Parallelized Low-Noise Amplifier Circuit for Scalable Qubit Readout
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Solution Overview
Problem
Current low noise amplifier (LNA) designs for quantum computers are inefficient in terms of area and power usage, especially as the number of qubits increases, leading to scalability issues and increased heat generation in the cryostat.
Innovation Solution
A low noise amplifier circuit with a plurality of input stages and a shared output stage, where a voltage controller selectively activates only the input stage being read, reducing unnecessary power consumption and area usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional amplifier circuits are used for each qubit, then each qubit can be read independently, but the total area and power usage increase significantly with the number of qubits
Solution Approach 1:
Multiple input stages corresponding to different qubits are merged and share a common output stage. This allows multiple qubit readout paths to be combined into a single amplifier output, significantly reducing the total area required compared to having separate amplifiers for each qubit.
Solution Approach 2:
The amplifier circuit is segmented into multiple independently controllable input stages, where each input stage can be selectively activated. This segmentation allows the system to activate only the necessary input stages for current readout operations, reducing power consumption and effective area usage.
2Reliability
If conventional amplifier circuits are used for each qubit, then each qubit can be read independently, but power consumption increases significantly with the number of qubits
Solution Approach 1:
The amplifier circuit implements dynamic control by selectively activating only the input stages that are currently needed for readout operations. The voltage controller dynamically switches between different input stages based on which qubits are being read, preventing continuous power consumption of all amplifier stages.
Solution Approach 2:
Multiple input stages share a common output stage and control infrastructure, reducing the total power consumption compared to having completely separate amplifier circuits for each qubit. The shared components consume power only when actively used.
3Productivity
If all amplifier stages are always active, then all qubits can be read simultaneously, but unnecessary power is consumed by inactive stages
Solution Approach 1:
The voltage controller implements periodic activation of different input stages based on readout requirements. Instead of continuous activation, input stages are activated in a periodic or on-demand manner corresponding to which qubits need reading at any given time, reducing overall power consumption while maintaining readout capability.
4Ease of operation
If the voltage controller is placed outside the cryostat, then control is easier, but the distance to input stages increases causing higher latency and more heat transfer
Solution Approach 1:
The voltage controller is nested within the cryostat environment, placing it in close proximity to the input stages and qubits. This nested arrangement minimizes the physical distance for signal transmission, reducing latency and minimizing heat transfer through long cables, while still allowing for controlled operation.
Data Source
AI summary
Provided is a low noise amplifier circuit for a quantum computer. The low noise amplifier circuit comprises a plurality of input stages, a shared output stage, and a voltage controller. Each input stage is coupled to one or more qubits. The shared output stage is coupled to the plurality of input stages. The voltage controller is coupled to the plurality of input stages and the shared output stage. The voltage controller is configured to selectively activate an input stage of the plurality of input stages in order to read a qubit coupled to the input stage.