Execution of readout and reset of a flux qubit

Abstract

Techniques for performing readout and reset of fluxonium qubits are disclosed. When a fluxonium hardware component is coupled to a quantum metamaterial through a readout resonator, the component can be dispersively coupled such that the quantum state of the corresponding fluxonium qubit is read out through the quantum metamaterial, and then, subsequently, the state of the fluxonium qubit is reset in order to proceed with a quantum computation to be performed. Alternatively, when a fluxonium hardware component is directly coupled to a quantum metamaterial, the quantum state of the fluxonium qubit is read out using resonant fluorescence, and then, subsequently, the quantum state can also be reset back to its ground state using resonant fluorescence. The passband width of the quantum metamaterial, as well as the frequency of the control sequence used, can be tuned such that readout or reset is selectively activated.

Description

Background Technology

[0001] Quantum computing uses the laws of quantum physics to process information. Quantum physics is a theory that describes the behavior of reality at a fundamental level. It is currently the only physical theory that can consistently predict the behavior of microscopic quantum objects such as photons, molecules, atoms, and electrons.

[0002] A quantum computer is a device that uses quantum physics to write, store, process, and read information encoded in quantum states (e.g., the states of quantum objects). A quantum object is a physical object that operates according to the laws of quantum physics. The state of a physical object is a description of that object at a given time.

[0003] In quantum physics, the states of a two-level quantum system, or simply a qubit, are a list of two complex numbers whose squares sum to one. Each of these two numbers is called an amplitude or quasi-probability, and the square of their absolute values ​​is the probability that a measurement of the qubit will result in zero or one. The fundamental and counterintuitive difference between a probabilistic bit (e.g., a classical zero or one bit) and a qubit is that a probabilistic bit represents a lack of information about a two-level classical system, while a qubit contains the maximum amount of information about a two-level quantum system.

[0004] Quantum computers are based on qubits, which can exhibit phenomena called "superposition" and "entanglement." Superposition allows a quantum system to be in multiple states simultaneously. For example, while classical computers are based on bits that are either zero or one, a qubit can be both zero and one at the same time, with different probabilities assigned to zero and one. Entanglement is a strong correlation between quantum systems, making them inevitably linked together even when separated by great distances.

[0005] Quantum algorithms involve reversible transformations acting on qubits in a desired and controlled manner, followed by measurements on one or more qubits. For example, if the system has two qubits, a single transformation might modify four numbers; with three qubits, this becomes eight numbers, and so on. Therefore, quantum algorithms operate on an exponentially large list of numbers determined by the number of qubits. To implement transformations, for example, a transformation can be broken down into small operations acting on a single qubit or a pair of qubits. Such small operations can be called quantum gates, and a specific arrangement of quantum gates implements a quantum circuit.

[0006] Different types of qubits exist that can be used in quantum computers, each with its own advantages and disadvantages. For example, some quantum computers may include qubits constructed from superconductors, trapped ions, semiconductors, photonics, etc. Each may experience different levels of interference, error, and decoherence. Furthermore, some may be more useful for generating specific types of quantum circuits or quantum algorithms, while others may be more useful for generating other types. Additionally, the cost, runtime, error rate, and availability of quantum computing technologies may vary. Attached Figure Description

[0007] Figure 1 A hardware layout of a quantum hardware device according to some embodiments is shown, the quantum hardware device being configured to perform readout of the fluxion qubit by dispersively coupling hardware components implementing the fluxion qubit to a readout resonator, which in turn is coupled to a quantum metamaterial.

[0008] Figure 2 The steps applied according to some embodiments for executing a given quantum circuit between two fluxion qubits are illustrated, wherein the steps include at least a reset (e.g., initialization) step for the fluxion qubits, the execution of one or more quantum gates between the two fluxion qubits, and the execution of a readout step for the quantum superposition state of the two fluxion qubits.

[0009] Figure 3A An energy state diagram of a given fluxion is shown according to some embodiments, wherein the computational basis states of the fluxion qubit have been logically mapped to the ground state and the first excited state of the fluxion.

[0010] Figure 3B Demonstrates the ability to drive according to some embodiments Figure 3A The fluxons shown in the figure are used to drive the various transition frequencies between the energy states of the fluxons.

[0011] Figure 4A and 4B Control sequences in the frequency and time domains, according to some embodiments, are shown respectively, and these control sequences are used for hardware layout (e.g., Figure 1 The hardware layout shown is used to perform the readout of fluxion qubits.

[0012] Figure 5 Another hardware layout of a quantum hardware device according to some embodiments is shown, the quantum hardware device being configured to perform readout of the fluxion qubit by dispersively coupling hardware components implementing the fluxion qubit to a readout resonator, which in turn is coupled to a Purcell filter, which in turn is coupled to a quantum metamaterial.

[0013] Figure 6 The process of using dispersive coupling to perform the readout of the quantum superposition state of a fluxion qubit according to some embodiments is illustrated.

[0014] Figure 7 A hardware layout of a quantum hardware device according to some embodiments is shown, the quantum hardware device being configured to perform both fluorescence readout and fluorescence reset of the fluxion qubit by coupling hardware components implementing the fluxion qubit to a quantum metamaterial.

[0015] Figure 8A and 8B Control sequences in the frequency and time domains, according to some embodiments, are shown respectively, and these control sequences are used for hardware layout (e.g., Figure 7 The hardware layout shown is used to perform the readout of fluxion qubits.

[0016] Figure 9A and 9B First control sequences in the frequency and time domains, according to some embodiments, are shown respectively. These first control sequences are used for hardware layout (e.g., Figure 7 The hardware layout shown is used to perform the reset of the fluxion qubits.

[0017] Figure 10A and 10B The second control sequence in the frequency domain and time domain, according to some embodiments, is shown respectively. The second control sequence is used for hardware layout (such as...) Figure 7 The hardware layout shown is used to perform the reset of the fluxion qubits.

[0018] Figure 11A and 11B Third control sequences in the frequency and time domains, according to some embodiments, are shown respectively, and these third control sequences are used for hardware layout (e.g., Figure 7 The hardware layout shown is used to perform the reset of the fluxion qubits.

[0019] Figure 12A and 12B The fourth control sequence in the frequency domain and time domain, according to some embodiments, is shown respectively. This fourth control sequence is used with hardware layout (e.g., Figure 7 The hardware layout shown is used to perform the reset of the fluxion qubits.

[0020] Figure 13 The process of performing fluorescence readout and reset of fluxion qubits according to some embodiments is demonstrated.

[0021] Figure 14This is a block diagram illustrating an example quantum hardware device according to some embodiments, which can be configured to perform quantum gates between flux-quantum qubits and to perform readout and reset steps between the execution of the quantum gates.

[0022] Figure 15 This is a block diagram illustrating an example classical computing device that can be used in at least some of the embodiments.

[0023] Although embodiments have been described herein by way of example with respect to several embodiments and illustrative drawings, those skilled in the art will recognize that the embodiments are not limited to the described embodiments or drawings. It should be understood that the drawings and detailed description thereof are not intended to limit the embodiments to the specific forms disclosed, but rather are intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope defined by the appended claims. The headings used herein are for organizational purposes only and are not intended to limit the scope of the specification or claims. As used throughout this application, the word “may” is used in a permissive sense (i.e., meaning “possibly”) rather than a mandatory sense (i.e., meaning “must”). Similarly, the word “include / including / includes” means including but not limited to. When used in the claims, the term “or” is used inclusively rather than exclusively. For example, the phrase “at least one of x, y, or z” means any one of x, y, and z, and any combination thereof. Detailed Implementation

[0024] This disclosure relates to methods and apparatus for performing readouts and resets (also referred to herein as “initialization” and / or “reinitialization”) of fluxion qubits. In the embodiments described herein, fluxion hardware components that can be used to implement fluxion qubits are coupled to quantum metamaterials using various quantum hardware configurations, enabling fast and high-fidelity execution of the readout and reset steps.

[0025] In noisy medium-sized quantum (NISQ) hardware environments, quantum error correction and / or mitigation techniques face the daunting task of developing methods to correct single-qubit and multi-qubit errors, logic errors, and / or additional issues such as coherence time and / or lifetime problems, crosstalk noise levels, etc., specific to a quantum processing unit (QPU). Further complexity can arise if a quantum readout device configured to perform readouts to obtain the quantum states of qubits in a given QPU at varying intervals during quantum computing cannot overcome Purcell decay, and / or cannot perform readouts fast enough to ensure that the time to perform the readout measurement is much shorter than the expected coherence time and / or lifetime of the qubits involved in a given quantum computing. There is also a risk of further error propagation when qubits are not properly reset to an arbitrary quantum state (e.g., the ground state) before the execution of a quantum gate.

[0026] Therefore, since customers utilizing such quantum computing resources may be concerned with the repeatability, reliability, and efficiency of quantum task execution, it is crucial to provide quantum readout devices that overcome the Purcell decay rate and ensure rapid and accurate delivery of readout results to classical measurement devices. Because current quantum error correction and / or mitigation techniques can only compensate for a limited number of errors in a given quantum task, ensuring that no additional changes and / or uncertainties propagate during the quantum readout process allows for greater bandwidth to correct errors occurring during the various quantum gates of a given quantum task, rather than during the readout step. Similarly, after performing such a readout step, successfully resetting the fluxion qubit ensures that the next stage of a given quantum computation (e.g., one or more additional quantum gates between fluxion qubits) can proceed without propagating errors from the previous stage. In some embodiments, the execution characteristics of a quantum hardware device capable of performing both readout and reset of fluxion qubits can be defined by fidelity and speed. This execution characteristic has previously been generally considered a trade-off. However, using the techniques and architectures described in this paper, by coupling fluxion qubits to quantum metamaterials, it is possible to provide customers who utilize this quantum computing resource with higher fidelity and faster readout and reset.

[0027] In some embodiments, fluxonic hardware components that can be used to implement fluxonic qubits can be dispersively coupled to a readout resonator to perform readout, which in turn is coupled to a quantum metamaterial. In other embodiments, fluxonic hardware components that can be used to implement fluxonic qubits can be directly coupled to a quantum metamaterial to perform readout and reset using resonant fluorescence. Depending on the design constraints of a given implementation of a quantum computer, any architecture can be selected and subsequently fabricated to ensure that fluxonic qubit-based quantum computing architectures have higher fidelity and faster readout and reset.

