English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The standard formulation of quantum theory relies on a fixed space-timemetric determining the localisation and causal order of events. In generalrelativity, the metric is influenced by matter, and is expected to becomeindefinite when matter behaves quantum mechanically. Here, we develop aframework to operationally define events and their localisation with respect toa quantum clock reference frame, also in the presence of gravitating quantumsystems. We find that, when clocks interact gravitationally, the timelocalisability of events becomes relative, depending on the reference frame.This relativity is a signature of an indefinite metric, where events can occurin an indefinite causal order. Even if the metric is indefinite, for any eventwe can find a reference frame where local quantum operations take theirstandard unitary dilation form. This form is preserved when changing clockreference frames, yielding physics covariant with respect to quantum referenceframe transformations.

Quantum clocks and the temporal localisability of events in the presence of gravitating quantum systems