Tel Aviv-based photonic hardware developer Quantum Source has published the technical details of its proprietary quantum interconnect, QS-LINK. Designed to address scaling limits in multi-processor quantum networks, the system utilizes a single cavity-trapped rubidium-87 atom as an asynchronous quantum memory buffer to establish remote entanglement between separate quantum processing units (QPUs). The architecture operates at room temperature over standard optical fiber and supports multi-vendor interconnectivity across distinct physical hardware modalities, including trapped-ion, neutral-atom, superconducting, and photonic platforms.
Conventional photonic Bell-state measurements (BSM) rely on linear-optics type-II fusion gates, which require photons from two independent QPUs to arrive simultaneously at a beam splitter in identical quantum states. Because per-attempt photon delivery probabilities (p) across fiber channels typically remain at or below 1%, simultaneous arrival succeeds probabilistically at an order of p2 (roughly once in 10,000 attempts). QS-LINK replaces the two-photon interference requirement with a single-atom cavity quantum electrodynamics (QED) interface. The trapped atom executes a near-deterministic controlled-Z (CZ) gate with an incoming photon from the first QPU, storing the resulting atom-QPU entanglement state while the second QPU continues execution attempts. Once a photon from the second QPU interacts with the atom, a local atomic state measurement projects the two remote QPUs into a shared Bell pair.
| [ Quantum Interconnect Architecture Comparison ] | ||
|---|---|---|
| Architectural Parameter | Linear-Optics Type-II Fusion | QS-LINK Cavity-QED Memory |
| • Entanglement Scaling | • Quadratic scaling (p2) • Requires simultaneous photon arrivals | • Linear scaling (p) • Asynchronous photon arrival & storage |
| • Attempts for 10k Pairs/sec | • ~190 million attempts/sec | • ~3.2 million attempts/sec |
| • Photon Indistinguishability | • Mandatory (Identical temporal envelopes & phase matching required) | • Not required (Photons interact sequentially with central atom) |
| • Cross-Modality Support | • Highly restricted (Requires identical QPU photon sources) | • Hardware-agnostic (Connects trapped-ion, neutral-atom, & superconducting) |
Because entanglement is mediated sequentially through the atomic memory rather than direct photon-photon interference, the interconnect eliminates the requirement for mutually indistinguishable photon envelopes or joint optical phase stabilization. Mathematical modeling and Monte Carlo simulations published by the company indicate that achieving a target threshold of 10,000 entangled pairs per second—a rate required by fault-tolerant distributed architectures—demands approximately 3.2 million attempt cycles per second using QS-LINK, compared to 190 million attempts per second under linear-optics fusion gates. The projected parameters assume a photon-atom CZ gate duration of approximately 20 nanoseconds at 98.4% photon-survival efficiency.
Review the technical paper on arXiv here and inspect product specs on the Quantum Source Portal here.
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