Photons Quantum Computer Innovation Center Ulm


We are developing a universal and error corrected photonic quantum computer with up to 64 qubits

Over the course of its four-year project, QuiX Quantum is developing a photonic quantum computer for universal quantum computing in several expansion stages on behalf of DLR. Quix Quantum will deliver a photonic processor to DLR in its first year, which will allow for initial experience with the generation and processing of photonic quantum states. This construction phase will be followed by the development of a processor with 64 input channels. Finally two photonic quantum computers will be developed: a universal eight-qubit system in the third project year and a universal and additionally error-correctable system with 64 qubits or more in the fourth year.


Photonic quantum computers are fundamentally based on the encoding and processing of quantum information using light. In the measurement-based quantum processor, squeezed light states are first generated for the processing of quantum states. They are then processed by information technology and, finally, detected. The individual light pulses are guided in the same way as conductor paths for electrons in waveguides on the chip.

The advantage of photonic qubits is that the quantum states are preserved even over long transmission paths due to their high coherence length and transmission even at room temperatures. The photonic quantum processor is founded upon integrated photonic circuits based on silicon nitride. The silicon nitride platform is a mature technology that offers low losses, which are the main source of errors for photonic qubits. It is also compatible with methods used by the telecommunications industry and can be connected to other photonic technologies such as fibre optic networks.


Creating a scalable, universal photonic quantum processor requires a high degree of integration of components such as light sources and detectors. This integration will be continuously increased over the course of the project. Error correction also requires special light states that are not generated deterministically. This means that several light sources working in parallel are required to generate a state suitable for quantum error correction. Once they have been generated, fast switches then route the error-correctable light states to the processor’s inputs. Photon number resolving detectors need to be integrated into the silicon nitride architecture in order to be able to detect these states. Another challenge is to ensure the indistinguishability of the states from different light sources. As such, rapid control of beam sources is also necessary for the implementation of this project.

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