Single spin probe of Many-Body Localization

We use an external spin as a dynamical probe of many body localization. The probe spin is coupled to an interacting and disordered environment described by a Heisenberg spin chain in a random field. The spin-chain environment can be tuned between a thermalizing delocalized phase and non-thermalizing localized phase, both in its ground- and high-energy states. We study the decoherence of the probe spin when it couples to the environment prepared in three states: the ground state, the infinite temperature state and a high energy N\'eel state. In the non-thermalizing many body localized regime, the coherence shows scaling behaviour in the disorder strength. The long-time dynamics of the probe spin shows a logarithmic dephasing in analogy with the logarithmic growth of entanglement entropy for a bi-partition of a many-body localized system. In summary, we show that decoherence of the probe spin provides clear signatures of many-body localization.Comment: 5 pages, 4 figure

Classical many-body time crystals

Discrete time crystals are a many-body state of matter where the extensive system's dynamics are slower than the forces acting on it. Nowadays, there is a growing debate regarding the specific properties required to demonstrate such a many-body state, alongside several experimental realizations. In this work, we provide a simple and pedagogical framework by which to obtain many-body time crystals using parametrically coupled resonators. In our analysis, we use classical period-doubling bifurcation theory and present a clear distinction between single-mode time-translation symmetry breaking and a situation where an extensive number of degrees of freedom undergo the transition. We experimentally demonstrate this paradigm using coupled mechanical oscillators, thus providing a clear route for time crystals realizations in real materials.Comment: 23 pages, 5 figures, comments are welcom

Computer Crimes: A Case Study of What Malaysia Can Learn from Others?

Rapid development of information technology (IT) has brought with it many new applications such as e-commerce and global business. The past few years have seen activities in the legislative arena covering issues such as digital signatures, the international recognition of electronic documents and privacy and data protection. Both the developed and developing countries have exhibited keenness to embrace the IT environment. Securing this electronic environment from intrusion, however, continues to be problematic. A particular favorite form of computer crime would be ‘hacking’. As more computer systems move on to on-line processing and improved telecommunications, computer hackers are now a real threat. Legislation criminalizing intrusion and destruction activities directed at computers are needed. Malaysia joined the list of countries with computer-specific legislation with the enactment of its Computer Crime Act 1997 (CCA). This paper focuses on hacking as a criminal act, and compares the Malaysian CCA with legislation from other countries. The current computer crime situation in Malaysia is looked at and exposes the difficulties and obstacles Malaysia faces in enforcing the Act. The paper concludes with recommendations for Malaysia in terms of policy, practices and penalties

Rapid flipping of parametric phase states

Since the invention of the solid-state transistor, the overwhelming majority of computers followed the von Neumann architecture that strictly separates logic operations and memory. Today, there is a revived interest in alternative computation models accompanied by the necessity to develop corresponding hardware architectures. The Ising machine, for example, is a variant of the celebrated Hopfield network based on the Ising model. It can be realized with artifcial spins such as the `parametron' that arises in driven nonlinear resonators. The parametron encodes binary information in the phase state of its oscillation. It enables, in principle, logic operations without energy transfer and the corresponding speed limitations. In this work, we experimentally demonstrate flipping of parametron phase states on a timescale of an oscillation period, much faster than the ringdown time \tau that is often (erroneously) deemed a fundamental limit for resonator operations. Our work establishes a new paradigm for resonator-based logic architectures.Comment: 6 pages, 3 figure

The role of fluctuations in quantum and classical time crystals

Discrete time crystals (DTCs) are a many-body state of matter whose dynamics are slower than the forces acting on it. The same is true for classical systems with period-doubling bifurcations. Hence, the question naturally arises what differentiates classical from quantum DTCs. Here, we analyze a variant of the Bose-Hubbard model, which describes a plethora of physical phenomena and has both a classical and a quantum time-crystalline limit. We study the role of fluctuations on the stability of the system and find no distinction between quantum and classical DTCs. This allows us to probe the fluctuations in an experiment using two strongly coupled parametric resonators subject to classical noise.Comment: 11 pages, 5 figure

Effect of supplementary sugar feeding on colony growth of Asiatic hive bee, Apis cerana indica F.

Honey bees also known as "Angels of Agriculture" are arguably the most vital insects on the planet. Bee nutrition is an important aspect of colony management. Supplementary feeding is essential for maintaining the strength and health of honey bee colonies, especially during dearth periods. Experiments were conducted to evaluate a suitable, cheaper carbohydrate supplement and its effect on the colony growth of the Asiatic hive bee Apis cerana indica. Four different sugar syrup components, viz., sugar, water, milk and glucose, were combined to form  seven treatments : T1-Sugar: water (1:1), T2-Sugar: water (1:1) + Glucose (2%),T3- Sugar: water (1:1) + Desi cow’s milk (2%),T4- Sugar + water (2:1), T5- Sugar + water (2:1) + Glucose (2%) ,T6- Sugar + water (2:1) + Desi cow’s milk (2%) and T7-Control and evaluated to select honey bee colonies . Among the different sugar syrup feeding treatments, the colonies fed with T2 - Sugar: water (1:1) + Glucose (2%) had a profound effect within a month and the colonies recorded an increase in sealed brood area from 175.66 cm2 to 425.00 cm2, honey store area from 49.00 cm2 to 130.33 cm2, pollen store area from 47. 33 cm2 to 125.33 cm2, adult bee population from 4318.66 bees/colony to 4933.33 bees/colony. The work is new to A. cerana indica. Many of their bee colonies suffer from poor nutrition and absconding during the dearth period. The present study will help the beekeeping farmers maintain these Asiatic honey bee colonies during the starved period and will be useful in income generation.          

Solvent Evaporation Technique Of Microencapsulation: A Systemic Review

Solvent evaporation is one of the most widely employed and investigated technique in pharmaceutical industries and research area for microencapsulation process.Microspheres are particles coated with a continuous film of polymeric material, having a diameter in range of 1 to 1000 ?m and are widely used as drug carriers. This technique provides a controlled drug release, having various clinical benefits. While initial lab scale experiments are carried out in simple beaker, stirrer setups, clinical trials and market introduction needs more sophisticated technologies, permitting economic robust, well-controllable and aseptic production of microspheres. In this review article our aim is to review and compile recent research work on solvent evaporation technique while focusing on different methods of above said technique and various factors affecting microencapsulation prepared by solvent evaporation technique