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  • richardmitnick 3:16 pm on June 2, 2018 Permalink | Reply
    Tags: , , , Chinese Academy of Sciences, Chinese CEPC project, , , ,   

    From CERN Courier: “China’s bid for a circular electron–positron collider” 


    From CERN Courier

    Jun 1, 2018
    Jie Gao
    Institute of High Energy Physics
    University of Chinese Academy of Sciences

    1
    A future collider in China

    Physicists in China have completed a conceptual design report for a 100 km-circumference collider that, in conjunction with a possible linear collider in Japan, would open a new era for high-energy physics in Asia.

    ILC schematic, being planned for the Kitakami highland, in the Iwate prefecture of northern Japan

    Chinese accelerator-based research in high-energy physics is a relatively recent affair. It began in earnest in October 1984 with the construction of the 240 m-circumference Beijing Electron Positron Collider (BEPC) at the Institute of High Energy Physics. BEPC’s first collisions took place in 1988 at a centre-of-mass energy of 1.89 GeV. At the time, SLAC in the US and CERN in Europe were operating their more energetic PEP and LEP electron–positron colliders, respectively, while the lower-energy electron–positron machines ADONE (Frascati), DORIS (DESY) and VEPP-4 (BINP Novosibirsk) were also in operation.



    Beijing Electron Positron Collider (BEPC)

    SLAC SSRL


    SLAC SSRL PEP collider map

    CERN LEP Collider


    CERN LEP Collider

    ADONE INFN-LNF synchrotron radiation beamline

    DESY DORIS


    DESY DORIS III

    VEPP-4 (BINP Novosibirsk)

    Beginning in 2006, the BEPCII upgrade project saw the previous machine replaced with a double-ring scheme capable of colliding electrons and positrons at the same beam energy as that of BEPC but with a luminosity 100 times higher (1033 cm−2 s−1). BEPCII, whose collisions are recorded by the Beijing Spectrometer III (BES III) detector, switched on two years later and continues to produce results today, with a particular focus on the study of charm and light-hadron decays.

    BESS III

    China also undertakes non-accelerator-based research in high-energy physics via the Daya Bay neutrino experiment, which was approved in 2006 and announced the first observation of the neutrino mixing angle θ13 in March 2012.

    Daya Bay, approximately 52 kilometers northeast of Hong Kong and 45 kilometers east of Shenzhen, China

    The discovery of the Higgs boson at CERN’s Large Hadron Collider [see below] in July 2012 raises new opportunities for a large-scale accelerator.

    CERN CMS Higgs Event


    CERN ATLAS Higgs Event

    Thanks to the low mass of the Higgs, it is possible to produce it in the relatively clean environment of a circular electron–positron collider – in addition to linear electron–positron colliders such as the International Linear Collider (ILC) [see schematic above] and the Compact Linear Collider (CLIC) – with reasonable luminosity, technology, cost and power consumption.

    CLIC Collider annotated


    CERN/CLIC

    The Higgs boson is the cornerstone of the Standard Model (SM), yet is also responsible for most of its mysteries: the naturalness problem, the mass-hierarchy problem and the vacuum-stability problem, among others. Therefore, precise measurements of the Higgs boson serve as excellent probes of the fundamental physics principles underlying the SM and of exploration beyond the SM.

    The Standard Model of elementary particles (more schematic depiction), with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth.


    Standard Model of Particle Physics from Symmetry Magazine

    4
    Fig. 1.

    In September 2012, Chinese scientists proposed a 50–70 km circumference 240 GeV Circular Electron Positron Collider (CEPC) in China, serving two large detectors for Higgs studies. The tunnel for such a machine could also host a Super Proton Proton Collider (SppC) to reach energies beyond the LHC (figure 1). CERN is also developing, via the Future Circular Collider (FCC) study, a proposal for a large (100 km circumference) tunnel, which could host high-energy electron–positron (FCC-ee), proton–proton (FCC-hh) or electron–proton (FCC-he) colliders (see CERN thinks bigger).

    CERN Future Circular Collider


    FCC Future Circular Collider at CERN

    Progress in both projects is proceeding fast, although many open questions remain – not least how to organise and fund these next great steps in our exploration of fundamental particles.

