Jamaicas Government Increases Allocations for CrimeFighting

first_imgFacebook Twitter Google+LinkedInPinterestWhatsApp Facebook Twitter Google+LinkedInPinterestWhatsApp#Jamaica, March 9, 2018 – Kingston – The allocation to the Ministry of National Security for fiscal year 2018/19 has increased by 23.4 per cent, moving to $78.5 billion up from $63.6 billion in 2017/18.Opening the Budget Debate in the House of Representatives on March 8, Minister of Finance and the Public Service, Hon. Audley Shaw, said the increase will facilitate the provision of machinery and equipment, and implementation of physical infrastructure and social-intervention programmes.Mr. Shaw said projects to be undertaken in the new fiscal year include construction of new facilities for the Jamaica Defence Force (JDF) and Jamaica Constabulary Force (JCF); expansion of crime-fighting training facilities; building and improvement of several correctional facilities; procurement of motor vehicles and other specialised equipment to respond to both physical threats and cyberattacks; and continuation of social-intervention initiatives.He said the Government has identified national security and the rule of law as among the main strategic priorities for fiscal year 2018/19 and for the medium-term.The theme of the Minister’s presentation was ‘Stability, Growth and Prosperity – Our Goal, Our Responsibility’.Release: JIS Related Items:last_img read more

Amazon will open a new Denver office add 400 jobs

first_img Share your voice Amazon,I’m shocked — shocked! — to learn that stores are turning Labor Day into an excuse to sell stuff. Wait — no, I’m not. As much as I respect the original intent of the holiday (which became official back in 1894), to most of us, it’s just a bonus day off — one that’s blissfully tacked onto a weekend. So, yeah, stores; go ahead, run your sales. I’m listening. Perhaps unsurprisingly, Labor Day doesn’t bring out bargains to compete with the likes of Black Friday (which will be here before you know it), but there are definitely some sales worth your time.For example:We’ve rounded up the best Labor Day mattress deals.We’ve also gathered the best Labor Day laptop deals at Best Buy.The 2019 Vizio P Series Quantum is back under $999.Be sure to check out Amazon’s roughly three dozen Labor Day deals on TVs and audio. Google Express is having a big sale as well, one that includes deals on game consoles, AirPods, iPhones, laptops and more.Below I’ve rounded up a handful of individual items I consider to be the cream of the crop, followed by a handy reference guide to other Labor Day sales. Keep in mind, of course, that products may sell out at any time, even if the sale itself is still running. Note that CNET may get a share of revenue from the sale of the products featured on this page. Recently updated to include digital-photo-frame capabilities, the Lenovo Smart Clock brings Google Assistant goodness to your nightstand. It’s a little smaller than the Amazon Echo Show 5, but also a full $30 less (and tied with Prime Day pricing) during this Best Buy Labor Day sale. 4:00 Though not technically a Labor Day sale, it’s happening during Labor Day sale season — and it’s too good not to share. Nationwide Distributors, via Google Express, has just about the best AirPods deal we’ve seen (when you apply promo code ZBEDWZ at checkout). This is for the second-gen AirPods with the wireless charging case. Can’t imagine these will last long at this price, so if you’re interested, act fast. $210 at Best Buy Angela Lang/CNET Sarah Tew/CNET Read Lenovo Smart Clock review Now playing: Watch this: HP Laptop 15t Value: $520 (save $780) I thought this might be a mistake, but, no, the weirdly named HP Laptop 15t Value is indeed quite the value at this price. Specs include an Intel Core i7 processor, 12GB of RAM, a 256GB solid-state drive and a 15.6-inch display. However, I strongly recommend paying an extra $50 to upgrade that display to FHD (1,920×1,080), because you’re not likely to be happy with the native 1,366×768 resolution. See It The problem with most entry-level laptops: They come with mechanical hard drives. That makes for a mighty slow Windows experience. This Lenovo model features a 128GB solid-state drive, so it should be pretty quick to boot and load software, even with its basic processor. Plus, it has a DVD-burner! That’s not something you see in many modern laptops, especially at this price. Spotify and most other streaming services rely on compressed audio, which robs the listener of full fidelity. Enter Tidal, the only “major” service that delivers lossless audio — meaning at least on par with CD quality, if not better. Want to see (er, hear) the difference for yourself? Grab this excellent extended trial while you can. It’s just $6 for three months, and it’s good for up to six listeners. Lenovo 130-15AST 15.6-inch laptop: $210 (save $90) Free Echo Dot with an Insignia or Toshiba TV (save $50) Read Google Home Hub review See It Turo: Save $30 on any car rental Google Nest Hub: $59 (save $70) $155 at Google Express Read DJI Osmo Action preview Mentioned Above Apple iPhone XS (64GB, space gray) $6 at Tidal $90 at Daily Steals via Google Express Tags $261 at Daily Steals via Google Express $59 at eBay Rylo 7 Best laptops for college students: We’ve got an affordable laptop for every student. Best live TV streaming services: Ditch your cable company but keep the live channels and DVR. $520 at HP Share your voice Chris Monroe/CNET Turo is kind of like Uber meets Airbnb: You borrow someone’s car, but you do all the driving. I’ve used it many times and found it a great alternative to traditional car-rental services — in part because you get to choose exactly the vehicle you want (not just, say, “midsize”) and in part because you can often do pickup and dropoff right outside baggage claim.Between now and Sept. 1, the first 300 people to check out can get $30 off any Turo rental with promo code LDW30. $999 Lenovo Smart Clock: $59.99 (save $20) Apple AirPods with Wireless Charging Case: $155 (save $45) $60 at Best Buy Sarah Tew/CNET Apple iPhone XS Read the AirPods review DJI Osmo Action camera: $261 (save $89) $999 Sarah Tew/CNET See at Amazon Rylo 5.8K 360 Video Camera: $250 (save $250) 1 What’s cooler: A snapshot of a firework exploding in front of you, or full 360-degree video of all the fireworks and all the reactions to seeing them? Oooh, ahhh, indeed. At $250, the compact Rylo dual-lens camera is selling for its lowest price yet. And for an extra $50, you can get the bundle that includes the waterproof housing.This deal runs through Sept. 3; it usually costs $500. $299 at Amazon Read the Rylo camera preview Amazon Other Labor Day sales you should check out Best Buy: In addition to some pretty solid MacBook deals that have been running for about a week already, Best Buy is offering up to 40% off major appliances like washers, dryers and stoves. There are also gift cards available with the purchase of select appliances. See it at Best BuyDell: Through Aug. 28, Dell is offering an extra 12% off various laptops, desktops and electronics. And check back starting Aug. 29 for a big batch of Labor Day doorbusters. See it at DellGlassesUSA: Aug. 29 – Sept. 3 only, you can save 65% on all frames with promo code labor65. See it at GlassesUSALenovo: The tech company is offering a large assortment of deals and doorbusters through Labor Day, with the promise of up to 56% off certain items — including, at this writing, the IdeaPad 730S laptop for $700 (save $300).See it at LenovoLensabl: Want to keep the frames you already love and paid for? Lensabl lets you mail them in for new lenses, based on your prescription. From now through Sept. 2 only, you can save 20% on the blue light-blocking lens option with promo code BLOCKBLUE. See it at LensablSears: Between now and Sept. 7, you can save up to 40% on appliances (plus an additional 10% if you shop online), up to 60% on mattresses, up to 50% on Craftsman products and more. The store is also offering some fairly hefty cashback bonuses. See it at SearsNote: This post was published previously and is continuously updated with new information.CNET’s Cheapskate scours the web for great deals on tech products and much more. For the latest deals and updates, follow the Cheapskate on Facebook and Twitter. Questions about the Cheapskate blog? Find the answers on our FAQ page, and find more great buys on the CNET Deals page. Amazon is expanding its Denver tech hub. Amazon Amazon is opening a new office in downtown Denver and adding 400 new high-tech jobs, the company said Tuesday. This expansion of its Denver hub will more than double Amazon’s tech workforce in the area. The e-commerce giant opened an office in Boulder last fall. The new jobs will be in fields such as software and hardware engineering, cloud computing and advertising.”We’re excited to continue to grow and invest in the Denver area,” said Dave Wood, site lead for Amazon’s Denver tech hub, in a statement. “Our new office will offer our teams the convenience of a downtown location with an array of outdoor adventures just up the road.”The Denver office will be part of a network of 17 development centers across North America, in addition to the company’s main headquarters in Seattle, Washington, and its future second headquarters in Arlington, Virginia. These hubs employ more than 20,000 in total, according to Amazon. In November, Amazon said it’d build two 25,000-employee campuses: one in Long Island City in New York’s Queens borough and another in Arlington. In February, Amazon canceled its plans to build the New York City campus, but said it’d continue with the Virginia location.  Formerly known as the Google Home Hub, Google’s Nest Hub packs a wealth of Google Assistant goodness into a 7-inch screen. At $59, this is within a buck of the best price we’ve seen. It lists for $129 and sells elsewhere in the $89-to-$99 range.This is one item of many available as part of eBay’s Labor Day Sale (which, at this writing, doesn’t specifically mention Labor Day, but that’s how it was pitched to us). An Echo Dot makes a fine match for any Fire edition TV, because you can use the latter to say things like, “Alexa, turn on the TV.” Right now, the 24-inch Insignia Fire TV Edition starts at just $100, while the 32-inch Toshiba Fire TV Editions is on sale for $130. Just add any Fire TV Edition to your cart, then add a third-gen Echo Dot, and presto: The latter is free. See It $999 Turo See at Turo Best Buy Comment Sarah Tew/CNET Tags Sprint $999 Review • iPhone XS review, updated: A few luxury upgrades over the XR JBL Soundgear wearable speaker: $90 (save $160) CNET may get a commission from retail offers. Amazon kills plans for NYC headquarters DJI’s answer to GoPro’s action cameras is rugged little model that’s shockproof, dustproof and waterproof down to 11 meters. It normally runs $350, but this deal drops it to $261 when you apply promo code 19LABOR10 at checkout. TVs Speakers Mobile Accessories Cameras Laptops Automobiles Smart Speakers & Displays Preview • iPhone XS is the new $1,000 iPhone X Use promo code 19LABOR10 to get an unusually good deal on JBL’s interesting hybrid product — not quite headphones, and not quite a traditional speaker, but something you wear like neckphones to listen to music on the go. The Cheapskate Tidal 3-month family subscription: $5.99 (save $54) See it Comments Tech Industry Boost Mobilelast_img read more

The path to perfection Quantum dots in electricallycontrolled cavities yield bright nearly

first_img © 2016 Phys.org , Nature Communications Researchers develop ideal single-photon source Figure 1. a, Schematic of the sources: a single semiconductor quantum dot, represented by a red dot, is positioned within 50 nm from the center of the cavity, which consists of a 3 µm pillar connected to a circular frame through 1.3 µm wide waveguides. The top electrical contact is defined on a large mesa adjacent to the circular frame. By applying a bias to the cavity, the wavelength of the emitted photons can be tuned and the charge noise strongly reduced. b, Emission map of the device: the strong signal coming from the quantum dot located at the center of the cavity demonstrates the precise positioning of the quantum dot in the cavity and the enhanced collection efficiency obtained by accelerating the quantum dot spontaneous emission. Credit: Courtesy: Dr. Pascale Senellart. Figure 2. a, Photon correlation histogram measuring the indistinguishability of photons successively emitted by one of the devices. The area of the peak at zero delay allows measuring the photon indistinguishability: it should be zero for fully indistinguishable photons. We test here two configurations: the coalescence of photons with orthogonal polarization (fully distinguishable – blue curve) and the coalescence of photon with the same polarization (red curve). The disappearance of the zero delay peak in the latter case show the near unity indistinguishability of the emitted photons. b, Graph summarizing all the source characteristics as a function of excitation power: brightness (probability of collecting a photon per pulse – red – right scale), autocorrelation function g(2)(0) (characterizing the probability of emitting more than one photon – blue – left bottom scale), indistinguishablity M (purple – left top scale). Credit: Courtesy: Dr. Pascale Senellart. Explore further , Optica , Nature Nanotechnology , Nature Dr. Pascale Senellart and Phys.org discussed the paper, Near-optimal single-photon sources in the solid state, that she and her colleagues published in Nature Photonics, which reports the design and fabrication of the first optoelectronic devices made of quantum dots in electrically controlled cavities that provide bright source generating near-unity indistinguishability