Computers Math

One of the cornerstones of the implementation of quantum technology is the creation and manipulation of the shape of external fields that can optimise the performance of quantum devices. Known as quantum optimal control, this set of methods comprises a field that has rapidly evolved and expanded over recent years.
A new review paper published in EPJ Quantum Technology and authored by Christiane P. Koch, Dahlem Center for Complex Quantum Systems and Fachbereich Physik, Freie Universität Berlin along with colleagues from across Europe assesses recent progress in the understanding of the controllability of quantum systems as well as the application of quantum control to quantum technologies. As such, it lays out a potential roadmap for future technology.
While quantum optimal control builds on conventional control theory encompassing the interface of applied mathematics, engineering, and physics, it must also factor in the quirks and counter-intuitive nature of quantum physics.
This includes superposition, the concept that a quantum system can exist in multiple states at one time, one of the keys to the advanced computing power of machines that rely on quantum bits — or qubits.
Ultimately the main goal of quantum optimal control is to make emerging quantum technologies operate at their optimal performance and reach physical limits.
“Each device architecture comes with specific limits but these limits are often not attained by more traditional ways to operate the device,” Koch says. “Using pulse shaping may push the devices to the limits in terms of accuracy or operation speed that is fundamentally possible.”
The authors of this review consider factors in the discipline including the extent to which a quantum system can be established, controlled and observed without causing this superposition to collapse, something which seriously impedes the stability of quantum computers.
The review also suggests that just as conventional engineers have a control theoretical framework to rely on, the training of future “quantum engineers” may require a similar framework which is yet to be developed.
A quantum system that unifies theory and experiment is one of the current research goals of the field with the authors pointing out that this will also form the basis for the development of optimal control strategies.
As well as assessing the recent progress towards this goal, the team lay out some of the roadblocks that may lie ahead for the field. Roadblocks that will need to be overcome if a quantum technological future is to be manifested.
Story Source:
Materials provided by Springer. Note: Content may be edited for style and length. More

Artificial vision systems find a wide range of applications, including self-driving cars, object detection, crop monitoring, and smart cameras. Such vision is often inspired by the vision of biological organisms. For instance, human and insect vision have inspired terrestrial artificial vision, while fish eyes have led to aquatic artificial vision. While the progress is remarkable, current artificial visions suffer from some limitations: they are not suitable for imaging both land and underwater environments, and are limited to a hemispherical (180°) field-of-view (FOV).
To overcome these issues, a group of researchers from Korea and USA, including Professor Young Min Song from Gwangju Institute of Science and Technology in Korea, have now designed a novel artificial vision system with an omnidirectional imaging ability, which can work in both aquatic and terrestrial environments. Their study was made available online on 12 July 2022 and published in Nature Electronics on 11 July 2022.
“Research in bio-inspired vision often results in a novel development that did not exist before. This, in turn, enables a deeper understanding of nature and ensure that the developed imaging device is both structurally and functionally effective,” says Prof. Song, explaining his motivation behind the study.
The inspiration for the system came from the fiddler crab (Uca arcuata), a semiterrestrial crab species with amphibious imaging ability and a 360° FOV. These remarkable features result from the ellipsoidal eye stalk of the fiddler crab’s compound eyes, enabling panoramic imaging, and flat corneas with a graded refractive index profile, allowing for amphibious imaging.
Accordingly, the researchers developed a vision system consisting of an array of flat micro-lenses with a graded refractive index profile that was integrated into a flexible comb-shaped silicon photodiode array and then mounted onto a spherical structure. The graded refractive index and the flat surface of the micro-lens were optimized to offset the defocusing effects due to changes in the external environment. Put simply, light rays traveling in different mediums (corresponding to different refractive indices) were made to focus at the same spot.
To test the capabilities of their system, the team performed optical simulations and imaging demonstrations in air and water. Amphibious imaging was performed by immersing the device halfway in water. To their delight, the images produced by the system were clear and free of distortions. The team further showed that the system had a panoramic visual field, 300o horizontally and 160o vertically, in both air and water. Additionally, the spherical mount was only 2 cm in diameter, making the system compact and portable.
“Our vision system could pave the way for 360° omnidirectional cameras with applications in virtual or augmented reality or an all-weather vision for autonomous vehicles,” speculates Prof. Song excitedly.
Story Source:
Materials provided by GIST (Gwangju Institute of Science and Technology). Note: Content may be edited for style and length. More