    China Circular Electron Positron Collider (CEPC) map

    Precision leap

    CEPC is a Higgs factory capable of producing one million clean Higgs bosons over a 10 year period. As a result, the couplings between the Higgs boson and other particles could be determined to an accuracy of 0.1–1% – roughly one order of magnitude better than that expected of the high-luminosity LHC upgrade and challenging the most advanced next-to-next-to-leading-order SM calculations (figure 2). By lowering the centre-of-mass energy to that of the Z pole at around 90 GeV, without the need to change hardware, CEPC could produce at least 10 billion Z bosons per year. As a super Z – and W – factory, CEPC would shed light on rare decays and heavy-flavour physics and mark a factor-10 leap in the precision of electroweak measurements.

    4
    Fig. 2.

    The latest CEPC baseline design is a 100 km double ring (figure 3, left) with a single-beam synchrotron-radiation power of 30 MW at the Higgs pole, and with the same superconducting radio-frequency accelerator system for both electron and positron beams. CEPC could work both at Higgs- and Z-pole energies with a luminosity of 2 × 1034 cm–2 s–1 and 16 × 1034 cm–2 s–1, respectively. The alternative design of CEPC is based on a so-called advanced partial double-ring scheme (figure 3, right) with the aim of reducing the construction cost. Preliminary designs for the two CEPC detectors are shown in figure 4.

    5
    Fig. 3.

    Concerning the SppC baseline, it has been decided to start with 12 T dipole magnets made from iron-based high-temperature superconductors to allow proton–proton collisions at a centre-of-mass energy of 75 TeV and a luminosity of 1035 cm–2 s–1. The SppC SC magnet design is different to the Nb3Sn-based magnets planned by the FCC-hh study, which are targeting a field of 16 T to allow protons to collide at a centre-of-mass energy of 100 TeV. The Chinese design also envisages an upgrade to 20 T magnets, which will take the SppC collision energy to beyond 100 TeV. Discovered just over a decade ago, iron-based superconductors have a much higher superconducting transition temperature than conventional superconductors, and therefore promise to reduce the cost of the magnets to an affordable level. To conduct the relevant R&D, a national network in China has been established and already more than 100 m of iron-based conductor cable has been fabricated.

    6
    Fig. 4.

    The CEPC is designed as a facility where both machines can coexist in the same tunnel (figure 5). It will have a total of four detector experimental halls, each with a floor area of 2000 m2 – two for CEPC and another two for SppC experiments. The tunnel is around 6 m wide and 4.8 m high, hosting the CEPC main ring (comprising two beam pipes), the CEPC booster and SppC. The SppC will be positioned outside of CEPC to accommodate other collision modes, such as an electron–proton, in the far future. The FCC study, which is aiming to complete a Conceptual Design Report (CDR) by the end of the year, adopts a similar staged approach (see CERN thinks bigger [link is above]).

    7
    Fig. 5.

    China on track

    Since the first CEPC proposal, momentum has grown. In June 2013, the 464th Fragrant Hill Meeting (a national meeting series started in 1994 for the long-term strategic development of China’s science and technology) was held in Beijing and devoted to developing China’s high-energy physics following the discovery of the Higgs boson. Two consensuses were reached: the first was to support the ILC and participate in its construction with in-kind contributions, with R&D funds to be requested from the Chinese government; the second was a recognition that a circular electron–positron Higgs factory – the next collider after BEPCII in China – and a Super proton–proton collider built afterwards in the same tunnel is an important historical opportunity for fundamental science.

    n 2014, the International Committee for Future Accelerators (ICFA) released statements supporting studies of energy-frontier circular colliders and encouraged global coordination. ICFA continues to support international studies of circular colliders, in addition to support for linear machines, reflecting the strategic vision of the international high-energy community. In April 2016, during the AsiaHEP and Asian Committee for Future Accelerators (ACFA) meeting in Kyoto, positive statements were made regarding the ILC and a China-led effort on CEPC-SppC. In September that year, at a meeting of the Chinese Physics Society, it was concluded that CEPC is the first option for a future high-energy accelerator project in China, with the strategic aim of making it a large international scientific project. Pre-conceptual design reports (pre-CDRs) for CEPC-SppC were completed at the beginning of 2015 with an international review, based on a single ring-based “pretzel” orbit scheme. A CEPC International Advisory Committee (IAC) was established and, in 2016, the Chinese Ministry of Science and Technology (MOST) allocated 36 million RMB (€4.6 million) for the CEPC study, and in 2018 another 32 million RMB (€4.1 million) has been approved by MOST.

