Randomized Dynamical Decoupling Techniques for Quantum Information Processing

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Quantum mechanics provides novel paradigms for processing information by harnessing phenomena that have no classical analog. Physical realizations of quantum information promise, in particular, great improvements in our abilities to solve hard computational problems and simulate complex systems. However, quantum information is incredibly more vulnerable than its classical counterpart to the effects of both environmental noise and operational errors. Although powerful approaches based on fault-tolerant quantum error correction have been developed to cope with the challenge of counteracting quantum noise, practical exploitation of these results remains severely constrained due to the large overheads and design complexity involved.Dynamical decoupling techniques have recently emerged as an increasingly attractivestrategy for coherent dynamical control and error suppression in quantum information pro-cessing. Broadly inspired by spin-echo phenomena and coherent averaging techniques innuclear magnetic resonance spectroscopy, decoupling methods offer the compelling advan-tage of avoiding auxiliary memory resources and measurement capabilities, while remainingapplicable to a large class of physically relevant devices and error processes.The central theme of the proposed research is to further push the theoretical and practical significance of dynamical decoupling methods, by investigating a novel randomized setting which overcomes important limitations of existing deterministic schemes. The focus will be on both (i) exploring randomized decoupling schemes within a device-independent control-theoretic framework, by identifying in particular optimal ways for merging advantageous features of purely deterministic and random protocols and by obtaining analytical error bounds on expected performance; (ii) benchmarking the actual performance of randomized control schemes in qubit devices of direct relevance to proposed quantum information processing technologies, with emphasis on solid-state spin-based qubit implementations.