A roadmap for the future direction of quantum simulation has been set out in a paper co-authored at the University of Strathclyde.
Quantum computers are hugely powerful devices with a capacity for speed and calculation which is well beyond the reach of classical, or binary, computing. Instead of a binary system of zeroes and ones, it operates through superpositions, which may be zeroes, ones or both at the same time.
The continuously-evolving development of quantum computing has reached the point of having an advantage over classical computers for an artificial problem. It could have future applications in a wide range of areas. One promising class of problems involves the simulation of quantum systems, with potential applications such as developing materials for batteries, industrial catalysis and nitrogen fixing.
The paper, published in Nature, explores near- and medium-term possibilities for quantum simulation on analogue and digital platforms to help evaluate the potential of this area. It has been co-written by researchers from Strathclyde, the Max Planck Institute of Quantum Optics, Ludwig Maximilians University in Munich, Munich Center for Quantum Science and Technology, the University of Innsbruck, the Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences, and Microsoft Corporation.
Professor Andrew Daley, of Strathclyde’s Department of Physics, is lead author of the paper. He said: “There has been a great deal of exciting progress in analogue and digital quantum simulation in recent years, and quantum simulation is one of the most promising fields of quantum information processing. It is already quite mature, both in terms of algorithm development, and in the availability of significantly advanced analogue quantum simulation experiments internationally.
“In computing history, classical analogue and digital computing co-existed for more than half a century, with a gradual transition towards digital computing, and we expect the same thing to happen with the emergence of quantum simulation. More

At the beginning of the COVID-19 pandemic, car manufacturing companies such as Ford quickly shifted their production focus from automobiles to masks and ventilators.
To make this switch possible, these companies relied on people working on an assembly line. It would have been too challenging for a robot to make this transition because robots are tied to their usual tasks.
Theoretically, a robot could pick up almost anything if its grippers could be swapped out for each task. To keep costs down, these grippers could be passive, meaning grippers pick up objects without changing shape, similar to how the tongs on a forklift work.
A University of Washington team created a new tool that can design a 3D-printable passive gripper and calculate the best path to pick up an object. The team tested this system on a suite of 22 objects — including a 3D-printed bunny, a doorstop-shaped wedge, a tennis ball and a drill. The designed grippers and paths were successful for 20 of the objects. Two of these were the wedge and a pyramid shape with a curved keyhole. Both shapes are challenging for multiple types of grippers to pick up.
The team will present these findings Aug. 11 at SIGGRAPH 2022.
“We still produce most of our items with assembly lines, which are really great but also very rigid. The pandemic showed us that we need to have a way to easily repurpose these production lines,” said senior author Adriana Schulz, a UW assistant professor in the Paul G. Allen School of Computer Science & Engineering. “Our idea is to create custom tooling for these manufacturing lines. That gives us a very simple robot that can do one task with a specific gripper. And then when I change the task, I just replace the gripper.”
Passive grippers can’t adjust to fit the object they’re picking up, so traditionally, objects have been designed to match a specific gripper. More

Researchers from Aarhus and Berlin have developed a new algorithm that can teach computers to predict how complex molecules will bind to the surface of catalysts. This is important when you have to produce synthetic fuels, for example. And it’s almost like playing extreme Tetris.
Imagine a game of Tetris where you not only have to stack the pieces in three dimensions, but the pieces are also much more complicated than the seven geometric shapes you normally use in the game.
In this case, the pieces are large and complex molecules that are to bind to another material in a chemical reaction.
To make things even harder, both the molecules and the other material have several places on the surface where they can bind to each other — and it is crucial that the binding is neither too weak nor too strong.
The binding has to be exactly right, otherwise the other material cannot function as a catalyst (see fact box at the end of the text).
Such an extreme game of Tetris perfectly illustrates the challenges that researchers all over the world encounter when working on developing new and better catalysts for a wide range of technical-chemical processes. More

Ultrasound imaging is a safe and noninvasive window into the body’s workings, providing clinicians with live images of a patient’s internal organs. To capture these images, trained technicians manipulate ultrasound wands and probes to direct sound waves into the body. These waves reflect back out to produce high-resolution images of a patient’s heart, lungs, and other deep organs.
Currently, ultrasound imaging requires bulky and specialized equipment available only in hospitals and doctor’s offices. But a new design by MIT engineers might make the technology as wearable and accessible as buying Band-Aids at the pharmacy.
In a paper appearing today in Science, the engineers present the design for a new ultrasound sticker — a stamp-sized device that sticks to skin and can provide continuous ultrasound imaging of internal organs for 48 hours.
The researchers applied the stickers to volunteers and showed the devices produced live, high-resolution images of major blood vessels and deeper organs such as the heart, lungs, and stomach. The stickers maintained a strong adhesion and captured changes in underlying organs as volunteers performed various activities, including sitting, standing, jogging, and biking.
The current design requires connecting the stickers to instruments that translate the reflected sound waves into images. The researchers point out that even in their current form, the stickers could have immediate applications: For instance, the devices could be applied to patients in the hospital, similar to heart-monitoring EKG stickers, and could continuously image internal organs without requiring a technician to hold a probe in place for long periods of time.
If the devices can be made to operate wirelessly — a goal the team is currently working toward — the ultrasound stickers could be made into wearable imaging products that patients could take home from a doctor’s office or even buy at a pharmacy. More

