Unbounded sequence of observers exhibiting Einstein-Podolsky-Rosen steering via probabilistic projective measurements
Phys. Rev. A 114, 012411 – Published 6 July, 2026
DOI: https://doi.org/10.1103/hsh7-14h3
Abstract
Recent studies have demonstrated that coherent weak measurements allow Einstein-Podolsky-Rosen steering to be shared sequentially between a single Alice and multiple Bobs. Theoretically, this permits an unbounded sequence in the high-dimensional limit. In this work, we investigate whether the experimentally simpler strategy of probabilistic projective measurements (PPM) can achieve similar results. We identify a fundamental distinction between the two approaches: while coherent weak measurements perturb the quantum state quadratically , PPM induces an effective linear depolarizing contribution . We prove that this linear scaling restricts the information-to-disturbance ratio to , causing the quantum correlations to decay in an arithmetic progression. This imposes a strict bound on the number of accessible Bobs in finite-dimensional systems, severely limiting sequence lengths for qubits. However, we demonstrate that high-dimensional entanglement is robust enough to sustain the sequence, yielding an asymptotic sharing capacity of . Ultimately, our results reveal a crucial physical trade-off: while PPM offers experimental simplicity, it consumes quantum correlations at a significantly higher rate than coherent weak measurements.