and pure single photons. “The ideal single photon source is a device that produces light pulses, each of them containing exactly one, and no more than one, photon. Moreover, all the photons should be identical in spatial shape, wavelength, polarization, and a spectrum that is the Fourier transform of its temporal profile,” Senellart tells Phys.org. “As a result, to obtain near optimal single photon sources in an optoelectronic device, we had to solve many scientific and technological challenges, leading to an achievement that is the result of more than seven years of research.”While quantum dots can be considered artificial atoms that therefore emit photons one by one, she explains, due to the high refractive index of any semiconductor device, most single photons emitted by the quantum dot do not exit the semiconductor and therefore cannot be used. “We solved this problem by coupling the quantum dot to a microcavity in order to engineer the electromagnetic field around the emitter and force it to emit in a well-defined mode of the optical field,” Senellart points out. “To do so, we need to position the quantum dot with nanometer-scale accuracy in the microcavity.”Senellart notes that this is the first challenge that the researchers had to address since targeting the issue of quantum dots growing with random spatial positions. “Our team solved this issue in 20081 by proposing a new technology, in-situ lithography, which allows measuring the quantum dot position optically and drawing a pillar cavity around it. With this technique, we can position a single quantum dot with 50 nm accuracy at the center of a micron-sized pillar.” In these cavities, two distributed Bragg reflectors confine the optical field in the vertical direction, and the contrast of the index of refraction between the air and the semiconductor provides the lateral confinement of the light. “Prior to this technology, the fabrication yield of quantum dot cavity devices was in the 10-4 – but today it is larger than 50%.” The scientists used this technique to demonstrate the fabrication of bright single photon sources in 20132, showing that the device can generate light pulses containing a single photon with a probability of 80% – but while all photons had the same spatial shape and wavelength, they were not perfectly identical. More information: Near-optimal single-photon sources in the solid state, Nature Photonics 10, 340–345 (2016), doi:10.1038/nphoton.2016.23Related:1Controlled light–matter coupling for a single quantum dot embedded in a pillar microcavity using far-field optical lithography, Physical Review Letters 101, 267404 (2008), doi:10.1103/PhysRevLett.101.2674042Bright solid-state sources of indistinguishable single photons, Nature Communications 4, 1425 (2013), doi:10.1038/ncomms24343Deterministic and electrically tunable bright single-photon source, Nature Communications 5, 3240 (2014), doi:10.1038/ncomms42404On-demand semiconductor single-photon source with near-unity indistinguishability, Nature Nanotechnology 8, 213–217 (2013), doi:10.1038/nnano.2012.2625Coherent control of a solid-state quantum bit with few-photon pulses, arXiv:1512.04725 [quant-ph]6Charge noise and spin noise in a semiconductor quantum device, Nature Physics 9, 570–575 (2013), doi:10.1038/nphys26887Scalable performance in solid-state single-photon sources, Optica 3, 433-440 (2016), doi:10.1364/OPTICA.3.0004338BosonSampling with single-photon Fock states from a bright solid-state source, arXiv:1603.00054 [quant-ph]9Downconversion quantum interface for a single quantum dot spin and 1550-nm single-photon channel,Optics Express Vol. 20, Issue 25, pp. 27510-27519 (2012), doi:10.1364/OE.20.02751010Ultrabright source of entangled photon pairs, Nature 466, 217–220 (08 July 2010), doi:10.1038/nature09148 Citation: The path to perfection: Quantum dots in electrically-controlled cavities yield bright, nearly identical photons (2016, June 7) retrieved 18 August 2019 from https://phys.org/news/2016-06-path-quantum-dots-electrically-controlled-cavities.html Journal information: Nature Photonics Optical quantum technologies are based on the interactions of atoms and photons at the single-particle level, and so require sources of single photons that are highly indistinguishable – that is, as identical as possible. Current single-photon sources using semiconductor quantum dots inserted into photonic structures produce photons that are ultrabright but have limited indistinguishability due to charge noise, which results in a fluctuating electric field. Conversely, parametric down conversion sources yield