[0028] Furthermore, in connection with the description herein, it is understood that quantum hardware, such as quantum hardware devices, can be used to implement quantum computers and / or various components of quantum computers (e.g., quantum processing units / cores, routing spaces, magic distillation plants, other components for performing logical quantum computing, etc.). For example, a given quantum hardware device may resemble the “building blocks” of a quantum computer, such as a grid of qubits (e.g., a one-dimensional grid, a two-dimensional grid, etc.), which can be initialized in various ways to form various components of a quantum computer, such as topological quantum codes. The quantum hardware device can be further configured to enable the execution of single-qubit gates, multi-qubit gates, and / or other operations of quantum circuits between the qubits of the quantum hardware device (based on a physical qubit connectivity graph of the given quantum hardware device, which details which physical qubits are connected to corresponding other physical qubits via edges). The quantum hardware device may also include and / or be connected to various control devices (e.g., microwave pulse generators, devices for temperature, magnetism, and / or other environmental controls related to the local environment of the physical qubits, etc.), which can be used to maintain and / or transform various properties of the qubits and / or other physical components of the given quantum computer.

[0029] Furthermore, in relation to the description herein, a qubit can refer to both a logical bit (e.g., one or zero with a certain probability) and one or more physical components used to construct a given qubit, at least in part based on the type of qubit technology applied. For example, a fluxion qubit can be constructed using at least one superconducting and non-superconducting material, wherein the non-superconducting material is located between segments of the superconducting material (see also the description relating to fluxion hardware components herein). With this understanding, it should also be understood that quantum hardware can therefore be used to implement physical qubits in the manner described above, which can again be combined in various ways to implement one or more logical qubits, such that logical quantum operations can be performed using the physical elements of the quantum hardware. This document references at least... Figure 14 Further examples of the interaction between the hardware layout of quantum hardware devices and related classical measurement and control devices are discussed.

[0030] Figure 1 A hardware layout of a quantum hardware device according to some embodiments is shown, the quantum hardware device being configured to perform readout of the fluxion qubit by dispersively coupling hardware components implementing the fluxion qubit to a readout resonator, which in turn is coupled to a quantum metamaterial.

[0031] In some embodiments, a group of fluxtron hardware components can be arranged in parallel, such as Figure 1As shown, a fluxion qubit is implemented. For example, fluxion 102 includes an inductor, a capacitor, and a Josephson junction arranged in parallel with each other. In some embodiments, fluxions, such as fluxion 102, can be defined by three degrees of freedom in terms of circuit parameters: the energy associated with the capacitor ( ), and the energy associated with Josephson knots ( ) and the energy associated with an inductive shunt for a given flux. Furthermore, control over these circuit parameters allows for logical mapping of two given energy states in the energy state diagram. This logical mapping is implemented through the hardware configuration of fluxtron 102 and is defined as the corresponding fluxtron qubit, while also allowing tuning of the qubit's frequency and the expected lifetime of the qubit's energy. ) and the dephase time of a quantum bit ( Furthermore, according to some embodiments, they can be tuned independently of each other.

[0032] As this article is about Figure 3A and 3B As further explained in the fluxion energy state diagram 300, the computational basis states of a given fluxion qubit, implemented using the hardware components of the quantum hardware device 100, can be logically mapped as follows: and Furthermore, it can correspond to the ground state and the first excited state of the energy state diagram of the fluxion.

[0033] In some embodiments, a given configuration of the quantum hardware components (such as...) Figure 1 The given configuration shown can be used to achieve dispersive coupling between fluxtron 102, readout resonator 104, and quantum metamaterial 106. It is understood that, due to the hardwiring of capacitive coupling between the respective components, it can be assumed that dispersive coupling is "continuous" throughout the execution of the various quantum gates and the entire execution of readout, etc. (See also the individual steps in the execution of quantum circuit 200, as described herein regarding...) Figure 2 (As described elsewhere).

[0034] Therefore, in order to extract information about the quantum state of a fluxion qubit at different intervals during a given quantum computation (see also this article and...), Figure 2 As described in the example quantum circuit 200, the readout of a fluxonic qubit implemented using fluxonic hardware components of fluxonic qubit 102 can be performed by transmitting a control sequence, which causes a signal corresponding to information about the quantum state to be transmitted through readout resonator 104 and subsequently through quantum metamaterial 106, wherein the signal can then be read out by a classical measuring device. Figure 4A and 4BFurthermore, it is demonstrated that the readout resonator can be driven from its ground state to its excited state by transmitting a control sequence having a frequency corresponding to the resonant frequency of the readout resonator 104. According to some embodiments, this adds energy to... Figure 1 The system described in the hardware layout shown results in the energy decaying into the quantum metamaterial 106, thereby allowing information about the quantum state to be indirectly transmitted from the fluxion qubit and through to the quantum metamaterial 106. Furthermore, the dispersive coupling further defines a frequency offset that depends on the given quantum state of the fluxion qubit at the time of readout, thus allowing classical measurement devices to determine which of the two possible quantum states of the fluxion qubit has been transmitted during the execution of the readout.

[0035] In some embodiments, when coupled to the fluxtron 102 via the readout resonator 104, the quantum metamaterial 106 can act as a transmission line, allowing the signal to propagate rapidly through the corresponding resonator of the quantum metamaterial 106 and outward toward the classical measurement device. For example... Figure 1 As shown, the quantum metamaterial 106 includes at least harmonic oscillators 108, 110, 112, and 114. It is understood that other embodiments of the quantum metamaterial 106 may include... Figure 1 The number of resonators depicted in the text is fewer or more, and the number of resonators included within the quantum metamaterial 106, in addition to various other circuit parameters of the overall hardware configuration of the quantum hardware device 100, can at least partially determine the passband width of the quantum metamaterial 106. Furthermore, in Figure 1 In this embodiment, the readout resonator 104 is shown as being directly coupled to the resonator 108. However, in other embodiments, the readout resonator 104 may instead be directly coupled to the resonators 110, 112, or 114, etc.

[0036] Furthermore, quantum metamaterial 106 can also be referred to as a "bus" in this paper because the corresponding harmonic oscillators in harmonic oscillators 108, 110, 112, and 114 are configured (as shown in the image). Figure 1 In the configuration shown, they are capacitively coupled to each other. Further references used herein regarding quantum metamaterials having “unit cells” and / or “conical units” should also be understood as using harmonic oscillators (such as…) Figure 1 The unit cell implementing the resonance shown. In some embodiments, the tapered unit cell may be physically placed at the respective ends of a given resonator array within a quantum metamaterial. For example, refer to Figure 1 The resonators shown, resonators 108 and 114 within the quantum metamaterial 106, can be defined in some embodiments as a tapered unit cell, wherein the quantum metamaterial 106 comprises a total of four resonators. Furthermore, such a tapered unit cell can be configured to reduce the frequency at which external ports (e.g., such as...) are used within the passband of a given quantum metamaterial. Figure 1Impedance mismatch at the port marked "Output to Classical Measurement Device" (in the middle) (Continue to refer to...) Figure 1 The harmonic oscillators shown, the harmonic oscillators 110 and 112 within the quantum metamaterial 106, can therefore be defined as unit cells.

[0037] In some embodiments, the driver 116 may resemble a microwave pulse generator configured to emit microwave pulses having a frequency corresponding to the resonant frequency of the readout resonator 104. The driver 116 may be further configured to receive drive control instructions from a classical computing device (such as classical computing device 1500), wherein the drive control instructions may include information such as the duration of the pulse to be emitted, the frequency of the pulse to be emitted, and the timing of when the pulse is emitted in the overall execution of a given quantum computation.

[0038] In some embodiments, to perform the readout of a fluxion qubit implemented using fluxion 102, the following combination of values ​​for the circuit parameters of the quantum hardware device 100 can be used. The degrees of freedom of fluxion 102 can be configured such that... , and Then, the fluxtron 102 can be capacitively coupled to the readout resonator 104, where the capacitive coupling strength is... The readout resonator 104 can be configured such that the resonant frequency of the readout resonator 104 is... And make its impedance be Then, the readout resonator 104 can be capacitively coupled to the quantum metamaterial 106, where the capacitive coupling strength is... Then, quantum metamaterial 106 can be configured to have two pyramidal unit cells, six unit cells, and capacitive coupling strength. and impedance However, it should be understood that the above-described combination of parameters may represent a given embodiment of the quantum hardware device 100, and other embodiments of the quantum hardware device 100 configured to have different combinations of circuit parameter values ​​but still allow the components of the quantum hardware device 100 to be dispersion-coupled and to perform readouts are also intended to be included in the discussion herein.

[0039] In some embodiments, in order to configure the dispersive coupling between corresponding components of the quantum hardware device 100, such as Figure 1 As shown, fluxtron 102 can be capacitively coupled to readout resonator 104, and readout resonator 104 can be capacitively coupled to quantum metamaterial 106. However, in some embodiments, inductive coupling can be used to configure dispersive coupling between the respective components of the quantum hardware device 100.

[0040] Furthermore, it should be understood that in some embodiments, fluxion 102 may be connected to one or more other fluxion hardware components of a large-scale quantum hardware device implementing corresponding and additional fluxion qubits. For example, such as Figure 14 As shown, the fluxtron 102 can be implemented within the quantum processing core 1420, wherein the readout resonator 104, the quantum metamaterial 106, and the actuator 116 can then be implemented within the quantum readout device 1440, as... Figure 14 As shown in the figure below. Furthermore, it should be understood that grounding of one or more hardware components of the quantum hardware device 100 may also be necessary, and is meant to be covered in discussions of a given larger architectural design implementation including the quantum hardware device 100, as described with respect to the implementation of the quantum computer 1430.

[0041] In some embodiments, configuration (such as) Figure 1 The configuration shown for quantum hardware device 100 can also be used to perform a reset of the flux-particle qubit implemented using flux-particle 102. In some embodiments, such a reset can occur actively via a sideband between the flux-particle qubit and the readout resonator 104 (e.g., a sideband corresponding to a frequency that is not the resonant frequency of the readout resonator 104).

