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QI: Fachverband Quanteninformation

QI 21: Quantum Information: Concepts and Methods III

QI 21.3: Vortrag

Freitag, 13. März 2026, 10:15–10:30, BEY/0245

Analysis of multi-detector quantum measurements via their cross-correlation polyspectra — •Armin Ghorbanietemad, Markus Sifft, and Daniel Hägele — Ruhr University Bochum, Faculty of Physics and Astronomy, Experimental Physics VI, Germany

Recent work has shown that higher-order spectra of continuous quantum measurement records provide characteristic fingerprints of stochastic system dynamics. These polyspectra capture essential features of measurement processes in platforms as diverse as nano-transport, single-photon emission from quantum dots, and spin-noise spectroscopy [1 - 3]. This makes them a more versatile analysis tool than traditional approaches such as full counting statistics or Langevin-based methods. The framework naturally incorporates measurement-induced damping, detector backaction, and the quantum Zeno effect. Key system parameters can be extracted by comparing experimental polyspectra with their analytical counterparts [2].

Here, we extend our single-detector theory to the case of multiple observables monitored simultaneously. We derive general expressions for spectra up to fourth order, apply the formalism to a coupled quantum system, and present a GPU-accelerated implementation that enables efficient computation of cross-correlation polyspectra from arbitrary Liouvillians.

[1] Hägele et al., PRB 98, 205143 (2018)

[2] Sifft et al., PRR 3, 033123 (2021)

[3] Sifft et al., PRA 109, 062210 (2024)

Keywords: Quantum measurements; Polyspectra; Signal analysis