064] Quantum entanglement requires that the third qubit of the first quantum node and the third qubit of the second quantum node be measured to be in the 1 state through 510 and 518. In fact, if 510 does not measure that the third qubit of the first quantum node and the third qubit of the second quantum node are in the 1 state, the protocol can be rerun from 504 until a 1 state measurement value is generated in 510, after which the protocol can continue to reset the relevant state in 512. Similarly, if the third qubit of the first quantum node and the third qubit of the second quantum node are not measured to be in the 1 state in 518, the protocol can be rerun from 504 until a 1 state measurement value is generated in 510 and 518, after which the first and second entanglements are established in 520. For example, step 512 further includes repeating 502, 504, 506, and 508 until the third qubit of the first quantum node is detected to be in the 1 state in 510. In another example, step 518 further includes repeating 502 , 504 , 506 , 508 , 510 , 512 , 514 , and 516 until the third qubit of the first quantum node is detected in 512 and 518 to be in the 1 state.

[0065] Alternatively, the protocol may be run for multiple rounds from 504 to 524 without real-time feedforward control, and the results that produce 1-state measurements in 510 and 518 are post-selected, after which the first and second entanglements are established in 520. It should be noted that this sequence is less efficient than the sequence with real-time feedforward control described in the previous paragraph.

[0066] The fundamental reason for repeating the sequence until the measurements produce the desired results in the correct order (hence the term "prediction") for generating entanglement is that the system quantum state is designed to be in a so-called superposition of several possible results at the same time, and the measurements will non-deterministically produce ("project" to) one of the possible results. Only results in the correct time sequence can ("project") the quantum system into the desired quantum entangled state.

[0067] Reference Fig. 6A Protocol diagram and FIG. 7A to FIG. 7BFlowchart 700 of the present invention will describe an anti-loss entanglement protocol between node 1 and node 2 in one embodiment of the present invention. Two quantum nodes are provided in step 702. The two quantum nodes include a first quantum node connected to a second quantum node via a coaxial cable or a coplanar waveguide, and wherein the first quantum node and the second quantum node both include: a first qubit, a second qubit, a third qubit, a first internal tunable coupler connected between the first qubit and the second qubit, a second internal tunable coupler connected between the second qubit and the three qubits, a first communication tunable coupler connected to the first qubit, a second communication tunable coupler connected to the third qubit, a first communication resonator coupled to the first communication tunable coupler, and a second communication resonator coupled to the second communication tunable coupler. As used herein, coaxial cable or coplanar waveguide may also refer to other types of suitable connectors or waveguides.

[0068] In step 704, the third qubit of the first quantum node and the communication channel mode (formed by the second communication resonator of the first quantum node, the first communication resonator of the second quantum node and the coaxial cable or coplanar waveguide) are set to the 0 state, and the second qubit of the first quantum node and the first qubit of the second quantum node are set to the 1 state.

[0069] In step 706, one half of a two-qubit swap is performed between: (1) the second qubit of the first quantum node and the third qubit of the first quantum node; and (2) the coaxial cable or coplanar waveguide and the first qubit of the second quantum node.

[0070] In step 708, one half of the two-qubit exchange is performed between the third qubit of the first quantum node and the coaxial cable or coplanar waveguide.

[0071] In step 710, a third qubit of the first quantum node is measured.

[0072] In step 712, if the third quantum bit of the first quantum node is measured to be in the 1 state in step 710, the third quantum bit of the first quantum node and the communication channel mode (formed by the second communication resonator of the first quantum node, the first communication resonator of the second quantum node and the coaxial cable or coplanar waveguide) are set to the 0 state.

[0073] In step 714, (1) if the second qubit of the first quantum node is in the 1 state, one of the states of the third qubit of the first quantum node is inverted, and (2) if the first qubit of the second quantum node is in the 1 state, the state of the coaxial cable or coplanar waveguide is inverted. It should be noted that these are actually quantum controlled NOT gates (CNOTs), which are blind (i.e., the qubit state should not be observed to determine whether the inversion (NOT) operation occurred). The quantum nature of the gate means that it occurs as a natural, intrinsic quantum process that does not require observation.

[0074] In step 716, one half of the two-qubit exchange is performed between the third qubit of the first quantum node and the coaxial cable or coplanar waveguide.

[0075] In step 718, the third qubit of the first quantum node is measured.

[0076] In step 720, if the third qubit of the first quantum node is detected to be in the 1 state in steps 710 and 718, entanglement is established between the second qubit of the first quantum node and the first qubit of the second quantum node.