[0042] Figure 2 The steps applied according to some embodiments for executing a given quantum circuit between two fluxion qubits are illustrated, wherein the steps include at least a reset (e.g., initialization) step for the fluxion qubits, the execution of one or more quantum gates between the two fluxion qubits, and the execution of a readout step for the quantum superposition state of the two fluxion qubits.

[0043] As described above, the readout of a flux-qubit implemented using the flux-qubit hardware components described herein can be performed after one or more quantum gates have been executed on such a flux-qubit. In some embodiments, since logical quantum operations are performed on the flux-qubit during the duration of the gate, the execution of the quantum gate on the flux-qubit may affect the quantum state of the flux-qubit prior to the execution of the quantum gate, which is related to how the quantum state is initialized during reset. Therefore, in order to extract the quantum state of such a flux-qubit after the execution of the gate, the readout can be performed using a hardware layout (such as the hardware layout depicted in quantum hardware device 100) (other than the hardware layouts separately described below with respect to quantum hardware device 500 and quantum hardware device 700).

[0044] like Figure 2As shown, quantum circuit 200 involves two fluxion qubits, such as fluxion qubit 202 and fluxion qubit 204. The first time step of quantum circuit 200 can be similar to resets 206 and 208, where fluxion qubits 202 and 204 are initialized to some arbitrary quantum state, such as the ground state. In some embodiments, the ground state can be... Indicates, such as Figure 3A The fluxion energy state diagram 300 is also shown in the figure. Furthermore, resets 206 and 208 can occur simultaneously or sequentially, depending on the various embodiments of the quantum circuit execution instructions provided to the quantum hardware device and used to execute the quantum circuit 200.

[0045] After initialization of flux qubits 202 and 204, one or more quantum gates 210 can be executed using flux qubits 202 and 204. In some embodiments, one or more quantum gates 210 may include two-qubit quantum gates (e.g., CZ gates, CX gates, SWAP gates, etc.) executed using both flux qubits 202 and 204. In other embodiments, one or more quantum gates 210 may include two separate single-qubit gates (e.g., Pauli-X, -Y or -Z gates, Hadamard gates, phase gates, etc.) executed using flux qubits 202 and 204, respectively. In yet another embodiment, one or more quantum gates 210 may include a combination of single-qubit and / or multi-qubit quantum gates executed using flux qubits 202 and 204. Furthermore, the single and / or multi-qubit quantum gates executed during a frame represented by one or more quantum gates 210 are analogous to logical quantum operations that may affect the quantum states of flux qubits 202 and 204, and therefore, the next time step of quantum circuit 200 may involve the execution of readout.

[0046] like Figure 2 As shown, after executing one or more quantum gates 210, readout step 212 of fluxion qubit 202 and readout step 214 of fluxion qubit 204 can be performed. Readouts 212 and 214 can be performed using quantum hardware devices (such as quantum hardware device 100) and can be performed using control sequences (such as those described herein). Figure 4A and 4B The control sequence described elsewhere is executed. Furthermore, resets 206 and 208 can occur simultaneously or sequentially, depending on the various embodiments provided to the quantum hardware device for executing quantum circuit execution instructions of quantum circuit 200. In some embodiments, this readout step may resemble repeated parity measurements, or other quantum nondestructive (QND) measurements, which allow indirect readout of the quantum state without causing the state to collapse.

[0047] After the readouts of 212 and 214, fluxion qubits 202 and 204 can be reinitialized to their ground state during the next time step, as follows: Figure 2 Regarding resets 216 and 218, as described above, resets 216 and 218 can occur simultaneously or sequentially. Furthermore, as shown in the diagram with one or more additional quantum gates 220 and subsequent ellipses... Figure 2 As depicted, quantum circuit 200 may include two or more rounds of quantum gates executed using fluxions 202 and 204. In some embodiments, after a respective round of the quantum gate between fluxions 202 and 204, both readout and reset may be performed using the techniques described herein.

[0048] Furthermore, it is understandable. Figure 2 The given configuration of the quantum circuit 200 shown, which includes the execution of multiple sets of quantum gates between two fluxion qubits, is meant to be illustrative in nature. Further embodiments of quantum circuits involving one or more fluxion qubits are also intended to be covered in the discussion herein and can be similarly applied to methods for performing readout and reset using the quantum hardware device architecture described herein.

[0049] Figure 3A An energy state diagram of a given fluxion is shown according to some embodiments, wherein the computational basis states of the fluxion qubit have been logically mapped to the ground state and the first excited state of the fluxion.

[0050] like Figure 3A As shown, fluxtron hardware components (such as...) Figure 1 The hardware component shown in fluxion 102 can be configured to enable the energy states of fluxion energy state diagram 300. It is understood that, although... Figure 3A The ground state is shown in the figure. ), first excited state ( ), second excited state ( ), third excited state ( ) and the fourth excited state ( However, other high-energy states enabled by the configuration of fluxtron hardware components can also be covered in the discussion of fluxtron energy state diagram 300 in this paper.

[0051] like Figure 3A Furthermore, as shown, two energy states enabled by a given configuration of the fluxtron hardware components can be logically mapped to the computational basis states of the corresponding fluxtron qubits. For example, the computational basis states can be logically mapped to the ground state of the energy states in fluxtron energy state diagram 300 ( ) and the first excited state ( ).

[0052] Figure 3BDemonstrates the ability to drive according to some embodiments Figure 3A The fluxons shown in the figure are used to drive the various transition frequencies between the energy states of the fluxons.

[0053] As shown in the graph of fluxtron energy state transition frequencies 320, according to some embodiments, the frequencies that can be used to excite a particle (such as a photon) from one of the energy states depicted in the fluxtron energy state graph 300 to a given energy state can be related to... Figure 3B The frequencies shown in the diagram, increasing along the x-axis, correspond to these frequencies. These frequencies, which cause various excitations between energy states, can also be referred to as "transition frequencies" in this paper.

[0054] For example, the fluxion qubit frequency can refer to the frequency required to drive a photon from the ground state to the first excited state, or vice versa. The fluxion 2-3 state transition frequency can refer to the frequency required to drive a photon from the second excited state to the third excited state, or vice versa. The fluxion 1-2 state transition frequency can refer to the frequency required to drive a photon from the first excited state to the second excited state, or vice versa. The fluxion 3-4 state transition frequency can refer to the frequency required to drive a photon from the third excited state to the fourth excited state, or vice versa. The fluxion 0-3 state transition frequency can refer to the frequency required to drive a photon from the ground state to the third excited state, or vice versa. The fluxion 1-4 state transition frequency can refer to the frequency required to drive a photon from the first excited state to the fourth excited state, or vice versa. Using the methods and techniques described herein, such state transition frequencies can be used in a control sequence to perform readout and / or reset steps of the fluxion qubit.

[0055] Figure 4A and 4B Control sequences in the frequency and time domains, according to some embodiments, are shown respectively, and these control sequences are used for hardware layout (e.g., Figure 1 The hardware layout shown is used to perform the readout of fluxion qubits.

[0056] In some embodiments, a control sequence (such as control sequence 118) is configured to be emitted by driver 116 and cause a non-destructive measurement of the quantum state to be transmitted from the corresponding fluxion hardware component (e.g., fluxion 102), through readout resonator 104, and into quantum metamaterial 106 for readout, which may be similar to the description in frequency domain 400 and time domain 420.

[0057] As shown in frequency domain 400, the circuit parameters of the quantum hardware device 100 are configured such that the passband of the quantum metamaterial 106 includes a frequency range higher than both the fluxon qubit frequency and the fluxon 1-2 state transition frequency (see also the description herein relating to the fluxon energy state transition frequency 320). Furthermore, the circuit parameters of the quantum hardware device 100 are additionally configured such that the resonant frequency of the readout resonator 104 is within the frequency range defining the passband of the quantum metamaterial 106. Thus, when the transmission control sequence 118 is executed, the readout resonator 104 is driven at its resonant frequency, and since this resonant frequency is configured within the passband of the quantum metamaterial 106, information relating to the quantum state of the fluxon qubit implemented using fluxon 102 is dispersively transmitted through the readout resonator 104 and then through the quantum metamaterial 106 toward the classical measurement device.

[0058] Furthermore, since the fluxion qubit frequency is configured outside the passband of the quantum metamaterial, the energy remaining in the energy state corresponding to the computational basis state of the fluxion qubit cannot decay into the quantum metamaterial through the readout resonator, thus protecting the quantum state of the fluxion qubit even during readout execution. In some embodiments, the fluxion 1-2 state transition frequency can also be configured outside the passband of the quantum metamaterial, since this particular transition frequency can be used during the execution of some quantum gates (which sequentially precede and / or follow such readouts), and therefore should also be isolated from the passband so that the energy at this frequency does not decay into the quantum metamaterial.

[0059] In some embodiments, Figure 4A The passband width of the quantum metamaterial shown can be approximately 1-2 GHz, the frequency of the fluxion qubit can be approximately 254 MHz, the frequency of the fluxion 1-2 state transition can be approximately 7.13 GHz, and the resonant frequency of the readout resonator can be approximately 8.494 GHz.

[0060] As further described with respect to time domain 420, control sequence 118 may have a sequence determined by readout time. The defined duration. In some embodiments, the readout time. This can be used to define the amount of time during which the readout resonator 104 undergoes charge modulation at a drive frequency corresponding to the resonant frequency of the readout resonator 104. According to some embodiments, the readout time... It could be approximately 10 ns.

[0061] In some embodiments, the execution characteristics of the control sequence 118 can be determined by the qubit-readout dispersion coupling parameters. and readout bandwidth parameters To define. In order to use the subject Limiting the readout rate achieves critical coupling, which can be defined and The following relationships exist between them: .

[0062] In some embodiments, Figure 4A and 4B The illustrations depict an implementation of a control sequence that can be used to perform readout via dispersive coupling between the fluxtron hardware component and the readout resonator. This implementation of the control sequence can be further applied to perform readout via dispersive coupling between the fluxtron 502 and the readout resonator 504. Figure 5 As shown.

