Lifeboat Foundation: Safeguarding Humanity
Toggle light / dark theme

Blog

Category: quantum physics – Page 579

The first 256-qubit quantum computer has been announced by startup company QuEra, founded by MIT and Harvard scientists.

QuEra Computing Inc. – a new Boston, Massachusetts-based company – has emerged from stealth mode with $17 million in funding and has completed the assembly of a 256-qubit device. Its funders include Japanese e-commerce giant Rakuten, Day One Ventures, Frontiers Capital, and the leading tech investors Serguei Beloussov and Paul Maritz. The company recently received a DARPA award, and has already generated $11 million in revenue.

QuEra Computing recently achieved ground-breaking research on neutral atoms, developed at Harvard University and the Massachusetts Institute of Technology, which is being used as the basis for a highly scalable, programmable quantum computer solution. The QuEra team is aiming to build the world’s most powerful quantum computers to take on computational tasks that are currently deemed impossibly hard.

Read more | >

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 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.

Read more | >

And that’s where physicists are getting stuck.

Zooming in to that hidden center involves virtual particles — quantum fluctuations that subtly influence each interaction’s outcome. The fleeting existence of the quark pair above, like many virtual events, is represented by a Feynman diagram with a closed “loop.” Loops confound physicists — they’re black boxes that introduce additional layers of infinite scenarios. To tally the possibilities implied by a loop, theorists must turn to a summing operation known as an integral. These integrals take on monstrous proportions in multi-loop Feynman diagrams, which come into play as researchers march down the line and fold in more complicated virtual interactions.

Physicists have algorithms to compute the probabilities of no-loop and one-loop scenarios, but many two-loop collisions bring computers to their knees. This imposes a ceiling on predictive precision — and on how well physicists can understand what quantum theory says.

Read more | >

Over the past several decades, researchers have moved from using electric currents to manipulating light waves in the near-infrared range for telecommunications applications such as high-speed 5G networks, biosensors on a chip, and driverless cars. This research area, known as integrated photonics, is fast evolving and investigators are now exploring the shorter—visible—wavelength range to develop a broad variety of emerging applications. These include chip-scale LIDAR (light detection and ranging), AR/VR/MR (augmented/virtual/mixed reality) goggles, holographic displays, quantum information processing chips, and implantable optogenetic probes in the brain.

The one device critical to all these applications in the is an optical phase modulator, which controls the phase of a light wave, similar to how the phase of radio waves is modulated in wireless computer networks. With a phase modulator, researchers can build an on-chip that channels light into different waveguide ports. With a large network of these optical switches, researchers could create sophisticated integrated optical systems that could control light propagating on a tiny chip or light emission from the chip.

But phase modulators in the visible range are very hard to make: there are no materials that are transparent enough in the visible spectrum while also providing large tunability, either through thermo-optical or electro-optical effects. Currently, the two most suitable materials are silicon nitride and lithium niobate. While both are highly transparent in the visible range, neither one provides very much tunability. Visible-spectrum phase modulators based on these materials are thus not only large but also power-hungry: the length of individual waveguide-based modulators ranges from hundreds of microns to several mm and a single modulator consumes tens of mW for phase tuning. Researchers trying to achieve large-scale integration—embedding thousands of devices on a single microchip—have, up to now, been stymied by these bulky, energy-consuming devices.

Read more | >

The most promising application in biomedicine is in computational chemistry, where researchers have long exploited a quantum approach. But the Fraunhofer Society hopes to spark interest among a wider community of life scientists, such as cancer researchers, whose research questions are not intrinsically quantum in nature.

“It’s uncharted territory,” says oncologist Niels Halama of the DKFZ, Germany’s national cancer center in Heidelberg. Working with a team of physicists and computer scientists, Halama is planning to develop and test algorithms that might help stratify cancer patients, and select small subgroups for specific therapies from heterogeneous data sets.

This is important for precision medicine, he says, but classic computing has insufficient power to find very small groups in the large and complex data sets that oncology, for example, generates. The time needed to complete such a task may stretch out over many weeks—too long to be of use in a clinical setting, and also too expensive. Moreover, the steady improvements in the performance of classic computers are slowing, thanks in large part to fundamental limits on chip miniaturization.