    Ensuring that a large future circular collider maximises its luminosity is a major challenge. The CEPC project has studied the use of a crab-waist collision scheme, which is also being studied for FCC-ee. Each of the double-ring schemes for CEPC have been studied systematically with the aim of comparing the luminosity potentials. On 15 January last year, CEPC-SppC baseline and alternative designs for the CDR were decided, laying the ground for the completion of the CEPC CDR at the end of 2017. Following an international review in June, the CEPC CDR will be published in July 2018.

    While technical R&D continues – both for the CEPC machine and its two large detectors – a crucial issue is how to pay for such a major international project. In addition to the initial funding from MOST, other potential channels include the National Science Foundation of China (NSFC), the Chinese Academy of Sciences (CAS) and local governments. For example, two years ago Beijing Municipal allocated more than 500 million RMB (€65 million) to the Institute of High Energy Physics for superconducting RF development, and in 2018 CAS plans to allocate 200 million RMB (€26 million) to study high-temperature superconductors for magnets, including studies in materials science, industry and projects such as SppC. While not specifically intended for CEPC-SppC, such investments will have strong synergies with high-energy physics and, in November 2017, the CEPC-SppC Industrial Promotion Consortium was established with the aim of supporting mutual efforts between CEPC-SppC and industry.

    A five-year-long Technical Design Report (TDR) effort to optimise the CEPC-SppC design and technologies, and prepare for industrial production, started this year. Construction of CEPC could begin as early as 2022 and be completed by the end of the decade. CEPC would operate for about 10 years, while SppC is planned to start construction in around 2040 and be completed by the mid-2040s. The CEPC-SppC TDR phase after the CDR is critical, both for key-component R&D and industrialisation. R&D has already started towards high-Q, high-field 1.3 GHz and 650 MHz superconducting cavities; 650 MHz high-power high-efficiency klystrons; 12 kW cryogenic systems, 12 T iron-based high temperature superconducting dipoles, and other enabling technologies. Construction of a new 4500 m2 superconducting RF facility in Beijing called the Platform of Advanced Photon Source began in May 2017 to be completed in 2020, and could serve as a supporting facility for different projects.

    International ambition

    CEPC-SppC is a Chinese-proposed project to be built in China, but its nature is an international collaboration for the high-energy physics community worldwide. Following the creation of the CEPC-SppC IAC in 2015, more than 20 MoUs have been signed with many institutes and universities around the world, such as the Budker Institute of Nuclear Physics (BINP; Russia); National Research Nuclear University MEPhI (Moscow, Russia) and the University of Rostock (Germany).

    In August 2017, ICFA endorsed an ILC operating at a centre-of-mass energy of 250 GeV (ILC250), with energy-upgrade possibilities in the future (CERN Courier January/February 2018 p7). Although CEPC and ILC250 start with the same energy to study the Higgs boson, the ultimate goals are totally different from each other: SppC is for a 100 TeV proton–proton collider and ILC is a 1 TeV (maximum) electron–positron collider. The existence of both, however, would offer a highly complementary physics programme operating for a period of decades. The specific feature of CEPC is its small-scale superconducting RF system, (and its relatively large AC power consumption (300 MW for CEPC compared to 110 MW for ILC250). As for the cost, CEPC in its first phase includes part of the cost of SppC for its long tunnel, whereas ILC would upgrade its energy by increasing tunnel length accordingly later.

    8

    Deciding where to site the CEPC-SppC involves numerous considerations. Technical criteria are roughly quantified as follows: earthquake intensity less than seven on the Richter scale; earthquake acceleration less than 0.1 g; ground surface-vibration amplitude less than 20 nm at 1–100 Hz; granite bedrock around 50–100 m deep, and others. The site-selection process started in February 2015, and so far six sites have been considered: Qinhuangdao in Hebei Province; Huangling county in Shanxi Province; Shenshan Special District in Guangdong Province; Baoding (Xiongan) in Heibei Province; Huzhou in Zhejiang Province and Changchun in Jilin Province, where the first three sites have been prospected underground (figure 6). More sites, such as Huzhou in Zhejiang Province, will be considered in the future before a final selection decision. According to Chinese civil construction companies involved in the siting process, a 100 km tunnel will take less than five years to dig using drill-and-blast methods, and around three years if a tunnel boring machine is employed.

    2018 is a milestone year for Higgs factories in Asia. As CEPC completes its CDR, the global high-energy physics community is waiting for a potential positive declaration from the Japanese government, by the end of the year, on their intention to host ILC250 in Japan, upgradable to higher energies. It is also a key moment for high-energy physics in Europe. FCC will complete its CDR by the end of the year, while CLIC released an updated 380 GeV baseline-staging scenario (CERN Courier November 2016 p20), and the European Strategy for Particle Physics update process will get under way (CERN Courier April 2018 p7). Hopefully, both ILC250 and CEPC-SppC will be included in the update together with FCC, while with respect to the US strategy we are looking forward to the next “P5” meeting following the European update.

