a r t i s t ’ s a r t i c l e Quantum Computing and Complexity in Art L i bb y H e A n e y The author draws on her research experience in quantum computing of the universe. Quantum mechanics describes the universe to discuss the conception and form of an interactive installation, at its most basic level, and quantum systems are inherently CLOUD. CLOUD explores complexity in the postdigital by referencing complex [11]. Importantly, this complexity is different from the principles of quantum superposition, quantum entanglement and ABSTRACT quantum measurement. that of classical (nonquantum) systems. For instance, the superposition principle enables a single quantum particle to span infinite dimensions [12], and entangled states of many Understanding complexity is the most critical issue of our particles increase the complexity further. Eisert has argued times. So often, intricately detailed concepts or narratives that most composite quantum systems are too complex (en- are reduced to simple natural versus artificial, or good ver- tangled) to perform computation upon them [13]. Therefore sus evil, tales propagated by the (social) media. For instance, we may ask whether referencing quantum effects through Adam Curtis explores complexity in popular reductive nar- art and design practices would provide new methods for ar- ratives through his films Bitter Lake [1] and HyperNormali- ticulating complexity. I argue in the affirmative, while noting sation [2], and George Marshall explores narratives around some challenges along the way. climate change in his book Don’t Even Think About It [3]. For First, it is important to question why quantum physics is all cultural practitioners, it is important to research and ex- relevant to our everyday experience, since the physics of the periment with new forms and techniques that enable people systems mentioned above, from the notes in a jazz composi- to understand, experience and interact with complexity on tion to a biological cell, is classical. And while quantum phys- their own terms. I believe concepts from quantum comput- ics is not usually applied to macroscopic systems, a recent ing will bring new and broader techniques into our toolbox theory called quantum interactions [14] argues that quantum for articulating complexity and I use my postdigital installa- logic can be applied away from quantum physics’ usual mi- tion CLOUD to unpack these issues throughout this paper. croscopic domain. That is, parts of the quantum mathemati- Complexity is a generic feature of large systems [4] and cal framework appear in nonphysical aspects of psychology, thus occurs across disciplines from biology to finance. As economics, cognition and computational linguistics. Quan- such its definition is notoriously difficult to pin down—for tum theory is thus related to how humans think and com- instance, one may talk about computational complexity (the municate and therefore a potential tool for the exploration difficulty of solving certain computational problems [5]) or of complexity through creative practices. the complexity of an artwork or jazz composition (as the In fact, using quantum physics as a metaphor for com- depth to the piece [6]). Johnson [7] wrote about properties plex systems is not new. Ascott has discussed it extensively of classical complex systems in Emergence, and artists such as in the context of telematic systems and meaning since the Heather Barnett, Keith Tyson and Jennifer Steinkamp [8–10] 1960s. More recently, Barad used Bohr’s philosophy-physics focus on investigating concepts from such systems and creat- to develop her theory of agential reality [15], and Plotnitsky ing metaphorical connections. explores relationships/disparities between Bohr’s comple- It is easy to believe that systems cannot be more complex mentarity and poststructuralist theory, notably Derrida [16]. than biology or finance. However, complexity increases expo- There are some contradictions in referencing quantum nentially when zooming into the fundamental constituents effects through creative practices, however, since genuine quantum effects cannot be represented in macroscopic, Libby Heaney (artist, physicist, tutor), Royal College of Art, Kensington Gore, physical artworks, as the Schrödinger’s cat paradox high- London, SW7 2EU, U.K. Email: [email protected]. lights (supplementary appendix Part 1). However, I do not See www.mitpressjournals.org/toc/leon/52/3 for supplemental files associated believe this is a problem. As James Elkins puts it when dis- with this issue. cussing quantum physics imagery, “there is an inherent, 230 LEONARDO, Vol. 52, No. 3, pp. 230–235, 2019 doi:10.1162/LEON_a_01572 ©2019 ISAST Downloaded from http://www.mitpressjournals.org/doi/pdf/10.1162/leon_a_01572 by guest on 24 September 2021 Fig. 1. CLOUD, 2015. (© Libby Heaney) Fig. 3. People moving around in the space in front of CLOUD and remotely altering the patterns displayed, 2015. (© Libby Heaney) Fig. 2. Close-up of CLOUD showing graphite and white octahedrons, 2015. (© Libby Heaney) Fig. 4. The pixels in CLOUD randomly positioning, 