Multi-Pole Purcell Filter for Faster Qubit Readout
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Solution Overview
Problem
Existing quantum computing architectures face challenges in accurately and quickly reading out information from qubits due to limited rejection levels and design flexibility of Purcell filters, which can result in longer readout times and impact the quality of signal readout.
Innovation Solution
A multi-pole Purcell filter with a singly-terminated arrangement is employed, allowing for sharper filter responses and enhanced out-of-band rejection, which is adaptable to different quantum computing approaches by varying the number of poles and configuration, such as 2, 3, or 4 poles, to accommodate multiple readout resonators and improve signal readout efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If single-pole based pass band filters are employed, then the device complexity is reduced, but the rejection level and design flexibility are limited
Solution Approach 1:
The filter is divided into multiple poles (2, 3, or 4 poles) instead of using a single pole, with each pole contributing to the overall frequency selectivity. This segmentation allows achieving higher rejection levels through cascaded filtering stages while maintaining modular design flexibility
Solution Approach 2:
The filter employs composite reactive elements combining inductors, capacitors, and transmission line elements to create multi-pole configurations. This composite approach enables tailored frequency responses with enhanced out-of-band rejection while adapting to different quantum processor implementations
2Reliability
If multi-pole filters are employed, then the rejection level and filter response sharpness are improved, but the device size increases
Solution Approach 1:
Different sections of the filter (individual poles) are designed with locally optimized characteristics, allowing each pole to contribute efficiently to the overall rejection performance. This enables achieving high out-of-band rejection without proportionally increasing the total filter area
Solution Approach 2:
The filter design transitions from a single-plane layout to a multi-dimensional configuration by stacking or arranging multiple poles in different spatial dimensions. This allows compact integration of multi-pole structures that provide sharp filter responses and enhanced rejection within a reduced footprint
3Measurement precision
If multi-pole filters are employed, then the signal readout accuracy is improved, but the readout time increases
Solution Approach 1:
The filter is designed with pre-optimized pole configurations and reactive element values that are predetermined for specific quantum processor types. This preliminary design optimization ensures that the filter provides accurate signal readout with minimized group delay, preventing excessive readout time while maintaining high measurement precision
Data Source
AI summary
The technology relates to quantum computing devices and test arrangements for detecting information from the qubits of such devices. According to aspects of the technology, a Purcell filter is structured in a multi-pole architecture to provide a sharper filter response having a flatter signal pass band, sharper turn-off skirt, and enhanced out of band rejection. The system is able to determine the states of the qubits by detecting the frequency of the readout resonators of the test arrangement. The Purcell filter is configured to be sharply tuned to enable faster readout to avoid issues associated with a longer relaxation time (T1) of the qubits.