Finance income (Details) $ in Thousands	12 Months Ended
Sep. 30, 2020 USD ($)
Finance income
Initial recognition difference of convertible loan notes	$ 65

Represents the initial recognition difference of convertible loan notes, recognised within finance income (expense)

No definition available.

Name:	arqq_InitialRecognitionDifferenceOfConvertibleLoanNotes
Namespace Prefix:	arqq_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration