Flip-Chip Resonator Layout for Low-Footprint Quantum Coupling
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Solution Overview
Problem
Existing quantum computing devices face limitations in qubit density and coupling due to the architecture, which restricts the ability to perform complex operations requiring large numbers of qubits, and distributed element resonators like co-planar waveguides have large footprints, making it difficult to reduce size while maintaining resonant frequency and minimizing losses.
Innovation Solution
The use of 3D integration in flip-chip geometries for quantum information processing devices, where circuit elements are formed across multiple substrates and connected using superconducting bump bonds, allowing for a more compact design with reduced losses and maintaining resonant frequency, and employing multiple bump bonds for redundancy and impedance control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If distributed element resonators like co-planar waveguides are used, then resonant frequency can be maintained, but the footprint area becomes large
Solution Approach 1:
The patent transitions from planar 2D resonator designs to 3D vertical stacking architecture. Multiple resonators are positioned on different substrates (first substrate, second substrate, interposer) and connected through vertical bump bonds, effectively utilizing the third dimension (Z-axis) to reduce the horizontal footprint area while maintaining resonant frequency characteristics through controlled electrical connections.
Solution Approach 2:
The resonator system is segmented into multiple independent resonators positioned on separate substrates. Each resonator can be independently designed and optimized, and the overall system achieves the desired functionality through the collective behavior of these segmented components connected via bump bonds, thereby reducing the footprint of any single resonator.
2Quantity of substance
If qubit density is increased, then more complex quantum operations can be performed, but coupling losses increase
Solution Approach 1:
The patent introduces bump bonds as intermediary connection elements between resonators and qubits. These superconducting bump bonds serve as low-loss transmission pathways that enable coupling between densely packed qubits while minimizing energy loss. The intermediary structure provides controlled impedance matching and reduces direct capacitive coupling losses that would occur with closer spacing.
3Area of stationary object
If flip-chip geometry is used, then footprint area is reduced, but manufacturing complexity increases
Solution Approach 1:
The device is segmented into three separate fabricable substrates (first substrate, second substrate, interposer) that can be manufactured independently using standard semiconductor fabrication processes. This segmentation allows each layer to be optimized and fabricated separately, then assembled through flip-chip bonding, reducing the overall footprint while managing manufacturing complexity through modular assembly.
Solution Approach 2:
The patent employs a nested hierarchical structure where resonators on the first and second substrates are positioned above and below the interposer layer. The bump bonds penetrate through the interposer substrate, creating a nested vertical arrangement that maximizes space utilization and reduces horizontal footprint while maintaining manufacturability through standardized through-substrate via techniques.
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 approach increases qubit density, reduces decoherence, and allows for a higher number of qubits while maintaining low losses and proper resonant frequency, enabling more complex quantum operations.
Implementation Method 1
connected using indium bump bonds
Implementation Method 2
electrically connected to one another with superconducting bump bonds
Implementation Method 3
maintaining resonant frequency
Implementation Method 4
distributed element resonators like co-planar waveguides
Implementation Method 5
distributed element resonators like co-planar waveguides
Implementation Method 6
reduces decoherence
Implementation Method 7
in the presence of galvanic, capacitive, and inductive coupling between the chips
Implementation Method 8
in the presence of galvanic, capacitive, and inductive coupling between the chips
Implementation Method 9
in the presence of galvanic, capacitive, and inductive coupling between the chips
Data Source
Figure 1
Figure 2A~2C
Figure 2D
AI summary
A device includes a first substrate having a principal surface; a second substrate having a principal surface, in which the first substrate is bump-bonded to the second substrate such that the principal surface of the first substrate faces the principal surface of the second substrate; a circuit element having a microwave frequency resonance mode, in which a first portion of the circuit element is arranged on the principal surface of the first substrate and a second portion of the circuit element is arranged on the principal surface of the second substrate; and a first bump bond connected to the first portion of the circuit element and to the second portion of the circuit element, in which the first superconductor bump bond provides an electrical connection between the first portion and the second portion.