[0077] Quantum entanglement requires that the third qubit of the first quantum node is measured to be in the 1 state in both steps 710 and 718. In fact, if the third qubit of the first quantum node is not measured to be in the 1 state in step 710, the protocol can be rerun from step 704 until step 710 produces a 1 state measurement value, after which the protocol can continue to reset the relevant state in step 712. Similarly, if the third qubit of the first quantum node is not measured to be in the 1 state in step 718, the protocol can be rerun from step 704 until steps 710 and 718 produce a 1 state measurement value, after which entanglement is established in step 720. For example, step 712 further includes repeating steps 702, 704, 706, and 708 until the third qubit of the first quantum node is detected to be in the 1 state in step 710. In another example, step 718 further includes repeating steps 702 , 704 , 706 , 708 , 710 , 712 , 714 , and 716 until the third qubit of the first quantum node is detected to be in the 1 state in steps 712 and 718 .

[0078] Alternatively, the protocol may be run for multiple rounds from step 704 to step 720 without real-time feedforward control, and the results that produce 1-state measurements in steps 710 and 718 are post-selected, after which entanglement is established in step 720. It should be noted that this sequence is less efficient than the sequence with real-time feedforward control described in the previous paragraph.

[0079] FIG. 6B is a plot of click probability and entanglement fidelity of a loss-proof entanglement protocol between node 1 and node 2 in one embodiment of the present invention. FIG. 7A to FIG. 7B , the success of the anti-loss entangling protocol step 710 is the first click 602 (solid black line), and the success of the anti-loss entangling protocol step 718 is the second click 604 (dashed black line). The success of both steps 710 and 718 in one execution sequence is the double click 606 (dotted black line), which is a sign of a sequence that successfully entangling Node 1 and Node 2 from start to finish. The first click fidelity 608 (solid blue line) and the second click fidelity 610 (dashed blue line) are also shown.

[0080] Figure 6C 1 is a plot of the finite fidelity of decoherence of qubits for a loss-proof entanglement protocol between node 1 and node 2 in one embodiment of the present invention. The first click state 650 (solid black line), the second click state 655 (dashed black line), and the intersection of the second click state 655 with the state fidelity of 0.9 are shown, represented by line 660 (solid blue line).

[0081] Figure 8 402. FIG. 403 is a photon exchange (SWAP) between the communication qubit of a quantum node and the communication resonators of two quantum nodes (node ​​1, node 2) and the coaxial cable / coplanar waveguide 402 in one embodiment of the present invention. Q0, Q1 and Q2 are the qubits of the quantum nodes (node ​​1, node 2). Line 802 (blue line) is the qubit, line 804 (orange line) is the coupler, line 806 (green line) is the first communication resonator, line 808 (red line) is the coaxial cable / coplanar waveguide mode, and line 810 (purple line) is the second communication resonator.

[0082] Now return to reference Figure 1 , Figure 3 and Figure 4, a distributed quantum computing system in an embodiment of the present invention will be described. The distributed quantum computing system includes two or more quantum nodes (node ​​1, ..., node N), wherein each quantum node (node ​​1, ..., node N) includes: one or more communication qubits 102, 106; one or more internal qubits 104, which are coupled to each one or more communication qubits 102, 106 through an internal tunable coupler 108; a communication tunable coupler 110, which is coupled to each one or more communication qubits 102, 106; and a communication resonator 112, which is coupled to each communication tunable coupler 110. One or more coaxial cables or coplanar waveguides 402 use at least one communication resonator 112 of two or more quantum nodes (node ​​1, ..., node N) to connect the two or more quantum nodes (node ​​1, ..., node N) together. The two or more quantum nodes (node ​​1, ..., node N) can be different from each other or substantially the same. In addition, the two or more quantum nodes (node ​​1, ..., node N) can be superconducting quantum nodes. A dark mode is used to reduce the effective loss of photon transmission into and out of two or more quantum nodes (node ​​1, ..., node N). The system is scalable.

[0083] One or more communication qubits 102, 106 and one or more internal qubits 104 are identical to each other. Likewise, internal tunable coupler 108 and communication tunable coupler 110 are identical to each other. The names simply refer to the placement of the components within the quantum node. In addition, as indicated by the label "N" in the block diagram, there can be any number of internal qubits 104. One or more internal qubits 104 can be arranged together in any desired configuration, such as (but not limited to) a group of qubits connected in series ( Figure 2A ), a set of qubits connected in parallel ( Figure 2B ), an interconnected array of qubits ( Figure 2C ) etc. In addition, any internal qubit 104 can be connected to a communication tunable coupler 110, which is connected to a communication resonator 112. Thus, quantum node 100 is configurable and scalable to meet any desired operating characteristics.

