Towards Spin-based Quantum Computing in the Solid State: Tomography of a Spin Node

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Harnessing the quantum behavior of nanoscopic physical systems is at the center of a broad cross-disciplinary effort driven by the promise of various applications for information processing and secure communication. The prospect of performance gains and increased complexity is driving interest in new devices for existing or new functions (particularly, quantum information processing (QIP) protocols) as well as new paradigms for system architectures beyond present technology. Implementations based on solid-state "spin complexes" formed by individual paramagnetic dopants and neighboring nuclear and electronic spins are of particular importance because spin-based quantum technology is well positioned to overcome the obstacles to scaling. Assembling atomically identical spin clusters, however, is unlikely in the near term future, making new protocols necessary to precisely determine the spatial structure of an individual node and selectively address single spins within the complex. In line with these ideas, this grant articulates state-of-the-art nanoscale technology and novel spin manipulation schemes to resolve the network of relative couplings of nuclear spins in the vicinity of the so-called NV center in diamond, arguably one of the most promising platforms for future spintronic and QIP devices. Underlying our effort is the notion of circuits configured to exploit the atomic scale differences between logic units so as to process quantum information in optimal ways. Capitalizing on multi-dimensional spectroscopy and high-resolution imaging schemes, it will be possible to expose the structure and connectivity within the nuclear spin network of a given node in ways resembling the solving of a complex molecular structure. Such information will be crucial to identifying and exploiting long-lived nuclear memories, or to implementing quantum correction protocols without resorting to additional, ad-hoc coupling interfaces. Besides the technological and scientific advantages, our work is expected to have a broad educational outcome because it will offer students a unique inter-disciplinary scientific training and the ability to interact with a network of collaborating labs. These partnerships not only will provide a broad dissemination platform but also will allow the PI to advance ongoing outreach programs designed to provide meaningful research experiences to underprivileged students through summer activities. These plans gain special meaning at City College, a minority serving institution with a uniquely diverse population of inner-city students. Capitalizing on the various recruitment channels at hand, the teaching, mentoring and career counseling components of this project will truly broaden participation, while encouraging groups underrepresented in the sciences to pursue scientific careers both in academia and in industry.