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New Computer Bridges Classical and Quantum Computing A new type of machine could rival quantum computers in exceeding the power of classical computers, researchers say. Quantum computers rely on the bizarre properties of atoms and the other construction blocks of the universe. The world is a fuzzy place at its very smallest levels — in this realm where quantum physics dominates, things can seemingly exist in two places at once or spin in opposite directions at the same time. The new computers rely on “boson” particles, and resemble quantum computers, which differ from traditional computers in important ways. Normal computers represent data as ones and zeroes, binary digits known as bits that are expressed by flicking switch-like transistors on or off. Quantum computers, however, use quantum bits, or qubits (pronouced “cue-bits”), that can be on and off at the same time, a state known as “superposition.” This allows the machines to carry out two calculations simultaneously. Quantum physics permits such behavior because it allows for particles that can exist in two places at once or spin in opposite directions at the same time. In principle, quantum computers could solve certain problems much faster than can classical computers, because the quantum machines could run through every possible combination at once. A quantum computer with 300 qubits could run more calculations in an instant than there are atoms in the universe. However, keeping qubits in superposition is challenging, and the problem grows more difficult as more qubits are involved. As such, building quantum computers that are more powerful than classical computers has proven very difficult. Now, though, two independent teams of scientists have built a novel kind of device known as a boson-sampling computer. Described as a bridge between classical and quantum computers, these machines also make use of the bizarre nature of quantum physics. Although boson-sampling computers theoretically offer less power than quantum computers are capable of producing, the machines should still, in principle, out-perform classical computers in certain problems. In addition, a boson-sampling computer does not require qubits. As such, “it’s technologically far simpler to create than building a full-scale quantum computer,” said researcher Matthew Broome, a quantum physicist at the University of Queensland in Australia. Boson-sampling computers are actually a specialized kind of quantum computer (which is known more formally as a universal quantum computer).

New Computer Bridges Classical and Quantum Computing

A new type of machine could rival quantum computers in exceeding the power of classical computers, researchers say.

Quantum computers rely on the bizarre properties of atoms and the other construction blocks of the universe. The world is a fuzzy place at its very smallest levels — in this realm where quantum physics dominates, things can seemingly exist in two places at once or spin in opposite directions at the same time.

The new computers rely on “boson” particles, and resemble quantum computers, which differ from traditional computers in important ways. Normal computers represent data as ones and zeroes, binary digits known as bits that are expressed by flicking switch-like transistors on or off. Quantum computers, however, use quantum bits, or qubits (pronouced “cue-bits”), that can be on and off at the same time, a state known as “superposition.”

This allows the machines to carry out two calculations simultaneously. Quantum physics permits such behavior because it allows for particles that can exist in two places at once or spin in opposite directions at the same time.

In principle, quantum computers could solve certain problems much faster than can classical computers, because the quantum machines could run through every possible combination at once. A quantum computer with 300 qubits could run more calculations in an instant than there are atoms in the universe.

However, keeping qubits in superposition is challenging, and the problem grows more difficult as more qubits are involved. As such, building quantum computers that are more powerful than classical computers has proven very difficult.

Now, though, two independent teams of scientists have built a novel kind of device known as a boson-sampling computer. Described as a bridge between classical and quantum computers, these machines also make use of the bizarre nature of quantum physics. Although boson-sampling computers theoretically offer less power than quantum computers are capable of producing, the machines should still, in principle, out-perform classical computers in certain problems.

In addition, a boson-sampling computer does not require qubits. As such, “it’s technologically far simpler to create than building a full-scale quantum computer,” said researcher Matthew Broome, a quantum physicist at the University of Queensland in Australia.

Boson-sampling computers are actually a specialized kind of quantum computer (which is known more formally as a universal quantum computer).

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Consider the world around you. You are holding a book made of paper, the crushed pulp of a tree. Trees are machines able to take a supply of atoms and molecules, break them down and rearrange them into cooperating colonies composed of many trillions of individual parts. They do this using a molecule known as chlorophyll, composed of over a hundred carbon, hydrogen and oxygen atoms twisted into an intricate shape with a few magnesium and nitrogen atoms bolted on. This assembly of particles is able to capture the light that has travelled the 93 million miles from our star, a nuclear furnace the volume of a million earths, and transfer that energy into the heart of cells, where it is used to build molecules from carbon dioxide and water, giving out life-enriching oxygen as it does so. It’s these molecular chains that form the superstructure of trees and all living things, the paper in your book. You can read the book and understand the words because you have eyes that can convert the scattered light from the pages into electrical impulses that are interpreted by your brain, the most complex structure we know of in the Universe. We have discovered that all these things are nothing more than assemblies of atoms, and that the wide variety of atoms are constructed using only three particles: electrons, protons and neutrons. We have also discovered that the protons and neutrons are themselves made up of smaller entities called quarks, and that it is where things stop, as far as we can tell today. Underpinning all of this is quantum theory.

