Fast GHZ encoding with $1-o(1)$ fidelity

Abstract:We prove that $(1-o(1))$-fidelity $N$-qubit Greenberger--Horne--Zeilinger (GHZ) encoding can be performed in time $O(\log N/N)$ using all-to-all 2-local Hamiltonians with bounded 2-qubit interaction terms. This saturates the theoretical lower bound $\Omega(\log N/N)$, and by rescaling, also saturates the lower bound on signaling time for Hamiltonians with power-law interaction strengths $1/r^\gamma$, $\gamma<d$ in dimension $d$. The protocol uses spin-squeezing dynamics combined with quantum signal processing.

arXiv:2608.26241 [quant-ph]

(or arXiv:2608.26241v1 [quant-ph] for this version)

https://doi.org/10.48550/arXiv.2608.26241 Focus to learn more arXiv-issued DOI via DataCite (pending registration)

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