photons that while being highly indistinguishable have very low brightness. Recently, however, scientists at CNRS – Université Paris-Saclay, Marcoussis, France; Université Paris Diderot, Paris, France; University of Queensland, Brisbane, Australia; and Université Grenoble Alpes, CNRS, Institut Néel, Grenoble, France; have developed devices made of quantum dots in electrically-controlled cavities that provide large numbers of highly indistinguishable photons with strongly reduced charge noise that are 20 times brighter than any source of equal quality. The researchers state that by demonstrating efficient generation of a pure single photon with near-unity indistinguishability, their novel approach promises significant advances in optical quantum technology complexity and scalability. , Physical Review Letters Senellart adds that while removing scattered photons when transmitting light in processed microstructures is typically complicated, in their case this step was straightforward. “Because the quantum dot is inserted in a cavity, the probability of the incident laser light to interact with the quantum dot is actually very high. It turns out that we send only a few photons – that is, less than 10 – on the device to have the quantum dot emitting one photon. This beautiful efficiency, also demonstrated in the excitation process, which we report in another paper5, made this step quite easy.”The devices reported in the paper have a number of implications for future technologies, one being the ability to achieve strongly-reduced charge noise by applying an electrical bias. “Charge noise has been extensively investigated in quantum dot structures,” Senellart says, “especially by Richard Warburton’s group.” Warburton and his team demonstrated that in the best quantum dot samples, the charge noise could take place on a time scale of few microseconds6 – which is actually very good, since the quantum dot emission lifetime is around 1 nanosecond. However, this was no longer the case in etched structures, where a strong charge noise is always measured on very short time scale – less than 1 ns – that prevents the photon from being indistinguishable. “I think the idea we had – that this problem would be solved by applying an electric field – was an important one,” Senellart notes. “The time scale of this charge noise does not only determine the degree of indistinguishability of the photons, it also determines how many indistinguishable photon one can generate with the same device. Therefore, this number will determine the complexity of any quantum computation or simulation scheme one can implement.” Senellart adds that in a follow-up study7 the scientists generated long streams of photons that can contain more than 200 being indistinguishable by more than 88%.In addressing how these de novo devices may lead to new levels of complexity and scalability in optical quantum technologies, Senellart first discusses the historical sources used develop optical quantum technologies. She makes the point that all previous implementations of optical quantum simulation or computing have been implemented using Spontaneous Parametric Down Conversion (SPDC) sources, in which pairs of photons are generated by the nonlinear interaction of a laser on a nonlinear crystal, wherein one photon of the pair is detected to announce the presence of the other photon. This so-called heralded source can present strongly indistinguishable photons, but only at the cost of extremely low brightness. “Indeed, the difficulty here is that the one pulse does not contain a single pair only, but some of the time several pairs,” Senellart explains. “To reduce the probability of having several pairs generated that would degrade the fidelity of a quantum simulation, calculation or the security of a quantum communication, the sources are strongly attenuated, to the point where the probability of having one pair in a pulse is below 1%. Nevertheless, with these sources, the quantum optics community has demonstrated many beautiful proofs of concept of optical quantum technologies, including long-distance teleportation, quantum computing of simple chemical or physical systems, and quantum simulations like BosonSampling.” (A BosonSampling device is a quantum machine expected to perform tasks intractable for a classical computer, yet requiring minimal non-classical resources compared to full-scale quantum computers.) “Yet, the low efficiency of these sources limits the manipulation to low photon numbers: It takes typically hundreds of hours to manipulate three photons, and the measurement time increases