This cavity-on-a-chip was used in the scientists’ single-atom detection experiments. The atom detector counts atoms by sensing photons that scatter off the atoms – an ability that will assist in a variety of new developments in atom optics devices. Photo credit: Igor Teper. MIT scientists Igor Teper, Yu-Ju Lin and Vladan Vuletic have developed a method for counting individual atoms that will likely assist in future developments of many different types of atom optics devices. Using an optical cavity – an arrangement of mirrors that forms a standing wave (a major component of lasers) – the detector counts atoms by detecting the photons that scatter off the atoms, either into the cavity or out of it. The group’s results are published in a recent issue of Physical Review Letters.In atom optics devices, atoms must be cooled to temperatures close to absolute zero (-459 degrees Fahrenheit) in order for them to exhibit their wave-like nature. Such ultra-cold atoms can then be manipulated much like light waves, but fully exploiting this ability requires high atom-number resolution.“Many interesting and novel atom optics applications, such as quantum information processing, that could potentially be implemented on atom chips require precise knowledge of atom numbers and atom statistics, and, in some cases, the ability to prepare and detect single atoms,” Teper told PhysOrg.com. “The challenge is that the signal from a single atom is generally very small, so you need to either collect the signal for a long time or find some way to enhance the signal and reduce background noise. In our case, the cavity does both, since it enhances atom scattering and also filters out most of the background light.”In their set-up, Teper, Lin and Vuletic first trapped and cooled rubidium atoms in a magnetic trap. The team used two different measurements – fluorescence and absorption – to detect the photons scattering off the atoms. The fluorescence method works by illuminating the atoms with laser light of a specific frequency and measuring the amount of laser light scattered into the cavity. Although with this method atom number resolution decreases with larger quantities of atoms because larger light signals have larger fundamental uncertainty, the method allowed detection of a single atom with 75% efficiency in 250 microseconds.“There are various limits on how long ultracold atom experiments can take, both in terms of how long the atoms survive in the trap before they are lost and also in terms of how long various properties of the atoms are preserved,” said Teper. “One would want atom number measurements to take much less time than these limits so that one can perform the detection, or possibly many detections, without significantly cutting into the time available for the rest of the experiment. Also, one may need to measure an atom in motion, so that it spends only a short time in the detection region. Different applications can have very different constraints on the detection time.” Explore further Citation: Detector can count atom by atom (2006, August 10) retrieved 18 August 2019 from https://phys.org/news/2006-08-detector-atom.html More than 80 years have passed since Louis de Broglie discovered that matter can act like a wave as well as a particle. With advances in technology, scientists have recently begun exploiting this strange property of everyday matter for applications such as atom lasers and nanofabrication. To further their understanding of these applications with matter waves, however, scientists need a way to detect and count the exact number of atoms used. Using the absorption method, the scientists measured the rate of photons taken in by an atom, in effect looking at the atoms’ shadow, and achieved a resolution of about one atom. Because more atoms absorb more photons, which reduces the observed light signal, the absorption method is not limited the way fluorescence is when measuring a large number of atoms. Using a combination of fluorescence and absorption methods provides versatility for counting atoms in different applications.“Current atom optics capabilities include atom lasers, mirrors and beam-splitters for matter waves, atom interferometry (using both thermal atoms and Bose-Einstein condensates (BECs)), and BEC Josephson junctions,” said Teper. “Some of these have been achieved in magnetic traps on chips, some in free-space magnetic traps, some in optical traps, and some with untrapped atoms.”Many atom optics applications seem very futuristic, but the laws of quantum mechanics also seem to predict that such applications are possible with the proper technology. For example, scientists speculate on atom holography, which would be like laser holography but would replicate objects with actual matter instead of light. Also, more advanced atom lasers might act like the opposite of an optical laser, using light to direct beams of matter waves. “There has been rapid progress in the past few years in all these experimental regimes; many technical problems have been solved, and there’s a lot of excitement in the field,” said Teper. “BEC interferometry with magnetically trapped atoms on chips is one area where there’s been a series of breakthroughs recently, and there’s lots of interesting experiments ahead. Quantum information processing is one of the big goals of atom optics on chips, and while there’s been a lot of progress on some of the necessary components, there’s still a tremendous amount of work to do and many challenges to overcome.”Citation: Teper, Igor, Lin, Yu-Ju and Vuletic, Vladan. ”Resonator-Aided Single-Atom Detection on a Microfabricated Chip.” Physical Review Letters 97 023002 (2006). By Lisa Zyga, Copyright 2006 PhysOrg.com NIST’s compact atomic gyroscope displays new twists 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.