    During the past five years, CEPC-SppC has kept to schedule both in design and R&D, together with strong team development and international collaboration. On 28 March this year, the Chinese government announced the “Implementation method to support China-initiated large international science projects and plans”, with the goal of identifying between three and five preparatory projects, one or two of which will be put to construction, by 2020. Hopefully, CEPC will be among those selected.

    Related journal articles
    _________________________________________________
    See the full article for further references with some links.

    See the full article here .


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    THE FOUR MAJOR PROJECT COLLABORATIONS

    ATLAS
    CERN ATLAS New

    ALICE
    CERN ALICE New

    CMS
    CERN CMS New

    LHCb
    CERN LHCb New II

    LHC

    CERN LHC Map
    CERN LHC Grand Tunnel

    CERN LHC particles

     
  • richardmitnick 10:20 am on May 4, 2018 Permalink | Reply
    Tags: Chinese Academy of Sciences, , MSP PSR J0318+0253, MSP-radio millisecond pulsar, , , The Kavli Institute for Astronomy and Astrophysics at Peking University   

    From The Kavli Institute for Astronomy and Astrophysics at Peking University: “FAST’s First Discovery of a Millisecond Pulsar” 

    The Kavli Institute for Astronomy and Astrophysics at Peking University

    April 27, 2018 at Chinese Academy of Sciences
    No writer credit

    China’s Five-hundred-meter Aperture Spherical radio Telescope(FAST), still under commissioning, discovered a radio millisecond pulsar (MSP) coincident with the unassociated gamma-ray source 3FGL J0318.1+0252 in the Fermi Large Area Telescope (LAT) point-source list. This is another milestone of FAST.

    FAST radio telescope, now operating, located in the Dawodang depression in Pingtang county Guizhou Province, South China, https://astronomynow.com

    NASA/Fermi Gamma Ray Space Telescope


    NASA/Fermi LAT

    1
    The Gamma-ray sky map and integrated pulse profiles of the new MSP: Upper panel shows the region of the gamma-ray sky where the new MSP is located. Lower panel a) shows the observed radio pulses in a one-hour tracking observation of FAST. Lower panel b) shows the folded pulses from more than nine years of Fermi-LAT gamma-ray data. (Credit: Pei Wang/NOAC)

    FAST, the world’s largest single-dish radio telescope, operated by the National Astronomical Observatory of the Chinese Academy of Sciences, has discovered more than 20 new pulsars so far. This first MSP discovery was made by FAST on Feb. 27 and later confirmed by the Fermi-LAT team in reprocessing of Fermi data on April 18th.

    The newly discovered pulsar, now named PSR J0318+0253, is confirmed to be isolated through timing of gamma-ray pulsations. This discovery is the first result from the FAST-Fermi LAT collaboration outlined in a MoU signed between the FAST team and Fermi-LAT team.

    “This discovery demonstrated the great potential of FAST in pulsar searching, highlighting the vitality of the large aperture radio telescope in the new era,” said Kejia Lee, scientist at the Kavli Institute of Astronomy and Astrophysics, Peking University.

    Radio follow-up of Fermi-LAT unassociated sources is an effective way for finding new pulsars. Previous radio observations, including three epochs with Arecibo in June 2013, failed to detect the MSP. In a one-hour tracking observation with the FAST ultra-wide band receiver, the radio pulses toward 3FGL J0318.1+0252 were detected with a spin period of 5.19 milliseconds, an estimated distance of about 4 thousand light-years, and as potentially one of the faintest radio MSPs.

    Millisecond pulsar is a special kind of neutron stars that rotate hundreds of times per second. It is not only expected to play an important role in understanding the evolution of neutron stars and the equation of state of condense matter, but also can be used to detect low-frequency gravitational waves.

    The pulsar timing array (PTA) attempts to detect low-frequency gravitational waves from merging supermassive black holes using the long-term timing of a set of stable millisecond pulsars. Pulsar search is the basis of gravitational wave detection through PTAs.

    The planned Commensal Radio Astronomy FAST Survey (CRAFTS, arxiv:1802.03709; http://crafts.bao.ac.cn/) is expected to discover many millisecond pulsars and thus will make significant contribution to the PTA experiment.