exponentially with the number of photons. Obviously, with the possibility to generate more many indistinguishable photons with an efficiency more than one order of magnitude greater than SPDC sources, our devices have the potential to bring optical quantum technologies to a whole new level.”Other potential applications of the newly-demonstrated devices will focus on meeting near-future challenges in optical quantum technologies, including scalability of photonic quantum computers and intermediate quantum computing tasks. “The sources presented here can be used immediately to implement quantum computing and intermediate quantum computing tasks. Actually, very recently – in the first demonstration of the superiority of our new single photon sources – our colleagues in Brisbane made use of such bright indistinguishable quantum dot-based single photon sources to demonstrate a three photon BosonSampling experiment8, where the solid-state multi-photon source was one to two orders-of-magnitude more efficient than downconversion sources, allowing to complete the experiment faster than those performed with SPDC sources. Moreover, this is a first step; we’ll progressively increase the number of manipulated photons, in both quantum simulation and quantum computing tasks.”Another target area is quantum communications transfer rate. “Such bright single photon sources could also drastically change the rate of quantum communication protocols that are currently using attenuated laser sources or SPDC sources. Yet, right now, our sources operate at 930 nm when 1.3 µm or 1.55 µm sources are needed for long distance communications. Our technique can be transferred to the 1.3 µm range, a range at which single photon emission has been successfully demonstrated – in particular by the Toshiba research group – slightly changing the quantum dot material. Reaching the 1.55 µm range will be more challenging using quantum dots, as it appears that the single photon emission is difficult to obtain at this wavelength. Nevertheless, there’s a very promising alternative possibility: the use of a 900 nm bright source, like the one we report here, to perform quantum frequency conversion of the single photons. Such efficient frequency conversion of single photons has recently been demonstrated, for example, in the lab of Prof. Yoshie Yamamoto at Stanford9.”Regarding future research, Senellart says “There are many things to do from this point. On the technology side, we will try to improve our devices by further increasing the source brightness. For that, a new excitation scheme will be implemented to excite the device from the side, as was done by Prof. Valia Voliotis and her colleagues on the Nanostructures and Quantum Systems team at Pierre and Marie Curie University in Paris and Prof. Glenn Solomon’s group at the National Institute of Standards and Technology (NIST) in Gaithersburg, Maryland. Applying this technique to our cavities should allow gaining another factor of four on source brightness. In addition, operating at another wavelength would be another important feature for our devices, since as discussed above, this would allow using the source for quantum telecommunication. For example, a shorter wavelength, in the visible/near infrared range, would open new possibilities to interconnect various quantum systems, including ions or atoms through their interaction with photons, as well as applications in quantum imaging and related fields.” The researchers also want to profit from the full potential of these sources and head to high photon number manipulation in, for instance, quantum simulation schemes. “We’re aiming at performing BosonSampling measurements with 20-30 photons, with the objective of testing the extended Church Turing thesis and proving the superiority of a quantum computer over a classical one.” The original Church Turing thesis, based on investigations of Alonzo Church and Alan Turing into computable functions, states that, ignoring resource limitations, a function on the natural numbers is computable by a human being following an algorithm, if and only if it is computable by a Turing machine.Another promising impact on future optical quantum technologies is the generation of entangled photon pairs. “A quantum dot can also generate entangled photon pairs, and in 2010 we demonstrated that we could use the in situ lithography to obtain the brightest source of entangled photon pairs10. That being said, photon indistinguishability needs to be combined with high pair brightness – and this is the next challenge we plan to tackle. Such a device would play an important