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  • richardmitnick 11:23 am on May 10, 2021 Permalink | Reply
    Tags: "New light emitters developed for quantum circuits", , Harnessing optical photons to integrate quantum computing seamlessly with fiber-optic networks., KTH Royal Institute of Technology [Kungliga Tekniska högskolan] (SE), Quantum internet,   

    From KTH Royal Institute of Technology [Kungliga Tekniska högskolan] (SE): “New light emitters developed for quantum circuits” 

    From KTH Royal Institute of Technology [Kungliga Tekniska högskolan] (SE)

    May 10, 2021
    David Callahan

    A close-up look at the integrated chip that emits photons. Courtesy of Ali Elshaari.

    The promise of a quantum internet depends on the complexities of harnessing light to transmit quantum information over fiber optic networks. A potential step forward was reported today by researchers at KTH who developed integrated chips that can generate light particles on demand and without the need for extreme refrigeration.

    Quantum computing today relies on states of matter, that is, electrons which carry qubits of information to perform multiple calculations simultaneously, in a fraction of the time it takes with classical computing.

    KTH Professor Val Zwiller says that in order to integrate quantum computing seamlessly with fiber-optic networks—which are used by the internet today—a more promising approach would be to harness optical photons.

    “The photonic approach offers a natural link between communication and computation,” he says. “That’s important, since the end goal is to transmit the processed quantum information using light.”

    Deterministic rather than random

    But in order for photons to deliver qubits on-demand in quantum systems, they need to be emitted in a deterministic, rather than probabilistic, fashion. This can be accomplished at extremely low temperatures in artificial atoms, but today the research group at KTH reported a way to make it work in optical integrated circuits—at room temperature [Advanced Quantum Technologies].

    The new method enables photon emitters to be precisely positioned in integrated optical circuits that resemble copper wires for electricity, except that they carry light instead, says Associate Professor Ali Elshaari.

    The researchers harnessed the single-photon-emitting properties of hexagonal boron nitride (hBN), a layered material. hBN is a compound commonly used is used ceramics, alloys, resins, plastics and rubbers to give them self-lubricating properties. They integrated the material with silicon nitride waveguides to direct the emitted photons.

    Quantum circuits with light are either operated at cryogenic temperatures—plus 4 Kelvin above absolute zero—using atom-like single photon sources, or at room temperature using random single photon sources, Elshaari says. By contrast, the technique developed at KTH enables optical circuits with on-demand emission of light particles at room temperature.

    “In existing optical circuits operating at room temperature, you never know when the single photon is generated unless you do a heralding measurement,” Elshaari says. “We realized a deterministic process that precisely positions light-particles emitters operating at room temperature in an integrated photonic circuit.”

    The researchers reported coupling of hBN single photon emitter to silicon nitride waveguides, and they developed a method to image the quantum emitters. Then in a hybrid approach, the team built the photonic circuits with respect to the quantum sources locations using a series of steps involving electron beam lithography and etching, while still preserving the high quality nature of the quantum light.

    The achievement opens a path to hybrid integration, that is, incorporating atom-like single-photon emitters into photonic platforms that cannot emit light efficiently on demand.

    See the full article here.


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    KTH Royal Institute of Technology [Kungliga Tekniska högskolan](SE) is a public research university in Stockholm, Sweden. KTH conducts research and education within engineering and technology, and is Sweden’s largest technical university. Currently, KTH consists of five schools with four campuses in and around Stockholm.

    KTH was established in 1827 as Teknologiska Institutet (Institute of Technology), and had its roots in Mekaniska skolan (School of Mechanics) that was established in 1798 in Stockholm. But the origin of KTH dates back to the predecessor to Mekaniska skolan, the Laboratorium Mechanicum, which was established in 1697 by Swedish scientist and innovator Christopher Polhem. Laboratorium Mechanicum combined education technology, a laboratory and an exhibition space for innovations. In 1877 KTH received its current name, Kungliga Tekniska högskolan (KTH Royal Institute of Technology). It is ranked top 100 in the world among all universities in the 2020 QS World University Rankings.

