Tourism Minister Cathy Hugheswith Guyana just a few days away from observing one of its most monumental events, the Public Telecommunications and Tourism Ministry has recorded a high tourist influx to Guyana, the result of which has hotels across the country filled to capacity, leading to more persons opening their homes as part of the “Bed and Breakfast” initiative.This was confirmed by Tourism Minister Cathy Hughes, who told Guyana Times on Friday that the feedback has been “tremendous” in terms of tourists and the Diaspora showing their interest in being a part of the grand celebrations.The Minister additionally reported that the support from the Guyanese population has been outstanding as more persons are indicating their interest in opening their homes to house the tourists.Hughes related that only on Thursday, 60 persons had turned out at the Ministry to enlist their names and undergo training to be part of the “bed and breakfast” initiative which is being implemented to facilitate the large turnout expected from the Diaspora.These training sessions, according to the Minister, provides a comprehensive approach to how these persons can house their guests, and what is expected of them. “The people are excited to get on board with the initiative and they are ready to go,” she noted.Since rooms are booked at the hotels, Hughes announced that persons visiting from the Diaspora or those in Guyana, who are looking for a city hotel, need to first make contact with the Ministry so that they could assist in locating places for them.She said that once contacted, the Ministry may be able to assign a place under the “Bread and Breakfast” initiative where the guests can stay for the period of time leading up to the anniversary, and after.According to the information received, frequent inspections of the premises earmarked to house the impending guests are carried out by the members of the initiative’s committee.The Tourism Minister outlined that restaurants across the city have recorded a significant improvement in their businesses as the demand for fast food is escalating with the increased number of visitors from the Diaspora.Smaller restaurants, however, have reported that their businesses remain the same since many are not aware of the locations, and prefer the larger food outlets, Hughes said.Nonetheless, it has been reported that there is an overall improvement to the tourism sector in Guyana, as the long list of activities are attracting a large number of tourists from countries across the world.Even before most of the activities had been hosted, the number of tourist arrivals had been on the rise, as airlines had recorded a boost to their services.Hughes said that as early as March, hotels and airlines were all booked up as persons, on hearing of the events, rushed to purchase tickets and make reservations.The Tourism Ministry, prior to the lead up to the 50th anniversary celebrations, had expressed optimism about the positive responses they would receive as the country celebrates its independence.Over the past months, a number of events have been planned to mark the Golden Jubilee Anniversary.Most persons, however, are anticipating the Jubilee Float Parade set for May 26, which will pattern of the Republic Day float parade.
© 2014 Phys.org (Phys.org) —Optical transistors and switches are fundamental in both classical and quantum optical information processing. A key objective in optics research is determining and developing the structural and performance limits of such all-optical devices, in which a single gate photon modifies the transmission or phase accumulation of multiple source photons – a feature necessitating strong interaction between individual photons. While significant progress has been made – especially in cavity QED experiments, which use resonators to enhance interaction between photons, confined in a reflective enclosure, and natural or artificial atoms – the goal is to achieve high optical gain and high efficiency using a free-space – that is, cavity-free – approach. Recently, scientists at Universität Stuttgart, Germany demonstrated a free-space single-photon transistor based on two-color Rydberg interaction, which they say could lead to a high optical gain, high efficiency optical transistor through further improvements. (In a Rydberg atom a single electron is excited to a state with a large principal quantum number, meaning that it has high potential energy.) Moreover, the researchers state that the finding may lead to advances in quantum information processing, condensed matter physics, single step multi-photon entanglement, and other important areas. In addition, the paper notes that their novel approach could enable a high optical gain, high efficiency optical transistor, which so far has been realized only in a cavity QED setup, in which attenuation of hundreds of source photons has been demonstrated. “Cavity QED experiments employ an optical resonator to increase light-matter interaction,” Gorniaczyk says. “However, resonators come with technological challenges and fundamental limitations, such as limited bandwidth, which free-space experiments do not suffer.””Optical transistors open a wide range of potential optics applications, one of which is the single-shot detection of single photons,” Hofferberth tells Phys.org. “In addition, investigating different state combinations can lead to an increase in optical gain. In particular, the use of so-called Förster resonances1, as well as working with states that are directly coupled, can significantly boost performance. Modification of trap geometry for the cold atomic cloud would also improve our system by leading to a greater optical depth for source photons in the presence of gate photons – and thus to a higher attenuation. Finally, the retrieval of gate photons after the transistor experiment would open up the door to quantum computation.”Furthermore, the paper points out that the combination of two independently controlled Rydberg-EIT (electromagnetically induced transparency) schemes offers high flexibility. With two excitation schemes, the gate photon can efficiently be stored using a detuning to the intermediate state, whereas the source photons can propagate through the medium with reduced group velocity. Additionally, the two-color scheme enables novel fields of study, such as Förster resonances or directly dipole-dipole coupled Rydberg states. “Förster resonances occur when a pair state involving two Rydberg states resonantly couples to another pair state,” Tresp explains. “Using a suitable resonance allows to increase the interaction between gate and source photons, while the interaction among source photons can be kept low. This can lead to an increase in gain.” Theoretically, the researchers say, their optical transistor can be extended such that an imaging system with source photons can determine the position of gate excitations in a single shot. If the interaction between gate and source photons is very high, the exact position of gate excitations cannot be tracked back, so the resolution decreases with increasing interaction, especially if more gate excitations are present. “Moreover, our optical transistor can be seen as a device that entangles the gate photon with many source photons,” Gorniaczyk says. “The presence of source photons, for instance, implies the absence of the gate photon in the first place. Systems with strong many-body correlations are of high interest in quantum information technology, and many ideas could be realized including quantum gate arrays.” Quantum gate arrays are basic quantum circuits that process small numbers of qubits and are combined to construct quantum circuits.Another possible quantum computation application is the experimental embodiment of a two-photon phase gate based on Rydberg-polariton collisions(Polaritons are part matter, part light quasiparticles).) “We currently show that a gate photon efficiently attenuates source photons –or in other words, the gate photon causes absorption of source photons,” Hofferberth tells Phys.org. “It’s also possible, though, to modify the scheme such that the gate photon causes dispersion of the source photons, causing a phase shift of the source photons. The only modification required for this is to send the source photons with a different detuning into the medium. Currently they are tuned exactly onto resonance with an optical transition to cause strong absorption, but by detuning them the effect can be turned into a conditional phase shift.” A two-qubit phase-gate is a universal quantum gate, meaning that if a reliable phase gate is available along with single qubit gates), any quantum computation can be realized. “Our system would be the first purely photonic deterministic two qubit gate,” Hofferberth adds.In addition to the research plans discussed above, Gorniaczyk says since their work demonstrates controlled interaction between individual photons , the scientists can now turn towards realizing long-standing goals such as all-optical quantum computation. “Our explicit next goal is to demonstrate that the transistor can be operated with gain greater than 1, and the gate photon retrieved afterwards with all of its quantum properties intact. This will enable multi-photon entanglement in a single step and entangled states of multiple particles – in this case, the latter being photons – which are a key quantum information resource.”Another of their ideas is similar to the non-destructive detection of single atoms: If the gate photon can survive the transistor process, it will enable non-destructive quantum state detection of single photons. “Currently, all photon detection methods are destructive and limited in efficiency – in practice, usually to below 0.3,” Tresp explains. “A non-destructive detector with high fidelity would be an innovation