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Category: quantum physics

Scientists are getting closer to being able to spot Hawking radiation – that elusive thermal radiation thought to be produced by a black hole’s event horizon. Just understanding the concept of this radiation is tricky though, let alone finding it.

A new proposal suggests creating a special kind of quantum circuit to act as a ‘black hole laser’, essentially simulating some of the properties of a black hole. As with previous studies, the idea is that experts can observe and study Hawking radiation without actually having to look at any real black holes.

The basic principle is relatively straightforward. Black holes are objects that warp spacetime so much, not even a wave of light can escape. Swap spacetime for some other material (such as water) and make it flow quickly enough so that waves passing through are too slow to escape, and you’ve got yourself a fairly rudimentary model.

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The interior of the Earth is a mystery, especially at greater depths (660 km). Researchers only have seismic tomographic images of this region and, to interpret them, they need to calculate seismic (acoustic) velocities in minerals at high pressures and temperatures. With those calculations, they can create 3D velocity maps and figure out the mineralogy and temperature of the observed regions. When a phase transition occurs in a mineral, such as a crystal structure change under pressure, scientists observe a velocity change, usually a sharp seismic velocity discontinuity.

In 2,003 scientists observed in a lab a novel type of phase change in minerals—a spin change in iron in ferropericlase, the second most abundant component of the Earth’s lower mantle. A spin change, or spin crossover, can happen in minerals like ferropericlase under an external stimulus, such as pressure or temperature. Over the next few years, experimental and theoretical groups confirmed this phase change in both ferropericlase and bridgmanite, the most abundant phase of the lower mantle. But no one was quite sure why or where this was happening.

In 2,006 Columbia Engineering Professor Renata Wentzcovitch published her first paper on ferropericlase, providing a theory for the spin crossover in this mineral. Her theory suggested it happened across a thousand kilometers in the lower mantle. Since then, Wentzcovitch, who is a professor in the and applied mathematics department, earth and environmental sciences, and Lamont-Doherty Earth Observatory at Columbia University, has published 13 papers with her group on this topic, investigating velocities in every possible situation of the spin crossover in ferropericlase and bridgmanite, and predicting properties of these minerals throughout this crossover. In 2,014 Wenzcovitch, whose research focuses on computational quantum mechanical studies of materials at extreme conditions, in particular planetary materials predicted how this spin change phenomenon could be detected in seismic tomographic images, but seismologists still could not see it.

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Quantum technology typically employs qubits (quantum bits) consisting of, for example, single electrons, photons or atoms. A group of TU Delft researchers has now demonstrated the ability to teleport an arbitrary qubit state from a single photon onto an optomechanical device—consisting of a mechanical structure comprising billions of atoms. Their breakthrough research, now published in Nature Photonics, enables real-world applications such as quantum internet repeater nodes while also allowing quantum mechanics itself to be studied in new ways.

Quantum optomechanics

The field of quantum optomechanics uses optical means to control mechanical motion in the quantum regime. The first quantum effects in microscale mechanical devices were demonstrated about ten years ago. Focused efforts have since resulted in entangled states between optomechanical devices as well as demonstrations of an optomechanical quantum memory. Now, the group of Simon Gröblacher, of the Kavli Institute of Nanoscience and the Department of Quantum Nanoscience at Delft University of Technology, in collaboration with researchers from the University of Campinas in Brazil, has shown the first successful teleportation of an arbitrary optical qubit state onto a micromechanical quantum memory.

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A Japanese startup at CES is claiming to have solved one of the biggest problems in medical technology: Noninvasive continuous glucose monitoring. Quantum Operation Inc, exhibiting at the virtual show, says that its prototype wearable can accurately measure blood sugar from the wrist. Looking like a knock-off Apple Watch, the prototype crams in a small spectrometer which is used to scan the blood to measure for glucose. Quantum’s pitch adds that the watch is also capable of reading other vital signs, including heart rate and ECG.

The company says that its secret sauce is in its patented spectroscopy materials which are built into the watch and its band. To use it, the wearer simply needs to slide the watch on and activate the monitoring from the menu, and after around 20 seconds, the data is displayed. Quantum says that it expects to sell its hardware to insurers and healthcare providers, as well as building a big data platform to collect and examine the vast trove of information generated by patients wearing the device.