As scientists push the boundaries of machine learning, the amount of time, energy, and money required to train increasingly complex neural network models is skyrocketing. A new area of artificial intelligence called analog deep learning promises faster computation with a fraction of the energy usage.
Programmable resistors are the key building blocks in analog deep learning, just like transistors are the core elements for digital processors. By repeating arrays of programmable resistors in complex layers, researchers can create a network of analog artificial “neurons” and “synapses” that execute computations just like a digital neural network. This network can then be trained to achieve complex AI tasks like image recognition and natural language processing.
A multidisciplinary team of MIT researchers set out to push the speed limits of a type of human-made analog synapse that they had previously developed. They utilized a practical inorganic material in the fabrication process that enables their devices to run 1 million times faster than previous versions, which is also about 1 million times faster than the synapses in the human brain.
Moreover, this inorganic material also makes the resistor extremely energy-efficient. Unlike materials used in the earlier version of their device, the new material is compatible with silicon fabrication techniques. This change has enabled fabricating devices at the nanometer scale and could pave the way for integration into commercial computing hardware for deep-learning applications.
“With that key insight, and the very powerful nanofabrication techniques we have at MIT.nano, we have been able to put these pieces together and demonstrate that these devices are intrinsically very fast and operate with reasonable voltages,” says senior author Jesús A. del Alamo, the Donner Professor in MIT’s Department of Electrical Engineering and Computer Science (EECS). “This work has really put these devices at a point where they now look really promising for future applications.”
“The working mechanism of the device is electrochemical insertion of the smallest ion, the proton, into an insulating oxide to modulate its electronic conductivity. Because we are working with very thin devices, we could accelerate the motion of this ion by using a strong electric field, and push these ionic devices to the nanosecond operation regime,” explains senior author Bilge Yildiz, the Breene M. Kerr Professor in the departments of Nuclear Science and Engineering and Materials Science and Engineering. More

What are the chances you will contract Covid-19 on a plane flight? A study led by MIT scholars offers a calculation of that for the period from June 2020 through February 2021. While the conditions that applied at that stage of the Covid-19 pandemic differ from those of today, the study offers a method that could be adapted as the pandemic evolves.
The study estimates that from mid-2020 through early 2021, the probability of getting Covid-19 on an airplane surpassed 1 in 1,000 on a totally full flight lasting two hours at the height of the early pandemic, roughly December 2020 and January 2021. It dropped to about 1 in 6,000 on a half-full two-hour flight when the pandemic was at its least severe, in the summer of 2020. The overall risk of transmission from June 2020 through February 2021 was about 1 in 2,000, with a mean of 1 in 1,400 and a median of 1 in 2,250.
To be clear, current conditions differ from the study’s setting. Masks are no longer required for U.S. domestic passengers; in the study’s time period, airlines were commonly leaving middle seats open, which they are no longer doing; and newer Covid-19 variants are more contagious than the virus was during the study period. While those factors may increase the current risk, most people have received Covid-19 vaccinations since February 2021, which could serve to lower today’s risk — though the precise impact of those vaccines against new variants is uncertain.
Still, the study does provide a general estimate about air travel safety with regard to Covid-19 transmission, and a methodology that can be applied to future studies. Some U.S. carriers at the time stated that onboard transmission was “virtually nonexistent” and “nearly nonexistent,” but as the research shows, there was a discernible risk. On the other hand, passengers were not exactly facing coin-flip odds of catching the virus in flight, either.
“The aim is to set out the facts,” says Arnold Barnett, a management professor at MIT and aviation risk expert, who is co-author of a recent paper detailing the study’s results. “Some people might say, ‘Oh, that doesn’t sound like very much.’ But if we at least tell people what the risk is, they can make judgments.”
As Barnett also observes, a round-trip flight with a change of planes and two two-hour segments in each direction counts as four flights in this accounting, so a 1 in 1,000 probability, per flight, would lead to approximately a 1 in 250 chance for such a trip as a whole. More