If a time traveller, or someone who has travelled time had no clue as to their temporal whereabouts, they might at least be curious as to:
a. Knowing what ‘time’ they are in
b. Knowing how/having a method of discerning the period
The latter point is sometimes stated in very uncritical terms sometimes; often there are plot devices such as ‘chronometer’ (being some fancy science-watch that is more sophisticated than a ticking clock), or satellite/radio tranismissions, or simply by asking anyone or finding clues (ie. big hair = 60s-90s). The latterly solution is a fairly simple one, insofar as there are actually people there. The satellite/radio idea is tenuous as it presumes the same degree of technological advancement in the periods of time wherewhich the agent had jumped into.
The last and often unquestioned notion, involves some kind of ‘science-clock’ which is able to discern the period of time immediately. I wonder how they would actually make that work. my first thought would be to estimate the age of the nearest naturally significant object. Such as either the planet that they are on (usually earth), or the nearest star. Of course, this wouldn’t work if one were travelling into another galaxy. I wonder though, how one would account for this hitherto unquestioned gizmo that could tell the time.
Oh yes, and mentioning ‘quantum mechanics’ (ie, just those two words, rather than quantum mechanics proper) in a sentence is pretty crude as well as some kind of deus-ex-explanandum.