Often, in high school and undergraduate physics classes, atoms are intuitively presented according to the outdated planetary model: a swarm of electrons orbiting the nucleus, like planets around the sun. The progress in the understanding of the subatomic world in the early 20th century, and the advent of quantum mechanics, made the description of atoms much more complex. There is a boundary between the world of our everyday perception and the subatomic, distinctly quantum world—where Newtonian mechanics breaks down and the laws of quantum reality rule undisturbed. This boundary, however, is hard to place. For systems of sufficiently large sizes, their quantum behaviour can be better and better approximated by Newtonian mechanics, which rather accurately describes forces and motion up to the planetary scale and beyond. By studying large enough atoms and their cloud of electrons, Rice University researchers managed to simulate the orbits of Jupiter’s Trojan asteroids, just there, at the boundary between the baffling quantum world (where subatomic particles such as electrons are more accurately described by fuzzy, delocalised wave functions) and the reality of planetary orbits. “Rice lab mimics Jupiter’s Trojan asteroids inside a single atom”, Rice University press release Wyker et al., “Creating and Transporting Trojan Wave Packets”, Physical Review Letters (2012)
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Often, in high school and undergraduate physics classes, atoms are intuitively presented according to the outdated planetary model: a swarm of electrons orbiting the nucleus, like planets around the sun. The progress in the understanding of the subatomic world in the early 20th century, and the advent of quantum mechanics, made the description of atoms much more complex. There is a boundary between the world of our everyday perception and the subatomic, distinctly quantum world—where Newtonian mechanics breaks down and the laws of quantum reality rule undisturbed. This boundary, however, is hard to place. For systems of sufficiently large sizes, their quantum behaviour can be better and better approximated by Newtonian mechanics, which rather accurately describes forces and motion up to the planetary scale and beyond. By studying large enough atoms and their cloud of electrons, Rice University researchers managed to simulate the orbits of Jupiter’s Trojan asteroids, just there, at the boundary between the baffling quantum world (where subatomic particles such as electrons are more accurately described by fuzzy, delocalised wave functions) and the reality of planetary orbits.

“Rice lab mimics Jupiter’s Trojan asteroids inside a single atom”, Rice University press release

Wyker et al., “Creating and Transporting Trojan Wave Packets”, Physical Review Letters (2012)

Walking through walls takes some skill. It is in fact not quite humanly possible, unless you are a soldier specially trained in paranormal warfare—and, even in that case, as eloquently portrayed in the movie The Men Who Stare at Goats, running into a wall may not end up well. (Bursting through the wall, as Wile E. Coyote or the Kool-Aid Man would do, counts as cheating.) However, as quantum mechanics teaches us, nothing is impossible: only highly unlikely. Quantum particles, small, almost intangible, can in fact move through a barrier they wouldn’t ordinarily be able to climb over. This peculiar and well-established quantum effect, known as quantum tunnelling, may however not only be displayed by tiny quantum particles.In macroscopic objects, quantum effects are usually “washed out” due to the interactions of their intrinsically quantum components with each other and the environment. It is that one of the reasons we can’t walk through a wall, as one of the electrons that take part in the composition of our body may be able to do. Researchers at Aalto University in Finland, though, are looking for signs of quantum tunnelling in a system consisting of a suspended single-atom-thick carbon membrane. When cooled down to temperatures very close to absolute zero, the membrane can only bend in two ways, dissimilar enough that the difference between the energies associated with each position effectively acts as a barrier—a sort of quantum wall. Then, in order to bend more, the membrane could only take advantage of the tunnelling effect usually reserved for smaller, simpler systems. While for the moment this experiment only remains a theoretical proposal, just last year a microscopic man-made object was put in a quantum superposition. “Walk-Through-Wall Effect Might Be Possible With Humanmade Object, Physicists Predict”, ScienceNOW Sillanpää et al., “Macroscopic quantum tunneling in nanoelectromechanical systems”, Physical Review B 84 (2011)
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Walking through walls takes some skill. It is in fact not quite humanly possible, unless you are a soldier specially trained in paranormal warfare—and, even in that case, as eloquently portrayed in the movie The Men Who Stare at Goats, running into a wall may not end up well. (Bursting through the wall, as Wile E. Coyote or the Kool-Aid Man would do, counts as cheating.) However, as quantum mechanics teaches us, nothing is impossible: only highly unlikely. Quantum particles, small, almost intangible, can in fact move through a barrier they wouldn’t ordinarily be able to climb over. This peculiar and well-established quantum effect, known as quantum tunnelling, may however not only be displayed by tiny quantum particles.
In macroscopic objects, quantum effects are usually “washed out” due to the interactions of their intrinsically quantum components with each other and the environment. It is that one of the reasons we can’t walk through a wall, as one of the electrons that take part in the composition of our body may be able to do. Researchers at Aalto University in Finland, though, are looking for signs of quantum tunnelling in a system consisting of a suspended single-atom-thick carbon membrane. When cooled down to temperatures very close to absolute zero, the membrane can only bend in two ways, dissimilar enough that the difference between the energies associated with each position effectively acts as a barrier—a sort of quantum wall. Then, in order to bend more, the membrane could only take advantage of the tunnelling effect usually reserved for smaller, simpler systems. While for the moment this experiment only remains a theoretical proposal, just last year a microscopic man-made object was put in a quantum superposition.

“Walk-Through-Wall Effect Might Be Possible With Humanmade Object, Physicists Predict”, ScienceNOW

Sillanpää et al., “Macroscopic quantum tunneling in nanoelectromechanical systems”, Physical Review B 84 (2011)

A photon, the basic unit of light, can produce an excited electron and hole (that is, a pseudo-particle representing the absence of an electron). Electron and hole can then quickly annihilate, emitting a new photon of the same frequency as the original one. Researchers at the Laboratory for Physical Sciences and the University of Maryland accomplished the same quantum effect, but replacing light with vibrations. In the figure above, white arrows depict vibrations of atoms arranged in a crystal lattice, while colors show the quantum state of an electron belonging to an atom placed in the middle of the lattice. Vibrations and the electron state couple together to form what has been dubbed a “phoniton”, which may in the future act as a link in quantum computing devices. “Vibrations and Electrons Team Up in New Quantum Entity”, APS Physics
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A photon, the basic unit of light, can produce an excited electron and hole (that is, a pseudo-particle representing the absence of an electron). Electron and hole can then quickly annihilate, emitting a new photon of the same frequency as the original one. Researchers at the Laboratory for Physical Sciences and the University of Maryland accomplished the same quantum effect, but replacing light with vibrations. In the figure above, white arrows depict vibrations of atoms arranged in a crystal lattice, while colors show the quantum state of an electron belonging to an atom placed in the middle of the lattice. Vibrations and the electron state couple together to form what has been dubbed a “phoniton”, which may in the future act as a link in quantum computing devices.

“Vibrations and Electrons Team Up in New Quantum Entity”, APS Physics