role in developing quantum relays for long distance communication and quantum computing tasks.”Senellart tells Phys.org that other areas of research might well benefit from their findings, in that devices similar to the one the scientists developed to fabricate single photon sources could also provide nonlinearities at the low photon count scale. This capability could in turn allow the implementation of deterministic quantum gates, a new optical quantum computing paradigm in which reversible quantum logic gates – for example, Toffoli or CNOT (controlled NOT) gates– can simulate irreversible classical logic gates, thereby allowing quantum computers to perform any computation which can be performed by a classical deterministic computer. “Single photons can also be used to probe the mechanical modes of mechanical resonator and develop quantum sensing with macroscopic objects. Other applications,” she concludes, “could benefit from the possibility to have very efficient single photon sources, such as an imaging system with single photon sources that could allow dramatically increased imaging sensitivity. Such technique could have applications in biology where the lower the photon flux, the better for exploring in vivo samples.” “Indeed, for the photons to be fully indistinguishable, the emitter should be highly isolated from any source of decoherence induced by the solid-state environment. However, our study showed that collisions of the carriers with phonons and fluctuation of charges around the quantum dot were the main limitations.” To solve this problem, the scientists added an electrical control to the device3, such that the application of an electric field stabilized the charges around the quantum dot by sweeping out any free charge. This in turn removed the noise. Moreover, she adds, this electrical control allows tuning the quantum dot wavelength – a process that was previously done by increasing temperature at the expense of increasing vibration. “I’d like to underline here that the technology described above is unique worldwide,” Senellart stresses. “Our group is the only one with such full control of all of the quantum dot properties. That is, we control emission wavelength, emission lifetime and coupling to the environment, all in a fully deterministic and scalable way.”Specifically, implementing control of the charge environment for quantum dots in connected pillar cavities, and applying an electric field on a cavity structure optimally coupled to a quantum dot, required significant attention. “We had strong indications back in 2013 that the indistinguishability of our photons was limited by some charge fluctuations around the quantum dot: Even in the highest-quality semiconductors, charges bound to defects fluctuate and create a fluctuating electric field. In the meantime, several colleagues were observing very low charge noise in structures where an electric field was applied to the quantum dot – but this was not combined with a cavity structure.” The challenge, Senellart explains, was to define a metallic contact on a microcavity (which is typically a cylinder with a diameter of 2-3 microns) without covering the pillar’s top surface.”We solved this problem by proposing a new kind of cavity – that is, we showed that we can actually connect the cylinder to a bigger frame using some one-dimensional bridges without modifying too much the confinement of the optical field.” This geometry, which the researchers call connected pillars, allows having the same optical confinement as an isolated pillar while defining the metallic contact far from the pillar itself. Senellart says that the connected pillars geometry was the key to both controlling the quantum wavelength of dot and efficiently collecting its emission3.In demonstrating the efficient generation of a pure single photon with near-unity indistinguishability, Senellart continues, the researchers had one last step – combining high photon extraction efficiency and perfect indistinguishability – which they did by implementing a resonant excitation scheme of the quantum dot. “In 2013, Prof. Chao-Yang Lu’s team in Hefei, China showed that one could obtain photons with 96% indistinguishability by exciting the quantum dot state in a strictly resonant way4. Their result was beautiful, but again, not combined with an efficient extraction of the photons. The experimental challenge here is to suppress the scattered light from the laser and collect only the single photons radiated by the quantum dot.” 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. , Nature Physicslast_img read more