Squeezed Quantum prOcessing with Photonics and Electronics

Quantum information science is a new and exciting research field with the potential to transform many areas of information technology, including communications, computing, and simulation of complex systems. Unlike binary digits (bits) used in ordinary computer systems, quantum bits or qubits can operate in a superposition of states. In a simplified view this means that a qubit can be in both, the 0 state and the 1 state at the same time; This feature allows for example quantum computers to carry out computational tasks much faster, since the quantum computer can work with both values simultaneously, achieving a kind of quantum parallelism on a single computer. Hence, the computation based on qubits can solve problems that a traditional computer could never answer in a reasonable time. Across all physical systems acting as candidates for qubits in large-scale quantum information processing (e.g. trapped atoms/ions, superconducting circuits, spin states), photons distinguish themselves by the absence of decoherence, that means the photonic qubit is not disturbed by it environment. However, the lack of decoherence also implies a very small coupling to other photons, but such a coupling is essential to implement a large computation where many hundreds of qubits are needed to interact. Therefore, in order to use photons as qubits capable of interacting together, the path forward relies on squeezed states and their combination into large interacting clusters of photons. A squeezed state is a state of light where the uncertainty in phase and amplitude is not equally distributed but shows larger quantum mechanical uncertainties in one property than in the other one. For example, a squeezed light state might have a very well-defined phase but a large uncertainty in the number of photons in that state, this is in contrast to a coherent state (e.g. laser) where the uncertainties are equal in size. The advantage of squeezed states is that there are inherent interactions between the photons of the state and this interaction can be reproduced accurately. Generating, manipulating, and measuring squeezed states by the hundreds is therefore highly desirable. While early demonstrations have been impressive, the project SQOPE (Squeezed Quantum prOcessing with Photonics and Electronics) sets the route towards potential up-scaling to much bigger systems, which can only be enabled by integrating all the key elements onto small optical chips. SQOPE will show that both the light source (squeezer) and the optoelectronic detectors can be put together onto a unique silicon-based photonics chip. SQOPE is a four-year project jointly run by partners in Belgium (Ghent University, overall project coordinator) and partner institutions in Austria (Austrian Institute of Technology (AIT) and University of Vienna) funded by the FWF (Austria) and the FWO (Belgium).