Year: 2026
Type: preprint
Abstract: Partial transposition reveals mixed-state entanglement through the spectrum of $ρ_{AB}^{T_B}$, but this operator is not generally a physical state. Its power moments are accessible through collective permutations, whose coherent width grows with moment order. Here we introduce a streaming protocol that processes fresh copies sequentially while retaining one copy and a reusable ancilla. By realizing opposite cyclic permutations on the two subsystems, each measurement record yields unbiased estimators of all moments $p_2,\ldots,p_K$ through successive outcome products. For an $n$-qubit state, the protocol uses $2n+1$ active qubits independent of $K$ and $O(K\log K/ε_{\rm mom}^2)$ copies, matching $Ω(K/ε_{\rm mom}^2)$ lower bounds up to a logarithmic factor, including a PT-specific isospectral construction. Higher-order moments strengthen thermal-state entanglement certification toward the exact PPT threshold. Simulations cover pure and mixed states, and a cloud quantum processor implements a three-qubit instance.
Source: arXiv (Cornell University)
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7164839308