Decoherence Control in Open Quantum System via Classical Feedback

Abstract

In this work we propose a novel strategy using techniques from systems theory to completely eliminate decoherence and also provide conditions under which it can be done so. A novel construction employing an auxiliary system, the bait, which is instrumental to decoupling the system from the environment is presented. Our approach to decoherence control in contrast to other approaches in the literature involves the bilinear input affine model of quantum control system which lends itself to various techniques from classical control theory, but with non-trivial modifications to the quantum regime. The elegance of this approach yields interesting results on open loop decouplability and Decoherence Free Subspaces(DFS). Additionally, the feedback control of decoherence may be related to disturbance decoupling for classical input affine systems, which entails careful application of the methods by avoiding all the quantum mechanical pitfalls. In the process of calculating a suitable feedback the system has to be restructured due to its tensorial nature of interaction with the environment, which is unique to quantum systems. The results are qualitatively different and superior to the ones obtained via master equations. Finally, a methodology to synthesize feedback parameters itself is given, that technology permitting, could be implemented for practical 2-qubit systems to perform decoherence free Quantum Computing.

17 pages, 4 Figs

References in corpus (4)

• A Magnetic Resonance Realization of Decoherence-Free Quantum Computation
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• Inverse Engineering Control in Open Quantum Systems
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• Transition from weak to strong measurements by nonlinear quantum feedback control
• Dark Modes of Quantum Linear Systems
• Feedback-induced nonlinearity and superconducting on-chip quantum optics
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• Quantum Internal Model Principle: Decoherence Control
• Control-Induced Decoherence-Free Manifolds
• Quantum Markovian Subsystems: Invariance, Attractivity, and Control