• Accepted Paper

Theory of two-qubit T2 spectroscopy of quantum many-body systems

Hossein Hosseinabadi, Pavel E. Dolgirev, Sarang Gopalakrishnan, Amir Yacoby, Eugene Demler, and Jamir Marino

Phys. Rev. B - Accepted 24 September, 2026

DOI: https://doi.org/10.1103/nql5-tb4m

Abstract

Multi-qubit quantum sensors are rapidly emerging as platforms that extend the capabilities of conventional single-qubit sensing. In this work we show how suitable pulse sequences applied to a two-qubit sensor enable separate extraction of the response and noise of a probed environment within a T2 spectroscopy framework. By resorting to representative examples, we demonstrate that this approach can resolve the spatio-temporal spreading of correlations in a many-body system. In particular, the resulting correlated dephasing signal captures features such as the dispersion of low-energy excitations, which manifest as light-cone-like profiles in the propagation of correlations. We further show that non-equilibrium conditions, for instance those induced by external driving, can modify this profile by producing additional fringes outside the light-cone. As a complementary application, we demonstrate that the method clearly distinguishes between different transport regimes in the system, including ballistic spreading, diffusive broadening, and the crossover between them.

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