    “The international radio-astronomy community is excited about the amazing FAST telescope, already showing its power in these discoveries. FAST will soon discover a large number of millisecond pulsars and I am looking forward to seeing FAST’s contribution to gravitational wave detection,” said George Hobbs, scientist of the Commonwealth Scientific and Industrial Research Organization (CSIRO) of Australia and member of the Gravitational Wave International Committee (GWIC).

    FAST will be under commissioning until it reaches the designed specifications and becomes a Chinese national facility.

    See the full article here .

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    KIAA PKU one of many assemblages

    The Kavli Institute for Astronomy and Astrophysics (KIAA), at Peking University in Beijing, is both a tribute to China’s rich scientific tradition and an extension of it.

    Established in 2006 and becoming operational in 2007, KIAA is a global center of excellence in astronomy and astrophysics, attracting scientists from around the world (with English as its working language). It also promotes basic research in China with the highest international standards and carries out research on the origin and evolution of astrophysical structures from the scales of planetary systems and stars up to that of the Universe as a whole.

    The program of KIAA focuses on studies in three major areas of astrophysics:

    Cosmology, first light and galaxy assemblage;
    Gravitational physics and high-energy phenomena;
    Interstellar medium, stars and planets.

     
  • richardmitnick 9:28 pm on July 15, 2017 Permalink | Reply
    Tags: Chinese Academy of Sciences, , Leveraging existing tools, , , Passing through a satellite, QKD-message-encryption technique known as quantum key distribution, QUESS-Quantum Experiment at Space Scale also known as Micius or Mozi,   

    From Optics & Photonics: “Quantum Key Distribution Takes Flight” 

    Optics & Photonics

    June 15, 2017
    Patricia Daukantas

    Three research teams—in Canada, in China, and in Germany—have lifted the message-encryption technique known as quantum key distribution (QKD) out of optical fibers and into literal new heights: an airplane in flight and satellites orbiting Earth.

    Preparing for a proposed Canadian quantum-communications spacecraft, researchers from the University of Waterloo, Ontario, uplinked secure quantum keys from a ground-based transmitter to a receiver that was mounted on an aircraft passing overhead (Quantum Sci. Technol., doi:10.1088/2058-9565/aa701f).

    1
    Thanks to new research from two separate, global teams, QKDs may head up toward the sky and stars. [Image: iStock].

    Across the globe, a team from the Chinese Academy of Sciences sent entangled photon pairs from the country’s quantum-technology satellite to two different ground stations (Science, doi:10.1126/science.aan3211).

    And researchers at the Max Planck Institute for the Science of Light, Germany, were able to demonstrate ground-based measurements of quantum states sent by a laser from a satellite 38,000 kilometers above Earth’s surface—using components not even designed for quantum communication (Optica, doi:10.1364/OPTICA.4.000611).

    It’s a bird, it’s a plane, it’s QKD

    Scientists have been investigating QKD as an unbreakable encryption scheme for more than three decades, but transmitting the keys over optical fiber doesn’t work for distances greater than a few hundred kilometers, due to exponentially scaling losses. Short-range QKD has been demonstrated for a prototype handheld device, as well as key transmissions from aircraft to ground bases. However, until the Waterloo experiments, no one had sent quantum keys from a terrestrial transmitter to a moving aircraft, even though the uplink mode requires simpler airborne equipment than the downlink scheme.

    The team from the University of Waterloo’s Institute for Quantum Computing, led by professor Thomas Jennewein and doctoral student Christopher Pugh, used many space-rated electronic components for its QKD receiver in anticipation of use in future satellites. Its ground transmitter, which was situated near a general-aviation airport in southern Ontario, employed two infrared lasers and the standard BB84 photon-polarization protocol (the technique of QKD was proposed by Charles H. Bennett and Gilles Brassard in 1984). The receiver, carried aboard a research aircraft, consisted of a 10-cm-aperture refractive telescope hitched to custom-designed sensors and controllers, including a dichroic mirror that separated the quantum and beacon signals. Both the transmitter and receiver used beacon lasers and tracking mechanisms to help find each other.

    The aircraft made 14 passes at approximately 1.6-km above sea level, with line-of-sight distances to the transmitter of 3 to 10 km and the plane flying up to 259 km/h. The team registered a signal on seven of the 14 passes and extracted a secret key, up to 868 kilobits long, from six of those seven. According to the Canadian team, the equipment maintained milli-degree pointing precision while the receiver was moving at an angular speed simulating that of a low-Earth-orbit spacecraft. The experiments lay a foundation for Canada’s future Quantum Encryption and Science Satellite mission.

