From Aalto University [Aalto-yliopisto] (FI): “Controlling quantum states in individual molecules with two-dimensional ferroelectrics”

From Aalto University [Aalto-yliopisto] (FI)

1.9.23

Researchers demonstrated how to control the quantum states of individual molecules with an electrically controllable substrate.

Jose Lado
Assistant Professor
T304 Dept. Applied Physics
jose.lado@aalto.fi
+358503133730

Adam Foster
Professori
adam.foster@aalto.fi

Peter Liljeroth
Akatemiaprofessori
peter.liljeroth@aalto.fi
+358503636115

Researchers used electricity to control the internal states of molecules. Image: Jose Lado/Aalto University.

Controlling the internal states of quantum systems is one of the biggest challenges in quantum materials. At the deepest level, single molecules can display different quantum states even while possessing the same number of electrons. These states are associated with different electron configurations, which can lead to dramatically different properties.

The capability of controlling the electronic configuration of single molecules could lead to major developments in both fundamental science and technology. On the one hand, controlling the internal states of molecules may allow for the development of new artificial materials with exotic properties. On the other hand, it might also make possible the ultimate miniaturization of classical computer memories, with the two configurations could make it possible to encode a 0 and a 1 in a classical memory unit at the molecular level. However, controlling the internal states of molecules still remains a challenge, and realistic, scalable strategies for overcoming it have not been proposed.
Tuning internal states by applying voltage

In a recent experimental breakthrough researchers from Aalto University and the University of Jyväskylä demonstrated the ability to control the quantum states of individual molecules with an electrically controllable substrate. Their experiment showed how a specific two-dimensional material, known as SnTe, provides the instrumental strategy needed to control molecular states.

The mechanism demonstrated by the researchers is based on the ability of a substrate to tune the internal state of molecules due to internal electric fields. This mechanism, known as “ferroelectric molecular switching”, enables researchers to control individual molecules merely by applying a voltage to the substrate. The strategy relies on the strong tunability of SnTe by external voltages, which stems from a unique quantum property known as ferroelectricity.

The research team involved the groups of Professors Peter Liljeroth, Adam Foster, and Jose Lado from Aalto University, and the team was led by Professor Shawulienu Kezilebieke from the University of Jyväskylä.

‘Our results demonstrate how we can control individual molecules using electrically-tunable two-dimensional materials. From a practical point of view, two-dimensional ferroelectrics have been instrumental, as its ultraclean interface allows realizing this strategy of quantum control. These experiments put forward a strategy to engineer quantum states at the molecular level, opening exciting possibilities in artificial materials and single-molecule electronics,’ Kezilebieke says.

‘In our experiments, we demonstrated how two-dimensional ferroelectrics allow us to realize electrically switchable quantum states. Controlling quantum states electrically is a major milestone in quantum materials, and here we demonstrated one strategy for doing it at the deepest level of individual molecules,’ says PhD researcher Mohammad Amini, the first author of the study.

The quantum control of molecules via substrate effects opens up new possibilities in quantum matter, including engineering artificial molecular materials with switchable states. The research was recently published in Advanced Materials.
See the science paper for instructive material with images.

See the full article here.

Comments are invited and will be appreciated, especially if the reader finds any errors which I can correct. Use “Reply”.

five-ways-keep-your-child-safe-school-shootings

Please help promote STEM in your local schools.

Stem Education Coalition

Aalto University [Aalto-yliopisto] (FI) is a university located in Espoo, Finland. It was established in 2010 as a merger of three major Finnish universities: the Helsinki University of Technology (established 1849), the Helsinki School of Economics (established 1904), and the University of Art and Design Helsinki (established 1871). The close collaboration between the scientific, business and arts communities is intended to foster multi-disciplinary education and research. The Finnish government, in 2010, set out to create a university that fosters innovation, merging the three institutions into one.

The university is composed of six schools with close to 17,500 students and 4,000 staff members, making it Finland’s second largest university. The main campus of Aalto University is located in Otaniemi, Espoo. Aalto University Executive Education operates in the district of Töölö, Helsinki. In addition to the Greater Helsinki area, the university also operates its Bachelor’s Programme in International Business in Mikkeli and the Metsähovi Radio Observatory Metsähovi Radio Observatory [Metsähovin radiotutkimusasema] Aalto University [Aalto-yliopisto](FI) in Kirkkonummi. in Kirkkonummi.

Aalto University’s operations showcase Finland’s experiment in higher education. The Aalto Design Factory, Aalto Ventures Program and Aalto Entrepreneurship Society (Aaltoes), among others, drive the university’s mission for a radical shift towards multidisciplinary learning and have contributed substantially to the emergence of Helsinki as a hotbed for startups. Aaltoes is Europe’s largest and most active student run entrepreneurship community that has founded major concepts such as the Startup Sauna accelerator program and the Slush startup event.

The university is named in honour of Alvar Aalto, a prominent Finnish architect, designer and alumnus of the former Helsinki University of Technology, who was also instrumental in designing a large part of the university’s main campus in Otaniemi.

From Aalto University [Aalto-yliopisto] (FI): “Researchers use quantum mechanics to see objects without looking at them”

From Aalto University [Aalto-yliopisto] (FI)

12.21.22

Gheorghe-Sorin Paraoanu
Vanhempi yliopistonlehtori
sorin.paraoanu@aalto.fi
+358503442650

The new method bridges the quantum and classical worlds and could improve measurements in quantum computers and other applications.

A new protocol for interaction-free measurements relies on quantum coherence. Photo: Mikko Raskinen/Aalto University.

We see the world around us because light is being absorbed by specialized cells in our retina. But can vision happen without any absorption at all – without even a single particle of light? Surprisingly, the answer is yes.

Imagine that you have a camera cartridge that might contain a roll of photographic film. The roll is so sensitive that coming into contact with even a single photon would destroy it. With our everyday classical means there is no way there’s no way to know whether there’s film in the cartridge, but in the quantum world it can be done. Anton Zeilinger, one of the winners of the 2022 Nobel Prize in Physics, was the first to experimentally implement the idea of an interaction-free experiment using optics.

