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The first quantum revolution brought about semiconductor electronics, the laser and finally the internet. The coming, second quantum revolution promises spy-proof communication, extremely precise quantum sensors and quantum computers for previously unsolvable computing tasks. But this revolution is still in its infancy. A central research object is the interface between local quantum devices and light quanta that enable the remote transmission of highly sensitive quantum information. The Otto-Hahn group “Quantum Networks” at the Max-Planck-Institute of Quantum Optics in Garching is researching such a “quantum modem”. The team has now achieved a first breakthrough in a relatively simple but highly efficient technology that can be integrated into existing fiber optic networks. The work is published this week in Physical Review X.

The Corona pandemic is a daily reminder of how important the internet has become. The World Wide Web, once a by-product of basic physical research, has radically changed our culture. Could a quantum internet become the next major innovation out of physics?

It is still too early to answer that question, but basic research is already working on the quantum internet. Many applications will be more specialized and less sensual than video conferencing, but the importance of absolutely spy-proof long-distance communication is understandable to everyone. “In the future, a quantum internet could be used to connect quantum computers located in different places,” Andreas Reiserer says, “which would considerably increase their computing power!” The physicist heads the independent Otto-Hahn research group “Quantum Networks” at the Max-Planck-Institute of Quantum Optics in Garching.

The right indoor lighting can help set the mood, from a soft romantic glow to bright, stimulating colors. But some materials used for lighting, such as plastics, are not eco-friendly. Now, researchers reporting in ACS Nano have developed a bio-based, luminescent, water-resistant wood film that could someday be used as cover panels for lamps, displays and laser devices.

Consumer demand for eco-friendly, renewable materials has driven researchers to investigate wood-based thin films for optical applications. However, many materials developed so far have drawbacks, such as poor mechanical properties, uneven lighting, a lack of water resistance or the need for a petroleum-based polymer matrix. Qiliang Fu, Ingo Burgert and colleagues wanted to develop a luminescent wood film that could overcome these limitations.

The researchers treated balsa wood with a solution to remove lignin and about half of the hemicelluloses, leaving behind a porous scaffold. The team then infused the delignified wood with a solution containing quantum dots—semiconductor nanoparticles that glow in a particular color when struck by ultraviolet (UV) light. After compressing and drying, the researchers applied a hydrophobic coating. The result was a dense, water-resistant wood film with excellent mechanical properties. Under UV light, the quantum dots in the wood emitted and scattered an orange light that spread evenly throughout the film’s surface.

Researchers at the University of Rochester and Cornell University have taken an important step toward developing a communications network that exchanges information across long distances by using photons, mass-less measures of light that are key elements of quantum computing and quantum communications systems.

The research team has designed a nanoscale node made out of magnetic and semiconducting materials that could interact with other nodes, using laser light to emit and accept photons.

The development of such a quantum network—designed to take advantage of the physical properties of light and matter characterized by quantum mechanics—promises faster, more efficient ways to communicate, compute, and detect objects and materials as compared to networks currently used for computing and communications.

Quantum computers are now a reality, although they are still too rudimentary to factor numbers of more than two digits. But it is only a matter of time until quantum computers threaten Internet encryption.

Nature caught up with Shor to ask him about the impact of his work — and where Internet security is heading.

Nature talks to Peter Shor 25 years after he showed how to make quantum computations feasible — and how they could endanger our data.

When atoms get extremely close, they develop intriguing interactions that could be harnessed to create new generations of computing and other technologies. These interactions in the realm of quantum physics have proven difficult to study experimentally due the basic limitations of optical microscopes.

Now a team of Princeton researchers, led by Jeff Thompson, an assistant professor of electrical engineering, has developed a new way to control and measure atoms that are so close together no optical lens can distinguish them.

Described in an article published Oct. 30 in the journal Science, their method excites closely-spaced erbium atoms in a crystal using a finely tuned laser in a nanometer-scale optical circuit. The researchers take advantage of the fact that each atom responds to slightly different frequencies, or colors, of laser light, allowing the researchers to resolve and control multiple atoms, without relying on their spatial information.

Researchers from Sorbonne University in Paris have achieved a highly efficient transfer of quantum entanglement into and out of two quantum memory devices. This achievement brings a key ingredient for the scalability of a future quantum internet.

A quantum internet that connects multiple locations is a key step in quantum technology roadmaps worldwide. In this context, the European Quantum Flagship Programme launched the Quantum Internet Alliance in 2018. This consortium coordinated by Stephanie Wehner (QuTech-Delft) consists of 12 leading research groups at universities from eight European countries, in close cooperation with over 20 companies and institutes. They combined their resources and areas of expertise to develop a blueprint for a future quantum internet and the required technologies.

A quantum internet uses an intriguing quantum phenomenon to connect different nodes in a network together. In a normal network connection, nodes exchange information by sending electrons or photons back and forth, making them vulnerable to eavesdropping. In a quantum network, the nodes are connected by entanglement, Einstein’s famous “spooky action at a distance.” These non-classical correlations at large distances would allow not only secure communications beyond direct transmission but also distributed quantum computing or enhanced sensing.

Quantum computers can solve problems in seconds that would take “ordinary” computers millennia, but their sensitivity to interference is majorly holding them back. Now, researchers claim they’ve created a component that drastically cuts down on error-inducing noise.
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Quantum computers use quantum bits, or qubits, which can represent a one, a zero, or any combination of the two simultaneously. This is thanks to the quantum phenomenon known as superposition.

Continue reading “How Graphene Could Help Us Build Bigger and Better Quantum Computers” »

Lasers were created 60 years ago this year, when three different laser devices were unveiled by independent laboratories in the United States. A few years later, one of these inventors called the unusual light sources “a solution seeking a problem”. Today, the laser has been applied to countless problems in science, medicine and everyday technologies, with a market of more than US$11 billion per year.

A crucial difference between lasers and traditional sources of light is the “temporal coherence” of the light beam, or just coherence. The coherence of a beam can be measured by a number C, which takes into account the fact light is both a wave and a particle.

From even before lasers were created, physicists thought they knew exactly how coherent a laser could be. Now, two new studies (one by myself and colleagues in Australia, the other by a team of American physicists) have shown C can be much greater than was previously thought possible.

It’s exotic, incredibly cold stuff.