Noise in small-scale quantum computers

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Quantum computers use bits that behave quantum mechanically (qubits) to solve important problems faster and better than conventional computers. This includes factoring large integers, searching disordered databases, diagonalizing matrices, and simulating molecules and materials. Prototype "noisy'' quantum computers based on superconducting technology have been developed by many companies, and are now accessible over the cloud. However, the level of noise in current quantum computers is 10-100 times higher than the error correction threshold, hindering demonstrations of quantum advantage over conventional computers. This research program aims to formulate new models of noise and decoherence in solid state quantum computers, and relate them to the output of cloud-based devices, in order to develop strategies for noise mitigation. This will be done through the development of a novel theory of magnetic (flux) noise, whose measured frequency and temperature dependence has been a great puzzle in several experiments. The proposal aims to relate flux noise to the character of the materials and interfaces in quantum technology, and use these findings to improve the output of quantum algorithms in cloud-based devices. The research program will improve both quantum hardware and software in order to achieve the fundamental noise limit in the solid state environment. Its long term impact will be to transcend the era of noisy intermediate-scale quantum computers, providing a route to the demonstration of quantum advantage in useful applications.