[0084] In addition, a readout resonator 114 is coupled to each of the two or more communication qubits 102, 106 and the one or more internal qubits 104. The readout resonator 114 can be used for projection measurement to implement prediction-based entanglement. A control connector 116 is coupled to each of the internal tunable couplers 108 and the communication tunable coupler 110. An AC / RF signal can be applied to the internal tunable coupler 108 or the communication tunable coupler 110 through the control connector 116 to cause parametric photon exchange. A controller 118 can be coupled to the control connector 116, wherein the controller 118 can operate at room temperature and generate the AC / RF signal. A drive connector 120 is coupled to each of the one or more communication qubits 102, 106 and the one or more internal qubits 104.

[0085] The communication resonator 112 can define a communication channel for efficient photon exchange between the quantum node 100 and other quantum nodes (not shown). In addition, the communication resonator 112 enhances the parametric photon release rate by resonantly enhancing and modifying the electromagnetic state density of the communication channel. Two or more communication qubits 102, 106 and one or more internal qubits 104 can be released simultaneously into the frequency band of the communication channel. In addition, the communication resonator 112 can limit the propagation of noise into the quantum node 100 from the coaxial cable or coplanar waveguide (not shown) connected to the communication resonator 112. A dark mode can be used to reduce the effective loss of photon transmission in and out of the quantum node 100. The communication resonator can also reject an undesirable parametric sideband. Finally, the quantum node 100 does not require any RF single photon detector nodes or RF beam splitters.

[0086] Reference Fig. 9, showing a method 900 for manufacturing a quantum node in one embodiment of the present invention. In step 902, a first metal is deposited on top of a substrate, in step 904, the first metal is coated with a first photoresist, and in step 906, the first photoresist is selectively removed to leave a first pattern. In step 908, the first metal is etched to transfer the first pattern to the first metal to form a ground plane and one or more communication resonators, and in step 910, the first photoresist is removed. In step 912, a second metal is deposited in a second pattern, in step 914, an outer portion of the second metal is oxidized, and in step 916, a third metal is deposited in a third pattern. In step 918, the first metal, the second metal, the oxidized outer portion of the second metal, and the third metal are combined to form one or more communication qubits, one or more internal qubits coupled to the one or more communication qubits through an internal tunable coupler, and a communication tunable coupler coupled to each of the one or more communication qubits and the one or more communication resonators. The first metal can be (but is not limited to) aluminum, niobium, tantalum, or other superconducting metals. The second and third metals may be (but are not limited to) aluminum or other superconducting metals. Other steps may include: manufacturing a wiring wafer containing control lines and coplanar waves, and bonding the wiring wafer to a quantum node; or bonding the wiring wafer to a printed circuit board.

[0087] Reference Fig.10 , shows a manufacturing process 1000 of an embodiment of the present invention. It should be noted that aluminum can be niobium, tantalum or other superconducting metals.

[0088] Step 1: Initial wafer cleaning of silicon substrate 1002 (black): (1a) cleaned with piranha solution and (1b) cleaned with dilute HF solution.

[0089] Step 2: Deposit an aluminum ground plane 1004 (orange) on the silicon substrate 1002 .

[0090] Step 3: Patterning titanium 1006 (gray) as alignment marks on ground plane 1004: (3a) resist coating, (3b) e-beam exposure, (3c) development, (3d) titanium deposition, and (3e) acetone stripping.

[0091] Step 4: Patterning aluminum as ground plane 1004 and resonators: (4a) resist coating, (4b) e-beam exposure, (4c) development, (4d) etching aluminum to remove unwanted aluminum, and (4e) wafer cleaning to remove top resist. Ground plane 1004 will include one or more communication qubits, one or more internal qubits, one or more internal tunable couplers, one or more communication tunable couplers, one or more communication resonators, and control lines (collectively 1008).

[0092] Step 5: Patterning aluminum, aluminum oxide, and aluminum junctions: (5a) resist coating, (5b) electron beam exposure, (5c) development, (5d) first aluminum deposition 1010 (yellow), aluminum oxidation 1012 (blue), and second aluminum deposition 1014 (red) with different angles, and (5e) acetone stripping. The first metal, the second metal, the outer portion of the second metal oxidation, and the third metal are combined to form one or more communication qubits, one or more internal qubits coupled to the one or more communication qubits through one or more internal tunable couplers, and communication tunable couplers coupled to each of the one or more communication qubits and the one or more communication resonators.