Now, in a study exploring the connection between the quantum and classical worlds, Shruti Dogra, John J. McCord, and Gheorghe Sorin Paraoanu of Aalto University have discovered a new and much more effective way to carry out interaction-free experiments. The team used transmon devices –superconducting circuits that are relatively large but still show quantum behavior– to detect the presence of microwave pulses generated by classical instruments. Their research was recently published in Nature Communications [below]. 

The experimental protocol achieved much higher efficiency than previous methods. Image: John J. McCord/Aalto University.

An experiment with added layer of “quantumness”

Although Dogra and Paraoanu were fascinated by the work done by Zeilinger’s research group, their lab is centred around microwaves and superconductors instead of lasers and mirrors. ‘We had to adapt the concept to the different experimental tools available for superconducting devices. Because of that, we also had to change the standard interaction-free protocol in a crucial way: we added another layer of “quantumness” by using a higher energy level of the transmon. Then, we used the quantum coherence of the resulting three-level system as a resource,’ Paraoanu says.

Quantum coherence refers to the possibility that an object can occupy two different states at the same time – something that quantum physics allows for. However, quantum coherence is delicate and easily collapses, so it wasn’t immediately obvious that the new protocol would work. To the team’s pleasant surprise, the first runs of the experiment showed a marked increase in detection efficiency. They went back to the drawing board several times, ran theoretical models confirming their results, and double-checked everything. The effect was definitely there.

‘We also demonstrated that even very low-power microwave pulses can be detected efficiently using our protocol,’ says Dogra.

The experiment also showed a new way in which quantum devices can achieve results that are impossible for classical devices – a phenomenon known as quantum advantage. Researchers generally believe that achieving quantum advantage will require quantum computers with many qubits, but this experiment demonstrated genuine quantum advantage using a relatively simpler setup.

Potential applications in many types of quantum technology

Interaction-free measurements based on the less effective older methodology have already found applications in specialized processes such as optical imaging, noise-detection, and cryptographic key distribution. The new and improved method could increase the efficiency of these processes dramatically.

‘In quantum computing, our method could be applied for diagnosing microwave-photon states in certain memory elements. This can be regarded as a highly efficient way of extracting information without disturbing the functioning of the quantum processor,’ Paraoanu says.

The group led by Paraoanu is also exploring other exotic forms of information processing using their new approach, such as counterfactual communication (communication between two parties without any physical particles being transferred) and counterfactual quantum computing (where the result of a computation is obtained without in fact running the computer).

Science paper:
Nature Communications
See the science paper for instructive material with images.

See the full article here.

Comments are invited and will be appreciated, especially if the reader finds any errors which I can correct. Use “Reply”.

five-ways-keep-your-child-safe-school-shootings

Please help promote STEM in your local schools.

Stem Education Coalition

Aalto University [Aalto-yliopisto] (FI) is a university located in Espoo, Finland. It was established in 2010 as a merger of three major Finnish universities: the Helsinki University of Technology (established 1849), the Helsinki School of Economics (established 1904), and the University of Art and Design Helsinki (established 1871). The close collaboration between the scientific, business and arts communities is intended to foster multi-disciplinary education and research. The Finnish government, in 2010, set out to create a university that fosters innovation, merging the three institutions into one.

The university is composed of six schools with close to 17,500 students and 4,000 staff members, making it Finland’s second largest university. The main campus of Aalto University is located in Otaniemi, Espoo. Aalto University Executive Education operates in the district of Töölö, Helsinki. In addition to the Greater Helsinki area, the university also operates its Bachelor’s Programme in International Business in Mikkeli and the Metsähovi Radio Observatory Metsähovi Radio Observatory [Metsähovin radiotutkimusasema] Aalto University [Aalto-yliopisto](FI) in Kirkkonummi. in Kirkkonummi.

Aalto University’s operations showcase Finland’s experiment in higher education. The Aalto Design Factory, Aalto Ventures Program and Aalto Entrepreneurship Society (Aaltoes), among others, drive the university’s mission for a radical shift towards multidisciplinary learning and have contributed substantially to the emergence of Helsinki as a hotbed for startups. Aaltoes is Europe’s largest and most active student run entrepreneurship community that has founded major concepts such as the Startup Sauna accelerator program and the Slush startup event.

The university is named in honour of Alvar Aalto, a prominent Finnish architect, designer and alumnus of the former Helsinki University of Technology, who was also instrumental in designing a large part of the university’s main campus in Otaniemi.

From Aalto University [Aalto-yliopisto] (FI): “The smallest robotic arm you can imagine is controlled by artificial intelligence”

From Aalto University [Aalto-yliopisto] (FI)

12.7.22

Adam Foster
Professori
adam.foster@aalto.fi

Peter Liljeroth
Akatemiaprofessori
peter.liljeroth@aalto.fi
+358503636115

Researchers used deep reinforcement learning to steer atoms into a lattice shape with a view to building new materials or nanodevices.

In a very cold vacuum chamber, single atoms of silver form a star-like lattice. The precise formation is not accidental, and it wasn’t constructed directly by human hands either. Researchers used a kind of artificial intelligence called “deep reinforcement learning” to steer the atoms, each a fraction of a nanometer in size, into the lattice shape. The process is similar to moving marbles around a Chinese checkers board, but with very tiny tweezers grabbing and dragging each atom into place.

The main application for “deep reinforcement learning” is in robotics, says postdoctoral researcher I-Ju Chen. “We’re also building robotic arms with deep learning, but for moving atoms,” she explains. “Reinforcement learning is successful in things like playing chess or video games, but we’ve applied it to solve technical problems at the nanoscale.” 

So why are scientists interested in precisely moving atoms? Making very small devices based on single atoms is important for nanodevices like transistors or memory. Testing how and whether these devices work at their absolute limits is one application for this kind of atomic manipulation, says Chen. Building new materials atom-by-atom, rather than through traditional chemical techniques, may also reveal interesting properties related to superconductivity or quantum states.

The silver star lattice made by Chen and colleagues at the Finnish Center for Artificial Intelligence [FCAI] and Aalto University is a demonstration of what ‘deep reinforcement learning” can achieve. “The precise movement of atoms is hard even for human experts,” says Chen. “We adapted existing “deep reinforcement learning’ for this purpose. It took the algorithm on the order of one day to learn and then about one hour to build the lattice.” The reinforcement part of this type of deep learning refers to how the AI is guided—through rewards for correct actions or outputs. “Give it a goal and it will do it. It can solve problems that humans don’t know how to solve.”

