QubitWire 100

In 1972, Stuart Freedman and John Clauser measured correlations between pairs of photons that violated a Bell inequality. Their measurement settings stayed fixed during each run. A decade later, Aspect, Jean Dalibard and Gérard Roger switched the settings while the photons were travelling. The correlations still exceeded the bound predicted by local hidden-variable models under the assumptions of the test. Later experiments by Aspect’s team used individual photons to study interference and ultracold atoms to see how disorder can stop matter waves from spreading.

Documented work base: France

Ekert’s work helped make entanglement useful as a resource for communication. His 1991 proposal linked quantum key distribution to Bell’s theorem, giving a new way to reason about the security of shared keys. His role as founding director of the Centre for Quantum Technologies also contributed to the field’s research capacity. The combination illustrates how a foundational idea can shape a technical discipline and the institutions that support its development.

Documented work base: United Kingdom

Furusawa’s research explores how light can carry and process quantum information. His coauthored teleportation experiment demonstrated a central communication primitive for continuous-variable optical systems. Later work generated a two-dimensional cluster state using light arranged across time bins. These contributions connect individual quantum operations with the structured entanglement needed for a broader computing architecture, making his work a useful entry point into the possibilities and engineering challenges of photonic computation.

Documented work base: Japan

Gisin’s career connects optical-fiber engineering with questions about quantum correlations and secure communication. His Geneva group pursued quantum cryptography and long-distance entanglement, and he coauthored a substantial review that brought theoretical and experimental aspects of quantum cryptography together. He also cofounded ID Quantique. The combination makes his contribution relevant to readers exploring how a quantum-information idea moves between foundational research, laboratory systems and a commercial security product.

Guo’s contributions connect theoretical questions about quantum states with experimental components for communication. His work with Luming Duan explored probabilistic cloning under specified conditions, while later coauthored research demonstrated hour-scale coherent optical storage in a solid-state memory. These are different kinds of progress: one clarifies what quantum mechanics permits, and the other improves a physical resource that communication schemes may require. Neither should be confused with unrestricted cloning or an already deployed global quantum network.

Documented work base: China

Hanson’s work links fundamental physics with the building blocks of a quantum internet. He coauthored the Delft experiment that tested a Bell inequality while closing major experimental loopholes. His group subsequently demonstrated entanglement across a network with multiple quantum nodes. Both depend on controlling matter-based qubits and connecting them optically, making this research a useful guide to the demanding transition from individual quantum links to coordinated network operations.

Documented work base: Netherlands

Laflamme’s enduring contribution combines mathematical foundations with institution building. His work with Emanuel Knill formalized conditions for recovering encoded quantum information after noise. With Knill and Gerard Milburn, he also developed a route to quantum computation using linear optics, photon detection and feedback. At Waterloo he served as the founding executive director of the Institute for Quantum Computing. This historical profile recognizes that continuing scientific legacy while explicitly recording his death in June 2025.

Documented work base: Canada

Weedbrook connects the theoretical language of continuous-variable quantum information to an industrial photonic-computing effort. His co-authored review organized Gaussian states, operations and measurements across quantum communication and computation. His founding of Xanadu then created an organization working on photonic quantum technology. The contribution is both scientific and institutional, but the two are evaluated separately: a review establishes a documented research contribution, while company leadership establishes responsibility for a continuing development program.

White’s research links making a quantum operation work with establishing what the experiment actually produced. An optical controlled-NOT gate demonstrates interactions between photon-encoded qubits, while quantum-state tomography provides methods to reconstruct and assess the resulting states. Those contributions are complementary: an experimental device needs trustworthy characterization as well as control. His current Queensland research continues that focus on photonic technology and entanglement, with the early demonstrations credited to their collaborating teams.

Documented work base: Australia

Zeilinger helped make entanglement an experimentally usable resource as well as a test of quantum foundations. His work ranges from the theoretical structure of multipartite correlations to laboratory protocols that connect initially separate entangled pairs. These contributions matter for quantum information because a network must create and distribute correlations, not merely send ordinary signals. His inclusion reflects that foundational and experimental record, with the GHZ framework and entanglement-swapping experiment attributed to their collaborators.

Documented work base: Austria