[0093] Reference FIG. 11A to FIG. 11C , shows a method for manufacturing a flip chip quantum cluster on a wafer in one embodiment of the present invention. Each quantum node 1102 is bonded to a wiring wafer 1104, which is then connected to a PCB board 1106. The quantum node 1102 is connected to a coplanar waveguide 1108. The wiring wafer 1104 includes the necessary control lines and coplanar waveguides that form a communication channel with the communication resonator in the quantum node. It should be noted that aluminum can be niobium, tantalum or other superconducting metals. Fig. 11B The process steps 1110 of wiring wafer 1104 are shown:

[0094] Step 1: Initial wafer cleaning of silicon substrate 1112 (black): (1a) cleaned with piranha solution and (1b) cleaned with dilute HF solution.

[0095] Step 2: Through Silicon Via (TSV) definition: (2a) resist coating, (2b) photolithography, (2c) development, (2d) deep silicon etching using RIEBosch process to produce a channel 1114 that vertically penetrates the silicon wafer, (2e) ALD TiN conformal metallization of the silicon wafer channel to form a superconducting TSV (PECVD Al and other suitable materials can also be used), and (2f) chemical mechanical polishing (CMP) to remove the silicon thickness and expose the TSV to the surface.

[0096] Step 3: Define silicon hard spacers: (3a) resist coating, (3b) photolithography, (3c) development, (3d) silicon dry etching to remove most of the area 1116 to be used for superconducting circuit metallization, and the remaining unetched area is the silicon hard spacer 1118 for defining the height of flip chip bonding.

[0097] Step 4: Deposit superconducting metal (Nb) 1120 in the regions 1116 between the hard spacers 1118 .

[0098] Step 5: Patterning titanium as alignment mark 1122: (5a) resist coating, (5b) photolithography, (5c) development, (5d) titanium deposition, and (5e) acetone stripping.

[0099] Step 6: Patterning the ground plane and resonator 1124: (6a) resist coating, (6b) electron beam exposure, (6c) development, (6d) metal dry etching to remove unwanted metal, and (6e) wafer cleaning to remove the top resist.

[0100] Step 7: Define Indium Bonding Bumps 1126: (7a) Resist coating, (7b) Photolithography, (7c) Development, (7d) Indium evaporation, and (7e) Wafer cleaning to remove the top resist.

[0101] Fig. 11C The processing steps 1130 of the quantum node 1102 are shown in FIG.

[0102] Step 1: Initial wafer cleaning of silicon substrate 1132 (black): (1a) cleaned with piranha solution and (1b) cleaned with dilute HF solution.

[0103] Step 2: Deposit superconducting metal (Nb) 1134 (orange) on the silicon substrate 1132.

[0104] Step 3: Patterning titanium as alignment mark 1136 (gray): (3a) resist coating, (3b) e-beam exposure, (3c) development, (3d) titanium deposition, and (3e) acetone stripping.

[0105] Step 4: Patterning ground plane and resonator 1138 (orange): (4a) resist coating, (4b) electron beam exposure, (4c) development, (4d) metal dry etching to remove unwanted aluminum, and (4) wafer cleaning to remove the top resist.

[0106] Step 5: Patterning aluminum, aluminum oxide and aluminum junctions: (5a) resist coating, (5b) electron beam exposure, (5c) development, (5d) first aluminum deposition 1140 (yellow), aluminum oxidation 1142 (blue) and second aluminum deposition 1144 (red) with different angles, and (5e) acetone stripping.

[0107] Step 6: Define Indium Bonding Bumps 1146: (6a) Resist coating, (6b) Photolithography, (6c) Development, (6d) Indium evaporation, and (6e) Wafer cleaning to remove the top resist.

[0108] Circuits may be made of (but not limited to) discrete electrical and electronic components, integrated circuits, semiconductor devices, analog devices, digital devices, etc., alone or in combination. Components may be coupled together using any type of suitable direct or indirect connection means (including but not limited to wires, paths, channels, through-holes, electromagnetic induction, electrostatic charge, optical links, wireless communication links, etc.).

