4,344 research outputs found
Information coding with frequency of oscillations in Belousov-Zhabotinsky encapsulated disks
Information processing with an excitable chemical medium, like the Belousov-Zhabotinsky (BZ) reaction, is typically based on information coding in the presence or absence of excitation pulses. Here we present a new concept of Boolean coding that can be applied to an oscillatory medium. A medium represents the logical TRUE state if a selected region oscillates with a high frequency. If the frequency fails below a specified value, it represents the logical FALSE state. We consider a medium composed of disks encapsulating an oscillatory mixture of reagents, as related to our recent experiments with lipid-coated BZ droplets. We demonstrate that by using specific geometrical arrangements of disks containing the oscillatory medium one can perform logical operations on variables coded in oscillation frequency. Realizations of a chemical signal diode and of a single-bit memory with oscillatory disks are also discussed
Towards constructing one-bit binary adder in excitable chemical medium
Light-sensitive modification (ruthenium catalysed) of the
Belousov-Zhabotinsky medium exhibits various regimes of excitability depending
on the levels of illumination. For certain values of illumination the medium
switches to a sub-excitable mode. An asymmetric perturbation of the medium
leads to formation of a travelling localized excitation, a wave-fragment which
moves along a predetermined trajectory, ideally preserving its shape and
velocity. To implement collision-based computing with such wave-fragments we
represent values of Boolean variables in presence/absence of a wave-fragment at
specific sites of medium. When two wave-fragments collide they either
annihilate, or form new wave-fragments. The trajectories of the wave-fragments
after the collision represent a result of the computation, e.g. a simple
logical gate. Wave-fragments in the sub-excitable medium are famously difficult
to control. Therefore, we adopted a hybrid procedure in order to construct
collision-based logical gates: we used channels, defined by lower levels
illumination to subtly tune the shape of a propagating wave-fragment and allow
the wave-fragments to collide at the junctions between channels. Using this
methodology we were able to implement both in theoretical models (using the
Oregonator) and in experiment two interaction-based logical gates and assemble
the gates into a basic one-bit binary adder. We present the first ever
experimental approach towards constructing arithmetical circuits in
spatially-extended excitable chemical systems
Towards heterotic computing with droplets in a fully automated droplet-maker platform
The control and prediction of complex chemical systems is a difficult problem due to the nature of the interactions, transformations and processes occurring. From self-assembly to catalysis and self-organization, complex chemical systems are often heterogeneous mixtures that at the most extreme exhibit system-level functions, such as those that could be observed in a living cell. In this paper, we outline an approach to understand and explore complex chemical systems using an automated droplet maker to control the composition, size and position of the droplets in a predefined chemical environment. By investigating the spatio-temporal dynamics of the droplets, the aim is to understand how to control system-level emergence of complex chemical behaviour and even view the system-level behaviour as a programmable entity capable of information processing. Herein, we explore how our automated droplet-maker platform could be viewed as a prototype chemical heterotic computer with some initial data and example problems that may be viewed as potential chemically embodied computations
From memory to processing : a reaction-diffusion approach to neuromorphic computing
The goal of this research is to bridge the gap between the physiological brain and mathematically based neuromorphic computing models. As such, the reaction-diffusion method was chosen as it can naturally exhibit properties like propagation of excitation that are seen in the brain, but not current neuromorphic computing models. A reaction-diffusion memory unit was created to demonstrate the key memory functions of sensitization, habituation, and dishabituation, while a reaction-diffusion brain module was established to perform the specific processing task of single-digit binary addition. The results from both approaches were consistent with existing literature detailing physiological memory and processing in the human brain
Quantum Engineering in Diamond
Solid-state technologies for quantum mechanical application require delicate materials that can operate stably with a long coherence time. Nitrogen vacancy (NV) centers in diamond is one of the most promising candidates for quantum physics, with applications such as single photon emitters, quantum computation, and magnetic sensor.
To fully exploit the capability of defect centers in diamond for opto-electronics and quantum engineering, a number of improvements are needed. Among these are optimization of the NV centers yield in bulk diamond, nanodiamond (ND) size reduction, photocurrent study of the defect band-trap electronic structure in diamonds, and optimization of high-speed NV qubit control. For NV centers yield optimization, both the experimental magnetic sensitivity optimization as well as theoretical simulation of NV concentration are implemented. For NDs size characterization, we analyzed the size and photon autocorrelation function of NV in NDs after air oxidation treatment using a combined atomic force microscopy/confocal system. To study defect band-trap electronic structure in diamond, excitation and quenching as well as the recovery of the quenched photocurrent was investigated to better understand photocurrent dynamics in diamond. For qubit high-speed control optimization, a microwave pulse based on a nonlinear numeric solution of the Schrodinger equation is used to rotate the NV spin faster than the ordinary Rabi flip rate. Together these approaches promise to significantly speed up the development of diamond for quantum engineering applications
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