[0063] Figure 5 Another hardware layout of a quantum hardware device according to some embodiments is shown, the quantum hardware device being configured to perform readout of the fluxion qubit by dispersively coupling hardware components implementing the fluxion qubit to a readout resonator, which in turn is coupled to a Purcell filter, which in turn is coupled to a quantum metamaterial.

[0064] In some embodiments, the quantum hardware device 500 may be configured to use at least the concepts described herein. Figure 1-4B and Figure 6 The dispersive readout technique described above is used to perform the readout of flux-1 qubits implemented using flux-1502. For example... Figure 5 As shown, the fluxtron hardware components are configured in series (as depicted with respect to fluxtron 502) and can be coupled to readout resonator 504. Readout resonator 504 can then be coupled to Purcell filter 506, which in turn can be coupled to quantum metamaterial 508. A signal corresponding to the quantum state of the fluxtron qubit implemented using fluxtron 502 can be transmitted from fluxtron 502, through readout resonator 504, then through Purcell filter 506, and through resonators 510, 512, 514, and 516 of quantum metamaterial 508, where the signal can then be read out using classical measurement devices.

[0065] As mentioned above Figure 1-4B As described, a driver 518 can be used to transmit a control sequence 520, causing the readout resonator 504 to be driven at its resonant frequency, thereby allowing information related to the quantum state of the corresponding fluxion qubit to propagate through and reach the classical measurement device.

[0066] like Figure 5 The text further describes how the Purcell filter 506 can be coupled to the readout resonator 504 and the quantum metamaterial 508 to further protect the fluxtron qubits during readout. In use... Figure 1In a first example of the architecture shown, a readout resonator 104 can be placed between the fluxion 102 and the quantum metamaterial 106, such that when the control sequence 118 is emitted, the readout resonator 104 can act as a buffer between the fluxion 102 and the quantum metamaterial 106, which in turn acts as a transmission line during this readout. Providing isolation to the fluxion qubit allows readouts to be performed in such a way that the quantum state of the qubit does not collapse, which may also be referred to herein as QND measurement and / or any other method of performing readouts by indirectly extracting the quantum state from the fluxion qubit. References also include... Figure 4A Further evidence of protection provided by inserting a readout resonator 104 between the fluxion 102 and the quantum metamaterial 106 is described. As shown in frequency domain 400, the frequency of the fluxion qubit lies outside the passband of the quantum metamaterial, preventing the energy state of the fluxion qubit from decaying through the readout resonator 104 and entering the quantum metamaterial 106. Furthermore, since the resonant frequency of the readout resonator 104 is within the passband of the quantum metamaterial, when the readout resonator 104 is driven at its resonant frequency by the emission of the control sequence 118, the excited energy state of the readout resonator 104 then rapidly decays into the quantum metamaterial 106, thereby allowing readout to be performed.

[0067] In use Figure 5 In another example of the architecture shown, a readout resonator 504 and a Purcell filter 506 are placed between the fluxtron 502 and the quantum metamaterial 508 to further isolate and protect the quantum state of the fluxtron qubit. In some embodiments, the Purcell filter 506 can be configured to provide a buffer against radiation or "Purcell" decay. Furthermore, the Purcell filter 506 can also protect the fluxtron qubit from environmental noise, such as during readout.

[0068] In addition, as mentioned above... Figure 1 Furthermore, it should be understood that in some embodiments, fluxion 502 may be connected to one or more other sets of fluxion hardware components of a large-scale quantum hardware device implementing corresponding and additional fluxion qubits. For example, as... Figure 14 As shown, the fluxtron 502 can be implemented within the quantum processing core 1420, wherein the readout resonator 504, Purcell filter 506, quantum metamaterial 508, and actuator 518 can then be implemented within the quantum readout device 1440, as... Figure 14 As shown in the other example.

[0069] Figure 6 The process of using dispersive coupling to perform the readout of the quantum superposition state of a fluxion qubit according to some embodiments is illustrated.

[0070] In some embodiments, quantum hardware devices (such as quantum hardware devices 100 and 500) can be configured to induce dispersion coupling between a fluxonic hardware component implementing a fluxonic qubit and a readout resonator additionally coupled to a quantum metamaterial. This hardware configuration can then be used to read out the quantum state of the fluxonic qubit while the qubit remains protected from energy decay.

[0071] In block 600, fluxion qubits are used to execute quantum gates, wherein the quantum gates can be configured similarly to one or more quantum gates 210 in the overall execution of quantum circuit 200, as shown in Figure 2 Then, after the execution of the quantum gate, a readout can be performed to extract information about the quantum state of the fluxion qubit after performing logical quantum operations on the qubit during the gate, as shown in box 602.

[0072] In some embodiments, to perform the readout step, a control sequence having a frequency corresponding to the resonant frequency of the readout resonator is transmitted, as shown in box 604. By transmitting the control sequence, which drives the readout resonator at a frequency corresponding to its resonant frequency, information relating to the quantum state of the fluxtron qubit is transmitted from the fluxtron hardware component, through the readout resonator, and into the quantum metamaterial, whereby the information is then read out by a classical measurement device, as shown in box 606.

[0073] Figure 7 A hardware layout of a quantum hardware device according to some embodiments is shown, the quantum hardware device being configured to perform both fluorescence readout and fluorescence reset of the fluxion qubit by coupling hardware components implementing the fluxion qubit to a quantum metamaterial.

[0074] In some embodiments, the read and reset steps, such as Figure 2 The steps described in the text as reading out 212 and 214 and resetting 206, 208, 216 and 218 can be performed using resonant fluorescence from fluxonic qubits implemented using fluxonic hardware components to quantum metamaterials.

[0075] In some embodiments, a given configuration of the quantum hardware components (such as...) Figure 7 The given configuration shown can be used to achieve resonant fluorescence from fluxion 702 to quantum metamaterial 704. It is understood that, due to the hard wiring of capacitive coupling between the respective components, it can be assumed that the resonant fluorescence is "persistent" throughout the entire execution of the various quantum gates and the entire execution of readout and reset, etc. (See also the individual steps in the execution of quantum circuit 200, as described herein regarding...) Figure 2 (As described elsewhere).

[0076] In some embodiments, in order to extract information about the quantum state of a fluxion qubit at different intervals during a given quantum computation (see also this document and...), Figure 2 (As described in the example quantum circuit 200), the readout of a fluxonic qubit implemented using a fluxonic hardware component of fluxonic qubit 702 can be performed by transmitting a signal corresponding to information about the quantum state through a quantum metamaterial 704, wherein the signal can then be read out by a classical measuring device. (As described herein...) Figure 8A and 8B Additionally, it has been demonstrated that by emitting a frequency corresponding to the fluxtron 0-3 state transition frequency (see also the section above)... Figure 3B (As described in further detail) control sequences (such as control sequence 716) allow information about the quantum state of the corresponding fluxion qubit to be transmitted through the quantum metamaterial 704 without causing the superposition state of the fluxion qubit to collapse. Also, as described in this paper... Figure 8A and 8B As shown, the circuit parameters of the quantum hardware device 700 can be configured such that the frequency corresponding to the transition frequency of the fluxion 0-3 state is within the passband of the quantum metamaterial 704, thereby allowing the quantum state of the fluxion qubit to be read out without affecting the energy state of the computational basis state used for the logic mapping qubit.

[0077] Furthermore, another control sequence, which can also be incorporated into the discussion of control sequence 716 in this paper, can be emitted to return one or more energy states of the fluxion energy state diagram 300 with population particle decay (e.g., fluorescence) to the ground state, thus resetting the fluxion qubit to prepare for the next round of quantum gates. Examples of control sequences related to fluxion qubit reset are provided in this paper. Figure 9A-12B It will be shown separately in the middle.

[0078] In some embodiments, when directly coupled to the fluxtron 702, the quantum metamaterial 704 can act as a transmission line, allowing the signal to propagate rapidly through the corresponding resonator of the quantum metamaterial 704 and outward toward the classical measuring device. For example... Figure 7 As shown, the quantum metamaterial 704 includes at least harmonic oscillators 706, 708, 710, and 712. It is understood that other embodiments of the quantum metamaterial 704 may include... Figure 7 The number of harmonic oscillators depicted, whether fewer or more, and the number of harmonic oscillators included within the quantum metamaterial 704, in addition to various other circuit parameters of the overall hardware configuration of the quantum hardware device 700, can at least partially determine the passband width of the quantum metamaterial 704. Furthermore, in Figure 7 In this embodiment, fluxtron 702 is shown as being directly coupled to resonator 706. However, in other embodiments, fluxtron 702 may instead be directly coupled to resonators 706, 708, 710, or 712, etc.

[0079] In some embodiments, according to a given implementation of the control sequence 716 being emitted, the driver 714 may resemble a microwave pulse generator and / or be configured to emit or “irradiate” microwave pulses toward the fluxtron 702, and may perform readout or reset. The driver 714 may be further configured to receive drive control instructions from a classical computing device (such as classical computing device 1500), wherein the drive control instructions may include information such as the duration of the pulse to be emitted, the frequency of the pulse to be emitted, and the timing of when the pulse is emitted in the execution of a given quantum circuit 200.

[0080] Furthermore, it should be understood that, although Figure 7 An embodiment depicting a driver 714 coupled to a fluxtron 702 to perform readout and / or reset steps is described, but other embodiments of the quantum hardware device 700 (e.g., where the driver 714 is coupled to a quantum metamaterial 704) are intended to be incorporated into the discussion herein. These other embodiments can still be used to perform readout and reset steps using the resonant fluorescence of fluxtron qubits implemented using fluxtron hardware components within the quantum metamaterial. For example, in some embodiments where a control sequence 716 is used to perform readout and coupled to the fluxtron 702, the control sequence 716 can be used to “pump” energy into the system defined by the hardware components of the quantum hardware device 700 such that the energy corresponds to the fluxtron 0-3 state transition frequency, and the signal transmission depends on the given quantum state of the corresponding fluxtron qubit through the quantum metamaterial 704 and toward the classical measurement device. In another instance, in some embodiments where control sequence 716 is used to perform readout and couple to quantum metamaterial 704, control sequence 716 can be used to “pump” energy into a system defined by hardware components of quantum hardware device 700, such that a comparison of the energy input to the system using control sequence 716 with the energy of the signal read out by classical measurement devices provides information about a given quantum state of the corresponding fluxion qubit.

