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Massachusetts Institute of Technology has made significant progress towards fully implementing quantum computing

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Tunable Coupler Switch Qubit


A configurable coupling element can enable or disable the interaction of a qubit with a qubit. Unwanted residual (ZZ) interaction between two qubits is eliminated by using higher energy levels of the coupler. Credit: Krantz Nanoart.

Researchers at the Massachusetts Institute of Technology are demonstrating a way to dramatically reduce errors in two-qubit gates, a significant step forward towards fully implementing quantum computing.

Researchers at MIT have made significant progress towards fully realizing quantum computing by demonstrating a technique that eliminates common errors in the most important operation of quantum algorithms, the two-qubit or “gate” operation.

“Despite tremendous progress towards being able to perform low-error computations with superconducting quantum bits (qubits), errors in two-qubit gates, one of the building blocks of quantum computing, persist,” said Yongkyu Sun, a graduate student at MIT. Electrical Engineering and Computer Science, who is the lead author of an article on this topic published on June 16, 2021 in Physical view X… “We have demonstrated a way to dramatically reduce these errors.”

In quantum computers, information processing is an extremely delicate process performed by fragile qubits that are highly susceptible to decoherence, the loss of their quantum mechanical behavior. A previous study by Son and his research team, MIT Engineering Quantum Systems, proposed configurable coupling elements that allow researchers to turn two-qubit interactions on and off to control their operations while keeping qubits fragile. The idea of ​​a custom coupler represents a significant step forward and, for example, has been cited by Google as the key to their recent demonstration of the superiority of quantum computing over classical computing.

However, eliminating error mechanisms is like peeling an onion: peeling one layer reveals the next. In this case, even with the use of tunable couplers, the two-qubit gates were still prone to errors resulting from residual unwanted interactions between the two qubits and between the qubits and the coupler. Such unwanted interactions were usually ignored prior to custom taps as they were not highlighted, but now they are highlighted. And because such residual errors increase with the number of qubits and gates, they hinder the creation of larger quantum processors. IN Physical view X paper offers a new approach to reducing such errors.

“We have now gone beyond the tunable coupler concept and have demonstrated nearly 99.9% accuracy for the two basic types of two-qubit gates known as Controlled-Z gates and iSWAP gates,” says William D. Oliver, associate professor of electrical engineering. and Computer Science, Fellow at the MIT Lincoln Laboratory, Director of the Center for Quantum Engineering and Associate Director of the Electronics Research Laboratory, which houses the Quantum Systems Engineering group. “Higher precision gateways increase the number of operations that can be performed, and more operations lead to more complex algorithms being implemented on a larger scale.”

To eliminate the error-causing qubit-qubit interactions, the researchers used higher energy levels of the coupler to neutralize the problematic interactions. In previous work, such coupler energy levels were ignored, although they caused significant two-qubit interactions.

“Better control and better coupler design is the key to adapting the qubit-to-qubit interaction to our desires. This can be accomplished by developing existing multi-level dynamics, ”says Sun.

The next generation of quantum computers will have bug fixes, which means more qubits will be added to improve the reliability of quantum computing.

“Qubit bugs can be actively addressed by adding redundancy,” says Oliver, pointing out, however, that such a process only works if the gateways are good enough — above a certain threshold of accuracy that depends on the error correction protocol. “The softest threshold today is about 99 percent. In practice, however, to live with reasonable levels of hardware redundancy requires gate accuracy to be much higher than this threshold. ”

The devices used in the study at MIT’s Lincoln Laboratory played a fundamental role in achieving the demonstrated improvement in the accuracy of two-qubit operations, Oliver said.

“Making devices with high coherence is the first step towards realizing high-precision control,” he says.

Sun says that “the high error rate in two-qubit gates significantly limits the ability of quantum hardware to run quantum applications that are usually difficult to solve with classical computers, such as quantum chemical simulations and optimization problems.”

Until now, only small molecules have been simulated on quantum computers, and this simulation could easily be done on classical computers.

“In that sense, our new approach to reducing two-qubit gate errors is timely in the field of quantum computing and helps solve one of the most critical problems in quantum hardware today,” he says.

