Quantum computing and complexity in art

The author draws on her research experience in quantum computing to discuss the conception and form of an interactive installation CLOUD. CLOUD explores complexity in the post-digital by referencing the principles of quantum superposition, quantum entanglement and quantum measurement

MA Digital Direction, MA Information Experience Design

This paper addresses some of the key research imperatives two courses, MA Digital Direction and MA Information Experience Design, embody, including the status of virtual and augmented realities, two technologies that are ontologically unstable, raising urgent research questions for staff and students alike. For IED Information can be quantitative or qualitative, numerical data, personal narratives, or socio-political issues. These are examined through investigative and experiential research, through a range of methods, to create transformative, immersive and multisensory experiences, with emphasis on content, context, materiality and atmosphere. For MA Digital Direction, the catalysing impact of digital technologies associated with time based media are addressed, in particular the course is concerned with both experimental and established approaches to production, direction, content creation and communication, in order to create innovative forms of storytelling and narrative experience that engage audiences in new ways. Both courses deploy augmented and virtual realities, with MA Digital Direction devoting a term to Immersive Adventures. And yet, the status of VR is still uncertain and has been a challenge for some years (Hillis, 1996: 70). Like the photograph, it is not clear exactly what VR is, whether it is a medium, a tool, an event or an extension of cinema. The ontological status of what it feels like to encounter VR, is also an enigma, in line with Dennett’s (1991) assertions about ineffable, subjective experience, or qualia. These and other questions about VR/AR technologies, as well as teaching strategies, are at the core of a new research hub established by academics within the School of Communication. The hub aims to address the question of how we can best teach a subject which no one truly understands, identifying some of the possibilities inherent in our own uncertainty and disorientation

Spatial Entanglement From Off-Diagonal Long Range Order in a BEC

We investigate spatial entanglement - particle-number entanglement between regions of space - in an ideal Bosonic gas. We quantify the amount spatial entanglement around the transition temperature for condensation by probing the gas with two localised two-level systems. We show that spatial entanglement in the gas is directly related to filling of the ground state energy level and therefore to the off-diagonal long-range order of the system and the onset of condensation.Comment: 7 pages, 3 figures. Extended from 4 to 7 pages. More detailed derivations of key formula. Extended introduction and background. Results remain unchange

Detection and engineering of spatial mode entanglement with ultra-cold bosons

We outline an interferometric scheme for the detection of bi-mode and multi-mode spatial entanglement of finite-temperature,interacting Bose gases of fixed particle number. Whether entanglement is present in the gas depends on the existence of the single-particle reduced density matrix between different regions of space. We apply the scheme to the problem of a harmonically trapped boson pair and show that while entanglement is rapidly decreasing with temperature, a significant amount remains for all interaction strengths at zero temperature.Thus, by tuning the interaction parameter, the distribution of entanglement between many spatial modes can be modified.Comment: 5 pages, 3 figure

Bell inequality for pairs of particle-number-superselection-rule restricted states

Proposals for Bell inequality tests on systems restricted by superselection rules often require operations that are difficult to implement in practice. In this paper, we derive a new Bell inequality, where pairs of states are used to by-pass the superselection rule. In particular, we focus on mode entanglement of an arbitrary number of massive particles and show that our Bell inequality detects the entanglement in the pair when other inequalities fail. However, as the number of particles in the system increases, the violation of our Bell inequality decreases due to the restriction in the measurement space caused by the superselection rule. This Bell test can be implemented using techniques that are routinely used in current experiments.Comment: 9 pages, 6 figures; v2 is the published versio

Equilibrium and Disorder-induced behavior in Quantum Light-Matter Systems

We analyze equilibrium properties of coupled-doped cavities described by the Jaynes-Cummings- Hubbard Hamiltonian. In particular, we characterize the entanglement of the system in relation to the insulating-superfluid phase transition. We point out the existence of a crossover inside the superfluid phase of the system when the excitations change from polaritonic to purely photonic. Using an ensemble statistical approach for small systems and stochastic-mean-field theory for large systems we analyze static disorder of the characteristic parameters of the system and explore the ground state induced statistics. We report on a variety of glassy phases deriving from the hybrid statistics of the system. On-site strong disorder induces insulating behavior through two different mechanisms. For disorder in the light-matter detuning, low energy cavities dominate the statistics allowing the excitations to localize and bunch in such cavities. In the case of disorder in the light- matter coupling, sites with strong coupling between light and matter become very significant, which enhances the Mott-like insulating behavior. Inter-site (hopping) disorder induces fluidity and the dominant sites are strongly coupled to each other.Comment: about 10 pages, 12 figure

Dissipation enhanced vibrational sensing in an olfactory molecular switch

Motivated by a proposed olfactory mechanism based on a vibrationally-activated molecular switch, we study electron transport within a donor-acceptor pair that is coupled to a vibrational mode and embedded in a surrounding environment. We derive a polaron master equation with which we study the dynamics of both the electronic and vibrational degrees of freedom beyond previously employed semiclassical (Marcus-Jortner) rate analyses. We show: (i) that in the absence of explicit dissipation of the vibrational mode, the semiclassical approach is generally unable to capture the dynamics predicted by our master equation due to both its assumption of one-way (exponential) electron transfer from donor to acceptor and its neglect of the spectral details of the environment; (ii) that by additionally allowing strong dissipation to act on the odorant vibrational mode we can recover exponential electron transfer, though typically at a rate that differs from that given by the Marcus-Jortner expression; (iii) that the ability of the molecular switch to discriminate between the presence and absence of the odorant, and its sensitivity to the odorant vibrational frequency, are enhanced significantly in this strong dissipation regime, when compared to the case without mode dissipation; and (iv) that details of the environment absent from previous Marcus-Jortner analyses can also dramatically alter the sensitivity of the molecular switch, in particular allowing its frequency resolution to be improved. Our results thus demonstrate the constructive role dissipation can play in facilitating sensitive and selective operation in molecular switch devices, as well as the inadequacy of semiclassical rate equations in analysing such behaviour over a wide range of parameters.Comment: 12 pages, 6 figures, close to published version, comments welcom

Bell-inequality test of spatial mode entanglement of a single massive particle

Experiments showing the violation of Bell inequalities have formed our belief that the world at its smallest is genuinely non-local. While many non-locality experiments use the first quantised picture, the physics of fields of indistinguishable particles, such as bosonic gases, is captured most conveniently by second quantisation. This implies the possibility of non-local correlations, such as entanglement, between modes of the field. In this paper we propose an experimental scheme that tests the theoretically predicted entanglement between modes in space occupied by massive bosons. Moreover, the implementation of the proposed scheme is capable of proving that the particle number superselection rule is not a fundamental necessity of quantum theory but a consequence of not possessing a distinguished reference frame.Comment: 5 pages, 2 figures. Version two has been accepted for publication in Physical Review