 A striking feature of quantum mechanics is known as “quantum entanglement”. When two (or more) quantum particles or systems interact in certain ways and are then (even space-like) separated, their measurable features (e.g., position and momentum) will correlate in ways that cannot be accounted for in terms of “pure” quantum states of each particle or system separately. In other words, the two need to be thought of as a coupled system, having certain features which are in no sense a compositional or other resultant of individual states of the system’s components (see Silberstein &amp; McGeever 1999 and entries on  holism and nonseparability in physics  and  quantum entanglement and information).  Humphreys (2016) construes this as an instance of emergent fusion  (section 4.2.4).  Insofar as these features have physical effects, they indicate a near-ubiquitous failure of whole-part property supervenience at a very small scale. However, it should be observed that quantum entanglement does not manifest a fundamental novelty in feature or associated causal power, as it concerns only the value or magnitude of a feature/associated power had by its components. (Correlated “spin” values, e.g., are permutations on the fundamental feature of spin, rather than being akin to mass or charge as wholly distinctive features.) As such, it does not fit the criteria of many accounts of strongly emergence. It is, however, relevant to the epistemic status of such accounts: if one thinks that the existence of strong emergence is implausible on grounds that a kind of strong local supervenience is a priori very plausible for composed systems generally, then the surprising phenomenon of quantum entanglement should lead you to be more circumspect in your assumptions regarding how complex systems are put together.