Applying this approach to the world of nanoscience materials is new. Nanotechniques can become more powerful with the injection of machine learning, says Chen, because it can accelerate the parameter selection and trial-and-error usually done by a person. “We showed that this task can be completed perfectly through reinforcement learning,” concludes Chen. The group’s research, led by professors Adam Foster and Peter Liljeroth, was recently published in Nature Communications [below].

Science paper:
Nature Communications
See the science paper for instructive material with images.

See the full article here.

Comments are invited and will be appreciated, especially if the reader finds any errors which I can correct. Use “Reply”.

five-ways-keep-your-child-safe-school-shootings

Please help promote STEM in your local schools.

Stem Education Coalition

Aalto University [Aalto-yliopisto] (FI) is a university located in Espoo, Finland. It was established in 2010 as a merger of three major Finnish universities: the Helsinki University of Technology (established 1849), the Helsinki School of Economics (established 1904), and the University of Art and Design Helsinki (established 1871). The close collaboration between the scientific, business and arts communities is intended to foster multi-disciplinary education and research. The Finnish government, in 2010, set out to create a university that fosters innovation, merging the three institutions into one.

The university is composed of six schools with close to 17,500 students and 4,000 staff members, making it Finland’s second largest university. The main campus of Aalto University is located in Otaniemi, Espoo. Aalto University Executive Education operates in the district of Töölö, Helsinki. In addition to the Greater Helsinki area, the university also operates its Bachelor’s Programme in International Business in Mikkeli and the Metsähovi Radio Observatory Metsähovi Radio Observatory [Metsähovin radiotutkimusasema] Aalto University [Aalto-yliopisto](FI) in Kirkkonummi. in Kirkkonummi.

Aalto University’s operations showcase Finland’s experiment in higher education. The Aalto Design Factory, Aalto Ventures Program and Aalto Entrepreneurship Society (Aaltoes), among others, drive the university’s mission for a radical shift towards multidisciplinary learning and have contributed substantially to the emergence of Helsinki as a hotbed for startups. Aaltoes is Europe’s largest and most active student run entrepreneurship community that has founded major concepts such as the Startup Sauna accelerator program and the Slush startup event.

The university is named in honour of Alvar Aalto, a prominent Finnish architect, designer and alumnus of the former Helsinki University of Technology, who was also instrumental in designing a large part of the university’s main campus in Otaniemi.

From Aalto University [Aalto-yliopisto] (FI) Via “phys.org” : “The unimon – a new qubit to boost quantum computers for useful applications”

From Aalto University [Aalto-yliopisto] (FI)

Via

“phys.org”

11.15.22

Artistic impression of a unimon qubit in a quantum processor. Credit: Aleksandr Kakinen

A group of scientists from Aalto University, IQM Quantum Computers, and VTT Technical Research Center have discovered a new superconducting qubit, the unimon, to increase the accuracy of quantum computations. The team has achieved the first quantum logic gates with unimons at 99.9% fidelity—a major milestone on the quest to build commercially useful quantum computers. This research was just published in the journal Nature Communications [below].

Of all the different approaches to build useful quantum computers, superconducting qubits are in the lead. However, the qubit designs and techniques currently used do not yet provide high enough performance for practical applications. In this noisy intermediate-scale quantum (NISQ) era, the complexity of the implementable quantum computations is mostly limited by errors in single- and two-qubit quantum gates. The quantum computations need to become more accurate to be useful.

“Our aim is to build quantum computers which deliver an advantage in solving real-world problems. Our announcement today is an important milestone for IQM, and a significant achievement to build better superconducting quantum computers,” said Professor Mikko Möttönen, joint Professor of Quantum Technology at Aalto University and VTT, and also a Co-Founder and Chief Scientist at IQM Quantum Computers, who was leading the research.

Today, Aalto, IQM and VTT have introduced a new superconducting-qubit type, the unimon, which unites in a single circuit the desired properties of increased anharmonicity, full insensitivity to dc charge noise, reduced sensitivity to magnetic noise, and a simple structure consisting only of a single Josephson junction in a resonator. The team achieved fidelities from 99.8% to 99.9% for 13-nanoseconds-long single-qubit gates on three different unimon qubits.

“Because of the higher anharmonicity, or non-linearity, than in transmons, we can operate the unimons faster, leading to fewer errors per operation,” said Eric Hyyppä who is working on his Ph.D. at IQM.

To experimentally demonstrate the unimon, the scientists designed and fabricated chips, each of which consisted of three unimon qubits. They used niobium as the superconducting material apart from the Josephson junctions, in which the superconducting leads were fabricated using aluminum.

The team measured the unimon qubit to have a relatively high anharmonicity while requiring only a single Josephson junction without any superinductors, and bearing protection against noise. The geometric inductance of the unimon has the potential for higher predictability and yield than the junction-array-based superinductors in conventional fluxonium or quarton qubits.

“Unimons are so simple and yet have many advantages over transmons. The fact that the very first unimon ever made worked this well, gives plenty of room for optimization and major breakthroughs. As next steps, we should optimize the design for even higher noise protection and demonstrate two-qubit gates,” added Prof. Möttönen.

“We aim for further improvements in the design, materials, and gate time of the unimon to break the 99.99% fidelity target for useful quantum advantage with noisy systems and efficient quantum error correction. This is a very exciting day for quantum computing,” concluded Prof. Möttönen.

Science paper:
Nature Communications
See the science paper for detailed material with images.

See the full article here.

five-ways-keep-your-child-safe-school-shootings

Please help promote STEM in your local schools.

Stem Education Coalition

Aalto University [Aalto-yliopisto] (FI) is a university located in Espoo, Finland. It was established in 2010 as a merger of three major Finnish universities: the Helsinki University of Technology (established 1849), the Helsinki School of Economics (established 1904), and the University of Art and Design Helsinki (established 1871). The close collaboration between the scientific, business and arts communities is intended to foster multi-disciplinary education and research. The Finnish government, in 2010, set out to create a university that fosters innovation, merging the three institutions into one.