[0081] In some embodiments, in order to configure resonant fluorescence from a fluxion qubit implemented using fluxion 702 into a quantum metamaterial 704 using capacitive coupling, fluxion 702 can be capacitively coupled to the quantum metamaterial 704, such as... Figure 7 As shown. However, in some embodiments, inductive coupling can be used to configure this resonant fluorescence.

[0082] In addition, as mentioned above... Figure 1 and 5 Furthermore, it should be understood that in some embodiments, the fluxtron 702 may be connected to one or more other sets of fluxtron hardware components of a large-scale quantum hardware device implementing corresponding and additional fluxtron qubits. For example, as described above... Figure 14 As shown, the fluxtron 702 can be implemented within the quantum processing core 1420, wherein the quantum metamaterial 704 and the actuator 714 can then be implemented within the quantum readout device 1440, as... Figure 14 As shown in the figure below. Furthermore, it should be understood that grounding of one or more hardware components of the quantum hardware device 700 may also be necessary, and is meant to be covered in discussions of a given larger architectural design implementation including the quantum hardware device 700, as described with respect to the implementation of the quantum computer 1430.

[0083] Figure 8A and 8B Control sequences in the frequency and time domains, according to some embodiments, are shown respectively, and these control sequences are used for hardware layout (e.g., Figure 7 The hardware layout shown is used to perform the readout of fluxion qubits.

[0084] In some embodiments, a control sequence (such as control sequence 716) is configured to be emitted by driver 714 and cause a non-destructive measurement of the quantum state to be transmitted from the corresponding fluxion hardware component (e.g., fluxion 702) and into the quantum metamaterial 704 for readout, which may be similar to the description in frequency domain 800 and time domain 820.

[0085] As shown in frequency domain 800, the circuit parameters of the quantum hardware device 700 are configured such that the passband of the quantum metamaterial 704 includes a frequency range higher than both the fluxon qubit frequency and the fluxon 1-2 state transition frequency (see also the description relating to fluxon energy state transition frequency 320). Furthermore, the circuit parameters of the quantum hardware device 700 are additionally configured such that the fluxon 0-3 state transition frequency is within the frequency range defining the passband of the quantum metamaterial 704. Thus, when the control sequence 716 is transmitted, the population in the ground state is excited to the third excited state (see also the description relating to fluxon energy state diagram 300), and then decays back to the ground state, and then information relating to the quantum state of the fluxon qubit implemented using fluxon 702 is transmitted through the quantum metamaterial 704 toward the classical measurement device.

[0086] Furthermore, since the fluxion qubit frequency is configured outside the passband of the quantum metamaterial, the energy remaining in the energy state corresponding to the computational basis state of the fluxion qubit cannot decay into the quantum metamaterial, thus protecting the quantum state of the fluxion qubit even during readout execution. In some embodiments, the fluxion 1-2 state transition frequency can also be configured outside the passband of the quantum metamaterial, since this particular transition frequency can be used during the execution of some quantum gates and should therefore also be isolated from the passband so that the energy at this frequency does not decay into the quantum metamaterial.

[0087] As further described with respect to time domain 820, control sequence 716 may have a sequence determined by readout time. The defined duration. In some embodiments, the readout time. It can be used to define the amount of time during charge modulation and / or flux modulation of flux qubits at a driving frequency corresponding to the resonant frequency of the flux qubit 0-3 state transition frequency.

[0088] It is understandable that, based on a given moment during the overall execution of a quantum circuit (such as quantum circuit 200), the control sequence (such as...) Figure 7 The description of the control sequence 716 in the text can refer to a control sequence configured to read out the fluxion qubit or a control sequence configured to reset the fluxion qubit.

[0089] Figure 9A and 9B First control sequences in the frequency and time domains, according to some embodiments, are shown respectively. These first control sequences are used for hardware layout (e.g., Figure 7 The hardware layout shown is used to perform the reset of the fluxion qubits.

[0090] In some embodiments of the method for resetting flux quantum bits, such as Figure 9A-12B The frequency used for resetting in control sequence 716, as described, can refer to a continuous waveform (CW) pulse, a single-qubit pulse, or... Pulses and / or some combination of such pulses are used to induce fluorescence-based resets of fluxion qubits. Additionally, it can be understood that... Figure 9A-12B This can be similar to at least four implementation schemes that can be used to reset fluxion qubits. For example, in some embodiments, the control sequence (such as...) Figure 9A and 9B The depicted control sequence can be provided to the driver 714 as a drive control instruction to perform resets 206 and 208 in the overall execution of the quantum circuit 200, while the control sequence (such as...) Figure 10A and 10B The depicted control sequence can alternatively be provided to the driver 714 as drive control commands to perform resets 216 and 218, etc. Furthermore, in some embodiments, the control sequence (such as...) Figure 11A and 11B The described control sequence can be provided to the driver 714 as a drive control command to perform reset 206, while the control sequence (such as...) Figure 12A and 12B The described control sequence can be provided to the driver 714 as drive control instructions to sequentially execute reset 208, etc.

[0091] In some embodiments, a control sequence (such as control sequence 716) is configured to be emitted by driver 714 and cause the quantum state of the corresponding fluxion qubit to be reinitialized to the ground state of the fluxion, which may be similar to the description in frequency domain 900 and time domain 920.

[0092] As shown in frequency domain 900, the circuit parameters of the quantum hardware device 700 are configured such that the passband of the quantum metamaterial 704 includes a frequency range higher than both the fluxon qubit frequency and the fluxon 2-3 and 1-2 state transition frequencies (see also the description relating to fluxon energy state transition frequency 320). Furthermore, the circuit parameters of the quantum hardware device 700 are additionally configured such that the fluxon 0-3 state transition frequency is within the frequency range defining the passband of the quantum metamaterial 704. Thus, when the control sequence 716 is transmitted, the population of either or both of the first and second excitation states is excited to the third excitation state (see also the description relating to fluxon energy state diagram 300), then decays to the ground state, and is then transmitted through the quantum metamaterial 704 because the fluxon 0-3 state transition frequency is within the passband of the quantum metamaterial.

[0093] As further described with respect to time domain 920, control sequence 716 may have a reset time. Defined duration. In some embodiments, reset time. This can be used to define the amount of time during which charge modulation and / or flux modulation of fluxion qubits occurs at frequencies corresponding to both the fluxion 2-3 state transition frequency and the fluxion 1-2 state transition frequency. In some embodiments, this is defined by the reset time. The control sequence that simultaneously emits multiple frequencies within a defined duration can be further defined as a reset control sequence performed by “pumping” one or more population energy states (e.g., the first and / or second excitation energy states) to transition frequencies (e.g., fluxon 0-3 state transition frequencies) within the passband of the quantum metamaterial.

[0094] Figure 10A and 10B The second control sequence in the frequency domain and time domain, according to some embodiments, is shown respectively. The second control sequence is used for hardware layout (such as...) Figure 7 The hardware layout shown is used to perform the reset of the fluxion qubits.

[0095] In some embodiments, a control sequence (such as control sequence 716) is configured to be emitted by driver 714 and cause the quantum state of the corresponding fluxion qubit to be reset to the ground state of the fluxion, which may be similar to the description in frequency domain 1000 and time domain 1020.

[0096] As shown in frequency domain 1000, the circuit parameters of the quantum hardware device 700 are configured such that the passband of the quantum metamaterial 704 includes a frequency range higher than the fluxon qubit frequency and higher than the fluxon 2-3, 1-2, and 3-4 state transition frequencies (see also the description relating to fluxon energy state transition frequency 320). Furthermore, the circuit parameters of the quantum hardware device 700 are additionally configured such that the fluxon 0-3 state transition frequency is within the frequency range defining the passband of the quantum metamaterial 704. Thus, when the control sequence 716 is emitted, the population in any combination of the first, second, and fourth excitation energy states is excited to (or decays relative to the fourth excitation energy state to) the third excitation energy state (see also the description relating to fluxon energy state diagram 300), then decays to the ground state, and is then transmitted through the quantum metamaterial 704 because the fluxon 0-3 state transition frequency is within the passband of the quantum metamaterial.

[0097] As further described with respect to time domain 1020, control sequence 716 may have a reset time. Defined duration. In some embodiments, reset time. This can be used to define the amount of time during which charge modulation and / or flux modulation of fluxion qubits occurs at frequencies corresponding to the fluxion 2-3 state transition frequencies, fluxion 1-2 state transition frequencies, and fluxion 3-4 state transition frequencies. In some embodiments, this time is defined by the reset time. The control sequence that simultaneously emits multiple frequencies within a defined duration can be further defined as a reset control sequence performed by “pumping” one or more population energy states (e.g., first, second, and / or fourth excitation energy states) to transition frequencies (e.g., fluxon 0-3 state transition frequencies) within the passband of the quantum metamaterial.

[0098] Figure 11A and 11B Third control sequences in the frequency and time domains, according to some embodiments, are shown respectively, and these third control sequences are used for hardware layout (e.g., Figure 7 The hardware layout shown is used to perform the reset of the fluxion qubits.

[0099] In some embodiments, a control sequence (such as control sequence 716) is configured to be emitted by driver 714 and cause the quantum state of the corresponding fluxion qubit to be reset to the ground state of the fluxion, which may be similar to the description in frequency domain 1100 and time domain 1120.

[0100] As shown in frequency domain 1100, the circuit parameters of the quantum hardware device 700 are configured such that the passband of the quantum metamaterial 704 includes a frequency range higher than both the fluxon qubit frequency and the 3-4 state transition frequency (see also the description relating to the fluxon energy state transition frequency 320). Furthermore, the circuit parameters of the quantum hardware device 700 are configured such that the passband of the quantum metamaterial 704 includes a frequency range even lower than the fluxon 1-4 state transition frequency.

