Symmetrical Qubits with Alternating Capacitor Pads
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Solution Overview
Problem
Conventional quantum computing qubits face challenges with radiation losses and crosstalk due to capacitance-related issues, which affect circuit size and efficiency, and there is a need to reduce far-field radiation emitted by individual qubits to improve multi-qubit circuit performance.
Innovation Solution
A qubit device design featuring alternating superconducting capacitor pads with opposite polarities, connected by connectors with an oxide barrier forming a Josephson junction, and additional coupling pads to reduce radiation and qubit-to-qubit coupling, along with a method for fabricating these components to enhance mechanical stability and coherence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional transmon qubit design with large capacitance is used, then charge insensitivity is achieved, but far-field radiation and crosstalk increase
Solution Approach 1:
The patent employs asymmetric placement of Josephson junctions and capacitor pads, where Josephson junctions are positioned at opposite ends of the qubit structure while capacitor pads are located at intermediate positions. This asymmetric configuration creates an electric dipole moment that cancels far-field radiation while maintaining the charge insensitivity required for transmon qubit operation.
Solution Approach 2:
The patent introduces a vertical dimension by placing Josephson junctions and capacitor pads at different heights and positions along the qubit structure. This three-dimensional arrangement allows the system to maintain the capacitance values needed for charge insensitivity while geometrically canceling far-field radiation through dipole moment cancellation.
2Reliability
If capacitance values are increased to improve charge insensitivity, then qubit stability improves, but radiation losses increase
Solution Approach 1:
By asymmetrically positioning Josephson junctions at opposite ends and capacitor pads at intermediate locations, the patent creates a dipole configuration that maintains large capacitance values for charge insensitivity while the asymmetric geometry causes far-field radiation to cancel out, thus reducing radiation losses.
Solution Approach 2:
The patent converts the potentially harmful effect of large capacitance (which causes radiation) into a beneficial configuration by strategically positioning components to create dipole moment cancellation. The same large capacitance values that provide charge insensitivity are arranged to geometrically cancel radiation, turning a harmful effect into a beneficial one.
3Object-generated harmful factors
If qubit components are arranged to reduce crosstalk, then interference between qubits decreases, but device complexity increases
Solution Approach 1:
The asymmetric placement of Josephson junctions and capacitor pads creates a dipole moment that reduces crosstalk between adjacent qubits. This simple geometric arrangement achieves crosstalk reduction without requiring complex shielding structures or additional components, thus minimizing the increase in device complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design reduces far-field radiation and qubit device size, improves structural integrity, and increases coherence, allowing for more compact and efficient multi-qubit circuits with reduced energy loss.
Implementation Method 1
an oxide barrier formed onto a least a portion of a surface of the first set of connectors, and wherein at least a portion of the second set of connectors is formed onto a surface of the oxide barrier that is opposite the first set of connectors, thereby defining a Josephson junction between the first set of connectors and the second set of connectors
Data Source
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AI summary
Symmetrical qubits with reduced far-field radiation are provided. In one example, a qubit device (100) includes a first group (110) of superconducting capacitor pads positioned about a defined location of the qubit device, wherein the first group of superconducting capacitor pads comprise two or more superconducting capacitor pads having a first polarity, and a second group (112) of superconducting capacitor pads positioned about the defined location of the qubit device in an alternating arrangement with the first group of superconducting capacitor pads, wherein the second group of superconducting capacitor pads comprise two or more superconducting capacitor pads having a second polarity that is opposite the first polarity.