Cap Wafer Quantum Circuits for Microwave Noise Shielding
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Solution Overview
Problem
Existing quantum computing systems face challenges in constructing and packaging microwave integrated quantum circuits due to noise and coherence issues in superconducting qubits.
Innovation Solution
The use of cap wafers and thru vias in microwave integrated quantum circuits helps to isolate and shield quantum circuit devices from noise, improving coherence times by reducing participation ratios and suppressing electromagnetic wave propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If superconducting qubits are used to execute quantum algorithms, then quantum computational tasks can be performed, but noise and coherence issues arise that degrade performance
Solution Approach 1:
A cap wafer is introduced as an intermediary component between the quantum circuit devices and the external environment. The cap wafer includes a ground plane that acts as a shield, blocking external noise from reaching the superconducting qubits while maintaining their quantum coherence for algorithm execution
Solution Approach 2:
The patent applies different structural qualities to different regions: the cap wafer provides localized electromagnetic shielding directly over the quantum circuit devices, while the substrate wafer provides mechanical support and electrical connectivity. This localized approach targets noise reduction specifically at the quantum devices without compromising overall system functionality
2Duration of action of moving object
If quantum circuit devices are exposed to electromagnetic waves, then circuit operation is simplified, but coherence times are reduced due to increased participation ratios
Solution Approach 1:
The cap wafer's ground plane serves as an intermediary that blocks electromagnetic waves from directly interacting with the quantum circuit devices. This reduces the participation ratio of lossy substrates in the electromagnetic modes, thereby extending coherence times while still allowing controlled electromagnetic interaction for operation
Solution Approach 2:
The patent modifies the electromagnetic environment parameters by introducing the cap wafer structure, which changes the boundary conditions and mode structure of the electromagnetic fields. This parameter change reduces the coupling between lossy substrate modes and the quantum circuits, extending coherence without preventing necessary electromagnetic interaction
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
This configuration enhances the coherence times of quantum circuit devices, improves noise isolation, and reduces crosstalk, leading to more robust and efficient quantum computing operations.
Implementation Method 1
The use of cap wafers and thru vias in microwave integrated quantum circuits helps to isolate and shield quantum circuit devices from noise, improving coherence times by reducing participation ratios and suppressing electromagnetic wave propagation
Data Source
AI summary
In a general aspect, an integrated quantum circuit includes a first substrate and a second substrate. The first substrate includes a first surface and a recess formed in the first substrate along the first surface. The recess has a recess surface and is configured to enclose a quantum circuit element. The first substrate includes a first electrically-conductive layer disposed on the first surface and covering at least a portion of the recess surface. The first electrically-conductive layer includes a first superconducting material. The second substrate includes a second surface and a quantum circuit element. The second substrate includes a second electrically-conductive layer on the second surface that includes a second superconducting material. The first substrate is adjacent the second substrate to enclose the quantum circuit device within the recess. The first electrically-conductive layer of the first substrate is electrically-coupled to the second electrically-coupled layer of the second substrate.