[0101] Furthermore, the circuit parameters of the quantum hardware device 700 are additionally configured such that the fluxon 0-3 state transition frequency is within the frequency range defining the passband of the quantum metamaterial 704. Thus, when the control sequence 716 is emitted, the population in any combination of the first, second, and fourth excitation energy states is excited to (or decays relative to the fourth excitation energy state to) the third excitation energy state (see also the description relating to the fluxon energy state diagram 300), then decays to the ground state, and is then transmitted through the quantum metamaterial 704 because the fluxon 0-3 state transition frequency is within the passband of the quantum metamaterial.

[0102] As further described with respect to time domain 1120, control sequence 716 may have a reset time. Defined duration. In some embodiments, reset time. This can be used to define the amount of time during which charge modulation and / or flux modulation of fluxion qubits occurs at frequencies corresponding to the fluxion 3-4 state transition frequencies and fluxion 1-4 state transition frequencies. In some embodiments, this is defined by the reset time. The control sequence that simultaneously emits multiple frequencies within a defined duration can be further defined as a reset control sequence performed by “pumping” one or more population energy states (e.g., first, second, and / or fourth excitation energy states) to transition frequencies (e.g., fluxon 0-3 state transition frequencies) within the passband of the quantum metamaterial.

[0103] Figure 12A and 12B The fourth control sequence in the frequency domain and time domain, according to some embodiments, is shown respectively. This fourth control sequence is used with hardware layout (e.g., Figure 7 The hardware layout shown is used to perform the reset of the fluxion qubits.

[0104] In some embodiments, a control sequence (such as control sequence 716) is configured to be emitted by driver 714 and cause the quantum state of the corresponding fluxion qubit to be reset to the ground state of the fluxion, which may be similar to the description in frequency domain 1200 and time domain 1220.

[0105] As shown in frequency domain 1200, the circuit parameters of the quantum hardware device 700 are configured such that the passband of the quantum metamaterial 704 includes a frequency range higher than the fluxon qubit frequency and higher than the fluxon 2-3, 1-2, and 3-4 state transition frequencies (see also the description herein relating to fluxon energy state transition frequency 320). Additionally, the circuit parameters of the quantum hardware device 700 are configured such that the passband of the quantum metamaterial 704 includes a frequency range lower than the fluxon 1-4 state transition frequencies.

[0106] Furthermore, the circuit parameters of the quantum hardware device 700 are additionally configured such that the fluxon 0-3 state transition frequency is within the frequency range defining the passband of the quantum metamaterial 704. Thus, when the control sequence 716 is emitted, the population in any combination of the first, second, and fourth excitation energy states is excited to (or decays relative to the fourth excitation energy state to) the third excitation energy state (see also the description relating to the fluxon energy state diagram 300), then decays to the ground state, and is then transmitted through the quantum metamaterial 704 because the fluxon 0-3 state transition frequency is within the passband of the quantum metamaterial.

[0107] As further described with respect to time domain 1220, control sequence 716 may have a reset time. Defined duration. In some embodiments, reset time. This can be used to define the amount of time during which charge modulation and / or flux modulation of fluxion qubits occurs at frequencies corresponding to the fluxion 2-3 state transition frequencies, fluxion 3-4 state transition frequencies, and fluxion 1-4 state transition frequencies. In some embodiments, this time is defined by the reset time. The control sequence that simultaneously emits multiple frequencies within a defined duration can be further defined as a reset control sequence performed by “pumping” one or more population energy states (e.g., first, second, and / or fourth excitation energy states) to transition frequencies (e.g., fluxon 0-3 state transition frequencies) within the passband of the quantum metamaterial.

[0108] In some embodiments, this document is provided to driver 714 and enabled. Figures 9A to 12BThe driving control instructions for any control sequence described herein for resetting flux qubits may additionally include instructions for phase adjustment to suppress possible dark state trapping. Since such a control sequence for resetting flux qubits emits pulses simultaneously at multiple frequencies, the possibility that any of the first, second, third, or fourth excited states may become insensitive to the transition frequencies of the population's energy state "pumped" into the quantum metamaterial passband may increase, causing the population in one of the excited states to remain in said excited state instead of decaying into the quantum metamaterial. Thus, the driving control instructions for performing flux qubit reset via the method described herein concerning resonant fluorescence may include phase adjustment of the pulses emitted during the resetting phase of control sequence 716. By including a phase shift towards the corresponding pulses emitted simultaneously, the possibility of dark state trapping is suppressed. Figure 9B , 10B Figures 11B and 12B illustrate examples of such phase adjustments 922, 1022, 1122, and 1222, respectively, where the vertical dashed lines indicate the corresponding times when the phase adjustment occurs. As shown, the corresponding phase adjustment can occur at some point after the start of control sequence 716 and before the end of control sequence 716.

[0109] Figure 13 The process of performing fluorescence readout and reset of fluxion qubits according to some embodiments is demonstrated.

[0110] In some embodiments, the hardware layout of the quantum hardware device (such as the hardware layout of quantum hardware device 700) can be configured to cause resonant fluorescence from a fluxion qubit implemented using fluxion hardware components to a quantum metamaterial. This hardware configuration can then be used to read out the quantum state of the fluxion qubit while the qubit remains protected from energy decay, and to reset the fluxion qubit.

[0111] In block 1300, fluxion qubits are used to execute quantum gates, wherein the quantum gates can be configured similarly to one or more quantum gates 210 in the overall execution of quantum circuit 200, as shown in Figure 2 Then, after the execution of the quantum gate, a readout can be performed to extract information about the quantum state of the fluxion qubit after performing logical quantum operations on the qubit during the gate, as shown in box 1302.

[0112] In some embodiments, to perform readout, a control sequence having a frequency corresponding to the fluxon 0-3 state transition frequency is emitted, as shown in box 1304. By emitting the control sequence, the system is driven at the frequency corresponding to the fluxon 0-3 state transition frequency, and information relating to the quantum state of the fluxon qubit is transferred from the fluxon hardware component to the quantum metamaterial, wherein the information is then read out by a classical measurement device, as shown in box 1306.

[0113] After readout, resonant fluorescence can be used to induce the fluxion qubits to be reinitialized to the ground state, as shown in boxes 1308 and 1310. According to some embodiments, another control sequence can be emitted to excite or decay one or more population energy states into a third excited energy state, where the energy then decays (or emits fluorescence) back to the ground state and enters the quantum metamaterial. This control sequence for resetting can be applied to resets 206, 208, 216, and 218 during the overall execution of quantum circuit 200.

[0114] Figure 14 This is a block diagram illustrating an example quantum hardware device according to some embodiments, which can be configured to perform quantum gates between flux-quantum qubits and to perform readout and reset steps between the execution of the quantum gates.

[0115] like Figure 14 As shown, quantum hardware device 1400 may include one or more central quantum processing units (QPUs) and / or quantum processing cores 1420 that jointly implement quantum computer 1430. Various configurations of physical qubits may be included in embodiments of quantum computer 1430, wherein a given subset of the total number of qubits may represent quantum processing core 1420, and another given subset of qubits may be used to implement magic factories, additional routing spaces, and / or additional quantum processing cores accessible via lattice operations, as shown in box 1410. Parts of quantum computing and / or operation may be performed in quantum processing core 1430, wherein computationally intensive logic computations may use the magic factories in box 1410 to generate magic states that can be used to store intermediate computations, such that they are stored in memory during such quantum computing. In some embodiments, during procedures such as lattice operations, a given magic factory in box 1410 may be merged with quantum processing core 1420 to allow information to be transferred between these components of the quantum computer.

[0116] As described herein, one or more fluxion qubits in an embodiment of quantum computer 1430 may be additionally coupled to a quantum readout device for measuring the quantum state after executing one or more quantum gates, such as the two-qubit entanglement gate described herein. A given quantum readout device may be locally connected to various qubits of quantum processing core 1420, as indicated by the interactive arrows in box 1440.

[0117] Depending on factors such as the type of qubit technology used (e.g., superconducting architecture), the type of gates performed between the qubits (e.g., entanglement gates, QND measurements), the quantum hardware device 1410 may also include various control devices (e.g., microwave pulse generators, lasers, other environmental controls related to temperature, magnetism, and / or the local environment of the qubit grid in an embodiment of the quantum computer 1430), which can be used to maintain and / or transform various characteristics of the qubits and / or other physical components of a given quantum computer, as shown by the local environmental control device in block 1440. For example, drivers such as driver 116, driver 518, driver 714 may be locally coupled to one or more quantum hardware components within the quantum processing core 1420, such that various control sequences emanating from driver 116, driver 518, or driver 714 can be used to perform readouts and / or reinitialize the various qubits of the quantum processing core 1420 to their respective ground states.

[0118] In some embodiments where the local environment control device 1440 includes a processor such as processor 1510, the local environment control device 1440 may be additionally configured to interact with other devices 1460 via network 1450. In some embodiments, other devices 1460 may include classical computing devices such as classical computing device 1500, which may be configured to interact with quantum hardware device 1400 locally or remotely.

[0119] Explanatory computer system Figure 15 This is a block diagram illustrating an example classical computing device that can be used in at least some of the embodiments.

[0120] Figure 15 A general-purpose classical computing device 1500 that can be used in any of the embodiments described herein is illustrated. In the illustrated embodiment, the classical computing device 1500 includes one or more processors 1510 coupled to system memory 1520 (which may include both non-volatile and volatile memory modules) via an input / output (I / O) interface 1530. The classical computing device 1500 further includes a network interface 1540 coupled to the I / O interface 1530.

[0121] In various embodiments, the classical computing device 1500 may be a single-processor system including one processor 1510, or a multiprocessor system including several processors 1510 (e.g., two, four, eight, or another suitable number). The processor 1510 may be any suitable processor capable of executing instructions. For example, in various embodiments, the processor 1510 may be a general-purpose or embedded processor implementing any of a variety of instruction set architectures (ISAs), such as x86, PowerPC, SPARC, or MIPS ISA or any other suitable ISA. In a multiprocessor system, each processor in the processor 1510 may typically, but not necessarily, implement the same ISA. In some embodiments, a graphics processing unit (GPU) may be used in place of a conventional processor or as a supplement to a conventional processor.