with many applications in optical science.”Addressing other areas of research that might benefit from their study, Hofferberth notes that while their current work focuses on making the Rydberg-mediated interaction between photons useful for quantum applications, more generally it realizes a novel system of strongly interacting particles. “If the number of photons interacting with each other simultaneously can be further increased, such a system could be a novel approach to study many-body physics problems, as encountered in condensed matter physics. In addition,” he concludes, “the enormous flexibility of our system could be the foundation of a photon-based quantum simulator used to investigate systems that cannot easily be studied directly.” A transistor-like amplifier for single photons (a) Level scheme, (b) simplified schematic, and (c) pulse sequence of our all-optical transistor. (d) The absorption spectrum for the source field (dots) over the full intermediate state absorption valley shows the EIT window on resonance; the gate field spectrum (circles) is taken around the two-photon resonance at δg = 40 MHz. The solid lines are fits to the EIT spectra. The linewidth of the source EIT window Δν = 2 MHz and the optical depth OD ¼ 25 of our system are extracted from the brown curve. Credit: H. Gorniaczyk et al., Phys. Rev. Lett., 28 July 2014. Journal information: Physical Review Letters Doctoral students Hannes Gorniaczyk and Christoph Tresp, along with Dr. Sebastian Hofferberth, discussed the paper that they and their co-authors published in Physical Review Letters. They first addressed the challenge of devising a novel approach to implement a free-space single-photon all-optical transistor with an optical gain exceeding a factor of 10. “Photons do not inherently interact,” Gorniaczyk tells Phys.org. “Therefore, one has to think about ways of introducing interaction – and it’s been shown that the interaction of Rydberg atoms in a cold atomic cloud can be mapped onto the photons to create an effective interaction.””Due to the large micrometer size of these atoms,” Tresp points out, “the interaction between them is very strong – and we use this property to create strong interaction between single photons. The new aspect of our transistor scheme is that we use two different Rydberg states at the same time, allowing us to independently address the gate and source photons.” This approach enables the scientists to show that an optical gain G > 10 can be reached with, on average, less than one gate photon.Another challenge was mapping gate and source photons into Rydberg excitations with different principal quantum numbers in an ultra-cold atomic ensemble. “To map the gate and source photons of the optical transistor into Rydberg excitations requires experimental effort.” Gorniaczyk explains. “First, it’s necessary to create a cold and dense cloud of atoms in a favorable geometry; then, four excitation laser beams have to be overlapped and aligned on the atomic cloud; and finally, while the strong interaction between Rydberg atoms is the key to our scheme, they are also very susceptible to any external perturbation, requiring great care in shielding the experiment from external electric fields.”A key result was using the optical transistor to demonstrate the nondestructive detection of a single Rydberg atom. The conventional method is to ionize Rydberg atom and detect the resulting ion on an ion detector, with typical detection efficiencies below 0.5. However, by using their optical transistor the researchers mapped the existence of one Rydberg atom onto a probe light pulse by over 10 photons – which would be impossible if source photons destroyed gate excitations. This makes the new approach well-suited to independent control of gate and source photons. “While this is very similar to how electronic transistors are used to amplify signals,” Tresp notes, “our new approach is a clear improvement: Even with all imperfections taken into account, we achieve fidelity of 0.72 for the single shot detection of a Rydberg atom without destroying it during the process.” Moreover, optical transistors based on the interaction of Rydberg excitations are robust, and photon Interaction can be mediated by interaction between Rydberg states with different principal quantum numbers. Citation: Step lightly: All-optical transistor triggered by single photon promises advances in quantum applications (2014, August 29) retrieved 18 August 2019 from https://phys.org/news/2014-08-lightly-all-optical-transistor-triggered-photon.html More information: Single-Photon Transistor Mediated by Interstate Rydberg Interactions, Physical Review Letters 113, 053601 (28 July 2014), doi:10.1103/PhysRevLett.113.053601Related:1Single-Photon Transistor Using a Förster Resonance, Physical Review Letters 113, 053602 (28 July 2014), doi:10.1103/PhysRevLett.113.053602 Explore further This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