Reference: “Implementing High Precision iSWAP Gateways without CZ and ZZ with Custom Connector” by Jungkü Sung, Leon Ding, Jochen Braumüller, Antti Vepsäläinen, Bharat Kannan, Morten Kjargaard, Amy Green, Gabriel O. Samah, Chris McNally. David Kim, Alexander Melville, Bethany M. Nedzelsky, Molly E. Schwartz, Joniline L. Yoder, Terry P. Orlando, Simon Gustavsson and William D. Oliver, June 16, 2021, Physical view X
DOI: 10.1103 / PhysRevX.11.021058





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Farming robots are the future – we must prepare now to avoid dystopia

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Dystopian Farm Robots


This illustration shows the scenario of a utopian farming robot. Credit: Natalis Lorenz.

This is no longer science fiction, farm robots are already here – and they have created two possible extremes for the future of agriculture and its impact on the environment, says agricultural economist Thomas Daum in an article published July 13, 2021 in Science & Society. Journal Trends in ecology and evolution… One of them is a utopia, in which entire parks of small intelligent robots work in harmony with nature to produce a variety of organic crops. Another is a dystopia in which large, tractor-like robots conquer the landscape with heavy machinery and artificial chemicals.

He describes the utopian scenario as a mosaic of rich green fields, streams, wild flora and fauna, where fleets of small robots powered by sustained energy flutter around the fields, their buzzing mingling with the chirping of insects and the song of birds. “It’s like a Garden of Eden,” says Daum (@ThomDaum), a research associate at the University of Hohenheim in Germany who studies agricultural development strategies. “Small robots can help conserve biodiversity and combat climate change in ways that have never been possible before.”

He suggests that a utopian scenario that is too laborious for conventional farming, but possible with robots working around the clock, 7 days a week, is likely to benefit the environment in many ways. Plants would be more varied and the soil richer in nutrients. Thanks to micro-spraying of biopesticides and laser weed removal, nearby water, insect populations and soil bacteria will also become healthier. Organic crop yields, which are now often lower than traditional crop yields, will be higher and the impact of agriculture on the environment will be greatly reduced.

Dystopian farm robots

This illustration shows the scenario of a dystopian farming robot. Credit: Natalis Lorenz.

However, he believes that a parallel future with negative environmental consequences is quite possible. In this scenario, he says, large but technologically crude robots will bulldoze the natural landscape, and multiple monocultural cultures will dominate the landscape. Large fences would isolate people, farms and wildlife from each other. Once people are removed from farms, agrochemicals and pesticides can be used more widely. The ultimate goals will be structure and control: qualities that these simpler robots excel at, but which are likely to have detrimental effects on the environment.

While he notes that it’s unlikely the future will be limited to pure utopia or pure dystopia, by creating these two scenarios, Daum hopes to spark a conversation in what he sees as a crossroads in time. “Both utopia and dystopia are possible from a technological point of view. But without the right policy barriers, we could end up in a dystopia without even wanting to, if we don’t discuss it now, ”says Daum.

But this impact is not just limited to the environment – it affects normal people as well. “Robotic farming can also specifically impact you as a consumer,” he says. “In utopia, we don’t just grow crops – we have a lot of fruits and vegetables, the relative prices of which will fall, so a healthier diet will become more affordable.”

The small robots described in Daum’s utopian scenario would also be more suitable for small farmers who would find it easier to afford or share them through services like Uber. On the contrary, he argues that a family farm is less likely to survive in a dystopian scenario: only large producers, he says, will be able to manage huge tracts of land and high costs for large machinery.

In parts of Europe, Asia and Africa, where there are currently many small farms, deliberate efforts to implement a utopian scenario offer clear advantages. The situation is more difficult in countries such as the United States, Russia or Brazil, which have historically been dominated by large farms producing large volumes of low-value grains and oilseeds. There, small robots that are less efficient at performing energy-intensive tasks like threshing corn may not always be the most cost-effective option.

