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Nonergodic Measurements of Qubit Frequency Noise
Filip Wudarski1, Yaxing Zhang2, M I Dykman3
1USRA Research Institute for Advanced Computer Science (RIACS), Mountain View, California 94043, USA.
Physical Review Letters
|December 22, 2023
Summary
Slow qubit frequency fluctuations, a major quantum computing challenge, can be characterized by analyzing Ramsey measurement sequences. This method reveals noise properties before the system reaches its ergodic limit, aiding quantum computer stability.
Area of Science:
- Quantum computing
- Quantum information science
- Solid-state physics
Background:
- Slow frequency fluctuations in qubits are a significant obstacle for stable quantum computation.
- Traditional spectral analysis is insufficient for fully understanding the origin of these qubit frequency drifts.
- Characterizing noise is crucial for developing error mitigation strategies in quantum systems.
Purpose of the Study:
- To introduce a novel method for analyzing slow qubit frequency fluctuations.
- To demonstrate that Ramsey measurement sequences can reveal characteristic noise features.
- To investigate the dependence of noise characteristics on measurement parameters.
Main Methods:
- Utilizing periodically repeated Ramsey measurements with sequence durations shorter than the noise's ergodic limit.
- Analyzing the distribution of measurement outcomes and its sensitivity to sequence duration.
- Exploring the impact of measurement parameters on the time to observe quasiergodic behavior.
Main Results:
- Characteristic features of qubit frequency fluctuations are identifiable through short Ramsey measurement sequences.
- The distribution of outcomes and its dependence on sequence duration provide insights into the nature of the noise.
- The time required for quantum measurements to exhibit quasiergodic behavior is shown to be parameter-dependent.
Conclusions:
- Short Ramsey measurement sequences offer a viable alternative to spectral analysis for characterizing qubit noise.
- Understanding the parameter dependence of quasiergodic behavior is key to improving quantum measurement protocols.
- This approach aids in diagnosing and potentially mitigating noise sources affecting quantum computer performance.
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