The university is composed of six schools with close to 17,500 students and 4,000 staff members, making it Finland’s second largest university. The main campus of Aalto University is located in Otaniemi, Espoo. Aalto University Executive Education operates in the district of Töölö, Helsinki. In addition to the Greater Helsinki area, the university also operates its Bachelor’s Programme in International Business in Mikkeli and the Metsähovi Radio Observatory Metsähovi Radio Observatory [Metsähovin radiotutkimusasema] Aalto University [Aalto-yliopisto](FI) in Kirkkonummi. in Kirkkonummi.

Aalto University’s operations showcase Finland’s experiment in higher education. The Aalto Design Factory, Aalto Ventures Program and Aalto Entrepreneurship Society (Aaltoes), among others, drive the university’s mission for a radical shift towards multidisciplinary learning and have contributed substantially to the emergence of Helsinki as a hotbed for startups. Aaltoes is Europe’s largest and most active student run entrepreneurship community that has founded major concepts such as the Startup Sauna accelerator program and the Slush startup event.

The university is named in honour of Alvar Aalto, a prominent Finnish architect, designer and alumnus of the former Helsinki University of Technology, who was also instrumental in designing a large part of the university’s main campus in Otaniemi.

From Aalto University [Aalto-yliopisto] (FI): “Tapping hidden visual information: “An all-in-one detector for thousands of colours”

From Aalto University [Aalto-yliopisto] (FI)

10.21.22
Postdoctoral Researcher Hoon Hahn Yoon
Aalto University
hoonhahn.yoon@aalto.fi

Professor Zhipei Sun
Aalto University
zhipei.sun@aalto.fi
tel +358 50 4302 820

Professor Pertti Hakonen
Aalto University
pertti.hakonen@aalto.fi
tel +358 50 3442 316

A new chip from Aalto researchers puts photonic information at our fingertips.

A fingertip-sized on-chip spectrometer in the foreground compared to a commercial benchtop-size spectrometer in the background. Photo: Aalto University.

Spectrometers are widely used throughout industry and research to detect and analyse light. Spectrometers measure the spectrum of light – its strength at different wavelengths, like the colours in a rainbow – and are an essential tool for identifying and analysing specimens and materials. Integrated on-chip spectrometers would be of great benefit to a variety of technologies, including quality inspection platforms, security sensors, biomedical analysers, healthcare systems, environmental monitoring tools, and space telescopes.

An international research team led by researchers at Aalto University has developed high-sensitivity spectrometers with high wavelength accuracy, high spectral resolution, and broad operation bandwidth, using only a single microchip-sized detector. The research for this new ultra-miniaturised spectrometer was published today in the journal Science [below].

‘Our single-detector spectrometer is an all-in-one device. We designed this optoelectronic-lab-on-a-chip with artificial intelligence replacing conventional hardware, such as optical and mechanical components. Therefore, our computational spectrometer does not require separate bulky components or array designs to disperse and filter light. It can achieve high-resolution comparable to benchtop systems but in a much smaller package,’ says Postdoctoral Researcher Hoon Hahn Yoon.

‘With our spectrometer, we can measure light intensity at each wavelength beyond the visible spectrum using a device at our fingertips. The device is entirely electrically controllable, so it has enormous potential for scalability and integration. Integrating it directly into portable devices such as smartphones and drones could advance our daily lives. Imagine that the next generation of our smartphone cameras could be fitted with hyperspectral cameras that outperform colour cameras,’ he adds.

Shrinking computational spectrometers is essential for their use in chips and implantable applications. Professor Zhipei Sun, the head of the research team, says, ‘Conventional spectrometers are bulky because they need optical and mechanical components, so their on-chip applications are limited. There is an emerging demand in this field to improve the performance and usability of spectrometers. From this point of view, miniaturized spectrometers are very important for future applications to offer high performance and new functions in all fields of science and industry.’

Professor Pertti Hakonen adds that ‘Finland and Aalto have invested in photonics research in recent years. For example, there has been great support from the Academy of Finland’s Centre of Excellence on quantum technology, Flagship on Photonics Research and Innovation, InstituteQ, and the Otanano Infrastructure. Our new spectrometer is a clear demonstration of the success of these collaborative efforts. I believe that with further improvements in resolution and efficiency, these spectrometers could provide new tools for quantum information processing.’

In addition to Postdoctoral Researcher Hoon Hahn Yoon and Professors Zhipei Sun and Pertti Hakonen, the key Aalto members linked to the work included Postdoctoral Researchers Henry A. Fernandez and Faisal Ahmed, Doctoral Researchers Fedor Nigmatulin, Xiaoqi Cui, Md Gius Uddin, and Professor Harri Lipsanen. Professor Ethan D. Minot, from Oregon State University, joined this work as a visiting scholar at Aalto University for one year. The international research team led by Aalto university also included Professors Weiwei Cai (Shanghai Jiao Tong University), Zongyin Yang (Zhejiang University), Hanxiao Cui (Sichuan University), Kwanpyo Kim (Yonsei University), and Tawfique Hasan (University of Cambridge).

Science paper:
Science

See the full article here.

five-ways-keep-your-child-safe-school-shootings

Please help promote STEM in your local schools.

Stem Education Coalition

Aalto University [Aalto-yliopisto] (FI) is a university located in Espoo, Finland. It was established in 2010 as a merger of three major Finnish universities: the Helsinki University of Technology (established 1849), the Helsinki School of Economics (established 1904), and the University of Art and Design Helsinki (established 1871). The close collaboration between the scientific, business and arts communities is intended to foster multi-disciplinary education and research. The Finnish government, in 2010, set out to create a university that fosters innovation, merging the three institutions into one.

The university is composed of six schools with close to 17,500 students and 4,000 staff members, making it Finland’s second largest university. The main campus of Aalto University is located in Otaniemi, Espoo. Aalto University Executive Education operates in the district of Töölö, Helsinki. In addition to the Greater Helsinki area, the university also operates its Bachelor’s Programme in International Business in Mikkeli and the Metsähovi Radio Observatory Metsähovi Radio Observatory [Metsähovin radiotutkimusasema] Aalto University [Aalto-yliopisto](FI) in Kirkkonummi. in Kirkkonummi.

