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By adding some magnetic flair to an exotic quantum experiment, physicists produced an ultra-stable one-dimensional quantum gas with never-before-seen “scar” states – a feature that could someday be useful for securing quantum information.

As the story goes, the Greek mathematician and tinkerer Archimedes came across an invention while traveling through ancient Egypt that would later bear his name. It was a machine consisting of a screw housed inside a hollow tube that trapped and drew water upon rotation. Now, researchers led by Stanford University physicist Benjamin Lev have developed a quantum version of Archimedes’ screw that, instead of water, hauls fragile collections of gas atoms to higher and higher energy states without collapsing. Their discovery is detailed in a paper published today (January 142021) in Science.

As the story goes, the Greek mathematician and tinkerer Archimedes came across an invention while traveling through ancient Egypt that would later bear his name. It was a machine consisting of a screw housed inside a hollow tube that trapped and drew water upon rotation. Now, researchers led by Stanford University physicist Benjamin Lev have developed a quantum version of Archimedes’ screw that, instead of water, hauls fragile collections of gas atoms to higher and higher energy states without collapsing. Their discovery is detailed in a paper published Jan. 14 in Science.

“My expectation for our system was that the stability of the gas would only shift a little,” said Lev, who is an associate professor of applied physics and of physics in the School of Humanities and Sciences at Stanford. “I did not expect that I would see a dramatic, complete stabilization of it. That was beyond my wildest conception.”

Along the way, the researchers also observed the development of scar states—extremely rare trajectories of particles in an otherwise chaotic quantum system in which the particles repeatedly retrace their steps like tracks overlapping in the woods. Scar states are of particular interest because they may offer a protected refuge for information encoded in a quantum system. The existence of scar states within a quantum system with many interacting particles—known as a quantum many-body system—has only recently been confirmed. The Stanford experiment is the first example of the scar state in a many-body quantum gas and only the second ever real-world sighting of the phenomenon.

Working with theorists in the University of Chicago’s Pritzker School of Molecular Engineering, researchers in the U.S. Department of Energy’s (DOE) Argonne National Laboratory have achieved a scientific control that is a first of its kind. They demonstrated a novel approach that allows real-time control of the interactions between microwave photons and magnons, potentially leading to advances in electronic devices and quantum signal processing.

Microwave photons are elementary particles forming the electromagnetic waves that we use for wireless communications. On the other hand, magnons are the elementary particles forming what scientists call “spin waves”—wave-like disturbances in an ordered array of microscopic aligned spins that can occur in certain magnetic materials.

Microwave photon-magnon interaction has emerged in recent years as a promising platform for both classical and quantum information processing. Yet, this interaction had proved impossible to manipulate in real time, until now.

Metals and insulators are the yin and yang of physics, their respective material properties strictly dictated by their electrons’ mobility — metals should conduct electrons freely, while insulators keep them in place.

So when physicists from Princeton University in the US found a quantum quirk of metals bouncing around inside an insulating compound, they were lost for an explanation.

We’ll need to wait on further studies to find out exactly what’s going on. But one tantalising possibility is that a previously unseen particle is at work, one that represents neutral ground in electron behaviour. They’re calling it a ‘neutral fermion’.

China has hinted before that it would like to send missions to the outer planets. Chinese scientists, working with European collaborators, are now solidifying plans for two distinct Jupiter mission concepts, one of which will likely move forward. Both seek to unravel mysteries behind the planet’s origins and workings using a main spacecraft and one or more smaller vehicles.

The competing missions are called the Jupiter Callisto Orbiter and the Jupiter System Observer, or JCO and JSO, respectively. Both would launch in 2029 and arrive in 2035 after one Venus flyby and two Earth flybys. JCO and JSO would study the size, mass, and composition of Jupiter’s irregular satellites—those captured by Jupiter rather than formed in orbit, and often in distant, elliptical and even retrograde orbits—complementing science conducted by NASA’s Europa Clipper and Lucy missions, as well as the European Space Agency’s JUICE mission.

Both JCO and JSO would possibly include CubeSats with particle and field detector payloads to perform the first multi-point study of Jupiter’s magnetic field.

Basically speaking, metals conduct electricity and insulators don’t. On the molecular level, that comes down to how freely electrons can move through the materials – in metals, electrons are very mobile, while insulators obviously have high resistance that prevents them moving much.

As a side effect of this, metals can exhibit a phenomenon known as quantum oscillations. When exposed to a magnetic field at very low temperatures, electrons can shift into a quantum state that causes the material’s resistivity to oscillate. This doesn’t happen in insulators, however, since their electrons don’t move very well.

The French theoretical physicist Franck Laloë presents a modification of Schrödinger’s famous equation that ensures that all measured states are unique, helping to solve the problem that is neatly encompassed in the Schördinger’s cat paradox.

The paradox of Schrödinger’s cat – the feline that is, famously, both alive and dead until its box is opened – is the most widely known example of a recurrent problem in quantum mechanics: its dynamics seems to predict that macroscopic objects (like cats) can, sometimes, exist simultaneously in more than one completely distinct state. Many physicists have tried to solve this paradox over the years, but no approach has been universally accepted. Now, however, theoretical physicist Franck Laloë from Laboratoire Kastler Brossel (ENS-Université PSL) in Paris has proposed a new interpretation that could explain many features of the paradox. He sets out a model of this possible theory in a new paper in EPJ D.

One approach to solving this problem involves adding a small, random extra term to the Schrödinger equation, which allows the quantum state vector to ‘collapse’, ensuring that – as is observed in the macroscopic universe – the outcome of each measurement is unique. Laloë’s theory combines this interpretation with another from de Broglie and Bohm and relates the origins of the quantum collapse to the universal gravitational field. This approach can be applied equally to all objects, quantum and macroscopic: that is, to cats as much as to atoms.

In a surprising discovery, Princeton physicists have observed an unexpected quantum behavior in an insulator made from a material called tungsten ditelluride. This phenomenon, known as quantum oscillation, is typically observed in metals rather than insulators, and its discovery offers new insights into our understanding of the quantum world. The findings also hint at the existence of an entirely new type of quantum particle.

The discovery challenges a long-held distinction between metals and insulators, because in the established quantum theory of materials, insulators were not thought to be able to experience quantum oscillations.

“If our interpretations are correct, we are seeing a fundamentally new form of quantum matter,” said Sanfeng Wu, assistant professor of physics at Princeton University and the senior author of a recent paper in Nature detailing this new discovery. “We are now imagining a wholly new quantum world hidden in insulators. It’s possible that we simply missed identifying them over the last several decades.”

Eighty-six years since electron crystals were first proposed, physicists have now constructed them, trapping electrons in a repeating pattern. The achievement is reported in the journal Nature.

A crystal is made of a repeating pattern of particles but electrons are difficult to keep in place. So an electron crystal is like trying to organize a large number of electrons that won’t stay still — it’s the herding cats of particle physics.

However, this team had an ingenious solution. They built a Wigner crystal using layers of semi-conductors just one atom thick. They then used two different tungsten materials and created a hexagonal pattern known as a moiré superlattice by placing one material on top of the other.