Deterministic Photonics at Scale: Quantum Source’s Hybrid Path to Million-Qubit Machines
At Quantum World Congress 2025, Quantum Source laid out how photonics could leap from probabilistic lab demos to room-temperature, fault-tolerant systems. In a tightly argued talk, CEO Oded Melamed described a hybrid approach that couples single photons with single atoms on one platform, aiming to make resource-state generation deterministic and compact enough for a standard server room.
Why scaling matters now
Commercially valuable workloads demand logical qubits with extremely low error rates (~10⁻¹⁵). Under today’s error-correction overheads, that translates to 1,000–10,000 physical qubits per logical qubit. Melamed noted that headline applications—from Shor’s algorithm to chemically relevant simulation—quickly climb into the millions to tens of millions of physical qubits, far beyond today’s hundreds-to-thousands scale.
The photonics bottleneck—framed
Matter-based modalities (superconducting circuits, trapped ions, neutral atoms) can entangle hundreds to low thousands of qubits, but their path to million-qubit systems is unclear. Photonics flips that trade-off: its networked architecture is inherently modular, yet today’s resource-state generators (RSGs) rely on probabilistic photon sources and gates. The result is container-sized, cryogenic hardware that dominates system cost (Melamed estimated ~95–99% of bill of materials) and makes extrapolated million-qubit systems look factory-scale and ~$1B.
Inside Quantum Source’s “Origin” approach
Melamed’s answer is to combine single atoms and single photons on-chip. By trapping rubidium atoms near a high-Q resonator integrated in a photonic chip, the photon’s electric field is boosted long enough to interact deterministically with the atom. That interaction underpins on-demand single-photon generation and deterministic entangling operations, producing small photonic cluster states that are then “stitched” into larger graphs using standard photonic plumbing (RSGs → stitchers → detectors). The claimed outcome: orders-of-magnitude higher efficiency, room-temperature operation, and RSGs small and inexpensive enough to scale by “copy-paste.”
What “server-room scale” could change
If deterministic RSGs hold up, a million-qubit photonic machine could fit in a standard server room, removing cryogenics and collapsing footprint/cost barriers. That reframes not only technical roadmaps but also deployment models—from bespoke labs to enterprise and government data facilities.
Company snapshot
Quantum Source is four years old, has raised $77M, employs ~60 people (about half PhDs in physics/EE), and counts U.S./Israeli VCs and Dell among its backers (described as Dell’s first quantum investment). “With Origin, we can build quantum computers as large as we want—one million or ten million qubits—while keeping the cost structure and infrastructure within reach,” Melamed said.
Bottom line
By shifting photonics from probabilistic to deterministic building blocks, Quantum Source argues it can unlock modular, room-temperature scaling to the fault-tolerant regime. The next test is empirical: demonstrating that atomic-mediated photonics delivers the efficiency and stability needed for million-qubit class systems.