Tag Archives: Ruhr-University Bochum (RUB)

Nanoscopic advance of colossal (!) significance by Danish quantum physicists

it’s not often you see the word ‘colossal’ in a science news release but it seems these Danish researchers are very excited about their breakthrough. From a January 26, 2023 news item on Nanowerk,

In a new breakthrough, researchers at the University of Copenhagen, in collaboration with Ruhr University Bochum, have solved a problem that has caused quantum researchers headaches for years. The researchers can now control two quantum light sources rather than one. Trivial as it may seem to those uninitiated in quantum, this colossal breakthrough allows researchers to create a phenomenon known as quantum mechanical entanglement. This in turn, opens new doors for companies and others to exploit the technology commercially.

A January 26, 2023 University of Copenhagen press release (also on EurekAlert), which originated the news item, provides context and more detail,

Going from one to two is a minor feat in most contexts. But in the world of quantum physics, doing so is crucial. For years, researchers around the world have strived to develop stable quantum light sources and achieve the phenomenon known as quantum mechanical entanglement – a phenomenon, with nearly sci-fi-like properties, where two light sources can affect each other instantly and potentially across large geographic distances. Entanglement is the very basis of quantum networks and central to the development of an efficient quantum computer.  

Today [January 26, 2023], researchers from the Niels Bohr Institute published a new result in the highly esteemed journal Science, in which they succeeded in doing just that. According to Professor Peter Lodahl, one of the researchers behind the result, it is a crucial step in the effort to take the development of quantum technology to the next level and to “quantize” society’s computers, encryption and the internet.

“We can now control two quantum light sources and connect them to each other. It might not sound like much, but it’s a major advancement and builds upon the past 20 years of work. By doing so, we’ve revealed the key to scaling up the technology, which is crucial for the most ground-breaking of quantum hardware applications,” says Professor Peter Lodahl, who has conducted research the area since 2001.  

The magic all happens in a so-called nanochip – which is not much larger than the diameter of a human hair – that the researchers also developed in recent years.

Quantum sources overtake the world’s most powerful computer 

Peter Lodahl’s group is working with a type of quantum technology that uses light particles, called photons, as micro transporters to move quantum information about.

While Lodahl’s group is a leader in this discipline of quantum physics, they have only been able to control one light source at a time until now. This is because light sources are extraordinarily sensitive to outside “noise”, making them very difficult to copy. In their new result, the research group succeeded in creating two identical quantum light sources rather than just one.

“Entanglement means that by controlling one light source, you immediately affect the other. This makes it possible to create a whole network of entangled quantum light sources, all of which interact with one another, and which you can get to perform quantum bit operations in the same way as bits in a regular computer, only much more powerfully,” explains postdoc Alexey Tiranov, the article’s lead author. 

This is because a quantum bit can be both a 1 and 0 at the same time, which results in processing power that is unattainable using today’s computer technology. According to Professor Lodahl, just 100 photons emitted from a single quantum light source will contain more information than the world’s largest supercomputer can process.

By using 20-30 entangled quantum light sources, there is the potential to build a universal error-corrected quantum computer – the ultimate “holy grail” for quantum technology, that large IT companies are now pumping many billions into.

Other actors will build upon the research

According to Lodahl, the biggest challenge has been to go from controlling one to two quantum light sources. Among other things, this has made it necessary for researchers to develop extremely quiet nanochips and have precise control over each light source.

With the new research breakthrough, the fundamental quantum physics research is now in place. Now it is time for other actors to take the researchers’ work and use it in their quests to deploy quantum physics in a range of technologies including computers, the internet and encryption.

“It is too expensive for a university to build a setup where we control 15-20 quantum light sources. So, now that we have contributed to understanding the fundamental quantum physics and taken the first step along the way, scaling up further is very much a technological task,” says Professor Lodahl.  

The research was conducted at the Danish National Research Foundation’s “Center of Excellence for Hybrid Quantum Networks (Hy-Q)” and is a collaboration between Ruhr University Bochum in Germany and the the University of Copenhagen’s Niels Bohr Institute.

