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arXiv · 2603.18176

Theory of Two-Qubit $T_2$ Spectroscopy of Quantum Many-Body Systems

Hossein Hosseinabadi·Pavel E. Dolgirev·Sarang Gopalakrishnan·Amir Yacoby·Eugene Demler·Jamir Marino
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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 $T_2$ 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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Hossein Hosseinabadi, Pavel E. Dolgirev, Sarang Gopalakrishnan, Amir Yacoby, Eugene Demler, Jamir Marino. 2026-03-18. Theory of Two-Qubit $T_2$ Spectroscopy of Quantum Many-Body Systems. https://arxiv.org/abs/2603.18176

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