[0122] System memory 1520 can be configured to store instructions and data accessible by processor 1510. In at least some embodiments, system memory 1520 may include both volatile and non-volatile portions; in other embodiments, only volatile memory may be used. In various embodiments, the volatile portion of system memory 1520 may be implemented using any suitable memory technology, such as static random access memory (SRAM), synchronous dynamic RAM, or any other type of memory. For the non-volatile portion of the system memory (e.g., which may comprise one or more NVDIMMs), in some embodiments, flash-based memory devices, including NAND flash devices, may be used. In at least some embodiments, the non-volatile portion of the system memory may include a power source, such as a supercapacitor or other power storage device (e.g., a battery). In various embodiments, memristor-based resistive random access memory (ReRAM), 3D NAND technology, ferroelectric RAM, magnetoresistive RAM (MRAM), or any type of phase-change memory (PCM) may be used at least for the non-volatile portion of the system memory. In the illustrated embodiment, program instructions and data that implement one or more desired functions such as the methods, techniques, and data described above are shown as stored in system memory 1520 as code 1525 and data 1526.

[0123] In some embodiments, I / O interface 1530 may be configured to coordinate I / O traffic between processor 1510, system memory 1520, and any peripheral devices within the device, including network interface 1540 or other peripheral interfaces such as various types of persistent and / or volatile storage devices. In some embodiments, I / O interface 1530 may perform any necessary protocols, timing, or other data transformations to convert data signals from one component (e.g., system memory 1520) into a format suitable for use by another component (e.g., processor 1510). In some embodiments, I / O interface 1530 may include support for devices attached via various types of peripheral buses, such as the Peripheral Component Interconnect (PCI) bus standard or variants of the Universal Serial Bus (USB) standard. In some embodiments, the functionality of I / O interface 1530 may be divided into two or more separate components, such as a northbridge and a southbridge. Moreover, in some embodiments, some or all of the functionality of I / O interface 1530 (such as the interface to system memory 1520) may be directly incorporated into processor 1510.

[0124] For example, network interface 1540 can be configured to allow data to pass between classical computing device 1500 and other devices 1560 attached to one or more networks 1550 (such as...). Figures 1 to 14 (Exchange between other computer systems or devices shown). In various embodiments, network interface 1540 can support communication over any suitable wired or wireless general-purpose data network, such as an Ethernet network. Additionally, network interface 1540 can support communication over telecommunications / telephone networks, such as analog voice networks or digital fiber optic communication networks, over storage area networks (SANs), such as Fibre Channel, or over any other suitable type of network and / or protocol.

[0125] In some embodiments, system memory 1520 may represent an embodiment of a computer-accessible medium configured to store information for implementing... Figures 1 to 14The methods and apparatus discussed in the context of this document include at least a subset of program instructions and data. However, in other embodiments, program instructions and / or data may be received, transmitted, or stored on different types of computer-accessible media. Generally, computer-accessible media may include non-transitory storage media or memory media such as magnetic or optical media, for example, a disk or DVD / CD coupled to classical computing device 1500 via I / O interface 1530. Non-transitory computer-accessible storage media may also include any volatile or non-volatile media, such as RAM (e.g., SDRAM, DDR SDRAM, RDRAM, SRAM, etc.), ROM, etc., which may be included as system memory 1520 or another type of memory in some embodiments of classical computing device 1500. In some embodiments, multiple non-transitory computer-readable storage media may jointly store program instructions that, when executed on or across one or more processors, implement at least a subset of the methods and techniques described above. Computer-accessible media may further include transmission media or signals such as electrical signals, electromagnetic signals, or digital signals transmitted via communication media such as networks and / or wireless links, as may be implemented via network interface 1540. Can be used as Figure 15 The functions described in the various embodiments may be implemented using some or all of the classical computing devices, such as the classical computing devices shown herein; for example, software components running on various different devices and servers may cooperate to provide the functions. In some embodiments, in addition to or instead of implementing using a general-purpose computer system, storage devices, network devices, or dedicated computer systems may be used to implement portions of the described functions. As used herein, the term "classical computing device" refers to at least all of these types of devices, but is not limited to these types of devices.

[0126] The embodiments of this disclosure may be described in view of the following terms: Clause 1. A system comprising: Fluxon hardware components, the fluxon hardware components being configured to implement fluxon qubits; and A quantum readout device, the quantum hardware device being configured to perform the readout of the fluxtron qubit, wherein the quantum readout device comprises: A readout resonator is configured to dispersively couple to the fluxtron hardware component and the quantum metamaterial; The quantum metamaterial is coupled to an actuator and a classical measurement device and is configured to act as a bandpass filter; and The driver In order to perform the readout of the flux-quantum bit, the quantum readout device is configured to have a control sequence having the resonant frequency of the readout resonator emitted by the driver, wherein: The emission of the control sequence causes a signal transmission corresponding to the quantum information stored in the fluxion qubits to reach the classical measuring device via the quantum metamaterial; and The transmission rate of the signal is based at least in part on the strength of the dispersive coupling between the readout resonator and the fluxtron hardware component.

[0127] Clause 2. The system as described in Clause 1, wherein: The quantum metamaterial comprises multiple harmonic oscillators coupled in series with each other; and The passband of the quantum metamaterial includes the resonant frequencies of the plurality of harmonic oscillators.

[0128] Clause 3. The system described in Clause 2 further comprises: One or more classical computing devices, the one or more classical computing devices being configured to: The corresponding computational basis state logic of the fluxion qubit is mapped to the ground state and the first excited state of the energy state enabled by the configuration of the fluxion hardware component; Determine the resonant frequency of the readout resonator to be used in the transmission of the control sequence, such that: The resonant frequency is greater than the frequency corresponding to the transition frequency between the first and second excited states of the energy state enabled by the configuration of the fluxtron hardware component; and The resonant frequency is within the passband of the quantum metamaterial; and A drive control command to be used in the transmission of the control sequence is provided to the driver, wherein the drive control command includes an indication of the determined resonant frequency to be used.

[0129] Clause 4. The system according to any one of Clauses 1 to 3, wherein: The quantum readout device further includes a Purcell filter, which is coupled to both the readout resonator and the quantum metamaterial; and The Purcell filter is configured to suppress the rate of Purcell decay.

[0130] Clause 5. The system according to any one of Clauses 1 to 4, wherein: The fluxtron hardware component is capacitively coupled to the readout resonator; and The readout resonator capacitor is coupled to the quantum metamaterial, thereby achieving dispersive coupling.

[0131] Clause 6. The system according to any one of Clauses 1 to 4, wherein: The fluxtron hardware component is inductively coupled to the readout resonator; and The readout resonator is inductively coupled to the quantum metamaterial, thereby achieving dispersive coupling.

[0132] Clause 7. A system comprising: Fluxon hardware components, the fluxon hardware components being configured to implement fluxon qubits; and A quantum hardware device configured to perform the readout of the fluxtron qubit, wherein the quantum hardware device comprises: drive; and Quantum metamaterials, wherein the quantum metamaterials are configured as follows: Coupled to the fluxtron hardware component; and Acting as a bandpass filter, In order to perform the readout of the flux-tron qubit, the quantum hardware device is configured to emit a control sequence by the driver, the frequency of which corresponds to the transition frequency between the ground state and the third excited state of the energy state enabled by the configuration of the flux-tron hardware components, wherein: The emission of the control sequence induces a signal corresponding to the quantum information stored in the fluxion qubits, which is transmitted via resonant fluorescence through the quantum metamaterial to the classical measuring device; and The transmission rate of the signal is based, at least in part, on the intensity of the resonant fluorescence between the fluxion qubit implemented using the fluxion hardware component and the quantum metamaterial.

[0133] Clause 8. The system described in Clause 7, wherein: The quantum metamaterial comprises multiple harmonic oscillators coupled in series with each other; and The passband of the quantum metamaterial includes the resonant frequencies of the plurality of harmonic oscillators.

[0134] Clause 9. The system described in Clause 8 further comprises: One or more classical computing devices, the one or more classical computing devices being configured to: The corresponding computational basis state logic of the fluxion qubit is mapped to the ground state and the first excited state of the energy state enabled by the configuration of the fluxion hardware component; The frequency to be used in the emission of the control sequence is determined such that the transition frequency between the ground state and the third excited state of the energy state enabled by the configuration of the fluxtron hardware component is within the passband of the quantum metamaterial; and A drive control command to be used in the transmission of the control sequence is provided to the driver, wherein the drive control command includes an indication of the determined resonant frequency to be used.

[0135] Clause 10. The system as described in Clause 7, wherein: The quantum hardware device is further configured to reset the fluxion qubit to the ground state; and In order to reset the fluxion qubit, the quantum hardware device is configured to emit another control sequence containing multiple frequencies by the driver, wherein one or more of the multiple frequencies cause the population of the energy state enabled by the configuration of the fluxion hardware component to emit fluorescence to the ground state.

[0136] Clause 11. The system described in Clause 10 further comprises: One or more classical computing devices, the one or more classical computing devices being configured to: The corresponding computational basis state logic of the fluxtron qubit is mapped to the ground state and the first excited state of the energy state enabled by the configuration of the fluxtron hardware component; and A drive control command to be used in the transmission of the other control sequence is provided to the driver, wherein the drive control command includes an indication of the plurality of frequencies to be used.

[0137] Clause 12. The system according to Clause 10, wherein the plurality of frequencies of said other control sequence comprises: A first frequency, corresponding to the transition frequency between a first excited state and a second excited state of the energy state enabled by the configuration of the flux sub hardware component; and The second frequency corresponds to the transition frequency between the second excited state and the third excited state of the energy state enabled by the configuration of the fluxtron hardware component.

[0138] Clause 13. The system according to Clause 10, wherein the plurality of frequencies of said other control sequence comprises: A first frequency, which corresponds to the transition frequency between a first excited state and a second excited state of the energy state enabled by the configuration of the flux sub hardware component; A second frequency, corresponding to the transition frequency between the second excited state and the third excited state of the energy state enabled by the configuration of the flux sub hardware component; and The third frequency corresponds to the transition frequency between the third and fourth excited states of the energy state enabled by the configuration of the flux sub hardware component.

