Real-time adaptive estimation of decoherence timescales for a single qubit

Journal article

Characterizing the time over which quantum coherence survives is critical for any implementation of quantum bits, memories, and sensors. The usual method for determining a quantum system's decoherence rate involves a suite of experiments probing the entire expected range of this parameter, and extracting the resulting estimation in postprocessing. Here we present an adaptive multiparameter Bayesian approach, based on a simple analytical update rule, to estimate the key decoherence timescales (T1, T2∗ - , and T2) and the corresponding decay exponent of a quantum system in real time, using information gained in preceding experiments. This approach reduces the time required to reach a given uncertainty by a factor up to an order of magnitude, depending on the specific experiment, compared to the standard protocol of curve fitting. A further speedup of a factor approximately 2 can be realized by performing our optimization with respect to sensitivity as opposed to variance.

Authors: Arshad, MJ; Bekker, C; Haylock, B; Skrzypczak, K; White, D

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: American Physical Society
• Journal: Physical Review Applied
• Volume: 21
• Issue: 2
• Article number: 024026
• Publication date: 2024-02-13
• Acceptance date: 2024-01-18
• DOI: 10.1103/physrevapplied.21.024026
• EISSN: 2331-7019
• Language: English
• Keywords: open quantum systems and decoherence; quantum Fisher information; quantum control; quantum information processing; quantum metrology; quantum coherence and coherence measures