Aalto University’s operations showcase Finland’s experiment in higher education. The Aalto Design Factory, Aalto Ventures Program and Aalto Entrepreneurship Society (Aaltoes), among others, drive the university’s mission for a radical shift towards multidisciplinary learning and have contributed substantially to the emergence of Helsinki as a hotbed for startups. Aaltoes is Europe’s largest and most active student run entrepreneurship community that has founded major concepts such as the Startup Sauna accelerator program and the Slush startup event.

The university is named in honour of Alvar Aalto, a prominent Finnish architect, designer and alumnus of the former Helsinki University of Technology, who was also instrumental in designing a large part of the university’s main campus in Otaniemi.

From Aalto University [Aalto-yliopisto] (FI) via phys.org : “Using magnets to toggle nanolasers leads to better photonics”

From Aalto University [Aalto-yliopisto] (FI)

via

phys.org

December 23, 2021

Credit: CC0 Public Domain.

A magnetic field can be used to switch nanolasers on and off shows new research from Aalto University. The physics underlying this discovery paves the way for the development of optical signals that cannot be disturbed by external disruptions, leading to unprecedented robustness in signal processing.

Lasers concentrate light into extremely bright beams that are useful in a variety of domains, such as broadband communication and medical diagnostics devices. About ten years ago extremely small and fast lasers known as plasmonic nanolasers were developed. These nanolasers are potentially more power-efficient than traditional lasers, and they have been of great advantage in many fields—for example, nanolasers have increased the sensitivity of biosensors used in medical diagnostics.

So far, switching nanolasers on and off has required manipulating them directly, either mechanically or with the use of heat or light. Now, researchers have found a way to remotely control nanolasers.

“The novelty here is that we are able to control the lasing signal with an external magnetic field. By changing the magnetic field around our magnetic nanostructures, we can turn the lasing on and off,” says Professor Sebastiaan van Dijken of Aalto University.

The team accomplished this by making plasmonic nanolasers from different materials than normal. Instead of the usual noble metals, such as gold or silver, they used magnetic cobalt-platinum nanodots patterned on a continuous layer of gold and insulating silicon dioxide. Their analysis showed that both the material and the arrangement of the nanodots in periodic arrays were required for the effect.

Photonics advances towards extremely robust signal processing

The new control mechanism may prove useful in a range of devices that make use of optical signals, but its implications for the emerging field of topological photonics are even more exciting. Topological photonics aims to produce light signals that are not disturbed by external disruptions. This would have applications in many domains by providing very robust signal processing.

“The idea is that you can create specific optical modes that are topological, that have certain characteristics which allow them to be transported and protected against any disturbance,” explains van Dijken. “That means if there are defects in the device or because the material is rough, the light can just pass them by without being disturbed, because it is topologically protected.”

So far, creating topologically protected optical signals using magnetic materials has required strong magnetic fields. The new research shows that the effect of magnetism in this context can be unexpectedly amplified using a nanoparticle array of a particular symmetry. The researchers believe their findings could point the way to new, nanoscale, topologically protected signals.

“Normally, magnetic materials can cause a very minor change in the absorption and polarization of light. In these experiments, we produced very significant changes in the optical response—up to 20 percent. This has never been seen before,” says van Dijken.

Academy Professor Päivi Törmä adds that ‘these results hold great potential for the realization of topological photonic structures wherein magnetization effects are amplified by a suitable choice of the nanoparticle array geometry.”

The results are published in Nature Photonics.

These findings are the result of a long-lasting collaboration between the Nanomagnetism and Spintronics group led by Professor van Dijken and the Quantum Dynamics group led by Professor Törmä, both in the Department of Applied Physics at Aalto University.

See the full article here.

five-ways-keep-your-child-safe-school-shootings

Please help promote STEM in your local schools.

Stem Education Coalition

Aalto University [Aalto-yliopisto] (FI) is a university located in Espoo, Finland. It was established in 2010 as a merger of three major Finnish universities: the Helsinki University of Technology (established 1849), the Helsinki School of Economics (established 1904), and the University of Art and Design Helsinki (established 1871). The close collaboration between the scientific, business and arts communities is intended to foster multi-disciplinary education and research. The Finnish government, in 2010, set out to create a university that fosters innovation, merging the three institutions into one.

The university is composed of six schools with close to 17,500 students and 4,000 staff members, making it Finland’s second largest university. The main campus of Aalto University is located in Otaniemi, Espoo. Aalto University Executive Education operates in the district of Töölö, Helsinki. In addition to the Greater Helsinki area, the university also operates its Bachelor’s Programme in International Business in Mikkeli and the Metsähovi Radio Observatory in Kirkkonummi.

Aalto University’s operations showcase Finland’s experiment in higher education. The Aalto Design Factory, Aalto Ventures Program and Aalto Entrepreneurship Society (Aaltoes), among others, drive the university’s mission for a radical shift towards multidisciplinary learning and have contributed substantially to the emergence of Helsinki as a hotbed for startups. Aaltoes is Europe’s largest and most active student run entrepreneurship community that has founded major concepts such as the Startup Sauna accelerator program and the Slush startup event.

The university is named in honour of Alvar Aalto, a prominent Finnish architect, designer and alumnus of the former Helsinki University of Technology, who was also instrumental in designing a large part of the university’s main campus in Otaniemi.

From Aalto University [Aalto-yliopisto] (FI): “A new super-cooled microwave source boosts the scale-up of quantum computers”

From Aalto University [Aalto-yliopisto] (FI)

12.9.2021

Mikko Möttönen
Associate Professor
mikko.mottonen@aalto.fi
+358505940950

A newly designed microwave source could replace existing bulky control systems that hinder the scalability of quantum computers.

Artistic impression of an on-chip microwave source controlling qubits. Credit: Aleksandr Kakinen.

Researchers in Finland have developed a circuit that produces the high-quality microwave signals required to control quantum computers while operating at temperatures near absolute zero. This is a key step towards moving the control system closer to the quantum processor, which may make it possible to greatly increase the number of qubits in the processor.

One of the factors limiting the size of quantum computers is the mechanism used to control the qubits in quantum processors. This is normally accomplished using a series of microwave pulses, and because quantum processors operate at temperatures near absolute zero, the control pulses are normally brought into the cooled environment via broadband cables from room temperature.