Physical binary codes formed by nanodisks carved out of nanorods. Image courtesy Chad Mirkin. Researchers at Northwestern University have devised a way to use billionth-of-a-meter-sized disks to create codes that could be used to encrypt information, serve as biological labels, and even tag and track goods and personnel. Citation: Nanodisk Codes (2007, December 27) retrieved 18 August 2019 from https://phys.org/news/2007-12-nanodisk-codes.html Explore further Applying the Goldilocks principle to DNA structure The nanodisks can form a physical pattern, similar in concept to a barcode, as well as a spectroscopic code, meaning it can exhibit a specific, unique response to electromagnetic radiation, or light, depending on the type of molecule (or molecules) attached to the disks—in other words, how the disks are “functionalized.”Nanostructures can be ideal for encoding. Their small size allows them to be hidden easily in a variety of materials and objects, and scientists’ ability to easily tailor their physical and chemical properties makes it possible to design nanostructures for specific coding functions.In a paper describing this work, published in a recent edition of Nano Letters, the researchers, led by Northeastern chemist Chad Mirkin, describe how the nanodisks can form physical binary codes. The group started with nanorods made of gold and nickel and, using a method they developed, carved disks out of each rod. The disks are created in twos, with up to five pairs created per rod.Each of the five disk-pair locations along the rod can correspond to a “0” or a “1,” depending on whether that location is occupied by a disk pair. For example, if only one disk pair is present, and it is situated at the third location, that code is read as 00100. If two disk pairs are present, at the fourth and fifth locations, the code is 00011.“This is a rapid, low cost way of making many unique nanostructures that can identified and read based upon high sensitivity spectroscopic techniques,” Mirkin said to PhysOrg.com. “It’s a beautiful example of how the ability to shape and control the size and surface composition of a nanostructure can translate into significant technological advantages.”The group has made nanodisk arrays as long as 12 micrometers (millionths of a meter), which can support as many as 10 disk pairs, yielding 287 physical nanodisk codes.The researchers increased the codes’ usefulness by functionalizing them with a class of dye molecules called chromophores. This makes the codes spectroscopically active, allowing each to emit a unique light spectrum when illuminated by an exterior light source, typically a laser beam.Due to the physical and spectroscopic codes they can exhibit, the nanodisks are particularly suited for biological tagging, a method of tracking and detecting individual biological materials, such as DNA. The researchers proved this by attaching pieces of single-stranded DNA to the surfaces of the nanodisks in a 11011 code. Each of these strands was complementary to half of a “target” DNA strand—the strand being tagged. The other half of the target strand was complementary to a “reporter” strand, rendered spectroscopically active with dye. The overall structure formed a three-strand “sandwich,” with the target strand in the middle.The group also created a similar sandwich structure using a different reporter strand and a 10101 code, and then mixed the two samples. They were able to successfully detect and distinguish between the unique spectrums emitted by both reporter molecules.Citation: Nano Lett., 7 (12), 3849-3853, 2007Copyright 2007 PhysOrg.com. All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of PhysOrg.com. 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.
