Regensburg 2025 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 50: Superconducting Electronics: SQUIDs, Qubits, Circuit QED II

TT 50.10: Vortrag

Donnerstag, 20. März 2025, 17:30–17:45, H36

Exact and Dispersive Models for Superconducting Networks — •Adrian Parra-Rodriguez — Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching, Germany — Institute of Fundamental Physics IFF-CSIC, Calle Serrano 113b, 28006 Madrid, Spain — Institut Quantique and Département de Physique, Université de Sherbrooke, Sherbrooke, Quebec J1K 2R1, Canada

In this presentation, I will address the construction of exact quantum mechanical models for quasi-lumped electrical networks [1,2], comprising (nonlinear) capacitors, inductors, nonreciprocal elements (circulators), and transmission lines (TLs). Traditional quantization methods, such as node-flux or loop-charge approaches, often lead to singularities and unphysical predictions, stemming from incorrect identification of the TLs’ infinite-dimensional Hilbert space. Using a geometrical description [1] and the Faddeev-Jackiw method, we resolve these issues via a mixed charge-flux first-order quantization. I will also introduce a systematic method to construct effective dispersive Lindblad master equations for weakly anharmonic superconducting circuits coupled by generic linear nonreciprocal systems, deriving coupling parameters and decay rates from the coupler’s immittance parameters [3]. Extending the work of Solgun et al. (2019) on reciprocal couplers, this approach includes nonreciprocal elements, stray coupling, and collective dissipative effects from external environments, while avoiding potential singularities.

[1] A. Parra-Rodriguez et al., Quantum 8, 1466 (2024);

[2] A. Parra-Rodriguezet al., arxiv:2401.09120;

[3] Labarca et al., Phys. Rev. App. 22, 034038 (2024).

Keywords: Superconducting circuits; Canonical quantization; Quasi-lumped elements; Geometry and topology; Dispersive regime