---
title: "Sandu Popescu"
type: "entity"
entity_kind: "person"
status: "hub"
canonical_name: "Sandu Popescu"
aliases: []
first_seen: "2026-10-22T00:00:00.000Z"
writer_model: "claude-sonnet-5"
connects_to: ["quantum foundations","Popescu-Rohrlich nonlocality","conservation laws (quantum measurement)","Yakir Aharonov","Daniel Collins"]
seek_code_commit: "d40ee39"
---


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 [[entity-yakir-aharonov|Yakir Aharonov]] and Daniel Rohrlich of two 2021/2023 PNAS papers on conservation laws in quantum mechanics that motivated the 2025 proposal. [[entity-elias-okon|Okon]], [[entity-daniel-sudarsky|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]]