  • richardmitnick 11:59 pm on April 17, 2021 Permalink | Reply
    Tags: , Quantum internet, Technical University of Delft [Technische Universiteit Delft] (NL)   

    Technical University of Delft [Technische Universiteit Delft] (NL): “Dutch researchers establish the first entanglement-based quantum network” 

    From Technical University of Delft [Technische Universiteit Delft] (NL)

    15 April 2021

    Prof. Ronald Hanson

    A team of researchers from QuTech in the Netherlands reports realization of the first multi-node quantum network, connecting three quantum processors. In addition, they achieved a proof-of-principle demonstration of key quantum network protocols. Their findings mark an important milestone towards the future quantum internet and have now been published in Science.

    The quantum internet-The power of the Internet is that it allows any two computers on Earth to be connected with each other, enabling applications undreamt of at the time of its creation decades ago. Today, researchers in many labs around the world are working towards first versions of a quantum internet – a network that can connect any two quantum devices, such as quantum computers or sensors, over large distances. Whereas today’s Internet distributes information in bits (that can be either 0 or 1), a future quantum internet will make use of quantum bits that can be 0 and 1 at the same time. “A quantum internet will open up a range of novel applications, from unhackable communication and cloud computing with complete user privacy to high-precision time-keeping,” says Matteo Pompili, PhD student and a member of the research team. “And like with the Internet 40 years ago, there are probably many applications we cannot foresee right now.”

    Co-authors Matteo Pompili (left) and Sophie Hermans (right), both PhD student in the group of Ronald Hanson, at one of the quantum network nodes.

    Towards ubiquitous connectivity

    The first steps towards a quantum internet were taken in the past decade by linking two quantum devices that shared a direct physical link. However, being able to pass on quantum information through intermediate nodes (analogous to routers in the classical internet) is essential for creating a scalable quantum network. In addition, many promising quantum internet applications rely on entangled quantum bits, to be distributed between multiple nodes. Entanglement is a phenomenon observed at the quantum scale, fundamentally connecting particles at small and even at large distances. It provides quantum computers their enormous computational power and it is the fundamental resource for sharing quantum information over the future quantum internet. By realizing their quantum network in the lab, a team of researchers at QuTech – a collaboration between Delft University of Technology and TNO – is the first to have connected two quantum processors through an intermediate node and to have established shared entanglement between multiple stand-alone quantum processors.

    Operating the quantum network

    The rudimentary quantum network consists of three quantum nodes, at some distance within the same building. To make these nodes operate as a true network, the researchers had to invent a novel architecture that enables scaling beyond a single link. The middle node (called Bob) has a physical connection to both outer nodes (called Alice and Charlie), allowing entanglement links with each of these nodes to be established. Bob is equipped with an additional quantum bit that can be used as memory, allowing a previously generated quantum link to be stored while a new link is being established. After establishing the quantum links Alice–Bob and Bob–Charlie, a set of quantum operations at Bob converts these links into a quantum link Alice-Charlie. Alternatively, by performing a different set of quantum operations at Bob, entanglement between all three nodes is established.

    Researchers work on one of the quantum network nodes, where mirrors and filters guide the laser beams to the diamond chip.

    Ready for subsequent use

    An important feature of the network is that it announces the successful completion of these (intrinsically probabilistic) protocols with a “flag” signal. Such heralding is crucial for scalability, as in a future quantum internet many of such protocols will need to be concatenated. “Once established, we were able to preserve the resulting entangled states, protecting them from noise,” says Sophie Hermans, another member of the team. “It means that, in principle, we can use these states for quantum key distribution, a quantum computation or any other subsequent quantum protocol.”

    Higher-level layers

    In the lab, the researchers will focus on adding more quantum bits to their three-node network and on adding higher level software and hardware layers. Pompili: “Once all the high-level control and interface layers for running the network have been developed, anybody will be able to write and run a network application without needing to understand how lasers and cryostats work. That is the end goal.”

    See the full article here.


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    Delft University of Technology [Technische Universiteit Delft] (NL) campus

    University of Technology [Technische Universiteit Delft] (NL), is the oldest and largest Dutch public technological university. It Delft University of Technology [Technische Universiteit Delft] (NL)is consistently ranked as the best university in the Netherlands. As of 2020, it is ranked by QS World University Rankings among the top 15 engineering and technology universities in the world.

    With eight faculties and numerous research institutes, it has more than 19,000 students (undergraduate and postgraduate), and employs more than 2,900 scientists and 2,100 support and management staff.