“While it is true that the preconditions for small robots are more complex in these areas,” he says, “even with large robots – or a mixture of small and large ones – we can take steps towards utopia with practices like interbreeding, having hedges. agroforestry and the shift from large farms to smaller plots of land owned by large farmers. Some of these methods may even pay off to farmers when robots can do their job as previously unprofitable methods become profitable. ”

To do this, Daum said, you need to act now. While some aspects of the utopian scenario, such as laser weeding, are already developed and ready for widespread adoption, funding must go to other aspects of machine learning and artificial intelligence in order to develop robots intelligent enough to adapt to complex unstructured farming systems. Policy changes are also needed and can take the form of subsidies, regulations, or taxes. “In the European Union, for example, farmers receive money when they perform certain landscape services, such as growing many trees or rivers on their farms,” he says.

While it may seem like a dystopian scenario is more likely, it is not the only way forward. “I think utopia is achievable,” says Daum. “It won’t be as easy as a dystopia, but it’s quite possible.”

Link: “Farming robots: ecological utopia or dystopia?” Thomas Daum, July 13, 2021 Trends in ecology and evolution
DOI: 10.1016 / j.tree.2021.06.002

This work was supported by the “Companion Research Program for Agricultural Innovation”, which is funded by the German Federal Ministry for Economic Cooperation and Development (BMZ).





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Dynamic control of THz wavefronts due to rotation of layers of cascade metasurfaces

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Metadevice for Dynamically Controlling THz Wavefronts


Meta-device for dynamic control of THz wavefronts by rotating layers of cascade metasurfaces. Credit: Shanghai University.

Cascading metasurfaces for dynamic control of THz wave fronts

Electromagnetic (EM) waves in terahertz (THz) mode are used for critical applications in communications, security imaging, and bio and chemical sensing. This widespread applicability has led to significant technological progress. However, due to the weak interaction between natural materials and THz waves, conventional THz devices are usually cumbersome and ineffective. Although ultra-compact active devices in the THz range do exist, modern electronic and photonic approaches to dynamic control are ineffective.

Recently, the rapid development of metasurfaces has opened up new opportunities for creating highly efficient ultra-compact devices in the THz range for dynamic wavefront control. Ultra-thin metamaterials formed by subwavelength planar microstructures (i.e., metaatoms), metasurfaces allow tuning optical responses to control the fronts of electromagnetic waves. By creating metasurfaces that have certain predefined phase profiles for transmitted or reflected waves, scientists have demonstrated exciting wave manipulation effects such as abnormal light deflection, polarization manipulation, photon spin hall and holograms.

Dynamic beam steering metaservice

Demonstration of the dynamic beam steering meta-device: (a) Schematic of the meta-device, which consists of two layers of transmissive metasurfaces aligned with a motorized turntable. (b) top view (left) and (c) bottom view (right) of a SEM image of the fabricated meta-device. (d) Diagram of the experimental setup shown to characterize the meta-device. (e) Experimental and (f) simulated far-field scattering power distribution with a meta device illuminated with 0.7 THz LCP light and evolving along path I at different times. (g) Evolution of the directions of the transmitted waves on the sphere of direction k when the meta device moves along Path I and Path II, with the solid line (asterisks) denoting the results of the simulation (experiment). Here, the blue area denotes the solid angle for beam steering coverage. Credit: X. Cai et al., Doi 10.1117 / 1.AP.3.3.036003.

Moreover, the integration of active elements with individual meta-atoms within passive metasurfaces allows the creation of “active” meta-devices that can dynamically manipulate the fronts of electromagnetic waves. While active elements in deep subwavelengths are easy to find in microwave mode (e.g. PIN diodes and varactors) and successfully contribute to active meta-devices for beam steering, programmable holograms, and dynamic imaging, they are difficult to create at frequencies above THz. … This difficulty stems from size limitations and significant ohmic losses in electronic circuits. Although terahertz frequencies can drive terahertz beams uniformly, they usually cannot dynamically manipulate terahertz wave fronts. Ultimately this is due to the lack of local tuning capabilities at subwavelength depth scales in this frequency domain. Therefore, developing new approaches to avoid local customization is a priority.