    Passing through a satellite

    Last August, China launched the world’s first satellite for quantum optics experiments.

    4
    China’s 600-kilogram quantum satellite contains a crystal that produces entangled photons. Cai Yang/Xinhua via ZUMA Wire.

    Now researchers from multiple Chinese academic institutions have transmitted entangled photons from two widely separated ground stations via the orbiting satellite, officially named Quantum Experiment at Space Scale (QUESS) but informally dubbed Micius or Mozi after an ancient Chinese philosopher.

    The team sent the transmission between two ground stations separated by 1203 km; the path lengths between QUESS and the stations, Lijiang in southwestern China and Delingha in the northern province of Qinghai, varied from 500 to 2000 km. One of the corresponding authors, Jian-Wei Pan of the University of Science and Technology of China, Shanghai, likens the satellite-borne message exchange to seeing a single human hair at a distance of 300 m, or detecting from Earth a single photon that came from a match’s flame on the moon.

    Most of the photon loss and turbulence effects that plague free-space QKD occurs in the lower 10 km of the atmosphere, as the majority of the photons’ path is through a near vacuum. The Chinese researchers developed stable, bright two-photon entanglement sources with advanced pointing and tracking for both the satellite and the ground. Analysis of the received signals showed that the photons remained entangled and violated the Bell inequality. The researchers estimated that the link was 12 to 17 orders of magnitude more efficient than an equivalent long-distance connection along optical fibers.

    Pan had wanted to experiment with space-borne quantum communications since 2003, when quantum-optics experiments usually happened on a well-shielded optical table. The following year, he participated in a distribution of entangled photon pairs through a noisy, ground atmosphere of 13-km path length. In 2010 and 2012, the group extended the ground-based teleportation range to 16 km and 100 km. “Through these ground-based feasibility studies, we gradually developed the necessary tool box for the quantum science satellite, for example, high-precision and high-bandwidth acquiring, pointing, and tracking,” Pan says.

    And, according to Pan, the Chinese team will continue its quantum optical experiments at longer distances and also plan preliminary tests of quantum behavior under zero-gravity conditions.

    Leveraging existing tools

    A third set of experiments—conducted by a team led by OSA Member Christoph Marquardt, working in the research group of OSA Fellow Gerd Leuchs at the Max Planck Institute in Erlangen, Germany—built off of efforts toward satellite-to-earth optical communications by the German government, operating in partnership with the firm Tesat-Spacecom GmbH. And, notably, the experiments leveraged components not originally built for quantum communications.

    In the German experiments, coherent beams from a 1065-nm Nd:YAG laser communications terminal on the geostationary Earth orbiting satellite Alphasat I-XL, originally lofted into space in July 2013, were received at a transportable optical terminal then located at the Teide Observatory in Tenerife, Spain.

    5
    ESA/geostationary Earth orbiting satellite Alphasat I-XL

    The terminal was equipped with an adaptive-optics setup that corrected for phase distortions and piped the signal into a single-mode fiber, and used homodyne detection to pull out the quantum signature.

    To show that a true quantum link between satellite and ground, through the turbulent atmosphere, was possible, the Max Planck team used a phase modulator in the satellite equipment to encode a number of binary phase-modulated coherent states on the light field—states known to be compatible with quantum communication. With amplification and processing of the signal, the researchers were able to reliably pick up those quantum states at the ground station, from a beam that had “propagated 38,600 km through Earth’s gravitational potential, as well as its turbulent atmosphere.”

    “We were quite surprised by how well the quantum states survived traveling through the atmospheric turbulence to a ground station,” Marquardt noted in a press release. And, he said, the experiments suggested that the light beamed from a satellite to Earth could be “very well suited to be operated as a quantum key distribution network”—a surprising finding, he says, because the system was not built for quantum communication. In light of the work, he predicted that such a network “could be possible” in as little as five years.

    See the full article here .

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    Optics & Photonics News (OPN) is The Optical Society’s monthly news magazine. It provides in-depth coverage of recent developments in the field of optics and offers busy professionals the tools they need to succeed in the optics industry, as well as informative pieces on a variety of topics such as science and society, education, technology and business. OPN strives to make the various facets of this diverse field accessible to researchers, engineers, businesspeople and students. Contributors include scientists and journalists who specialize in the field of optics. We welcome your submissions.

     
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