Quantum key distribution session with 16-dimensional photonic states

The secure transfer of information is an important problem in modern telecommunications. Quantum key distribution (QKD) provides a solution to this problem by using individual quantum systems to generate correlated bits between remote parties, that can be used to extract a secret key. QKD with D-dimensional quantum channels provides security advantages that grow with increasing D. However, the vast majority of QKD implementations has been restricted to two dimensions. Here we demonstrate the feasibility of using higher dimensions for real-world quantum cryptography by performing, for the first time, a fully automated QKD session based on the BB84 protocol with 16-dimensional quantum states. Information is encoded in the single-photon transverse momentum and the required states are dynamically generated with programmable spatial light modulators. Our setup paves the way for future developments in the field of experimental high-dimensional QKD.Comment: 8 pages, 3 figure

High-dimensional decoy-state quantum key distribution over 0.3 km of multicore telecommunication optical fibers

Multiplexing is a strategy to augment the transmission capacity of a communication system. It consists of combining multiple signals over the same data channel and it has been very successful in classical communications. However, the use of enhanced channels has only reached limited practicality in quantum communications (QC) as it requires the complex manipulation of quantum systems of higher dimensions. Considerable effort is being made towards QC using high-dimensional quantum systems encoded into the transverse momentum of single photons but, so far, no approach has been proven to be fully compatible with the existing telecommunication infrastructure. Here, we overcome such a technological challenge and demonstrate a stable and secure high-dimensional decoy-state quantum key distribution session over a 0.3 km long multicore optical fiber. The high-dimensional quantum states are defined in terms of the multiple core modes available for the photon transmission over the fiber, and the decoy-state analysis demonstrates that our technique enables a positive secret key generation rate up to 25 km of fiber propagation. Finally, we show how our results build up towards a high-dimensional quantum network composed of free-space and fiber based linksComment: Please see the complementary work arXiv:1610.01812 (2016

Small task-oriented groups : a systems analysis : a thesis presented in partial fulfilment of the requirements for the degree of Master of Arts in Education at Massey University

Where two or more people are gathered together in order to engage in social interaction - there is a social system". (Anon.) The question of why it is that people come together in systems of interaction and how these systems persist as viable social arrangements is one which has been taken up by social philosophers and sociological theorists as far back as Hobbes. Subsequently Spencer, Durkheim, and such contemporary figures as Homans, Merton and Parsons have also taken issue with this problem. The present thesis shares a similar concern with the problem and derives its stimulus from the way in which sociologists have attempted to formulate adequate explanatory theories. The thesis exhibits a convergence in the interests of the two authors - on the one hand, an interest in the application of parsonian theory' to small group phenomena, and on the other, the use of 'systems theory' in the explanation of social interaction in educational settings. The specific focus of attention is on those groups which have the properties of being small and task-oriented. Such groups are ubiquitous in educational contexts. At the most general level the thesis uses Parsons' voluntaristic theory of social action as the frame of reference from which a theory of small task-oriented groups can be derived. The thesis is therefore an expedition into the realms of sociological theory and an exploration of the way in which parsons' theory in particular can be applied to an empirical situation. Elements of general systems theory have been employed to further limit the scope of the investigation by focussing only on the internal dynamic of small task-oriented groups, rather than the way in which they adapt to their surrounding environments, thus enabling such groups to be conceptualised as discrete social systems in their own right. [From Introduction

Secure quantum channels with correlated twin laser beams

This work is the development and analysis of the recently proposed quantum cryptographic protocol, based on the use of the two-mode coherently correlated states. The protocol is supplied with the cryptographic control procedures. The quantum noise influence on the channel error properties is examined. State detection features are proposed

Controlled order rearrangement encryption for quantum key distribution

A novel technique is devised to perform orthogonal state quantum key distribution. In this scheme, entangled parts of a quantum information carrier are sent from Alice to Bob through two quantum channels. However before the transmission, the orders of the quantum information carrier in one channel is reordered so that Eve can not steal useful information. At the receiver's end, the order of the quantum information carrier is restored. The order rearrangement operation in both parties is controlled by a prior shared control key which is used repeatedly in a quantum key distribution session.Comment: 5 pages and 2 figure

The impact of financial histories on individuals and societies: A replication of and extension of Berg el al. (1995)

We replicate and extend the social history treatment of the Berg, Dickhaut, and McCabe (1995) investment game, to further document how the reporting of financial history influences how laboratory societies organize themselves over time. We replicate Berg et al. (1995) by conducting a No History and a Financial History session to determine whether a report summarizing the financial transactions of a previous experimental session will significantly reduce entropy in the amounts sent by Investors and returned by Stewards in the investment game, as Berg et al. (1995) found. We extend Berg et al. (1995) in two ways. First, we conduct a total of five sessions (one No History and four Financial History sessions). Second, we introduce Shannon's (1948) measure of entropy from information theory to assess whether the introduction of financial transaction history reduces the amount of dispersion in the amounts invested and returned across generations of players. Results across sessions indicate that entropy declined in both the amounts sent by Investors and the percentage returned by Stewards, but these patterns are weaker and mixed compared to those in the Berg et al. (1995) study. Additional research is needed to test how initial conditions, path dependencies, actors' strategic reasoning about others' behavior, multiple sessions, and communication may mediate the impact of financial history. The study's multiple successive Financial History sessions and entropy measure are new to the investment game literature