[0109] It should be understood that the specific embodiments described herein are intended to illustrate rather than to limit the present invention. The main features of the present invention may be employed in various embodiments without departing from the scope of the present invention. Those skilled in the art will recognize or be able to determine using routine experiments that there are numerous equivalent methods for the specific procedures described herein. These equivalent methods are considered to be within the scope of the present invention and are covered by the scope of the invention application.

[0110] All publications and patent applications mentioned in this specification are intended to demonstrate the technical level of those skilled in the art to which the invention belongs. All publications and patent applications are incorporated herein by reference to the same extent as if each individual publication or patent application was specifically and individually incorporated by reference.

[0111] In this specification, reference may be made to the spatial relationships between the various components and the spatial orientation of various aspects of the components depicted in the accompanying drawings. However, those skilled in the art will recognize, after a thorough reading of this application, that the devices, components, equipment, etc. described herein may be arranged in any desired orientation. Therefore, the use of "upper," "lower," "above," "below," or other similar terms to describe the spatial relationships between components or to describe the spatial orientation of various aspects of a component should be understood to describe the relative relationships between components or the spatial orientation of various aspects of a component, respectively, because the devices described herein may be oriented in any desired direction.

[0112] In the claims and / or the specification, when "a" or "an" is used with the term "comprising", it can mean "one", but can also be understood as "one or more", "at least one", and "one or more than one". When the term "or" is used in the claims, it should be understood as "and / or", unless it is clearly indicated that only alternatives are indicated, or the alternatives are mutually exclusive, although the present invention supports definitions that only refer to alternatives and "and / or". Throughout the application, the term "about" is used to indicate that a value includes the inherent error of the instrument, the error of the method used to determine the value, or the differences between the subjects of study.

[0113] "Comprises," "having," "including," or "containing" as used in this specification and claims are inclusive or open-ended and do not exclude additional, unmentioned elements or method steps. In any of the embodiments of the compositions and methods provided herein, "comprising" may be replaced with "consisting essentially of" or "consisting of." As used herein, the phrase "consisting essentially of" requires (several) specified integers or steps, as well as those integers or steps that do not materially affect the characteristics or functions of the claimed invention. As used herein, the term "consisting of" is used to indicate that only the stated integer (e.g., one feature, one element, one characteristic, one attribute, one method / process step, or one limitation) or a set of integers (e.g., features, elements, characteristics, attributes, method / process steps, or limitations) are present.

[0114] As used herein, the term "or combinations thereof" refers to all permutations and combinations of all items listed before the term. For example, "A, B, C, or combinations thereof" is intended to include at least one of the following: A, B, C, AB, AC, BC, or ABC, and also BA, CA, CB, CBA, BCA, ACB, BAC, or CAB if the order is important in a particular context. Continuing with this example, combinations containing one or more items or terms repeated, such as BB, AAA, AB, BBC, AAABCCCC, CBBAAA, CABABB, and the like are expressly included. Those skilled in the art will understand that generally there is no limit to the number of items or terms in any combination unless otherwise apparent from the context.

[0115] As used herein, approximate words such as "approximately", "substantially" or "substantially" are not limited to absolute or perfect conditions, but are understood to be close enough to the degree recognized by ordinary technicians in the field to identify the condition as existing. The degree of possible variation in the description will depend on how much variation can be made while still allowing ordinary technicians in the field to recognize that the modified features still have the characteristics and capabilities required of the unmodified features. Generally, but subject to the limitations of the foregoing discussion, a value modified by an approximate word such as "approximately" may vary from the stated value by at least +1, 2, 3, 4, 5, 6, 7, 10, 12 or 15%. 。

[0116] In view of the present invention, all devices and / or methods disclosed and claimed herein can be made and implemented without undue experimentation. Although the devices and / or methods of the present invention have been described according to specific embodiments, it should be understood by those skilled in the art that the compositions and / or methods described herein and the steps or sequence of steps of the methods can be changed without departing from the concept, spirit and scope of the present invention. All such similar substitutions and modifications that can be thought of by those skilled in the art should be deemed to be within the spirit, scope and concept of the present invention as defined by the appended claims.

[0117] Furthermore, no limitations are intended to the details of construction or design herein shown, except as described in the appended claims. It is therefore evident that the particular embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the invention. The protection sought herein is therefore as set forth in the appended claims.

