$W$- and Dicke-state engineering using optimal global control in nearest-neighbor coupled ring-shaped qubit arrays

• URL: http://arxiv.org/abs/2512.19545v1
• Date: Mon, 22 Dec 2025 16:28:19 GMT
• Title: $W$- and Dicke-state engineering using optimal global control in nearest-neighbor coupled ring-shaped qubit arrays
• Authors: Andrea Muratori, Vladimir M. Stojanovic, Eloisa Cuestas, Tommaso Calarco, Felix Motzoi,
• Abstract summary: We consider a ring-shaped array of qubits with nearest-neighbor Ising-type ($zz$) coupling and transverse ($x$ and $y$) global control fields.<n>This system mimics -- outside of the Rydberg-blockade regime -- a circular array of neutral atoms interacting through van-der-Waals type interaction.<n>We show that our control schemes enable the preparation of the desired multiqubit states on time scales much shorter than the relevant coherence times of those systems.
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• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: Motivated by a compelling need for time-efficient and robust schemes for quantum-state engineering in systems of neutral atoms in optical tweezers, we consider a ring-shaped array of qubits with nearest-neighbor Ising-type ($zz$) coupling and transverse ($x$ and $y$) global control fields. This system to a large extent mimics -- outside of the Rydberg-blockade regime -- a circular array of neutral atoms interacting through van-der-Waals type interaction. We investigate the preparation of $W$ and Dicke states in this system starting from the default initial state $|00\ldots 0\rangle$ using two different optimal-control approaches: (i) NMR-like pulse sequence, which consists of instantaneous (delta-shaped) control- and Ising-interaction pulses, and (ii) time-dependent control scheme, which entails shaped control pulses in the presence of always-on Ising interaction between adjacent qubits. By making use of the underlying dihedral symmetry of this system -- which allows one to use a symmetry-adapted computational basis with $\mathcal{O}(2^N / N)$ states in an $N$-qubit system -- and utilizing advanced global-optimization methods, we find optimal sequences of pulses for realizing $W$ and Dicke states within both approaches. In addition, we demonstrate robustness of these sequences against unavoidable control errors. Finally, using typical values of parameters in realistic Rydberg-atom systems, we show that our control schemes enable the preparation of the desired multiqubit states on time scales much shorter than the relevant coherence times of those systems.

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