Abstract
Progress in controlling quantum systems is the major pre-requisite for the realization of quantum computing, yet the results of quantum computing research can also be useful in solving quantum control problems that are not related to computational problems. We arguethat quantum computing provides clear concepts and simple models for discussing quantum theoretical problems. In this article we describe examples from completely different fields where models of quantum computing and quantum communication shed light on quantum theory.
First we address quantum limits of classical low power computation and argue that the terms of quantum information theory allows us to discuss device-independent bounds. We argue that a classical bit behaves to some extent like a quantum bit in the time period where it switches its logical value. This implies that a readout during the switching process generates entropy. A related problem is the distribution of timing information like clock signals in low power devices. For low signal energy, the situation is close to phase-covariant cloning problems in quantum information theory.
Second we rephrase a classical statistical method to draw causal conclusions from data of a clinical drug-testing experiment. Since this method, as it is described in the literature, relies on a hidden-variable model of patient’s behaviour it leads to misconclusions if quantum theory infact does play a role in the human mind. The toy model we use to illustrate this is formally a quantum communication protocol in the presence of entanglement. We argue that quantum information theory could put classical statistical reasoning on a safer basis because it does not need hidden-variable models of nature.
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Janzing, D. Quantum computing models as a tool box for controlling and understanding the nanoscopic world . Informatik Forsch. Entw. 21, 83–90 (2006). https://doi.org/10.1007/s00450-006-0013-x
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DOI: https://doi.org/10.1007/s00450-006-0013-x