[0118] Without departing from the scope of the present invention, the systems and devices described herein may be modified, added, or omitted. The components of the systems and devices may be integrated or separated. In addition, the operations of the systems and devices may be performed by more, fewer, or other components. The method may include more, fewer, or other steps. In addition, the steps may be performed in any suitable order. To assist the Patent Office and any reader of any patent issued based on this application in interpreting the scope of the invention claims attached to the present invention, the applicant wishes to note that unless the words "for ... method" or "for ... step" are explicitly used in a particular claim, the applicant does not intend that any attached claim invoke 35 U.S.C. §112(f) in effect on the date of filing this application.

[0119] References

[0120] 1. Y Zhong, AN Clelland, et al. Nature 590, 571–575 (2021).

[0121] 2. C. Axline, MH Devoret, RJ Schoelkopf, et al. Nature Phys 14, 705–710 (2018).

[0122] 3. A. Narla, MH Devoret, RJ Schoelkopf, et al. PRX 6, 031036 (2016).

[0123] 4. N. Leung, Y. Lu, D.I. Schuster et al. npj Quantum Inf 5, 18 (2019).

Claims

1. A quantum node, comprising: one or more communicating qubits; one or more internal qubits, the one or more internal qubits coupled to the one or more communication qubits via an internal tunable coupler; a communication tunable coupler coupled to each of the one or more communication qubits; as well as A communication resonator is coupled to each of the communication tunable couplers.

2. The quantum node according to claim 1, characterized in that The one or more internal qubits include a set of qubits connected in series, a set of qubits connected in parallel, or an array of interconnected qubits.

3. The quantum node according to claim 1, characterized in that Further included is a readout resonator coupled to each of the one or more communication qubits and the one or more internal qubits.

4. The quantum node according to claim 3, characterized in that The readout resonator is used for projection measurements to implement prediction-based entanglement.

5. The quantum node according to claim 1, characterized in that Further included is a control connector coupled to each of the internal tunable couplers and the communication tunable coupler.

6. The quantum node according to claim 5, characterized in that An alternating current or radio frequency (AC / RF) signal is applied to the internal tunable coupler or the communication tunable coupler through the control connector to induce parametric photonic switching.

7. The quantum node according to claim 6, characterized in that Further included is a controller coupled to the control connector, wherein the controller generates the AC / RF signal.

8. The quantum node according to claim 1, characterized in that Further comprising a drive connector coupled to each of the one or more communication qubits and the one or more internal qubits.

9. The quantum node according to claim 1, characterized in that The communication resonator allows definition of a communication channel for efficient photonic exchange between the quantum node and other quantum nodes.

10. The quantum node according to claim 9, characterized in that The communication resonator enhances the parametric photon release rate by resonantly enhancing and modifying the electromagnetic density of states of the communication channel.

11. The quantum node according to claim 9, characterized in that The one or more communication qubits are released simultaneously into the frequency band of the communication channel.

12. The quantum node according to claim 1, characterized in that The communication resonator limits the propagation of noise from the coaxial cable or coplanar waveguide into the quantum node.

13. The quantum node according to claim 1, characterized in that Dark mode is used to reduce the effective losses in photon transmission into and out of the quantum node.

14. The quantum node according to claim 1, characterized in that The communication resonator may reject undesirable parametric sidebands.

15. The quantum node according to claim 1, characterized in that The quantum node does not require any RF single photon detector nodes or RF beam splitters.

16. A distributed quantum computing system, comprising: Two or more quantum nodes, wherein each of the quantum nodes comprises: one or more communicating qubits, one or more internal qubits, the one or more internal qubits coupled to the one or more communication qubits via an internal tunable coupler; a communications tunable coupler coupled to each of the one or more communications qubits; and a communications resonator coupled to each of said communications tunable couplings; and One or more coaxial cables or coplanar waveguides connecting the two or more quantum nodes together using at least one communicating resonator in the two or more quantum nodes.

17. The distributed quantum computing system according to claim 16, characterized in that: The two or more quantum nodes are different from each other or substantially the same.

18. The distributed quantum computing system of claim 16, wherein: The two or more quantum nodes are superconducting quantum nodes.

19. The distributed quantum computing system according to claim 16, wherein: The one or more internal qubits include a set of qubits connected in series, a set of qubits connected in parallel, or an array of interconnected qubits.

20. The distributed quantum computing system according to claim 16, wherein: Further included is a readout resonator coupled to each of the one or more communication qubits and the one or more internal qubits.

21. The distributed quantum computing system according to claim 20, characterized in that: The readout resonator is used for projection measurements to implement prediction-based entanglement.

22. The distributed quantum computing system of claim 16, wherein: Further included is a control connector coupled to each of the internal tunable couplers and the communication tunable coupler.