    The university was established on 8 January 1842 by William II of the Netherlands as a Royal Academy, with the primary purpose of training civil servants for work in the Dutch East Indies. The school expanded its research and education curriculum over time, becoming a polytechnic school in 1864 and an institute of technology (making it a full-fledged university) in 1905. It changed its name to Delft University of Technology in 1986.

    Dutch Nobel laureates Jacobus Henricus van ‘t Hoff, Heike Kamerlingh Onnes, and Simon van der Meer have been associated with TU Delft. TU Delft is a member of several university federations, including the IDEA League, CESAER, UNITECH International, and 4TU. 


    TU Delft has three officially recognized research institutes: Research Institute for the Built Environment; International Research Centre for Telecommunications-transmission and Radar; and Reactor Institute Delft. In addition to those three institutes, TU Delft hosts numerous smaller research institutes, including the Delft Institute of Microelectronics and Submicron Technology; Kavli Institute of Nanoscience; Materials innovation institute; Astrodynamics and Space Missions; Delft University Wind Energy Research Institute; TU Delft Safety and Security Institute; and the Delft Space Institute. Delft Institute of Applied Mathematics is also an important research institute which connects all engineering departments with respect to research and academia.

  • richardmitnick 9:07 am on December 31, 2020 Permalink | Reply
    Tags: "Opinion-The unhackable computers that could revolutionize the future", , , , , Quantum internet, ,   

    From CNN: “Opinion-The unhackable computers that could revolutionize the future” 

    From CNN

    December 29, 2020

    Don Lincoln-Fermi National Accelerator Laboratory.

    Modern science often makes some unbelievable claims, but the discipline that seems to be the most outrageous may well be quantum physics. Commonly mentioned quantum ideas include cats simultaneously being alive and dead until someone looks at them and multiple worlds where not only are all things possible, but all things actually happen — at least in a parallel reality.

    With such mind-bending predictions, it is entirely reasonable to imagine that no useful technology could arise from quantum physics. However, this is not true. Physicists, engineers and computer scientists are trying to harness the counterintuitive behavior of quantum mechanics to build quantum computers, leading eventually to a quantum internet.
    And this effort isn’t just an abstract goal of academics; it has been identified by the US government as an important national initiative.

    Federal agencies have begun to lay out the framework for an American quantum infrastructure. The Department of Energy, for example, plans to link together its laboratories with a quantum internet.

    A quantum internet is both similar and different to the ordinary internet. It is similar in that it connects computers, although only quantum ones.

    Google 54-qubit Sycamore superconducting processor quantum computer.

    IBM iconic image of Quantum computer.

    It is different because the way these computers interact is essentially unhackable.
    Any attempt to intercept a message tell the intended recipient that someone had read it before it was delivered. To comply with the new initiative, the country’s universities and national laboratories have begun to develop the capabilities necessary to make a successful quantum internet.

    One such advance was the successful transmission of quantum information announced this month by a consortium of universities, national labs and private industry.

    This is an important step toward building a quantum internet. (Disclosure: One of the affiliated laboratories is Fermi National Accelerator Laboratory, the facility at which I am a scientist, although I am not involved with this particular achievement.)

    Quantum computing differs from ordinary computing in many ways. First, ordinary computers are built around the concept of the bit, which is effectively a switch that can be flipped on or off — what computer professionals call a 1 or 0. In contrast, quantum computers use the qubit, short for “quantum bit.”

    Qubits are somewhat like ordinary bits, in that they are measured as 0s and 1s, but in between measurements, they are an indeterminate mix of 0s and 1s. This bit of quantum magic is exactly the same (and just as confusing) as Schrodinger’s cat.

    In 1935, Austrian physicist Erwin Schrodinger devised a thought experiment to illustrate the absurdity of a quantum theory called the Copenhagen interpretation of quantum mechanics [Stanford Encyclopedia of Philosophy]. The Copenhagen interpretation, named for the city in which it was invented, said that a quantum system could simultaneously be two opposite things until a measurement was performed.

    An example of a quantum system is a radioactive atom which, according to the Copenhagen interpretation, is both decayed and not decayed until someone measures it. Schrodinger imagined some radioactive material in a sealed box which included a radiation detector, a hammer, a vial of poisonous gas and a cat. If an atom of the radioactive substance decayed, the detector would record it and release a hammer to break the vial of poison, which would, in turn, kill the cat.

