Still awaiting the quantum turn: updated

Updated May 2019

Since this post was published, there has been an increasing interest in reformulating quantum mechanics in informational terms: an accessible introduction is given in an article in Quanta magazine by Philip Ball. Those who want to have a look at more technical examples might try a classic paper on an informational derivation of quantum theory, one on a unification of force and matter by quantum information, or a recent review of the topic.

This is associated with a continued emphasis on treating quantum theory as an abstract mathematical structure, based in probability theory, and divorced from physical applications. This in turn supports the validity of applying quantum formalism to ‘non-physical but information-related’ contexts, as described in the original post.

Two years ago (as of July 2017) a paper by myself and my colleagues Lyn Robinson and Tyabba Siddiqui was published in JASIST, introducing and explaining the idea of an emerging ‘quantum information science’. We argued that this could be seen in five respects: use of loose analogies and metaphors between concepts in quantum physics and library/information science; use of quantum concepts and formalisms in information retrieval; use of quantum concepts and formalisms in studying meaning and concepts; development of quantum social science, in areas adjacent to information science; and qualitative application of quantum concepts in the information disciplines themselves. This post discusses some developments since that paper was written.

Interest in the links between quantum theory and information continues. In the physics arena, an intriguing attempt is being made to construct the whole formalism of quantum mechanics on information-theoretic principles, as set out by D’Ariano, Chiribella and Perinotti in their new Quantum theory from first principles: an informational approach. A similar attempt is being made by the proponents of ‘QBism’ (Quantum Bayesianism), or ‘participatory realism’, according to which any the result of any quantum measurement will depend on the information possessed by the observer. Quantum computers are getting near the stage of demonstrating their practical utility, as shown by the stated intention of Google’s quantum computer team to produce, by the end of 2017, a small quantum device able to deal with problems previously the preserve of supercomputers.

In the application of quantum formalisms applied to information retrieval, a book by Massimo Melucci, several of whose papers were discussed in our JASIST paper, summarises the state of the art. He states particularly clearly the way in which the quantum ideas are applied: “The idea behind the quantum-like approach to disciplines of than physics is that, although the quantum properties exhibited by particles such as photons cannot be exhibited by macroscopic objects, some phenomena can be described by the language or have some characteristics of the phenomena (e.g. superposition or entanglement) described by the quantum mechanical framework in physics … This book is not about quantum phenomena in IR: in contrast, it aims to propose the use of the mathematical language of the quantum mechanical framework for describing the mode of action of a retrieval system” (pp viii and xi).

At a more general level, the idea of “quantum informational structural realism” (QISR) has caused some interest since it was introduced by Terrell Ward Bynum. An extension of “Information Structural Realism”, first proposed by Luciano Floridi, this provides a full ontological account of the universe in which there is an observer-independent reality, whose ultimate nature is neither physical or mental, but informational, and defined by the interactions between informational entities. QSIR insists that these entities have quantum properties. Betsy Van der Veer Martens was kind enough to note that this “links intriguingly” with the idea of a quantum turn in information studies identified in our JASIST paper

In the area of ‘quantum social science’, there has been one major contribution since the JASTST paper appeared. Alexander Wendt in his book Quantum mind and social science: unifying physical and social ontology starts from the idea of consciousness as a quantum phenomenon on the macro-scale, and uses it to argue that language, social interaction, and culture should be regarded also as quantum in nature, and hence that a quantum approach is of direct relevance to social science. Wave functions are real, and operate at the social level. However, the arguments seem, like some of those reviewed in our JASIST paper, to be essentially metaphorical. In an interview, Wendt, noting that he was influenced to think about the topic by Zohar and Marshall’s popular book, The Quantum Society, gives an example of what he considers quantum effects in social science. He considers a Vietnamese tourist in Denmark going into a shop. The tourist speaks no Danish, and the shopkeeper no Vietnamese; but if they discover that they have English as a common language, then their minds will, Wendt suggests, become “entangled” in a quantum sense. One has to say that this is not the sense of entanglement which would be understood by a physicist. Nonetheless, this book is symptomatic of a potential quantum turn in social science generally, which has clear relevance to the information sciences.

We may conclude that quantum concepts still intrigue and influence the social sciences, including the information sciences, but that no new paradigm has been accepted. The information retrieval applications of the mathematical formalisms of quantum mechanics seems most firmly grounded; claims of true quantum phenomena in settings are as yet un-evidenced, and the metaphorical use of terminology, though increasingly popular, has yet to show real benefit. Perhaps we need to wait for a new formulation of quantum mechanics in informational terms to emerge from physics and be fully accepted, before the quantum turn in information science can be realised; it may be that QISR is the first indicator of this.

Bawden, D., Robinson, L. and Siddiqui, T. (2015), “Potentialities or possibilities”: Towards quantum information science? Journal of the American Society for Information Science and Technology, 66(3), 437-449, open access version in the Humanities Commons at

Becker, C. (2015), Q and A: Alexander Wendt on ‘Quantum mind and social science’, Mershon Centrer for international Security Studies [online], available at

Courtland, R. (2017), Google plans to demonstrate the supremacy of quantum computing, IEEE Spectrum [online], available at

D’Ariano, G.M., Chiribella, G. and Perinotti, P. (2017), Quantum theory from first principles: an informational approach, Cambridge: Cambridge University Press

Melucci, M. (2015), Introduction to information retrieval and quantum mechanics, Berlin: Springer

Van der Veer Martens, B. (2015), An illustrated introduction to the infosphere, Library Trends, 63(3), 317-361

Waldrop, M.M. (2017) Painting a QBist picture of reality, FQXI Community [online], available at

Ward Bynum, T. (2013), On the possibility of quantum informational structural realism, Minds and Machines, 24(1), 123-139

Ward Bynum, T. (2016), Informational metaphysics, in Floridi, L. (ed.), The Routledge Handbook of the Philosophy of Information, London: Routledge, pp. 203-218

Wendt, A. (2015), Quantum mind and social science: unifying physical and social ontology, Cambridge: Cambridge University Press

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