Experimental characterization of coherent and non-Markovian errors using tangent space decomposition

• URL: http://arxiv.org/abs/2602.20128v1
• Date: Mon, 23 Feb 2026 18:42:40 GMT
• Title: Experimental characterization of coherent and non-Markovian errors using tangent space decomposition
• Authors: Elia Perego, Andrea Rodriguez-Blanco, K. Birgitta Whaley, Bharath Hebbe Madhusudhana,
• Abstract summary: We use a technique based on tangent-space decomposition to characterize coherent and non-Markovian errors in quantum devices.<n>We experimentally validate this method on a single-qubit gates implemented on a trapped $40$Ca$+$ ion.
• Score: 0.0
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: Accurate characterization of coherent and non-Markovian errors remains a central challenge in quantum information processing, as conventional benchmarking techniques typically rely on Markovian and time-independent noise assumptions. In practice, however, quantum devices exhibit both systematic coherent miscalibrations and temporally correlated fluctuations, which complicate error diagnosis and mitigation. Here, we apply a technique based on tangent-space decomposition to characterize such error in single-qubit quantum gates implemented on a trapped ion platform. Small imperfections in a quantum operation are treated as perturbations of the target quantum map, represented as tangent vectors in the space of quantum channels. This formulations enables a natural decomposition of the deviation into three components corresponding to coherent, Markovian and non-Markovian processes.The relative weights of these components provide a quantitative measure of the contribution from each type of error mechanism, directly from a single tomographic snapshot. We experimentally validate this method on a single-qubit gates implemented on a trapped $^{40}$Ca$^+$ ion, where control is achieved through laser-driven optical transitions. By analyzing experimentally reconstructed process matrices, expressed in the Pauli Transfer Matrix and Choi representations, we identify and quantify non-Markovian effects arising from controlled injection of slow fluctuations in the experimental environment. We also characterize deterministic coherent miscalibrations using the same technique. This approach provides a physically transparent and experimentally accessible tool for diagnosing complex error sources in quantum control systems.

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