    According to the laws of quantum mechanics, until the box is opened, the atom is simultaneously both decayed and not decayed, meaning the cat was both alive and dead. Schrodinger felt this was absurd and claimed that his thought experiment invalidated the Copenhagen interpretation of quantum mechanics.

    Yet the idea that quantum mechanics allows for an object to simultaneously be in two opposite configurations is actually true. A qubit in a quantum computer is both a 0 and 1 in a single moment. That sounds impossible, but it’s one of the things that distinguishes the quantum world from our familiar one. Subatomic particles like electrons can be in two places or once or can simultaneously spin in opposite directions. It’s these opposite spins that make up qubits. A clockwise spinning electron is a 0 and a counterclockwise one is a 1 (or vice versa).

    The first working quantum computer was demonstrated in 1998. It was very primitive, but it was a baby step. Quantum computing has strengths and weaknesses. For most problems, a quantum computer isn’t really faster than high-end ordinary computers. However, for certain problems — like code breaking — quantum computing leaves regular computers in the dust.

    When advanced quantum computers are a reality, they will be able to break codes incomparably faster than currently possible. What would take trillions of years using ordinary computers would take a few seconds with a quantum computer. For example, Google has announced an algorithm that runs a hundred million times faster on quantum computers than ordinary ones.

    What’s more, quantum computers not only excel at decryption; they also excel at encryption. Quantum algorithms have been developed that are thought to be unbreakable. It is these cryptographic capabilities that interest both nations and corporations involved in e-commerce.

    Of course, perfect quantum computers are not yet available, and may never be. Unlike ordinary computers, in which it is easy to tell if a bit is on or off, in quantum computers, the qubits are very sensitive to their environment, especially heat. Vibrations of the atoms of the computer can destroy the information stored in qubits, requiring that quantum computers be kept at very low temperatures.

    While many institutions are developing quantum computers, making a quantum internet requires a way to transfer the information between computers. This is accomplished by a phenomenon called quantum teleportation [INQNET], in which two atoms separated by large distances are made to act as if they are identical.

    A recent advance by the IN-Q-NET consortium [PRX Quantum], led by Caltech and with many institutional collaborators, has successfully demonstrated long distance quantum teleportation at two test beds, one located at Caltech, and the other at Fermilab, near Chicago. This achievement used commercially available equipment and is an important step in developing a quantum internet.

    It is still very early in the history of quantum computing and it is unclear exactly where it is going. Its proponents are very enthusiastic about its future, while others (including myself) view it cautiously. However, there is no question that its codemaking and -breaking capabilities make it an interesting prospect in the landscape of online protection and hacking.

    Where will quantum computing be in a decade? It is hard to say. But we have a long history of impressive scientific feats to make us optimistic. In 1783, when Benjamin Franklin viewed the first balloon flight, he was asked what good it was. He replied with the famous quip, “What good is a newborn baby?” And today we fly around the world and are conquering space.
    Quantum computing is still in its infancy, but one day it may change the world. We must wait and see.

    See the full article here .


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  • richardmitnick 2:42 pm on December 15, 2020 Permalink | Reply
    Tags: "Fermilab and partners achieve sustained high-fidelity quantum teleportation", Caltech Quantum Network, Chicagoland network-the Illinois Express Quantum Network- is being designed by Fermilab in collaboration with Argonne National Laboratory Caltech Northwestern University and industry partners., , Fermilab Quantum Network, Information stored in qubits is shared over long distances through entanglement., Quantum internet, Quantum teleportation is a “disembodied” transfer of quantum states from one location to another., The feat is a testament to success of collaboration across disciplines and institutions which drives so much of what we accomplish in science., The qubits were teleported over a fiber-optic network using state-of-the-art single-photon detectors and off-the-shelf equipment., The systems were designed; built; commissioned and deployed by Caltech’s public-private research program on Intelligent Quantum Networks and Technologies or IN-Q-NET.   

    From DOE’s Fermi National Accelerator Laboratory: “Fermilab and partners achieve sustained, high-fidelity quantum teleportation” 

    FNAL Art Image
    FNAL Art Image by Angela Gonzales

    From DOE’s Fermi National Accelerator Laboratory , an enduring source of strength for the US contribution to scientific research world wide.