2015. (© Libby Heaney) systemic contradiction in this practice: it says both ‘quantum phenomena need to be visualized [in order to teach it]’ and Each pixel is half shaded with graphite, and the other half that ‘quantum phenomena aren’t amenable to visualization’ ” is left as blank paper (Fig. 2). Behind are the electronics— [17]. However, quantum physics images are useful as “free namely a servo motor for each pixel and ~500m of wiring. versions of a rigorous practice, intended to be suggestive The orientations of the pixels are determined, in part, by data and approximate rather than dependable and exact” [18] and from a Microsoft Kinect depth camera, which senses the area “even images regarded by members of the physics commu- in front of the piece, where a coded, invisible copy of the nity as patently inadequate or misguided can also come to physical structure is digitally “reflected” across the floor. seem potentially helpful” [19]. So while CLOUD focuses on The presence of people in this space causes CLOUD to experience as well as representation, it could also be viewed change its configuration. Before anyone enters the space, the as a sequence of images that renders quantum computing pixels are in an ordered, low-entropy configuration: Every both “unpicturable and picturable,” articulating complexity single one is facing the same way (half-colored and half- through traces of properties that are essentially inconceivable. blank). Then, as participants walk around in the space, their paths are gradually mapped onto CLOUD through a random CLOUD orientation of the corresponding pixels (Fig. 3). Each location CLOUD is an installation that spans the digital and the in front of CLOUD has a one-to-one link with a pixel such physical. The physical consists of 54 independently rotating that when a person steps into a location, the code control- octahedral “pixels” made from paper, tessellated within a ling the installation randomly chooses to rotate the linked hand-knotted linen net that in turn is suspended by a scaffold pixel left or right to reveal fully its shaded or blank side [S-2 frame (commissioned as part of a wider exhibition) (Fig. 1). - code] (Fig. 4). Overall, the installation thus evolves from an Heaney, Quantum Computing and Complexity in Art 231 Downloaded from http://www.mitpressjournals.org/doi/pdf/10.1162/leon_a_01572 by guest on 24 September 2021 Fig. 5. Two Necker cubes placed next to each other illustrate the correlations of entanglement. ordered to a random state, contingent on how people move putation [23], where the utilization of entanglement and in the space, with the pixels slowly reordering themselves quantum measurement to drive computation can be seen after people have moved away from the piece for a certain most strikingly. amount of time. Measurement-based quantum computation proceeds The functioning ofCLOUD was inspired, in part, by three as follows. Before the computation takes place, a large en- features of quantum information science [20]. First, the su- tangled state, called a cluster state, is created between hun- perposition principle states that any quantum system can dreds of spatially localized qubits [24]. This forms a grid-like be in multiple states simultaneously—for instance, a single structure, in some sense like hundreds of Necker cubes ar- massive particle such as a carbon C-60 “buckyball” molecule ranged in a square. For massive particles, qubits are logically passing through two spatially separated spits [21]. When represented by electron spin. The entanglement between quantum mechanics is applied to computation, a bit becomes neighboring particles means that the information about the a quantum bit (or qubit) and is no longer in either a zero or orientations of individual spins is nonlocally distributed over one state but may be in both simultaneously. Superposition is the entire system [25]. Once a cluster state is engineered, the somewhat like, but fundamentally different from, the famous computation proceeds via a sequence of different measure- gestalt image of two faces or a vase—depending on where in ments that themselves encode the algorithm on the individ- the image the observer looks, they will see one or the other ual qubits in the cluster state. These measurements destroy representation. the spin-entanglement between the measured qubits and the The second feature that informed this installation is quan- rest of the lattice. The measured qubits are in random states, tum entanglement. This is the extension of quantum super- but the remaining parts of the cluster state—yet to be mea- position for two or more quantum particles. In entangled sured—draw closer to the final solution of the computation. states, the information about the properties of each particle Since measurement-based quantum computing was my (for instance their spin or position) is delocalized over all the starting point for CLOUD, it felt natural to explore complex- particles, and the entire system is in a superposition of vari- ity by promoting the viewer to the role of the measuring ous configurations [22].