Protostars as single objects or existing in binary systems are important for astronomers to study the mechanisms of star formation. In some protostellar binaries a peculiar “bridge” of material is clearly visible, which connects the recently formed components. This remnant material could be the key to better understand how stars form and evolve.IRAS 16293−2422 (or IRAS 16293 for short) exhibits such a bridge connection between the two companions. It is a young, Class 0 protostellar system located some 400 light years away in the Ophiuchus cloud complex, consisting of two protostars, designated IRAS 16293A and IRAS 16293B, separated by about 636 AU from each other.Besides an arc of dust and gas connecting the sources, previous observations of IRAS 16293 have also found outflows from the object “A.” These features make it a very complex system, where the observed gas line emission can only be explained by a combination of multiple physical components.In order to gather more information about on this subject, which could provide essential hints into the nature and evolutionary status of IRAS 16293, a group of astronomers led by Matthijs H.D. van der Wiel of the Netherlands Institute for Radio Astronomy (ASTRON), has employed ALMA to observe this binary.The observations were conducted between June 2014 and May 2015, as part of the ALMA-PILS spectral imaging survey. From the data provided by the survey, the researchers chose molecular gas line transitions of CO, H2CO, HCN, CS, SiO, and C2H and used them to kinematics, density, and temperature in IRAS 16293.Analyzing the results, the astronomers found that the kinematically quiescent bridge of dust and gas spanning between IRAS 16293A and IRAS 16293B has a density within the range between 40,000 and 30 million cm-3, and is stable against radial collapse. The data suggest that this bridge is a remnant substructure of a filamentary circumbinary envelope that has undergone turbulent fragmentation to form both protostellar sources.Moreover, the observations uncovered the presence of a separate, straight filament seemingly connected to IRAS 16293B and seen only in C2H, with a flat kinematic signature. This structure stretches straight across source “B” at position angle of about 15 degrees. The researchers noted that the properties of this filament indicate that its origin in outflow activity of IRAS 16293B can be ruled out. Taking into account the results from ALMA observations and also from previous studies, the authors of the paper found that IRAS 16293B may be in an earlier evolutionary stage than the source “A.” In general, they concluded that IRAS 16293 may represent a particular stage in the evolution of binaries, a phase which many other protostars may go through at one point in their evolution. An international team of astronomers used the Atacama Large Millimeter/submillimeter Array (ALMA) to investigate gas dynamics in a nearby young protostellar binary known as IRAS 16293−2422. Results of the observations, presented in a paper published March 29, provide more insights into the evolutionary status of this system. Illustration of physical components surrounding and bridging protostars A and B in the IRAS 16293 system, and outflows emanating from IRAS 16293A. Credit: Van der Wiel et al., 2019. Citation: Gas dynamics in a nearby protostellar binary system studied with ALMA (2019, April 9) retrieved 18 August 2019 from https://phys.org/news/2019-04-gas-dynamics-nearby-protostellar-binary.html ALMA finds ingredient of life around infant Sun-like stars More information: M. H. D. van der Wiel et al. The ALMA-PILS survey: Gas dynamics in IRAS 16293−2422 and the connection between its two. Astrophysics of Galaxies (astro-ph.GA). protostarsarxiv.org/abs/1903.12606 Explore further © 2019 Science X Network 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.
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. More information: Daniel M. Siegel et al. Collapsars as a major source of r-process elements, Nature (2019). DOI: 10.1038/s41586-019-1136-0 Citation: Researchers suggest collapsar accretion disks might be source of heaviest elements (2019, May 9) retrieved 18 August 2019 from https://phys.org/news/2019-05-collapsar-accretion-disks-source-heaviest.html Explore further Journal information: Nature © 2019 Science X Network
Indian paddlers enjoyed an all-win day on Tuesday at the Asian Games as country’s top doubles duo of Achanta Sharath Kamal and Anthony Amalraj reached the men’s doubles third round here on Tuesday. Amalraj and Kamal unexpectedly lost the first game before taming the Nepal’s Purshottam Bajracharya and Amar Lal Malla 6-11, 11-5, 11-8, 12-10.The Indian pair, who got a bye in the opening round, took 22 minutes to defeat players from the Himalayan nation. Also booking a third round berth in the men’s doubles was the pair of Harmeet Desai and Soumyajit Ghosh as they took just 15 minutes to disptach Yemen’s Omar Ahmed Ali and Mohammed Fahd Gubran 12-10, 11-5, 11-6.In the mixed doubles pre-quarterfinals, the combine of Amalraj and Madhurika Patkar rallied to beat Japan’s Seiya Kishikawa and Ai Fukuhara 5-11, 13-11, 11-8, 11-4 in 26 minutes to reach the quarter-finals.