23. The distributed quantum computing system of claim 22, wherein: An AC / RF signal is applied to the internal tunable coupler or the communication tunable coupler through the control connector to induce parametric photonic switching.

24. The distributed quantum computing system of claim 23, wherein: Further included is a controller coupled to the control connector, wherein the controller generates the AC / RF signal.

25. The distributed quantum computing system of claim 16, wherein: Further comprising a drive connector coupled to each of the one or more communication qubits and the one or more internal qubits.

26. The distributed quantum computing system of claim 16, wherein: The communication resonator allows definition of a communication channel for efficient photonic exchange between the quantum node and other quantum nodes.

27. The distributed quantum computing system of claim 26, wherein: The communication resonator enhances the parametric photon release rate by resonantly enhancing and modifying the electromagnetic shape density of the communication channel.

28. The distributed quantum computing system of claim 26, wherein: The one or more communication qubits are released simultaneously into the frequency band of the communication channel.

29. The distributed quantum computing system of claim 16, wherein: The communication resonator limits noise propagation from the coaxial cable or coplanar waveguide into the two or more quantum nodes.

30. The distributed quantum computing system of claim 16, wherein: The dark mode is used to reduce the effective losses in the transmission of photons into and out of the two or more quantum nodes.

31. The distributed quantum computing system of claim 16, wherein: The communication resonator may reject undesirable parametric sidebands.

32. The distributed quantum computing system of claim 16, wherein: The system does not require any RF single photon detector nodes or RF beam splitters.

33. The distributed quantum computing system of claim 16, wherein: The system is scalable.

34. A method for manufacturing a quantum node, comprising: depositing a first metal on top of the substrate; coating the first metal with a first photoresist; selectively removing the first photoresist to leave a first pattern; etching the first metal to transfer the first pattern to the first metal to form a ground plane, the ground plane will contain one or more communication qubits, one or more internal qubits, one or more internal tunable couplers, one or more communication tunable couplers, one or more communication resonators, and control lines; removing the first photoresist; depositing a second metal in a second pattern; oxidizing an outer portion of the second metal; depositing a third metal in a third pattern; and wherein the first metal, the second metal, the oxidized outer portion of the second metal, and the third metal combine to form the one or more communication qubits, the one or more internal qubits coupled to the one or more communication qubits via the one or more internal tunable couplers, and the communication tunable couplers coupled to each of the one or more communication qubits and the one or more communication resonators.

35. The method of claim 34, wherein: The first metal includes aluminum, niobium, or tantalum; and the second and third metals include aluminum.

36. The method of claim 34, wherein: Further including: A wiring wafer containing control lines and coplanar waveguides is fabricated; and the wiring wafer is bonded to the quantum node.

37. The method of claim 36, wherein: The method further includes bonding the wiring wafer to a printed circuit board.

38. A loss-proof entanglement protocol for three or more quantum nodes, comprising: (a) providing three or more quantum nodes, the three or more quantum nodes comprising: a first quantum node connected to a second quantum node via a first coaxial cable or a first coplanar waveguide, the second quantum node connected to a third quantum node via a second coaxial cable or a second coplanar waveguide, and wherein the first quantum node, the second quantum node, and the third quantum node all comprise: a first qubit, a second qubit, a third qubit, a first internal tunable coupler connected between the first qubit and the second qubit, a second internal tunable coupler connected between the second qubit and the third qubit, a first communication tunable coupler connected to the first qubit, a second communication tunable coupler connected to the third qubit, a first communication resonator coupled to the first communication tunable coupler, and a second communication resonator coupled to the second communication tunable coupler; (b) setting the third qubit of the first quantum node, the first communication channel mode, the third qubit of the second quantum node, and the second communication channel mode to a 0 state, and setting the second qubit of the first quantum node, the first qubit of the second quantum node, the second qubit of the second quantum node, and the first qubit of the third quantum node to a 1 state; (c) performing one half of a two-qubit swap between: (1) the second qubit of the first quantum node and the third qubit of the first quantum node, (2) the first coaxial cable or the first coplanar waveguide and the first qubit of the second quantum node, (3) the second qubit of the second quantum node, and (4) the second coaxial cable or the second coplanar waveguide and the first qubit of the third quantum node; (d) performing one half of the two-qubit exchange between: (1) a third qubit of the first quantum node and the first coaxial cable or the first coplanar waveguide, and (2) a third qubit of the second quantum node and the second coaxial cable or the second coplanar waveguide; (e) measuring a third qubit of the first quantum node and a third qubit of the second quantum node; (f) if the third qubit of the first quantum node is detected to be in the 1 state, the third qubit of the first quantum node and the first communication channel mode are set to the 0 state, and if the third qubit of the second quantum node is detected to be in the 1 state, the third qubit of the second quantum node and the second communication channel mode are set to the 0 state; (g) (1) if the second qubit of the first quantum node is in the 1 state, inverting the state of the third qubit of the first quantum node, (2) if the first qubit of the second quantum node is in the 1 state, inverting the state of the first coaxial cable or the first coplanar waveguide, (3) if the second qubit of the second quantum node is in the 1 state, inverting the state of the third qubit of the second quantum node, and (4) if the first qubit of the third quantum node is in the 1 state, inverting the state of the second coaxial cable or the second coplanar waveguide; (h) performing one half of the two-qubit exchange between: (1) a third qubit of the first quantum node and the first coaxial cable or the first coplanar waveguide, and (2) a third qubit of the second quantum node and the second coaxial cable or the second coplanar waveguide; (i) measuring a third qubit of the first quantum node and a third qubit of the second quantum node; (j) if the third qubit of the first quantum node is detected to be in the 1 state, establishing a first entanglement between the second qubit of the first quantum node and the first qubit of the second quantum node, and if the third qubit of the second quantum node is detected to be in the 1 state, establishing a second entanglement between the second qubit of the second quantum node and the first qubit of the third quantum node; (k) performing Bell measurement on the first qubit of the second quantum node and the second qubit of the second quantum node; and (l) wherein a third entanglement is established between the second qubit of the first quantum node and the first qubit of the third quantum node.

