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SYSB: Symposium Spin-Boson Models

SYSB 1: Spin-boson models

SYSB 1.2: Hauptvortrag

Dienstag, 3. März 2026, 11:30–12:00, RW 1

Spins, Qubits, and Bosons — •Guido Burkard — Department of Physics and IQST, University of Konstanz, 78457 Konstanz, Germany

The spin-boson model, along with related open-system approaches, constitutes a foundational tool for understanding noise and decoherence in contemporary quantum computing devices. We outline how these models describe realistic qubit properties and capture both temporal and spatial noise correlations. We illustrate the utility of these models across a series of representative scenarios. First, we present a quantum decoherence theory for superconducting qubit circuits, derived from electrical network graph methods and the spin-boson model, leading to Bloch-Redfield dynamics that include leakage beyond the computational subspace. Second, we discuss non-Markovian qubit dynamics under 1/f noise. Third, we investigate temporally correlated noise in superconducting transmon qubits using a time-local, non-Markovian master equation. Extending this framework to driven systems while avoiding both Markov and field-independent approximations enables an accurate tracking of time-dependent decay channels. Turning to spatially correlated noise, we present efficient methods, requiring only single-qubit control and measurement to detect correlated relaxation and dephasing. Finally, we examine temperature-dependent effects in semiconductor spin qubits, demonstrating how spin-phonon interactions may explain the observed non-monotonic qubit frequency shifts. Together, these examples highlight the breadth of noise phenomena captured by spin-boson-type models and their central role in the design and diagnosis of high-fidelity qubit architectures.

Keywords: qubits; non-Markovian noise; superconducting qubits; spin qubits; spin-boson model