Read more | >

Check out the physics courses that I mentioned (many of which are free!) and support this channel by going to https://brilliant.org/Sabine/ where you can create your Brilliant account. The first 200 will get 20% off the annual premium subscription.

What are the quantum technologies that are now attracting so much research funding? In this video I go through the most important ones: quantum computing, quantum metrology, the quantum internet, and quantum simulations. I explain what these are all about and how likely they are to impact our lives soon. I also tell you what frequently headline blunders to watch out for.

The White House report I mention at 10 mins 34 seconds is here:

https://www.quantum.gov/wp-content/uploads/2020/10/QuantumFrontiers.pdf.

Please consider supporting our channel on Patreon:

https://www.patreon.com/Sabine?fan_landing=true.

Continue reading “Don’t fall for quantum hype” | >

Work has potential applications in quantum computing, and introduces new way to plumb the secrets of superconductivity. MIT physicists and colleagues have demonstrated an exotic form of superconductivity in a new material the team synthesized only about a year ago. Although predicted in the 1960s.

“An important theme of our research is that new physics comes from new materials,” says Joseph Checkelsky, lead principal investigator of the work and the Mitsui Career Development Associate Professor of Physics. “Our initial report last year was of this new material. This new work reports the new physics.”

Checkelsky’s co-authors on the current paper include lead author Aravind Devarakonda PhD ’21, who is now at Columbia University. The work was a central part of Devarakonda’s thesis. Co-authors are Takehito Suzuki, a former research scientist at MIT now at Toho University in Japan; Shiang Fang, a postdoc in the MIT Department of Physics; Junbo Zhu, an MIT graduate student in physics; David Graf of the National High Magnetic Field Laboratory; Markus Kriener of the RIKEN Center for Emergent Matter Science in Japan; Liang Fu, an MIT associate professor of physics; and Efthimios Kaxiras of Harvard University.

New quantum material

Classical physics can be used to explain any number of phenomena that underlie our world — until things get exquisitely small. Subatomic particles like electrons and quarks behave differently, in ways that are still not fully understood. Enter quantum mechanics, the field that tries to explain their behavior and resulting effects.

Read more | >

Superconductivity occurs when electrons in a metal pair up and move through the material without resistance. But there may be more to the story than we thought, as scientists in Germany have now discovered that electrons can also group together into families of four, creating a new state of matter and, potentially, a new type of superconductivity.

Conductivity is a measure of how easily electrons (and therefore electricity) can move through a material. But even in materials that make good conductors, like gold, electrons will still encounter some resistance. Superconductors, however, remove all such barriers and provide zero resistance at ultracold temperatures.

The reason electrons can move through superconductors so easily is because they pair up through a quantum effect known as Cooper pairing. In doing so, they raise the minimum amount of energy it takes to interfere with the electrons – and if the material is cold enough, its atoms won’t have enough thermal energy to disturb these Cooper pairs, allowing the electrons to flow freely with no loss of energy.

Read more | >

What is entanglement theory? It is a Mystery, and here is a potential solution. But its implications are so paradigm shattering that most scientists refuse to believe it. Maybe we can’t handle the truth?

Imagine you found a pair of dice such that no matter how you tossed them, they always added up to 7. Besides becoming the richest man in Vegas, what you would have there is something called an entangled pair of dice.

You could now separate these entangled dice. You could have your friend Alice take one of these to Macau, while the other one stays with you in Las Vegas. And as soon as you rolled your dice, the other one would always instantly show a number that added up to 7.

Since this happens instantly, did your dice communicate at faster than speed of light to Macau?

Scientists can create entangled photons, for example, by shining a laser on a nonlinear optical crystal. The Entanglement means that a pair of photons act like a single entity rather than two separate particles. To understand entanglement better, you first have to accept the fact that at the quantum scale, reality is fuzzy. Reality really doesn’t know what it is, until it is measured.

This is like a single dice tossed in the air that doesn’t have a distinct face until it lands. When tossed up, it is 1, 2, 3, 4, 5, and 6 all at once. Quantum particles are similar in that they do not have distinct properties until they are measured. Particles such as a photon exists in all possible states simultaneously. But when it is measured, it is in only one state. And if the photon is entangled, this measurement of one particle causes its entangled pair to simultaneously exhibit the opposite state, no matter what the distance is between them.

Continue reading “Entanglement Theory may Reveal a Reality we can’t Handle” | >