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arXiv · 2502.16479

Enhanced response at exceptional points in multi-qubit systems for sensing

Tingting Shi·Vasilii Smirnov·Kaiye Shi·Wei Zhang
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Abstract

Exceptional points featuring enhanced energy response to perturbation hold significant potential in detection and measurement of weak signals. Of particular interest is the existence and property of high-order exceptional points in quantum systems, owing to the capability to provide high-order response to perturbations. We investigate the exceptional points in a system of $n$ identical qubits possessing parity-time-reversal symmetry. We prove that owing to an incomplete coalescence of eigenstates, the highest possible order of exceptional point is $n+1$, which is also the upper bound of the order of energy response to perturbation. More interestingly, by considering an Ising-type interaction, we analytically prove that to achieve an $(m+1)$-th order response for any $m \le n$, the system must acquire a nontrivial $m$-body interaction. Finally, we propose a Floquet driving scheme to implement an effective multi-body Ising-type interaction, which can be realized in trapped ions or superconducting qubits.

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Tingting Shi, Vasilii Smirnov, Kaiye Shi, Wei Zhang. 2025-02-23. Enhanced response at exceptional points in multi-qubit systems for sensing. https://doi.org/10.1103/physreva.111.032203

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