    December 15, 2020

    Leah Hesla

    In a demonstration of high-fidelity quantum teleportation at the Fermilab Quantum Network, fiber-optic cables connect off-the-shelf devices (shown above), as well as state-of-the-art R&D devices. Credit: Fermilab.

    A viable quantum internet — a network in which information stored in qubits is shared over long distances through entanglement — would transform the fields of data storage, precision sensing and computing, ushering in a new era of communication.

    This month, scientists at Fermilab, a U.S. Department of Energy Office of Science national laboratory, and their partners took a significant step in the direction of realizing a quantum internet.

    In a paper published in PRX Quantum, the team presents for the first time a demonstration of a sustained, long-distance (44 kilometers of fiber) teleportation of qubits of photons (quanta of light) with fidelity greater than 90%. The qubits were teleported over a fiber-optic network using state-of-the-art single-photon detectors and off-the-shelf equipment.

    “We’re thrilled by these results,” said Fermilab scientist Panagiotis Spentzouris, head of the Fermilab quantum science program and one of the paper’s co-authors. “This is a key achievement on the way to building a technology that will redefine how we conduct global communication.”

    Quantum teleportation is a “disembodied” transfer of quantum states from one location to another. The quantum teleportation of a qubit is achieved using quantum entanglement, in which two or more particles are inextricably linked to each other. If an entangled pair of particles is shared between two separate locations, no matter the distance between them, the encoded information is teleported.

    The joint team — researchers at Fermilab, AT&T, Caltech, Harvard University, NASA Jet Propulsion Laboratory and University of Calgary — successfully teleported qubits on two systems: the Caltech Quantum Network, or CQNET, and the Fermilab Quantum Network, or FQNET. The systems were designed, built, commissioned and deployed by Caltech’s public-private research program on Intelligent Quantum Networks and Technologies, or IN-Q-NET.

    “We are very proud to have achieved this milestone on sustainable, high-performing and scalable quantum teleportation systems,” said Maria Spiropulu, Shang-Yi Ch’en professor of physics at Caltech and director of the IN-Q-NET research program. “The results will be further improved with system upgrades we are expecting to complete by Q2 2021.”

    CQNET and FQNET, which feature near-autonomous data processing, are compatible both with existing telecommunication infrastructure and with emerging quantum processing and storage devices. Researchers are using them to improve the fidelity and rate of entanglement distribution, with an emphasis on complex quantum communication protocols and fundamental science.

    The achievement comes just a few months after the U.S. Department of Energy unveiled its blueprint for a national quantum internet at a press conference in Chicago.

    “With this demonstration we’re beginning to lay the foundation for the construction of a Chicago-area metropolitan quantum network,” Spentzouris said. The Chicagoland network, called the Illinois Express Quantum Network, is being designed by Fermilab in collaboration with Argonne National Laboratory, Caltech, Northwestern University and industry partners.

    This research was supported by DOE’s Office of Science through the Quantum Information Science-Enabled Discovery (QuantISED) program.

    “The feat is a testament to success of collaboration across disciplines and institutions, which drives so much of what we accomplish in science,” said Fermilab Deputy Director of Research Joe Lykken. “I commend the IN-Q-NET team and our partners in academia and industry on this first-of-its-kind achievement in quantum teleportation.”

    Learn more about the result.

    See the full here.


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    FNAL Icon

    Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics. Fermilab is America’s premier laboratory for particle physics and accelerator research, funded by the U.S. Department of Energy. Thousands of scientists from universities and laboratories around the world
    collaborate at Fermilab on experiments at the frontiers of discovery.

  • richardmitnick 12:51 pm on December 18, 2019 Permalink | Reply
    Tags: "Remote Quantum Systems Produce Interfering Photons", , , , , , , , Quantum internet,   

    From Joint Quantum Institute: “Remote Quantum Systems Produce Interfering Photons” 

    JQI bloc

    From Joint Quantum Institute

    December 17, 2019

    Research Contact
    Steve Rolston

    Story by Jillian Kunze

    A schematic showing the paths taken by photons from two different sources in neighboring buildings. (Credit: S. Kelley/NIST)

    Scientists at the Joint Quantum Institute (JQI) have observed, for the first time, interference between particles of light created using a trapped ion and a collection of neutral atoms. Their results could be an essential step toward the realization of a distributed network of quantum computers capable of processing information in novel ways.