Here’s a link to and a citation for this colossal research,

Collective super- and subradiant dynamics between distant optical quantum emitters by Alexey Tiranov, Vasiliki Angelopoulou, Cornelis Jacobus van Diepen, Björn Schrinski, Oliver August Dall’Alba Sandberg, Ying Wang, Leonardo Midolo, Sven Scholz, Andreas Dirk Wieck, Arne Ludwig, Anders Søndberg Sørensen, and Peter Lodahl. Science 26 Jan 2023 Vol 379, Issue 6630 pp. 389-393 DOI: 10.1126/science.ade9324

This paper is behind a paywall.

Observing individual silver nanoparticles in real time

A new technique for better understanding how silver nanoparticles might affect the environment was announced in a July 30, 2018 news item on ScienceDaily,

Chemists at Ruhr-Universität Bochum have developed a new method of observing the chemical reactions of individual silver nanoparticles, which only measure a thousandth of the thickness of a human hair, in real time. The particles are used in medicine, food and sports items because they have an antibacterial and anti-inflammatory effect. However, how they react and degrade in ecological and biological systems is so far barely understood. The team in the Research Group for Electrochemistry and Nanoscale Materials showed that the nanoparticles transform into poorly soluble silver chloride particles under certain conditions. The group led by Prof Dr Kristina Tschulik reports on the results in the Journal of the American Chemical Society from July 11, 2018.

A July 30,2018 Ruhr-University Bochum (RUB) press release (also on EurekAlert) by Julia Weiler, which originated the news item, provides more information,

Even under well-defined laboratory conditions, current research has yielded different, sometimes contradictory, results on the reaction of silver nanoparticles. “In every batch of nanoparticles, the individual properties of the particles, such as size and shape, vary,” says Kristina Tschulik, a member of the Cluster of Excellence Ruhr Explores Solvation. “With previous procedures, a myriad of particles was generally investigated at the same time, meaning that the effects of these variations could not be recorded. Or the measurements took place in a high vacuum, not under natural conditions in an aqueous solution.”

The team led by Kristina Tschulik thus developed a method that enables individual silver particles to be investigated in a natural environment. “Our aim is to be able to record the reactivity of individual particles,” explains the researcher. This requires a combination of electrochemical and spectroscopic methods. With optical and hyperspectral dark-field microscopy, the group was able to observe individual nanoparticles as visible and coloured pixels. Using the change in the colour of the pixels, or more precisely their spectral information, the researchers were able to follow what was happening in an electrochemical experiment in real time.

Degradation of the particles slowed down

In the experiment, the team replicated the oxidation of silver in the presence of chloride ions, which often takes place in ecological and biological systems. “Until now, it was generally assumed that the silver particles dissolve in the form of silver ions,” describes Kristina Tschulik. However, poorly soluble silver chloride was formed in the experiment – even if only a few chloride ions were present in the solution.

“This extends the lifespan of the nanoparticles to an extreme extent and their breakdown is slowed down in an unexpectedly drastic manner,” summarises Tschulik. “This is equally important for bodies of water and for living beings because this mechanism could cause the heavy metal silver to accumulate locally, which can be toxic for many organisms.”

Further development planned

The Bochum-based group now wants to further improve its technology for analysing individual nanoparticles in order to better understand the ageing mechanisms of such particles. The researchers thus want to obtain more information about the biocompatibility of the silver particles and the lifespan and ageing of catalytically active nanoparticles in the future.

Here’s a link to and a citation for the paper,

Simultaneous Opto- and Spectro-Electrochemistry: Reactions of Individual Nanoparticles Uncovered by Dark-Field Microscopy by Kevin Wonner, Mathies V. Evers, and Kristina Tschulik. J. Am. Chem. Soc., Article ASAP DOI: 10.1021/jacs.8b02367 Publication Date (Web): July 11, 2018

Copyright © 2018 American Chemical Society

This paper is behind a paywall.