Lifeboat Foundation: Safeguarding Humanity
Toggle light / dark theme

Blog

Category: quantum physics

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 , 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.

Read more | >

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.
» Subscribe to Seeker! http://bit.ly/subscribeseeker
» Watch more Elements! http://bit.ly/ElementsPlaylist
» Visit our shop at http://shop.seeker.com

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.

Another property, quantum entanglement, allows for qubits to be linked together, and changing the state of one qubit will also change the state of its entangled partner.

Thanks to these two properties, quantum computers of a few dozen qubits can outperform massive supercomputers in certain very specific tasks. But there are several issues holding quantum computers back from solving the world’s toughest problems, one of them is how prone qubits are to error.

#computers #quantumcomputers #science #seeker #elements

New detector breakthrough pushes boundaries of quantum computing
https://phys.org/news/2020-09-detector-breakthrough-boundaries-quantum.html
“‘Bolometers are now entering the field of quantum technology and perhaps their first application could be in reading out the quantum information from qubits. The bolometer speed and accuracy seems now right for it,’ says Professor Möttönen.”

Read more | >

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.

Read more | >

Patrick Windpassinger and his team demonstrate how light stored in a cloud of ultra-cold atoms can be transported by means of an optical conveyor belt.

A team of physicists led by Professor Patrick Windpassinger at Johannes Gutenberg University Mainz (JGU) has successfully transported light stored in a quantum memory over a distance of 1.2 millimeters. They have demonstrated that the controlled transport process and its dynamics has only little impact on the properties of the stored light. The researchers used ultra-cold rubidium-87 atoms as a storage medium for the light as to achieve a high level of storage efficiency and a long lifetime.

“We stored the light by putting it in a suitcase so to speak, only that in our case the suitcase was made of a cloud of cold atoms. We moved this suitcase over a short distance and then took the light out again. This is very interesting not only for physics in general, but also for quantum communication, because light is not very easy to ‘capture’, and if you want to transport it elsewhere in a controlled manner, it usually ends up being lost,” said Professor Patrick Windpassinger, explaining the complicated process.

Read more | >

We stored the light by putting it in a suitcase so to speak, only that in our case the suitcase was made of a cloud of cold atoms,” says physicist Patrick Windpassinger from Mainz University in Germany. “We moved this suitcase over a short distance and then took the light out again.

The storage and transfer of information is a fundamental part of any computing system, and quantum computing systems are no different – if we’re going to benefit from the speed and security of quantum computers and a quantum internet, then we need to figure out how to shift quantum data around.

One of the ways scientists are approaching this is through optical quantum memory, or using light to store data as maps of particle states, and a new study reports on what researchers are calling a milestone in the field: the successful storage and transfer of light using quantum memory.

The researchers weren’t able to transfer the light very far – just 1.2 millimetres or 0.05 inches – but the process outlined here could form the foundation of the quantum-powered computers and communication systems of the future.

Read more | >

Optical computing, which uses photons instead of electrons, has been one of the great promises of this field for decades.

According to Moore’s law —actually more like a forecast, formulated in 1965 by Intel co-founder Gordon Moore— the number of transistors in a microprocessor doubles about every two years, boosting the power of the chips without increasing their energy consumption. For half a century, Moore’s prescient vision has presided over the spectacular progress made in the world of computing. However, by 2015, the engineer himself predicted that we are reaching a saturation point in current technology. Today, quantum computing holds out hope for a new technological leap, but there is another option on which many are pinning their hopes: optical computing, which replaces electronics (electrons) with light (photons).

The end of Moore’s law is a natural consequence of physics: to pack more transistors into the same space they have to be shrunk down, which increases their speed while simultaneously reducing their energy consumption. The miniaturisation of silicon transistors has succeeded in breaking the 7-nanometre barrier, which used to be considered the limit, but this reduction cannot continue indefinitely. And although more powerful systems can always be obtained by increasing the number of transistors, in doing so the processing speed will decrease and the heat of the chips will rise.

The hybridization of electronics and optics

Hence the promise of optical computing: photons move at the speed of light, faster than electrons in a wire. Optical technology is also not a newcomer to our lives: the vast global traffic on the information highways today travels on fibre optic channels, and for years we have used optical readers to burn and read our CDs, DVDs and Blu-Ray discs. However, in the guts of our systems, the photons coming through the fibre optic cable must be converted into electrons in the microchips, and in turn these electrons must be converted to photons in the optical readers, slowing down the process.

Read more | >

Extreme events occur in many observable contexts. Nature is a prolific source: rogue water waves surging high above the swell, monsoon rains, wildfire, etc. From climate science to optics, physicists have classified the characteristics of extreme events, extending the notion to their respective domains of expertise. For instance, extreme events can take place in telecommunication data streams. In fiber-optic communications where a vast number of spatio-temporal fluctuations can occur in transoceanic systems, a sudden surge is an extreme event that must be suppressed, as it can potentially alter components associated with the physical layer or disrupt the transmission of private messages.

Recently, extreme events have been observed in quantum cascade lasers, as reported by researchers from Télécom Paris (France) in collaboration with UC Los Angeles (USA) and TU Darmstad (Germany). The giant pulses that characterize these extreme events can contribute the sudden, sharp bursts necessary for communication in neuromorphic systems inspired by the brain’s powerful computational abilities. Based on a quantum cascade laser (QCL) emitting mid-infrared light, the researchers developed a basic optical neuron system operating 10,000× faster than biological neurons. Their report is published in Advanced Photonics.

Read more | >

We know that our understanding of reality is pretty biased. Our senses, our cultures, and our knowledge shape how we see the world. And if you think that science will always give you objective reality, you might want to reconsider.

Physicists have finally been able to test a thought experiment first proposed in 1961 by Nobel Prize winner Eugen Wigner. The experiment is known as “Wigner’s Friend” and the setup is not too complicated. You start with a quantum system that has two states in superposition, which means that until you measure it, both states exist at the same time. For this example, a photon’s polarisation (the axis it spins on) is both horizontal and vertical.

Wigner’s friend is in the lab performing the experiment and once they measure it, the system will collapse and the photon will be fixed into one of those two states. But for Wigner, who is outside the lab unaware of the result of the measurement, the quantum system (which, importantly, also includes the lab) is still in superposition. Despite contradictory results, they are both correct. (This is similar to Schrödinger’s cat, a thought experiment also about superposition, if Schrödinger and his cat-in-a-box were also in a box.) So, two objective realities, Wigner’s and Wigner’s friend’s, appear to coexist. And this is a problem.

Read more | >

“Whenever we have developed better clocks, we’ve learned something new about the world,” said Alexander Smith, an assistant professor of physics at Saint Anselm College and adjunct assistant professor at Dartmouth College, who led the research as a junior fellow in Dartmouth’s Society of Fellows. “Quantum time dilation is a consequence of both quantum mechanics and Einstein’s relativity, and thus offers a new possibility to test fundamental physics at their intersection.”

A phenomenon of quantum mechanics known as superposition can impact timekeeping in high-precision clocks, according to a theoretical study from Dartmouth College, Saint Anselm College and Santa Clara University.

Research describing the effect shows that superposition — the ability of an atom to exist in more than one state at the same time — leads to a correction in atomic clocks known as “quantum time dilation.”

The research, published today (October 23, 2020) in the journal Nature Communications, takes into account quantum effects beyond Albert Einstein’s theory of relativity to make a new prediction about the nature of time.

Read more | >