Revenue from contracts with customers - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Disaggregation of Revenue [Line Items]
Total revenue, net	$ 1,583	$ 1,713
United States
Disaggregation of Revenue [Line Items]
Total revenue, net	247	777
Japan
Disaggregation of Revenue [Line Items]
Total revenue, net	308	434
Germany
Disaggregation of Revenue [Line Items]
Total revenue, net	288	263
United Kingdom
Disaggregation of Revenue [Line Items]
Total revenue, net	231	0
Other
Disaggregation of Revenue [Line Items]
Total revenue, net	509	239
Revenue recognized over the time
Disaggregation of Revenue [Line Items]
Total revenue, net	1,542	1,662
Revenue recognized at a point in time
Disaggregation of Revenue [Line Items]
Total revenue, net	41	51
QCaaS
Disaggregation of Revenue [Line Items]
Total revenue, net	1,168	1,384
Professional services
Disaggregation of Revenue [Line Items]
Total revenue, net	406	309
Other revenue
Disaggregation of Revenue [Line Items]
Total revenue, net	$ 9	$ 20