Kolkata: The Directorate of Drugs Control (DDC) in the state on Wednesday issued a notification asking the manufacturers and wholesalers to take back the medicines stored in various shops at Bagree Market as they might have been damaged due to the excessive heat generated during the fire.The step has been taken as a precautionary measure to check the medicines from being sold in the markets. The DDC apprehends that the quality of these medicines might be reduced and compromised due to the raging blaze. Also Read – Rain batters Kolkata, cripples normal lifeThe DDC has urged the medicine sellers, both retail and wholesale, to stop selling the affected drugs and also the biological products. It was stated that many of the drugs that were kept inside Bagree Market need to be refrigerated. As there had been power cuts in the building since the incident took place, the medicines might have been damaged. If these medicines are circulated in the market, it might adversely affect the people.A senior official of the DDC said the temperature in the building had gone up as a result of which the quality of the medicines would be hampered. Hence all the manufacturing houses have been asked to withdraw the stock or stop operations. Also Read – Speeding Jaguar crashes into Mercedes car in Kolkata, 2 pedestrians killedThese medicines cannot be sold until the authorities ensure that the quality of the medicines remain intact. The DDC also assured that stern action will be taken against those who will be found violating the instructions.An official of the DDC said that as they are short-staffed, it is not always possible for them to conduct raids at various places. Hence the body is trying to check the spread of the drugs which were recovered by some of the businessmen there. It may be mentioned that there was a wholesale market of medicines within Bagree Market that used to supply medicines in different places. It had the wholesale market of various important drugs including those of cancer and people used to obtain such medicines at much cheaper rates.It was learnt that around 25 wholesale shops were there in the market many of which have been damaged. The extent of the damage is yet to be ascertained as all the electronic gadgets that maintained the records have been gutted. Bengal Chemist and Druggist Association added that the devastating fire that took place at Bagree Market on Sunday will have no major impact on the supply of medicines in the state.
Yesterday, Google launched reCAPTCHA v3, a revamped version of their Captcha API that helps filter abusive traffic to a website without user interaction. reCAPTCHA v3 returns a score for each request. The score is based on interactions with a site, so website owners can take the most appropriate action. “Over the last decade, reCAPTCHA has continuously evolved its technology,” Google product manager Wei Liu wrote in a blog post. ReCAPTCHA is usually used on sign in pages. You can rate limit login attempts, exponentially increasing rate limit or just lock out IPs that exceed allowed login attempts and analyze your logs to ban abusive IPs. She adds,“ reCAPTCHA v3 helps to protect your sites without user friction and gives you more power to decide what to do in risky situations.” reCAPTCHA v3 also runs adaptive risk analysis in the background to alert you of suspicious traffic. The scoring logic Website owners can use the reCAPTCHA score in 3 different ways. They can set a threshold that determines when a user is let through or when further verification needs to be done. They can combine the score with their own signals that reCAPTCHA can’t access such as user profiles or transaction histories. They can use the reCAPTCHA score as one of the signals to train machine learning models to fight abuse. reCAPTCHA v3, uses a new tag “Action” which can be used to define the key steps of a user journey and enable reCAPTCHA to run its risk analysis in context. On adding action to multiple pages, reCAPTCHA adaptive risk analysis engine can identify the pattern of attackers more accurately by looking at the activities across different pages on your website. The reCAPTCHA admin console provides an overview of reCAPTCHA score distribution and a breakdown for the stats of the top 10 actions on your site. It also provides multiple ways to customize actions that occur for different types of traffic, to protect against bots and improve user experience based on a website’s specific needs. Source: Google You can visit the reCAPTCHA developer site for more details. Read Next OK Google, why are you ok with mut(at)ing your ethos for Project DragonFly? 90% Google Play apps contain third-party trackers, share user data with Alphabet, Facebook, Twitter, etc: Oxford University Study. A multimillion-dollar ad fraud scheme that secretly tracked user affected millions of Android phones. This is how Google is tackling it.