Sandu Popescu

Theoretical physicist (University of Bristol) known for foundational work on quantum nonlocality, including the "Popescu–Rohrlich box" model (with Daniel Rohrlich) of hypothetical non-signaling correlations stronger than quantum mechanics permits. In the vault he is the physicist whose work is the actual subject under scrutiny in its first foray into quantum-measurement conservation-law debates: co-author with Daniel Collins of "Conservation laws for every quantum measurement outcome" (Quantum 9, 1815, 2025), the proposal that a physical "preparer" system restores conservation to individual measurement outcomes, not just statistical averages — and co-author with Yakir Aharonov and Daniel Rohrlich of two 2021/2023 PNAS papers on conservation laws in quantum mechanics that motivated the 2025 proposal. Okon, Sudarsky & M. Wiedemann's 2026 critique (arXiv:2610.29804) argues this mechanism is not adequately justified and does not establish what it claims.

References

• claim-okon-sudarsky-wiedemann-reference-frame-regress-undermines-preparer-requirement

• claim-okon-sudarsky-wiedemann-preparer-never-definite-only-statistical-conservation-restored

• claim-okon-sudarsky-wiedemann-noncommuting-conserved-quantities-break-compensation-mechanism

• claim-okon-sudarsky-wiedemann-preparer-chain-restatement-matches-collins-popescu

• claim-okon-sudarsky-wiedemann-noncommuting-case-confirmed-as-open-conjecture

• claim-okon-sudarsky-wiedemann-regress-preempts-chain-of-preparers-rebuttal

• 2026-10-23: a direct read of Collins & Popescu's own paper against Okon, Sudarsky & Wiedemann's critique confirmed the critique restates their "chain of preparers" argument and their noncommuting-case acknowledgment accurately — this is evidence against Popescu's proposal being strawmanned, not evidence about whether the critique is correct (claim-okon-sudarsky-wiedemann-preparer-chain-restatement-matches-collins-popescu).

• 2026-10-23: a 2026 Aharonov oral-history interview (arXiv:2610.30998) names Popescu as a co-author (with Aharonov, Colombo, Sabadini, Struppa & Tollaksen) of the 2016 quantum pigeonhole principle paper, a separate quantum-foundations collaboration with Aharonov from the 2021/2023 conservation-laws work above (claim-aharonov-2016-quantum-pigeonhole-three-particles-two-boxes-weak-value).

• 2026-10-27: a University of Bristol press release (Popescu's home institution, 27 March 2017) independently confirms the 2016 Cozzarelli Prize for this paper, alongside PNAS's own Tier-1 press release naming the full byline — closing the previously-open question of whether the award itself was real and correctly attributed (claim-quantum-pigeonhole-paper-won-2016-cozzarelli-prize).