[0139] Clause 14. The system according to Clause 10, wherein the plurality of frequencies of said other control sequence comprises: A first frequency, corresponding to the transition frequency between the third and fourth excited states of the energy state enabled by the configuration of the flux sub hardware component; and The second frequency corresponds to the transition frequency between the first excited state and the fourth excited state of the energy state enabled by the configuration of the fluxtron hardware component.

[0140] Clause 15. The system according to Clause 10, wherein the plurality of frequencies of the other control sequence comprises: A first frequency, which corresponds to the transition frequency between the third and fourth excited states of the energy state enabled by the configuration of the flux sub hardware component; A second frequency, corresponding to the transition frequency between the second excited state and the third excited state of the energy state enabled by the configuration of the fluxtron hardware component; and The third frequency corresponds to the transition frequency between the first excited state and the fourth excited state of the energy state enabled by the configuration of the flux sub hardware component.

[0141] Clause 16. The method according to Clause 10, wherein the other control sequence further includes phase adjustment of the plurality of frequencies at a certain moment during the transmission of the other control sequence, wherein the phase adjustment causes dark state trapping to be suppressed.

[0142] Clause 17. A method comprising: A quantum gate is executed using flux-particle qubits, which are implemented using flux-particle hardware components, wherein the corresponding computational basis states of the flux-particle qubits are logically mapped to the ground state and the first excited state of the energy state enabled by the configuration of the flux-particle hardware components. Performing the readout of the flux subqubit, wherein performing the readout includes: The emission control sequence causes the signal corresponding to the quantum information stored in the flux qubits after the execution of the quantum gate to be transmitted through the quantum metamaterial; and The signal is provided to a classical measuring device.

[0143] Clause 18. The method described in accordance with Clause 17, wherein: The fluxtron hardware component is dispersively coupled to the quantum metamaterial via a readout resonator; and The transmission control sequence includes driving the readout resonator at a frequency corresponding to the resonant frequency of the readout resonator, wherein the resonant frequency is within the passband of the quantum metamaterial and causes the signal to be transmitted through the quantum metamaterial.

[0144] Clause 19. The method described in accordance with Clause 17, wherein: The fluxtron hardware component is coupled to the quantum metamaterial; and The transmission control sequence comprises driving the fluxtron hardware component at a frequency corresponding to the transition frequency between the ground state and the third excited state of the energy state enabled by the configuration of the fluxtron hardware component, wherein the transition frequency is within the passband of the quantum metamaterial, and causing the signal to be transmitted through the quantum metamaterial using resonant fluorescence.

[0145] Clause 20. The method described pursuant to Clause 19 further comprises: After the readout is performed, the flux quantum bit is reset to the ground state, wherein the reset includes: The emission comprises another control sequence of multiple frequencies, wherein one or more of the multiple frequencies cause the population of the energy state enabled by the configuration of the flux sub hardware component to emit fluorescence to the ground state.

[0146] in conclusion Various embodiments may further include receiving, transmitting, or storing instructions and / or data implemented as described above on a computer-accessible medium. Generally, a computer-accessible medium may include storage media or memory media (such as magnetic or optical media, e.g., magnetic disks or DVD / CD-ROMs), volatile or non-volatile media (such as RAM (e.g., SDRAM, DDR, RDRAM, SRAM, etc.), ROM, etc.), and transmission media or signals (such as electrical signals, electromagnetic signals, or digital signals) conveyed through communication media (such as networks and / or wireless links).

[0147] The various methods illustrated in the accompanying drawings and described herein represent exemplary embodiments of the methods. The methods can be implemented in software, hardware, or a combination thereof. The order of the methods can be changed, and various elements can be added, reordered, combined, omitted, modified, etc.

[0148] Various modifications and changes can be made, as will be apparent to those skilled in the art to which this disclosure pertains. It is intended to cover all such modifications and changes, and therefore the above description should be considered illustrative rather than restrictive.

Claims

1. A system comprising: Fluxon hardware components, the fluxon hardware components being configured to implement fluxon qubits; and A quantum hardware device configured to perform the readout of the fluxtron qubit, wherein the quantum hardware device comprises: drive; and Quantum metamaterials, wherein the quantum metamaterials are configured as follows: Coupled to the fluxtron hardware component; and Acting as a bandpass filter, in, In order to perform the readout of the flux-tron qubit, the quantum hardware device is configured to emit a control sequence by the driver, the frequency of which corresponds to the transition frequency between the ground state and the third excited state of the energy state enabled by the configuration of the flux-tron hardware components, wherein: The emission of the control sequence induces a signal corresponding to the quantum information stored in the fluxion qubits, which is transmitted via resonant fluorescence through the quantum metamaterial to the classical measuring device; and The transmission rate of the signal is based, at least in part, on the intensity of the resonant fluorescence between the fluxion qubit implemented using the fluxion hardware component and the quantum metamaterial.

2. The system according to claim 1, wherein: The quantum metamaterial comprises multiple harmonic oscillators coupled in series with each other; and The passband of the quantum metamaterial includes the resonant frequencies of the plurality of harmonic oscillators.

3. The system according to claim 1 or claim 2, wherein: The quantum readout device further includes a Purcell filter, which is coupled to both the readout resonator and the quantum metamaterial; and The Purcell filter is configured to suppress the rate of Purcell decay.

4. The system according to claim 2, further comprising: One or more classical computing devices, the one or more classical computing devices being configured to: The corresponding computational basis state logic of the fluxion qubit is mapped to the ground state and the first excited state of the energy state enabled by the configuration of the fluxion hardware component; The frequency to be used in the emission of the control sequence is determined such that the transition frequency between the ground state and the third excited state of the energy state enabled by the configuration of the fluxtron hardware component is within the passband of the quantum metamaterial; and A drive control command to be used in the transmission of the control sequence is provided to the driver, wherein the drive control command includes an indication of the determined resonant frequency to be used.

5. The system according to claim 1, wherein: The quantum hardware device is further configured to reset the fluxion qubit to the ground state; and In order to reset the fluxion qubit, the quantum hardware device is configured to emit another control sequence containing multiple frequencies by the driver, wherein one or more of the multiple frequencies cause the population of the energy state enabled by the configuration of the fluxion hardware component to emit fluorescence to the ground state.

6. The system of claim 5, further comprising: One or more classical computing devices, the one or more classical computing devices being configured to: The corresponding computational basis state logic of the fluxtron qubit is mapped to the ground state and the first excited state of the energy state enabled by the configuration of the fluxtron hardware component; and A drive control command to be used in the transmission of the other control sequence is provided to the driver, wherein the drive control command includes an indication of the plurality of frequencies to be used.

7. The system of claim 5 or claim 6, wherein the plurality of frequencies of the other control sequence comprises: A first frequency, corresponding to the transition frequency between a first excited state and a second excited state of the energy state enabled by the configuration of the flux sub hardware component; and The second frequency corresponds to the transition frequency between the second excited state and the third excited state of the energy state enabled by the configuration of the fluxtron hardware component.

8. The system of claim 5 or claim 6, wherein the plurality of frequencies of the other control sequence comprises: A first frequency, which corresponds to the transition frequency between a first excited state and a second excited state of the energy state enabled by the configuration of the flux sub hardware component; The second frequency corresponds to the transition frequency between the second excited state and the third excited state of the energy state enabled by the configuration of the flux sub hardware component; as well as The third frequency corresponds to the transition frequency between the third and fourth excited states of the energy state enabled by the configuration of the flux sub hardware component.

9. The system of claim 5 or claim 6, wherein the plurality of frequencies of the other control sequence comprises: A first frequency, corresponding to the transition frequency between the third and fourth excited states of the energy state enabled by the configuration of the flux sub hardware component; and The second frequency corresponds to the transition frequency between the first excited state and the fourth excited state of the energy state enabled by the configuration of the fluxtron hardware component.

10. The system of claim 5 or claim 6, wherein the plurality of frequencies of the other control sequence comprises: A first frequency, which corresponds to the transition frequency between the third and fourth excited states of the energy state enabled by the configuration of the flux sub hardware component; A second frequency, corresponding to the transition frequency between the second excited state and the third excited state of the energy state enabled by the configuration of the fluxtron hardware component; and The third frequency corresponds to the transition frequency between the first excited state and the fourth excited state of the energy state enabled by the configuration of the flux sub hardware component.

11. The method of claim 5 or claim 6, wherein the other control sequence further includes phase adjustment of the plurality of frequencies at a certain moment during the transmission of the other control sequence, wherein the phase adjustment causes dark-state trapping to be suppressed.

12. A method comprising: A quantum gate is executed using flux-particle qubits, which are implemented using flux-particle hardware components, wherein the corresponding computational basis states of the flux-particle qubits are logically mapped to the ground state and the first excited state of the energy state enabled by the configuration of the flux-particle hardware components. Performing the readout of the flux subqubit, wherein performing the readout includes: The emission control sequence causes the signal corresponding to the quantum information stored in the flux qubits after the execution of the quantum gate to be transmitted through the quantum metamaterial; and The signal is provided to a classical measuring device.

13. The method of claim 12, wherein: The fluxtron hardware component is dispersively coupled to the quantum metamaterial via a readout resonator; and The transmission control sequence includes driving the readout resonator at a frequency corresponding to the resonant frequency of the readout resonator, wherein the resonant frequency is within the passband of the quantum metamaterial and causes the signal to be transmitted through the quantum metamaterial.

14. The method of claim 12, wherein: The fluxtron hardware component is coupled to the quantum metamaterial; and The transmission control sequence comprises driving the fluxtron hardware component at a frequency corresponding to the transition frequency between the ground state and the third excited state of the energy state enabled by the configuration of the fluxtron hardware component, wherein the transition frequency is within the passband of the quantum metamaterial, and causing the signal to be transmitted through the quantum metamaterial using resonant fluorescence.

15. The method of claim 14, further comprising: After the readout is performed, the flux quantum bit is reset to the ground state, wherein the reset includes: The emission comprises another control sequence of multiple frequencies, wherein one or more of the multiple frequencies cause the population of the energy state enabled by the configuration of the flux sub hardware component to emit fluorescence to the ground state.

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