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arXiv · 2604.15209

Variational quantum state preparation within an entangle-rotate circuit framework for quantum-enhanced metrology in noisy systems

Juan C. Zuñiga Castro·Jeffrey Larson·Matt Menickelly·Sri Hari Krishna Narayanan·Yicheng Zhang·Michael A. Perlin·Robert J. Lewis-Swan
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Abstract

We investigate the generation of quantum states for precision metrology in noisy two-level systems. These states are obtained by optimizing a variational quantum circuit to maximize the quantum Fisher information (QFI) of the output state for a given decoherence rate and interaction Hamiltonian. The circuit architecture, inspired by twist-and-turn schemes, features a sequence of $n$ entangling layers, each consisting of entangling gates followed by a global rotation. We observe notable improvements in the QFI as the circuit layer depth increases, even for appreciable noise rates, demonstrating that our entangle-rotate architecture expands the accessible state space under realistic noise conditions. Our approach thus provides a general and efficient framework for generating quantum-enhanced sensing states. Our analysis extends to systems of power-law interactions spanning from all-to-all to nearest-neighbor interactions. We also analyze the capabilities of our circuit to prepare states for system sizes greater than $8$ qubits.

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Juan C. Zuñiga Castro, Jeffrey Larson, Matt Menickelly, Sri Hari Krishna Narayanan, Yicheng Zhang, Michael A. Perlin, Robert J. Lewis-Swan. 2026-04-16. Variational quantum state preparation within an entangle-rotate circuit framework for quantum-enhanced metrology in noisy systems. https://arxiv.org/abs/2604.15209

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