Property and equipment, net (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 25,299,000		$ 25,299,000		$ 25,050,000
Less: Accumulated depreciation	(22,762,000)		(22,762,000)		(21,801,000)
Property and equipment, net	2,537,000		2,537,000		3,249,000
Depreciation expense	338,000	$ 393,000	1,000,000	$ 1,100,000
Quantum computer systems
Property, Plant and Equipment [Line Items]
Total property and equipment	13,425,000		13,425,000		13,425,000
Lab equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	6,664,000		6,664,000		6,645,000
Computer equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	3,439,000		3,439,000		3,305,000
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total property and equipment	1,074,000		1,074,000		1,074,000
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Total property and equipment	318,000		318,000		316,000
Construction-in-progress
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 379,000		$ 379,000		$ 285,000