As reported in Advanced PhotonicsResearchers from Shanghai University and Fudan University have developed a general structure and meta-devices to achieve dynamic control of THz wave fronts. Instead of locally controlling individual meta-atoms in the THz metasurface (for example, via a PIN diode, varactor, etc.), They change the polarization of the light beam using rotating multilayer cascade metasurfaces. They demonstrate that rotating different layers (each exhibiting a specific phase profile) in a cascade meta-device at different speeds can dynamically change the effective Jones matrix property of the entire device, achieving unusual manipulations with the wavefront and polarization characteristics of terahertz rays. Two meta-devices are demonstrated: the first meta-device can effectively redirect a normally incident THz beam for scanning in a wide range of solid angles, and the second can dynamically manipulate both the wavefront and polarization of the THz beam.

This paper proposes an attractive alternative way to achieve inexpensive dynamic control of THz waves. The researchers hope this work will inspire future applications of terahertz radars as well as bio and chemical sensing and imaging.

Reference: “Dynamic control of terahertz wavefronts with cascading metasurfaces” Xiaodong Tsai, Rong Tang, Haoyang Zhou, Qiushi Li, Shaoji Ma, Dongyi Wang, Tong Liu, Xiaohui Lin, Wei Tang, Qiong He, Shii Xiao, and Lei Zhou, June 26 … 2021, Advanced Photonics
DOI: 10.1117 / 1.AP.3.3.036003





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Take part in ESA Space Camp 2021

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Take part in ESA Space Camp 2021


Space App Camp 2021. Credit: ESA.

ESA invites up to 25 dedicated mobile app developers and AI and machine learning specialists related to Earth observation from space to join this year’s Space App Camp, which will be a virtual event for eight weeks, from July 20 to September 20. …

The Space App Camp aims to make Earth observation data and services available to a wide range of citizens using their smartphones or personal devices. Numerous Earth observation satellites, including Copernicus Sentinel missions, collect a huge amount of data. This big data from space uncovers information about the atmosphere, land and water of our planet and offers countless possibilities for creating compelling, even transformative applications when combined with mobile applications.

Space App Camp attendees will experience Copernicus data and learn how big data from space can enrich mobile apps with a dedicated Earth observation data API. The 2021 virtual edition revolves around an expanded collaboration with ESA’s F-Lab, whose mission is to accelerate future Earth observation through new transformational ideas, and to select, develop, test and develop the most promising concepts.

2020 space camp winner

Quifer (aQuifer sUrveillance by sentInel InterFERometry) won the top prize in Space App Camp 2020. It uses terrain data from the Copernicus Sentinel-1 mission, combined with big data and artificial intelligence to monitor water use. Credit: ESA.

Although this is the tenth Space app campThis is the first time the camp has offered an expanded mentoring program that includes an end-to-end training and mobile software development scheme lasting eight weeks, supported by experts in Earth observation, artificial intelligence, intellectual property protection and business. development.

Winners will be awarded cash prizes of up to € 2,500 and a unique Earth observation support package that will allow them to continue working on their winning app idea. They will also be invited to participate in ESA exhibitions. Φ-week and Living Planet Symposium, with all expenses covered.

There is also a unique prize in the form of an Earth Observation Support Package worth around € 3,500. This includes technical advice on Earth observation data, eight hours of software development services, access to a global network of Earth observation experts in application and technical fields, and support from professional ESA business developers.

Carlos Garcia, member of the 2020 winning team, says: “The ESA Space App Camp is a great opportunity to build an app from scratch with guidance from tier 1 professionals. Although everything was virtual in my year, it was a fantastic learning experience – blocking the week and dedicating myself to building a meaningful app. “

The deadline for applications is July 8, 2021. Interested students, entrepreneurs, researchers, developers, and economists can register online individually or in a team (up to four people). This year’s edition is specifically targeted at contributors with profiles in mobile app development, Earth observation app development, machine learning, artificial intelligence, and business development.

To participate in the 8-week mentoring program from July 20 to September 20, 2021, up to 25 participants will be selected, within which special training and development sessions will be held every two weeks.

Since Space App Camp was created 10 years ago, about 480 developers from 30 countries have applied to participate and more than 60 applications have been developed. Some of them have already found use in commercially viable applications.





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