Optimizing Qubit Allocation on Hybrid Quantum Systems for Scalable Quantum Networks

The quantum internet will harness new reusable, functional building blocks to connect quantum computers and processors, quantum sensors, and quantum data centers over local and global scales. In fact, quantum networking is crucial even inside individual quantum computers, which will need to transport quantum information reliably between processing and memory modules. The quantum internet will enable transformative applications with wide-ranging societal impacts, including physics-based secure communications, enhanced data privacy, counterfeit-proof currency, tamper-proof sensors, ultra-precise global positioning, ultra-precise long-baseline astronomy, unprecedented medical imaging applications such as dynamic neural imaging using magnetic field sensors based on quantum-entangled atomic-like defect sites in diamond, high-resolution earth mapping with a satellite-cluster equipped with shared entanglement, and promising new dark-matter detectors. Analogous to how the developers of ARPANET could never have imagined the computing power, communications capabilities, and remarkable breadth of applications we hold in our hands today, the quantum internet will spur new technology industries and a competitive marketplace of quantum network service providers and quantum application developers. As quantum information technologies enter a new era in 2020 they are becoming more complex, consisting of interconnected physical systems each operating at the quantum limit. Experimental realities - correlated control errors, qubit-qubit cross-talk, structured noise - begin to play an ever greater role in technological performance. Quantum architecture at scale requires modeling that accurately describes these mesoscopic, hybrid phenomena across qubit modalities, such that system performance can be accurately predicted and optimized.  Problem identification: Quantum networks hold a tremendous promise for securing privileged communications in a way that completely eliminates the most common security threat: a man-in-the-middle attack. The current experimental quantum networks permit transferring quantum state across links spanning tens of miles, yet lack of adequate noise modeling results in extremely poor reliability. A recent publication describing  an advance in quantum satellite communications in China reported that transmission of a single digital key pair from a satellite to a ground station required 8 minutes; this suggests a huge volume of redundant messages required to compensate for a poor quality of the quantum channel. While state-of-the-art quantum networks and quantum computing protocols are often hybrid in nature, consisting of quantum systems using different hardware technologies, modeling hybrid quantum networks under realistic conditions is an unsolved problem.