The British Council, the UK’s international organisation for cultural relations and educational opportunities, brings to India Folk Nations Co?ncerts. This troupe is an outcome of Folk Nations, a programme by British Council that highlights folk culture across the UK and India through music. The three-city India tour, starting off with Delhi and ending with Shillong, will witness performances by renowned musicians Patsy Reid (Scotland), Hannah James (England), Georgia Ruth (Wales), Saurav Moni (India), Suhail Yusuf Khan (India) and James Mackintosh (Scotland). Also Read – ‘Playing Jojo was emotionally exhausting’Folk Nations is a British Council project that was devised to foster creative exchange and collaboration between traditional artists from the UK and the Indian Sub-continent. Following a week-long residency in February 2013 by British Council & English Folk Dance and Song Society (EFDSS) inviting a group of UK and Indian folk musicians, the musicians shared their folk music traditions and heritage, collaborated and immersed themselves in a week of intense music making. Also Read – Leslie doing new comedy special with NetflixThe six member group travelled to perform at Celtic Connections and London’s Alchemy Festival at Southbank Centre. The troupe represents a delicate weaving of UK and Indian folk that speaks immediately to the cultural heritage of these regions as well as its place in the contemporary music industry. Indian audiences will witness this showcase of original folk music collaborations among musicians from Scotland, England, Wales and India in Delhi, Kolkata and Shillong. For these concerts the British Council is pleased to partner with the Indian Council for Cultural Relations (ICCR) and the Government of Meghalaya, Department of Arts and Culture.WHEN: 15 October, 6.30 pm WHERE: Kamani Auditorium
Darjeeling: Two persons, including a citizen of Nepal were arrested from the Indo-Nepal border and Charas recovered in a joint operation by Sashastra Seema Bal, 41st Bn and the Narcotics Control Bureau (NCB).In another incident, a similar joint operation by the SSB, 17th Bn and the NCB in Falakata two persons were arrested and Ganja seized from their possession.Based on a tip off, two persons were apprehended from Dudhghat area under the Khoribari police station area on Thursday night. Ganesh Tamang, a Nepali citizen and Luka Sherpa, a resident of Kalimpong were arrested. Also Read – Rain batters Kolkata, cripples normal life3.2 kg of Charas was seized from them along with four debit cards, three mobile phones and Indian, Nepali and Bhutanese currency were recovered from their possession.During the interrogation, it was revealed that the Charas was being smuggled from Nepal to Kolkata through Siliguri. Police have initiated an investigation.In another incident, NCB and SSB apprehended a Bolero pickup van at Falakata in the Alipurduar district on Friday morning. 322 kg of Ganja was recovered from the vehicle leading to the arrest of one Naren Dutta and Namal Saikia, both from Assam.The consignment was being brought from Senapati district of Manipur and was to be delivered in Siliguri.
Actor Dwayne Johnson is reportedly being eyed by Universal Pictures to play the lead role in its The Wolf Man reboot. The project is part of its plan to revive its classic monsters.It will be included in the studio’s shared monster universe, which is being overseen by Alex Kurtzman and Chris Morgan, reports aceshowbiz.com. Morgan wrote the screenplay of Furious 7.There is no confirmation yet from the actor and no other details about The Wolf Man are available as of now. It has been reported that other famous characters such as the Mummy, Frankenstein and Dracula will inhabit the same universe and interact with one another across films and plots. The Wolf Man reboot is scheduled to release on April 13, 2018.
Kolkata: Mayor Firhad Hakim reiterated on Monday that funds in the fixed deposit of the civic body will be utilised only for development work and civic amenities and any wastage of such funds will not be tolerated.Replying to a query from Congress councillor Prakash Upadhyay regarding the existing amount in the fixed deposit of the Kolkata Municipal Corporation (KMC) at the monthly meeting, Hakim said: “We have an amount of Rs 17.10 crore till February 2018. The funds in the fixed deposit, whether it is more or less, does not matter. What matters most is offering services and civic amenities to the people. Since the Trinamool Congress took over the board of the KMC in 2010, it has provided civic amenities in the form of potable drinking water, lights, development of slums, an overhaul of the drainage system, scientific plan for solid waste management etc.” Also Read – Bose & Gandhi: More similar than apart, says Sugata BoseAccording to Hakim, when Subrata Mukherjee of the TMC ended his term as the Mayor in 2005, the amount of fixed deposit stood at Rs 377.16 crore. When Bikash Bhattacharya of the Left Front board took over as Mayor, he sold a number of plots of land and the fixed deposit went up to Rs 721.25 crore. Hakim further informed that when Bhattacharya’s term as Mayor ended in 2010, he left Rs 588. 67 crore in the fixed deposit of the KMC. “The revenue earning is a part our job but our main aim is to ensure that the citizens get the best of amenities,” he maintained. Also Read – Rs 13,000 crore investment to provide 2 lakh jobs: MamataThe Mayor further said that the KMC has set a target of three years to ensure the supply of potable drinking water to every single pocket in the city. “There are problems in certain pockets, particularly in the added areas in the southern part, and we are taking all possible measures to augment water supply. The capacity of the Garden Reach Waterways is being raised by 25 million gallon and we are also constructing small booster pumping stations in these areas to boost water supply,” he added.