    In the new experiment, atoms in neighboring buildings produced photons—the quantum particles of light—in two distinct ways. Several hundred feet of optical cables then brought the photons together, and the research team, which included scientists from JQI as well as the Army Research Lab, measured a telltale interference pattern. It was the first time that photons from these two particular quantum systems were manipulated into having the same wavelength, energy and polarization—a feat that made the particles indistinguishable. The result, which may prove vital for communicating over quantum networks of the future, was published recently in the journal Physical Review Letters.

    “If we want to build a quantum internet, we need to be able to connect nodes of different types and functions,” says JQI Fellow Steve Rolston, a co-author of the paper and a professor of physics at the University of Maryland. “Quantum interference between photons generated by the different systems is necessary to eventually entangle the nodes, making the network truly quantum.”

    The first source of photons was a single trapped ion—an atom that is missing an electron—held in place by electric fields. Collections of these ions, trapped in a chain, are leading candidates for the construction of quantum computers due to their long lifetimes and ease of control. The second source of photons was a collection of very cold atoms, still in possession of all their electrons. These uncharged, or neutral, atomic ensembles are excellent interfaces between light and matter, as they easily convert photons into atomic excitations and vice versa. The photons produced by each of these two systems are typically different, limiting their ability to work together.

    In one building, researchers used a laser to excite a trapped barium ion to a higher energy. When it transitioned back to a lower energy, it emitted a photon at a known wavelength but in a random direction. When scientists captured a photon, they stretched its wavelength to match photons from the other source.

    In an adjacent building, a cloud of tens of thousands of neutral rubidium atoms generated the photons. Lasers were again used to pump up the energy of these atoms, and that procedure imprinted a single excitation across the whole cloud through a phenomenon called the Rydberg blockade. When the excitation shed its energy as photons, they traveled in a well-defined direction, making it easy for researchers to collect them.

    The team used an interferometer to measure the degree to which two photons were identical. A single photon entering the interferometer is equally likely to take either of two possible exits. And two distinguishable photons entering the interferometer at the same time don’t notice each other, acting like two independent single photons.

    But when researchers brought together the photons from their two sources, they almost always took the same exit—a result of quantum interference and an indication that they were nearly identical. This was precisely what the research team had hoped for: the first demonstration of interference between photons from these two very different quantum systems.

    In this experiment, photons traveled from the first building to the second via hundreds of feet of optical fiber. Due to this distance, sending photons from both systems to meet at the interferometer simultaneously was a feat of precise timing. Detectors were placed at the exits of the interferometer to detect where the photons came out, but the team often had to wait—gathering all the data took 24 hours over a period of 3 days.

    Further experimental upgrades could be used to generate a special quantum connection called entanglement between the ion and the neutral atoms. In entanglement, two quantum objects become so closely linked that the results from measuring one are correlated with the results from measuring the other, even if the objects are separated by a huge distance. Entanglement is necessary for the speedy algorithms that scientists hope to run on quantum computers in the future.

    Generating entanglement between different quantum systems usually requires identical photons, which the researchers were able to create. Unfortunately, trapped ions emit photons in a random direction, making the probability of catching them low. This meant that only about eight photons from the trapped ion made it to the interferometer each second. If the researchers attempted to perform more intricate experiments with that rate, the data could take months to collect. However, future work may increase how frequently the ion emits photons and allow for a useful rate of entanglement production.

    “This is a stepping-stone on the way to being able to entangle these two systems,” says Alexander Craddock, a graduate student at JQI and the lead author of this study. “And that would be fantastic, because you can then take advantage of all the different weird and wonderful properties of both of them.”

    In addition to Rolston and Craddock, co-authors of the paper include JQI graduate students John Hannegan, Dalia Ornelas-Huerta, and Andrew Hachtel, JQI postdoctoral researcher James Siverns, Army Research Laboratory scientists and JQI Affiliates Elizabeth Goldschmidt (now an Assistant Professor of Physics at the University of Illinois) and Qudsia Quraishi, and JQI Fellow Trey Porto.

    See the full article here .


