Multiplexed Qubit Gate Bias Circuit for Scalable Cryogenic Control
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Solution Overview
Problem
Current approaches for controlling qubit devices in quantum computing face challenges due to the need for numerous control signals and cables from room temperature to the operating temperature of the quantum chip, leading to scalability issues, high thermal load, and power consumption, especially when using DACs that lack comprehensive closed-loop control and feedback circuits.
Innovation Solution
A semiconductor device circuit with a multiplexed array of capacitor cells, where each capacitor cell is transistor-controlled, connected between the transistor drain and ground, with a common source connection and individually voltage-controllable gates, along with a charging and discharging unit connected to a common control point, allowing for alternative activation and efficient generation of quasi-constant voltage or current levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If numerous control signals and cables are used to control qubit devices from room temperature, then comprehensive control capability is achieved, but scalability is limited and thermal load increases
Solution Approach 1:
The patent merges multiple control functions into a single integrated circuit located on the quantum chip. Instead of using numerous separate cables and control signals from room temperature, the invention integrates capacitor cells and control logic directly on the chip, allowing multiple qubit gates to be controlled through a unified structure with shared control mechanisms.
Solution Approach 2:
The invention moves the control functionality from the external dimension (cables and circuits at room temperature) to the internal dimension (integrated circuits on the quantum chip). By embedding capacitor cells and control logic within the chip structure, the system eliminates the need for extensive external cabling while maintaining comprehensive control capability.
2Ease of operation
If DACs are used for control, then signal generation capability is provided, but closed-loop control and feedback circuits are lacking
Solution Approach 1:
The patent incorporates feedback mechanisms within the integrated control circuit on the quantum chip. The capacitor cells can be selectively activated and deactivated based on operational requirements, and the circuit structure enables monitoring and adjustment of control signals, providing closed-loop control capability that was missing in simple DAC-based approaches.
3Measurement precision
If multiple capacitor cells are controlled independently, then individual gate control precision is achieved, but the number of required control lines increases
Solution Approach 1:
The patent creates a universal control structure where a single integrated circuit can control multiple qubit gates through shared control lines. The capacitor cells are designed to be selectively activated, allowing the same control infrastructure to serve multiple functions and multiple gates, thereby maintaining individual gate control precision while reducing the total number of required control lines.
4Device complexity
If standard control approaches are used, then simplicity is maintained, but energy consumption and form factor are unfavorable
Solution Approach 1:
The patent segments the control function into discrete capacitor cells that can be independently activated. This segmentation allows the system to activate only the necessary control elements for each operation, reducing overall energy consumption compared to continuously active standard control circuits, while maintaining a relatively simple integrated structure.
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 solution reduces the number of required input signals and cables, enables better scalability and cost reductions, and improves the form factor by allowing hundreds or thousands of gates to be controlled with a single circuit, while being more energy-efficient and compact compared to standard approaches.
Implementation Method 1
each capacitor cell may include a transistor-controlled capacitor
Implementation Method 2
each capacitor cell may include a transistor-controlled capacitor, each source of all transistors of all capacitor cells may be connected to a common control point
Data Source
AI summary
Embodiments including a semiconductor device circuit for biasing gates of a qubit device as well as a method for operating the device are disclosed. The embodiments may include a multiplexed array of capacitor cells, where each capacitor cell includes a transistor-controlled capacitor, where each capacitor is connected between a drain of a respective transistor and ground, where each source of all transistors of all capacitor cells are connected to a common control point, and where each gate of the transistors of the capacitor cells are individually voltage controllable. The embodiment may include a charging unit connected to the common control point, and a discharging unit connected to the common control point, where the charging unit and the discharging unit are alternatively activatable.