As the number of qubits grows, so does the number of cables needed. This limits the potential size of a quantum processor, because the refrigerators cooling the qubits would have to become larger to accommodate more and more cables while also working harder to cool them down – ultimately a losing proposition.

A research consortium led by Aalto University and VTT Technical Research Centre of Finland has now developed a key component of the solution to this conundrum. ‘We have built a precise microwave source that works at the same extremely low temperature as the quantum processors, approximately -273 degrees,’ says Mikko Möttönen, Professor at Aalto University and VTT Technical Research Centre of Finland, who led the team.

The new microwave source is an on-chip device that can be integrated with a quantum processor. Less than a millimetre in size, it potentially removes the need for high-frequency control cables connecting different temperatures. With this low-power, low-temperature microwave source, it may be possible to use smaller cryostats while still increasing the number of qubits in a processor.

‘Our device produces one hundred times more power than previous versions, which is enough to control qubits and carry out quantum logic operations,’ says Möttönen. ‘It produces a very precise sine wave, oscillating over a billion times per second. As a result, errors in qubits from the microwave source are very infrequent, which is important when implementing precise quantum logic operations.’

However, a continuous-wave microwave source, such as the one produced by this device, cannot be used as is to control qubits. First, the microwaves must be shaped into pulses. The team is currently developing methods to quickly switch the microwave source on and off.

Even without a switching solution to create pulses, an efficient, low-noise, low-temperature microwave source could be useful in a range of quantum technologies, such as quantum sensors.

‘In addition to quantum computers and sensors, the microwave source can act as a clock for other electronic devices. It can keep different devices in the same rhythm, allowing them to induce operations for several different qubits at the desired instant of time,’ explains Möttönen.

The theoretical analysis and the initial design were carried out by Juha Hassel and others at VTT. Hassel, who started this work at VTT, is currently the head of engineering and development at IQM, a Finnish quantum-computing hardware company. The device was then built at VTT and operated by postdoctoral research Chengyu Yan and his colleagues at Aalto University using the OtaNano research infrastructure. Yan is currently an associate professor at Huazhong University of Science and Technology [華中科技大學](CN), China.

The teams involved in this research are part of the Academy of Finland Centre of Excellence in Quantum Technology (QTF) and the Finnish Quantum Institute (InstituteQ).

Science paper:
Nature Electronics

See the full article here.

five-ways-keep-your-child-safe-school-shootings

Please help promote STEM in your local schools.

Stem Education Coalition

Aalto University [Aalto-yliopisto] (FI) is a university located in Espoo, Finland. It was established in 2010 as a merger of three major Finnish universities: the Helsinki University of Technology (established 1849), the Helsinki School of Economics (established 1904), and the University of Art and Design Helsinki (established 1871). The close collaboration between the scientific, business and arts communities is intended to foster multi-disciplinary education and research. The Finnish government, in 2010, set out to create a university that fosters innovation, merging the three institutions into one.

The university is composed of six schools with close to 17,500 students and 4,000 staff members, making it Finland’s second largest university. The main campus of Aalto University is located in Otaniemi, Espoo. Aalto University Executive Education operates in the district of Töölö, Helsinki. In addition to the Greater Helsinki area, the university also operates its Bachelor’s Programme in International Business in Mikkeli and the Metsähovi Radio Observatory in Kirkkonummi.

Aalto University’s operations showcase Finland’s experiment in higher education. The Aalto Design Factory, Aalto Ventures Program and Aalto Entrepreneurship Society (Aaltoes), among others, drive the university’s mission for a radical shift towards multidisciplinary learning and have contributed substantially to the emergence of Helsinki as a hotbed for startups. Aaltoes is Europe’s largest and most active student run entrepreneurship community that has founded major concepts such as the Startup Sauna accelerator program and the Slush startup event.

The university is named in honour of Alvar Aalto, a prominent Finnish architect, designer and alumnus of the former Helsinki University of Technology, who was also instrumental in designing a large part of the university’s main campus in Otaniemi.

From Aalto University [Aalto-yliopisto] (FI): “A new artificial material mimics quantum entangled rare earth compounds”

From Aalto University [Aalto-yliopisto] (FI)

24.11.2021

Peter Liljeroth
Akatemiaprofessori
peter.liljeroth@aalto.fi
+358503636115

Jose Lado
Assistant Professor
T304 Dept. Applied Physics
jose.lado@aalto.fi
+358503133730

Viliam Vano
Doctoral Candidate
viliam.vano@aalto.fi
+358505221843

By combining two-dimensional materials researchers create a macroscopic quantum entangled state emulating rare earth compounds.

An artistic rendition of quantum entanglement. Image: Heikka Valja.

Physicists have created a new ultra-thin two-layer material with quantum properties that normally require rare earth compounds. This material, which is relatively easy to make and does not contain rare earth metals, could provide a new platform for quantum computing and advance research into unconventional superconductivity and quantum criticality.

The researchers showed that by starting from seemingly common materials, a radically new quantum state of matter can appear. The discovery emerged from their efforts to create a quantum spin liquid which they could use for to investigate emergent quantum phenomena such as gauge theory. This involves fabricating a single layer of atomically thin tantalum disulphide, but the process also creates islands that consist of two layers.

When the team examined these islands, they found that interactions between the two layers induced a phenomenon known as the Kondo effect, leading to a macroscopically entangled state of matter producing a heavy-fermion system.

The Kondo effect is an interaction between magnetic impurities and electrons that causes a material’s electrical resistance to change with temperature. This results in the electrons behaving as though they have more mass, leading these compounds to be called heavy fermion materials. This phenomenon is a hallmark of materials containing rare earth elements.

A new artificial material mimics quantum entangled rare earth compounds.

Heavy fermion materials are important in several domains of cutting-edge physics including research into quantum materials. ‘Studying complex quantum materials is hindered by the properties of naturally occurring compounds. Our goal is to produce artificial designer materials that can be readily tuned and controlled externally to expand the range of exotic phenomena that can be realized in the lab,’ says Professor Peter Liljeroth.

For example, heavy fermion materials could act as topological superconductors which could be useful for building qubits that are more robust to noise and perturbation from the environment reducing error rates in quantum computers. ‘Creating this in real life would benefit enormously from having a heavy fermion material system that can be readily incorporated into electrical devices and tuned externally,’ explains Viliam Vaňo, a doctoral student in Liljeroth’s group and the paper’s lead author.