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    JQI supported by Gordon and Betty Moore Foundation

    We are on the verge of a new technological revolution as the strange and unique properties of quantum physics become relevant and exploitable in the context of information science and technology.

    The Joint Quantum Institute (JQI) is pursuing that goal through the work of leading quantum scientists from the Department of Physics of the University of Maryland (UMD), the National Institute of Standards and Technology (NIST) and the Laboratory for Physical Sciences (LPS). Each institution brings to JQI major experimental and theoretical research programs that are dedicated to the goals of controlling and exploiting quantum systems.

  • richardmitnick 11:24 am on February 4, 2019 Permalink | Reply
    Tags: A prototype for a key element of all-photonic quantum repeaters, Quantum internet,   

    From University of Toronto: “Towards a Quantum Internet” 

    U Toronto Bloc

    From University of Toronto

    January 31, 2019
    Jessica MacInnis

    U of T’s Hoi-Kwong Lo is among a group of quantum experts who are helping to develop a more secure and stable quantum internet. Photo by Jessica MacInnis

    A University of Toronto researcher is among a global group of experts who have demonstrated, in principle, a device that could serve as the backbone of a quantum internet.

    Hoi-Kwong Lo, a professor in the department of electrical and computer engineering in the Faculty of Applied Science & Engineering, and his collaborators have developed a prototype for a key element of all-photonic quantum repeaters, a critical step in long-distance quantum communication.

    “An all-optical network is a promising form of infrastructure for fast and energy-efficient communication that is required for a future quantum internet,” says Lo, who is cross-appointed to the department of physics in the Faculty of Arts & Science.

    A quantum internet is considered the Holy Grail of quantum information processing, enabling many novel applications including information-theoretic secure communication. By contrast, today’s internet was not specifically designed for security, and it shows: breaches, break-ins and computer espionage are common challenges. Nefarious hackers are constantly poking holes in sophisticated layers of defence erected by individuals, corporations and governments.

    In light of this, researchers have proposed other ways of transmitting data that would leverage key features of quantum physics to provide virtually unbreakable encryption. One of the most promising technologies involves a technique known as quantum key distribution, or QKD. QKD exploits the fact that the simple act of sensing or measuring the state of a quantum system disturbs that system. Because of this, eavesdropping by a third party would leave behind a detectable trace, and the communication could be aborted before sensitive information is lost.

    Until now, this type of quantum security has been only demonstrated in small-scale systems. Lo and his team are among a group of global researchers who are laying the groundwork for a future quantum internet by addressing some of the challenges of transmitting quantum information over great distances using optical fibre communication.

    Because light signals lose potency as they travel long distances through fibre-optic cables, devices called repeaters are inserted at regular intervals along the line. The repeaters boost and amplify the signals to help transmit the information.

    But existing repeaters for quantum information are highly problematic. They require storage of the quantum state at the repeater sites, making the repeaters error prone, difficult to build, and very expensive because they often operate at cryogenic temperatures.

    Lo and his team have proposed a different approach. They are working on the development of the next generation of repeaters, called all-photonic quantum repeaters, that would eliminate or reduce many of the shortcomings of standard quantum repeaters. With collaborators at Osaka University, Toyama University and NTT Corporation in Japan, Lo and his team have demonstrated proof-of-concept of their work in a paper recently published in Nature Communications.

    “We have developed all-photonic repeaters that allow time-reversed adaptive Bell measurement,” says Lo.

    “Because these repeaters are all-optical, they offer advantages that traditional – quantum-memory-based matter – repeaters do not. For example, this method could work at room temperature.”

    A quantum Internet could offer applications that are impossible to implement in the conventional Internet, such as impenetrable security and quantum teleportation, which takes advantage of the phenomenon of quantum entanglement to transmit information between atoms separated by large distances.

    “Our work helps pave the way toward this future,” Lo says.

    The research was funded by the Natural Sciences and Engineering Research Council of Canada, among others.

    See the full article here.


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    Founded in 1827, the University of Toronto has evolved into Canada’s leading institution of learning, discovery and knowledge creation. We are proud to be one of the world’s top research-intensive universities, driven to invent and innovate.

    Our students have the opportunity to learn from and work with preeminent thought leaders through our multidisciplinary network of teaching and research faculty, alumni and partners.

    The ideas, innovations and actions of more than 560,000 graduates continue to have a positive impact on the world.

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