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Category: quantum physics – Page 733

(Phys.org)—For the first time, physicists have demonstrated that hyperentangled photons can be transmitted in free space, which they showed by sending many thousands of these photons between the rooftops of two buildings in Vienna. Hyperentanglement means that the photons are simultaneously entangled in at least two different properties—in this experiment, the researchers combined two two-dimensionally entangled properties to achieve four-dimensional hyperentanglement.

By showing that hyperentanglement transmission is feasible in the real world and not only in the lab, the physicists expect that the demonstration could one day be scaled up to establish a highly secure quantum Internet that uses satellites to quickly and securely transmit across the globe.

The physicists, led by Rupert Ursin at the Institute for Quantum Optics and Quantum Information (IQOQI) at the Austrian Academy of Sciences in Vienna, have published a paper on the distribution of hyperentanglement via atmospheric free-space links in a recent issue of Nature Communications.

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That’s because so much of the technology is still in its infancy. Physicists still can’t control and manipulate quantum signals very well. Pan’s quantum satellite may have been able to send and receive signals, but it can’t really store quantum information—the best quantum memories can only preserve information for less than an hour. And researchers still don’t know what material makes the best quantum memory.

A Chinese physicist hopes that quantum communications will span multiple countries by 2030. So… what’s it for?

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A small tweak on a definitive experiment in quantum physics has allowed scientists to observe for the first time exactly how molecules behave as waves.

The results are solidly in line with what theory covering complex quantum phenomena predicts, so don’t expect any radical new physics here. But as with most quantum experiments, the implications of seeing such a counter-intuitive theory in action makes our head spin.

Researchers from the Universities of Vienna and Tel Aviv have recently collaborated on turning a two-decade old idea into a reality, replacing tiny particles with large organic molecules in a variation on Clinton Davisson and Lester Germer’s classic 1927 double slit experiment in order to test the limits of a law governing their behaviour.

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A new experiment at the Large Hadron Collider has confirmed one of the oldest predictions in quantum physics.

Physicists from the ATLAS experiment at CERN have revealed they’ve observed direct evidence of a process known as light-by-light scattering, in which light interacts with itself at high energy.

This phenomenon is critical to current understanding of quantum electrodynamics, and scientists have sought this ‘milestone result’ for decades – but now, for the first time, researchers say have evidence of photons that interact and change directions.

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The inventor of the EmDrive, a controversial space propulsion device that may speed up space travel, has revealed details of how it could be used to create a reusable launch vehicle to take rockets and satellites into space, as well as for personal flight.

Roger Shawyer has published a presentation about the third generation of the EmDrive, which he says is an improvement on the second generation. The original concept for the EmDrive, developed in 2008, was designed to enable in-orbit propulsion. The second generation, which has been in development since 2010, uses a superconducting cavity.

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BEIJING (Reuters) — China has sent an “unbreakable” code from a satellite to the Earth, marking the first time space-to-ground quantum key distribution technology has been realized, state media said on Thursday.

China launched the world’s first quantum satellite last August, to help establish “hack proof” communications, a development the Pentagon has called a “notable advance”.

The official Xinhua news agency said the latest experiment was published in the journal Nature on Thursday, where reviewers called it a “milestone”.

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An international team, led by a scientist from the University of Sussex, have today unveiled the first practical blueprint for how to build a quantum computer, the most powerful computer on Earth.

This huge leap forward towards creating a universal quantum computer is published today (1 February 2017) in the influential journal Science Advances. It has long been known that such a computer would revolutionise industry, science and commerce on a similar scale as the invention of ordinary computers. But this new work features the actual industrial blueprint to construct such a large-scale machine, more powerful in solving certain problems than any computer ever constructed before.

Once built, the computer’s capabilities mean it would have the potential to answer many questions in science; create new, lifesaving medicines; solve the most mind-boggling scientific problems; unravel the yet unknown mysteries of the furthest reaches of deepest space; and solve some problems that an ordinary computer would take billions of years to compute.

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The robot is building a tesseract. He motions at a glowing cube floating before him, and an identical cube emerges. He drags it to the left, but the two cubes stay connected, strung together by glowing lines radiating from their corners. The robot lowers its hands, and the cubes coalesce into a single shape—with 24 square faces, 16 vertices, and eight connected cubes existing in four dimensions. A tesseract.

This isn’t a video game. It’s a classroom. And the robot is Brian Greene, a physicist at Columbia University and bestselling author of several popular science books. His robot avatar teaches a semicircle of student robots, each wearing a shoulder badge of their home country’s flag. The classroom is outer space: Greene and the arc of student-robots orbit Earth. After he shows the students the tesseract, Greene directs his class to try making four, five, even six dimension objects. This is a virtual reality course on string theory; the lesson happens to be about objects with more than three dimensions.

In real life, Greene is wearing a dark blue shirt, black jeans, and boots, and his normal, non-hovering chair is sitting in a concrete-floored VR business called Step Into the Light planted firmly on Earth’s surface—Manhattan’s Lower East Side. An HTC Vive headset covers his face, and he gestures effusively—he’s a New York native—with the controllers.

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