Quantum computing startup Oratomic has raised $775 million in total funding for the development of fault-tolerant quantum systems.

The announcement comes three months after Oratomic announced it had raised $300 million in a Series A financing round.

Both rounds were co-led by Arch Venture Partners, Spark Capital, and Khosla Ventures, Bezos Expeditions, Index Ventures, and General Catalyst participating in the Series A, but signed on as additional co-leaders in the most recent round.

In a statement, Oratomic said the new funding will support the continued growth of its scientific and engineering team, laboratory infrastructure, and the systems required to build its quantum computers.

The Pasadena-based startup emerged from stealth in March 2026, and is “focused exclusively” on building a fault-tolerant quantum computer.

The company claims that its approach – which uses lasers to hold individual atoms in place – will allow it to develop a useful fault-tolerant computer using 10,000 - 20,000 qubits, far fewer than other companies working on this modality have previously claimed were necessary.

One of the startup’s founders, Manuel Endres, has previously said that Oratomic has already trapped arrays of 6,000 atomic qubits.