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Scalable Rare Earth Ion Quantum Computing Nodes

Project description

Light from rare-earth ions offers promise for scalable quantum computers

Quantum computers use several different qubit technologies, but independently of the technology, qubits must be scalable, high-quality and capable of fast quantum interactions. The EU-funded SQUARE project will leverage qubits made from rare-earth ions as fundamental building blocks for scalable quantum technologies. Rare-earth ions can store quantum states for a long time and can be activated separately by light in special solid-state crystals. This enables scientists to access a large number of qubits. Furthermore, such qubits can strongly interact with each other, which is promising for building quantum circuits. Although research on single rare-earth ions is still at an early stage, SQUARE will address the central challenges to find a scalable approach for quantum computing.


Quantum technologies rely on materials that offer the central resource of quantum coherence, that allow one to control this resource, and that provide suitable interactions to create entanglement. Rare earth ions (REI) doped into solids have an outstanding potential in this context and could serve as a scalable, multi-functional quantum material. REI provide a unique physical system enabling a quantum register with a large number of qubits, strong dipolar interactions between the qubits allowing fast quantum gates, and coupling to optical photons – including telecom wavelengths – opening the door to connect quantum processors in a quantum network. This project aims at establishing individually addressable rare earth ions as a fundamental building block of a quantum computer, and to overcome the main roadblocks on the way towards scalable quantum hardware. The goal is to realize the basic elements of a multifunctional quantum processor node, where multiple qubits can be used for quantum storage, quantum gates, and for coherent spin-photon quantum state mapping. Novel schemes and protocols targeting a scalable architecture will be developed. The central photonic elements that enable efficient single ion addressing will be engineered into deployable technologies.

Call for proposal


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Net EU contribution
€ 498 601,25
Kaiserstrasse 12
76131 Karlsruhe

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Baden-Württemberg Karlsruhe Karlsruhe, Stadtkreis
Activity type
Higher or Secondary Education Establishments
Other funding
€ 0,00

Participants (7)