Quantum Operation supplied a sampling of its data compared to that made by a commercial monitor, the FreeStyle Libre. And, at this point, there does seem to be a noticeable amount of variation between the wearable and the Libre. That, for now, may be a deal breaker for those who rely upon accurate blood glucose readings to determine their insulin dosage.

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In a rare non-magnetic kagome material, a topological metal cools into a superconductor through a sequence of novel charge density waves. Researchers have discovered a complex landscape of electronic states that can co-exist on a kagome lattice, resembling those in high-temperature superconductor.

The Computational Cosmology group of the Department of Astronomy and Astrophysics (DAA) of Valencia University (UV) has published an article in The Astrophysical Journal Letters, one of the international journals with the greatest impact in Astrophysics, which shows, with complex theoretical-computational models, that cosmic voids are constantly replenished with external matter.

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Most important, the encoded logical qubit performed better than the physical ones on which it depends, at least in some ways. For example, the researchers succeeded in preparing either the logical 0 or the logical 1 state 99.67% of the time—better than the 99.54% for the individual qubits. “This is really the first time that the quality of the [logical] qubit is better than the components that encode it,” says Monroe, who is cofounder of IonQ, a company developing ion-based quantum computers.

However, Egan notes, the encoded qubit did not outshine the individual ions in every way. Instead, he says, the real advance is in demonstrating fault tolerance, which means the error-correcting machinery works in a way that doesn’t introduce more errors than it corrects. “Fault tolerance is really the design principle that prevents errors from spreading,” says Egan, now at IonQ.

Martinis questions that use of the term, however. To claim true fault-tolerant error correction, he says, researchers must do two other things. They must show that the errors in a logical qubit get exponentially smaller as the number of physical qubits increases. And they must show they can measure the ancillary qubits repeatedly to maintain the logical qubit, he says.

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Since the discovery of superconductivity in Sr2RuO4 in 1,994 hundreds of studies have been published on this compound, which have suggested that Sr2RuO4 is a very special system with unique properties. These properties make Sr2RuO4 a material with great potential, for example, for the development of future technologies including superconducting spintronics and quantum electronics by virtue of its ability to carry lossless electrical currents and magnetic information simultaneously. An international research team led by scientists at the University of Konstanz has been now able to answer one of the most interesting open questions on Sr2RuO4: why does the superconducting state of this material exhibit some features that are typically found in materials known as ferromagnets, which are considered being antagonists to superconductors? The team has found that Sr2RuO4 hosts a new form of magnetism, which can coexist with superconductivity and exists independently of superconductivity as well. The results have been published in the current issue of Nature Communications.

After a research study that lasted several years and involved 26 researchers from nine different universities and research institutions, the missing piece of the puzzle seems to have been found. Alongside the University of Konstanz, the universities of Salerno, Cambridge, Seoul, Kyoto and Bar Ilan as well as the Japan Atomic Energy Agency, the Paul Scherrer Institute and the Centro Nazionale delle Ricerche participated in the study.

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For more than 20 years, D-Wave has been synonymous with quantum annealing. Its early bet on this technology allowed it to become the world’s first company to sell quantum computers, but that also somewhat limited the real-world problems its hardware could solve, given that quantum annealing works especially well for optimization problems like protein folding or route planning. But as the company announced at its Qubits conference today, a superconducting gate-model quantum computer — of the kind IBM and others currently offer — is now also on its roadmap.

D-Wave believes the combination of annealing, gate-model quantum computing and classic machines is what its businesses’ users will need to get the most value from this technology. “Like we did when we initially chose to pursue annealing, we’re looking ahead,” the company notes in today’s announcement. “We’re anticipating what our customers need to drive practical business value, and we know error-corrected gate-model quantum systems with practical application value will be required for another important part of the quantum application market: simulating quantum systems. This is an application that’s particularly useful in fields like materials science and pharmaceutical research.”

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Scientists have demonstrated new behaviour, vital for the creation of quantum computers, that marks a major breakthrough.

For the first time, researchers were able to show in an experiment that a variety of quantum computing pieces, taken together, were more accurate than the sum of their parts.

Individually, quantum computers are built out of a range of different pieces, some of which can sometimes break. But in the new experiment, scientists showed that those pieces stuck together can be less prone to error than any particular part.

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Imagine you sit down and pick up your favourite book. You look at the image on the front cover, run your fingers across the smooth book sleeve, and smell that familiar book smell as you flick through the pages. To you, the book is made up of a range of sensory appearances.

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