Although both layers in the new material are tantalum sulphide, there are subtle but important differences in their properties. One layer behaves like a metal, conducting electrons, while the other layer has a structural change that causes electrons to be localized into a regular lattice. The combination of the two results in the appearance of heavy fermion physics, which neither layer exhibits alone.

This new heavy fermion material also offers a powerful tool for probing quantum criticality. ‘The material can reach a quantum-critical point when it begins to move from one collective quantum state to another, for example, from a regular magnet towards an entangled heavy fermion material,’ explains Professor Jose Lado. ‘Between these states, the entire system is critical, reacting strongly to the slightest change, and providing an ideal platform to engineer even more exotic quantum matter.’

‘In the future, we will explore how the system reacts to the rotation of each sheet relative to the other and try to modify the coupling between the layers to tune the material towards quantum critical behaviour,’ says Liljeroth.

Science paper:
Nature

See the full article here.

five-ways-keep-your-child-safe-school-shootings

Please help promote STEM in your local schools.

Stem Education Coalition

Aalto University [Aalto-yliopisto] (FI) is a university located in Espoo, Finland. It was established in 2010 as a merger of three major Finnish universities: the Helsinki University of Technology (established 1849), the Helsinki School of Economics (established 1904), and the University of Art and Design Helsinki (established 1871). The close collaboration between the scientific, business and arts communities is intended to foster multi-disciplinary education and research. The Finnish government, in 2010, set out to create a university that fosters innovation, merging the three institutions into one.

The university is composed of six schools with close to 17,500 students and 4,000 staff members, making it Finland’s second largest university. The main campus of Aalto University is located in Otaniemi, Espoo. Aalto University Executive Education operates in the district of Töölö, Helsinki. In addition to the Greater Helsinki area, the university also operates its Bachelor’s Programme in International Business in Mikkeli and the Metsähovi Radio Observatory Metsähovi Radio Observatory [Metsähovin radiotutkimusasema] Aalto University [Aalto-yliopisto](FI) in Kirkkonummi. in Kirkkonummi.

Aalto University’s operations showcase Finland’s experiment in higher education. The Aalto Design Factory, Aalto Ventures Program and Aalto Entrepreneurship Society (Aaltoes), among others, drive the university’s mission for a radical shift towards multidisciplinary learning and have contributed substantially to the emergence of Helsinki as a hotbed for startups. Aaltoes is Europe’s largest and most active student run entrepreneurship community that has founded major concepts such as the Startup Sauna accelerator program and the Slush startup event.

The university is named in honour of Alvar Aalto, a prominent Finnish architect, designer and alumnus of the former Helsinki University of Technology, who was also instrumental in designing a large part of the university’s main campus in Otaniemi.

From Aalto University [Aalto-yliopisto] (FI): “Physicists find a new powerful method to explore phase transitions in strongly correlated quantum systems”

From Aalto University [Aalto-yliopisto] (FI)

17.11.2021

Sebastiano Peotta
Academy Research Fellow
sebastiano.peotta@aalto.fi
+358402159141

Christian Flindt
Associate Professor
T304 Dept. Applied Physics
christian.flindt@aalto.fi
+358504365501

Far-from-equilibrium dynamics of quantum many-body systems is one of the most active research areas in physics, with important connections to emerging quantum computers.

Photo: Mikko Raskinen.

Researchers from Aalto University and Tampere University of Technology[Tampereen yliopisto](FI) have developed a new theoretical method to study dynamical phase transitions in strongly correlated quantum systems. Far-from-equilibrium dynamics of quantum many-body systems is one of the most active research areas in physics. The breakthrough work was recently published in Physical Review X.

Besides the long-standing fundamental interest, quantum dynamics of correlated systems is highly topical for the emerging quantum computers. The first likely breakthrough application for the new technology is in the realm of quantum many-body simulations that are notoriously difficult for traditional computers.

On the other hand, the first-generation quantum computers are still limited, and quantum dynamics can be employed in benchmarking their performance.

‘Thus, comparing their predictions to those obtained by other means offers insights into their ability to simulate quantum systems. The new method to predict dynamical quantum phase transitions could be employed this way to study the performance of quantum computers,’ says Teemu Ojanen, Professor of computational physics at Tampere University.

Phase transitions is the basic phenomena of equilibrium statistical physics. A phase transition is a natural phenomenon in which a small change in a parameter-such as temperature-leads to drastic change in the properties of a substance, for instance water turning into ice. Phase transitions occur at a general level in systems composed by a large number of elementary constituents, for instance the molecules in a substance.

Phase transitions occur only in the limit of an infinite number of constituents, in which the system properties change in a truly discontinuous way. This limit is called the thermodynamic limit, an essential concept to understand phase transitions. The number of molecules in a macroscopic amount of water or any other substance is so astronomically large that the thermodynamic limit is in fact reached for all practical purposes.

The study of phase transitions in various forms has kept scientists busy since the very beginnings of the scientific endeavor. With the limited amount of funding at their disposal, scientists, and in particular physicists, do not have the luxury to study phase transitions directly in the thermodynamic limit. To overcome this limitation, they have devised various methods to infer the existence of a phase transition from the analysis of systems of small size. These methods are particularly important in the case of quantum systems which require a large amount of computational power even for an embarrassingly small number of constituents.

The Aalto University research group led by Professor Christian Flindt is part of the national Centre of Excellence, Quantum Technology Finland (QTF) and InstituteQ, The Finnish Quantum Institute.

See the full article here.

five-ways-keep-your-child-safe-school-shootings

Please help promote STEM in your local schools.

Stem Education Coalition

Aalto University [Aalto-yliopisto] (FI) is a university located in Espoo, Finland. It was established in 2010 as a merger of three major Finnish universities: the Helsinki University of Technology (established 1849), the Helsinki School of Economics (established 1904), and the University of Art and Design Helsinki (established 1871). The close collaboration between the scientific, business and arts communities is intended to foster multi-disciplinary education and research. The Finnish government, in 2010, set out to create a university that fosters innovation, merging the three institutions into one.

