Scalable Quantum Optical Interconnects

ongoing

Coherent quantum systems are globally pursued in the race to build a compelling technology. One fast-developing approach uses high-fidelity microwave qubits. Major research efforts in academia and industry are demonstrating an elementary form of supremacy over classical technology by moving to tens and hundreds of such cryogenic qubits. However, it is currently impossible to connect the qubits well beyond a single refrigerator while preserving their fragile quantum properties – limiting their use outside the laboratory. Optical photons, with their long-distance and near-noiseless propagation along room-temperature fibers, are uniquely placed to tackle this challenge. In QUSCALE, we will realize deployable converters between microwave and optical photons. We will build chips that convert between microwave and optical quantum information. The chips will let us increase the size of emerging quantum processors and networks to a level where we can perform useful tasks beyond the reach of classical systems. To find use outside the laboratory, the converters must minimize the energy that is dissipated per converted qubit between microwaves and optics. Dissipated energy will determine whether microwave quantum processors can scale up via optics. We will achieve major reductions in the dissipated energy per converted qubit. The proposed devices will create a fundamentally new tool for physicists and engineers. They will enable a series of increasingly impactful networking tasks on the way to entanglement between distant microwave qubits, addressing an urgent need for optical interconnects between microwave quantum processors.