39. The anti-loss entanglement protocol of claim 38, wherein: (f) further includes repeating (b), (c), (d), and (e) until the third qubit of the first quantum node and the third qubit of the second quantum node are detected in (e) to be in the 1 state.

40. The anti-loss entanglement protocol of claim 38, wherein: (j) further includes repeating (b), (c), (d), (e), (f), (g), (h), and (i) until the third qubit of the first quantum node and the third qubit of the second quantum node are detected in the 1 state in (e) and (i).

41. A loss-proof entanglement protocol for two quantum nodes, comprising: (a) providing two quantum nodes, the two quantum nodes comprising: a first quantum node connected to a second quantum node via a coaxial cable or a coplanar waveguide, wherein the first quantum node and the second quantum node both comprise: a first qubit, a second qubit, a third qubit, a first internal tunable coupler connected between the first qubit and the second qubit, a second internal tunable coupler connected between the second qubit and the third qubit, a first communication tunable coupler connected to the first qubit, a second communication tunable coupler connected to the third qubit, a first communication resonator coupled to the first communication tunable coupler, and a second communication resonator coupled to the second communication tunable coupler; (b) setting the third qubit of the first quantum node and the communication channel mode to a 0 state, and setting the second qubit of the first quantum node and the first qubit of the second quantum node to a 1 state; (c) performing one half of a two-qubit swap between: (1) the second qubit of the first quantum node and the third qubit of the first quantum node, and (2) the coaxial cable or the coplanar waveguide and the first qubit of the second quantum node; (d) performing one half of the two-qubit exchange between a third qubit of the first quantum node and the coaxial cable or the coplanar waveguide; (e) measuring a third qubit of the first quantum node; (f) if it is detected that the third qubit of the first quantum node is in the 1 state, setting the third qubit of the first quantum node and the communication channel mode to the 0 state; (g) (1) if the second qubit of the first quantum node is in the 1 state, inverting the state of the third qubit of the first quantum node, and (2) if the first qubit of the second quantum node is in the 1 state, inverting the state of the coaxial cable or the coplanar waveguide; (h) performing one half of the two-qubit exchange between a third qubit of the first quantum node and the coaxial cable or the coplanar waveguide; (i) measuring the third qubit of the first quantum node; and (j) If it is detected that the third qubit of the first quantum node is in the 1 state, entanglement is established between the second qubit of the first quantum node and the first qubit of the second quantum node.

42. The anti-loss entanglement protocol of claim 41, wherein: (f) further includes repeating (b), (c), (d) and (e) until the third qubit of the first quantum node is detected in (e) to be in the 1 state.

43. The anti-loss entanglement protocol of claim 41, wherein: (j) further includes repeating (b), (c), (d), (e), (f), (g), (h) and (i) until the third quantum bit of the first quantum node is detected in the 1 state in (e) and (i).

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