The university is composed of six schools with close to 17,500 students and 4,000 staff members, making it Finland’s second largest university. The main campus of Aalto University is located in Otaniemi, Espoo. Aalto University Executive Education operates in the district of Töölö, Helsinki. In addition to the Greater Helsinki area, the university also operates its Bachelor’s Programme in International Business in Mikkeli and the Metsähovi Radio Observatory Metsähovi Radio Observatory [Metsähovin radiotutkimusasema] Aalto University [Aalto-yliopisto](FI) in Kirkkonummi. in Kirkkonummi.

Aalto University’s operations showcase Finland’s experiment in higher education. The Aalto Design Factory, Aalto Ventures Program and Aalto Entrepreneurship Society (Aaltoes), among others, drive the university’s mission for a radical shift towards multidisciplinary learning and have contributed substantially to the emergence of Helsinki as a hotbed for startups. Aaltoes is Europe’s largest and most active student run entrepreneurship community that has founded major concepts such as the Startup Sauna accelerator program and the Slush startup event.

The university is named in honour of Alvar Aalto, a prominent Finnish architect, designer and alumnus of the former Helsinki University of Technology, who was also instrumental in designing a large part of the university’s main campus in Otaniemi.

From Aalto University [Aalto-yliopisto] (FI) and University of Marburg [Philipps-Universität Marburg](DE) : “A new form of carbon”

From Aalto University [Aalto-yliopisto] (FI)

and

University of Marburg [Philipps-Universität Marburg](DE)

20.5.2021

Not graphene: researchers in Germany and Finland discover new type of atomically thin carbon material.

Structure of the new network. The upper part schematically shows how the carbon atoms link as squares, hexagons, & octagons. The lower part is an image of the network, obtained with high resolution microscopy. Credit: University of Marburg [Philipps-Universität Marburg](DE) & Aalto University [ Aalto-yliopisto](FI)

Carbon exists in various forms. In addition to diamond and graphite, there are recently discovered forms with astonishing properties. For example graphene, with a thickness of just one atomic layer, is the thinnest known material, and its unusual properties make it an extremely exciting candidate for applications like future electronics and high-tech engineering. In graphene, each carbon atom is linked to three neighbours, forming hexagons arranged in a honeycomb network. Theoretical studies have shown that carbon atoms can also arrange in other flat network patterns, while still binding to three neighbours, but none of these predicted networks had been realized until now.

Researchers at the University of Marburg [Philipps-Universität Marburg](DE) in Germany and Aalto University [ Aalto-yliopisto](FI) in Finland have now discovered a new carbon network which is atomically thin like graphene but is made up of squares; hexagons; and octagons forming an ordered lattice. They confirmed the unique structure of the network using high-resolution scanning probe microscopy and interestingly found that its electronic properties are very different from those of graphene.

In contrast to graphene and other forms of carbon the new Biphenylene network — as the new material is named —has metallic properties. Narrow stripes of the network, only 21 atoms wide, already behave like a metal, while graphene is a semiconductor at this size. “These stripes could be used as conducting wires in future carbon-based electronic devices.” said professor Michael Gottfried, at University of Marburg, who leads the team that developed the idea. The lead author of the study, Qitang Fan from Marburg continues, “This novel carbon network may also serve as a superior anode material in lithium-ion batteries, with a larger lithium storage capacity compared to that of the current graphene-based materials.”

The team at Aalto University helped image the material and decipher its properties. The group of Professor Peter Liljeroth carried out the high-resolution microscopy that showed the structure of the material, while researchers led by Professor Adam Foster used computer simulations and analysis to understand the exciting electrical properties of the material.

The new material is made by assembling carbon-containing molecules on an extremely smooth gold surface. These molecules first form chains, which consist of linked hexagons, and a subsequent reaction connects these chains together to form the squares and octagons. An important feature of the chains is that they are chiral, which means that they exist in two mirroring types, like left and right hands. Only chains of the same type aggregate on the gold surface, forming well-ordered assemblies, before they connect. This is critical for the formation of the new carbon material, because the reaction between two different types of chains leads only to graphene. “The new idea is to use molecular precursors that are tweaked to yield biphenylene instead of graphene” explains Linghao Yan, who carried out the high-resolution microscopy experiments at Aalto University.

For now, the teams work to produce larger sheets of the material, so that its application potential can be further explored. However, “We are confident that this new synthesis method will lead to the discovery of other novel carbon networks.” said Professor Liljeroth.

Science paper:
Science

See the full article here.

five-ways-keep-your-child-safe-school-shootings

Please help promote STEM in your local schools.

Stem Education Coalition

Aalto University [Aalto-yliopisto] (FI) is a university located in Espoo, Finland. It was established in 2010 as a merger of three major Finnish universities: the Helsinki University of Technology (established 1849), the Helsinki School of Economics (established 1904), and the University of Art and Design Helsinki (established 1871). The close collaboration between the scientific, business and arts communities is intended to foster multi-disciplinary education and research. The Finnish government, in 2010, set out to create a university that fosters innovation, merging the three institutions into one.

The university is composed of six schools with close to 17,500 students and 4,000 staff members, making it Finland’s second largest university. The main campus of Aalto University is located in Otaniemi, Espoo. Aalto University Executive Education operates in the district of Töölö, Helsinki. In addition to the Greater Helsinki area, the university also operates its Bachelor’s Programme in International Business in Mikkeli and the Metsähovi Radio Observatory Metsähovi Radio Observatory [Metsähovin radiotutkimusasema] Aalto University [Aalto-yliopisto](FI) in Kirkkonummi. in Kirkkonummi.

Aalto University’s operations showcase Finland’s experiment in higher education. The Aalto Design Factory, Aalto Ventures Program and Aalto Entrepreneurship Society (Aaltoes), among others, drive the university’s mission for a radical shift towards multidisciplinary learning and have contributed substantially to the emergence of Helsinki as a hotbed for startups. Aaltoes is Europe’s largest and most active student run entrepreneurship community that has founded major concepts such as the Startup Sauna accelerator program and the Slush startup event.

The university is named in honour of Alvar Aalto, a prominent Finnish architect, designer and alumnus of the former Helsinki University of Technology, who was also instrumental in designing a large part of the university’s main campus in Otaniemi.