The Quantum Universe: Everything That Can Happen Does Happen

by physicist Brian Cox and University of Manchester professor Jeff Forshaw

(via ikenbot)
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joshbyard: Chinese Researchers Achieve Quantum Teleportation at Macro Scale So by entangling two photons, for instance, physicists have demonstrated the ability to transmit quantum information from one place to another by encoding it in these quantum states—influence one of the pair and a change can be measured in the other without any information actually passing between the two. Researchers have done this before, between photons, between ions, and even between a macroscopic object and a microscopic object. But now Chinese researchers have, for the first time, achieved quantum teleportation between two macroscopic objects across nearly 500 feet using entangled photons… The two bundles of rubidium atoms that served as sender and receiver are more or less analogs for what we hope will someday be our “quantum Internet”—a system of routers like the ones we have now that, instead of beaming information around a vast network of fiber optic wires, will send and receive information through entangled photons. So in a way, this is like a first proof of concept, evidence that the idea works at least in the lab. Now all we have to do is figure out is how to build several of these in series so they can actually pass information from one to the other. To do that, we only have to somehow force these quantum states to exist for longer than the hundred microseconds or so that they last now before degrading. Sounds easy enough. (via Researchers Achieve Quantum Teleportation Between Two Macroscopic Objects For The First Time | Popular Science)

joshbyard:

Chinese Researchers Achieve Quantum Teleportation at Macro Scale

So by entangling two photons, for instance, physicists have demonstrated the ability to transmit quantum information from one place to another by encoding it in these quantum states—influence one of the pair and a change can be measured in the other without any information actually passing between the two. Researchers have done this before, between photons, between ions, and even between a macroscopic object and a microscopic object.

But now Chinese researchers have, for the first time, achieved quantum teleportation between two macroscopic objects across nearly 500 feet using entangled photons…

The two bundles of rubidium atoms that served as sender and receiver are more or less analogs for what we hope will someday be our “quantum Internet”—a system of routers like the ones we have now that, instead of beaming information around a vast network of fiber optic wires, will send and receive information through entangled photons.

So in a way, this is like a first proof of concept, evidence that the idea works at least in the lab. Now all we have to do is figure out is how to build several of these in series so they can actually pass information from one to the other. To do that, we only have to somehow force these quantum states to exist for longer than the hundred microseconds or so that they last now before degrading. Sounds easy enough.

(via Researchers Achieve Quantum Teleportation Between Two Macroscopic Objects For The First Time | Popular Science)

(via ikenbot)

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science-junkie: Stanford researchers demonstrate the first step in a scalable quantum cryptography system that could lead to uncrackable telecommunications. Quantum mechanics offers the potential to create absolutely secure telecommunications networks by harnessing a fundamental phenomenon of quantum particles. Now, a team of Stanford University physicists has demonstrated a crucial first step in creating a quantum telecommunications device that could be built and implemented using existing infrastructure. Quantum cryptography relies on the curious aspect of quantum mechanics by which pairs of electrons can become “entangled.” Electrons have a property called “spin”: Just as a bar magnet can point up or down, so too can the spin of an electron. When electrons become entangled, their spins mirror each other. If the spin of electron A is found to be pointing “up,” then electron B’s spin will also point up. If electron A’s spin measures “down,” so too would electron B’s. An amazing feature of entangled electrons is that this pairing persists no matter the distance between electron A and electron B. (via Physicists and Engineers Take First Step Toward Quantum Cryptography | Lab Manager Magazine®)

science-junkie:

Stanford researchers demonstrate the first step in a scalable quantum cryptography system that could lead to uncrackable telecommunications.

Quantum mechanics offers the potential to create absolutely secure telecommunications networks by harnessing a fundamental phenomenon of quantum particles. Now, a team of Stanford University physicists has demonstrated a crucial first step in creating a quantum telecommunications device that could be built and implemented using existing infrastructure.

Quantum cryptography relies on the curious aspect of quantum mechanics by which pairs of electrons can become “entangled.” Electrons have a property called “spin”: Just as a bar magnet can point up or down, so too can the spin of an electron. When electrons become entangled, their spins mirror each other.

If the spin of electron A is found to be pointing “up,” then electron B’s spin will also point up. If electron A’s spin measures “down,” so too would electron B’s. An amazing feature of entangled electrons is that this pairing persists no matter the distance between electron A and electron B.

(via Physicists and Engineers Take First Step Toward Quantum Cryptography | Lab Manager Magazine®)

(via ikenbot)

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Quantum Entanglement Gets Extra ‘Twist’ Quantum physics is the science of the very small. But physicists are making it bigger, setting records for the size and energies of objects they can get to exhibit quantum effects. Image: Here, a false-color image of a laser beam showing a superposition of entangled photons spinning in opposite directions. Copyright: Robert Fickler/University of Vienna Now physicists at the University of Vienna in Austria have “virtually intertwined” or entangled two particles spinning faster than ever in opposite directions. Entanglement occurs when two particles remain connected so that actions performed on one affect the other, despite the distance between them. In the new study, Anton Fickler and his colleagues entangled two photons that had a high orbital angular momentum, a property that measures the twisting of a wave of light. In quantum physics, particles such as photons can behave as particles and waves. “It’s a stepping stone on the development of new technologies,” said Anton Zeilinger, director of the Institute for Quantum Optics and Quantum Information and a co-author of the study, which is detailed in the Nov. 5 issue of the journal Science. Such entanglement experiments have been carried out for decades. In this case, though, the researchers did something a bit different. They created entangled photons and gave them lots of angular momentum, more than in any experiment before. Usually the energy contained in a photon is very small: its quantum number is low. At higher energies, this changes. Quantum physics and “normal” or classical physics start to look similar when quantum numbers get high; this is called the correspondence principle, and it applies to many areas of physics. To create entangled photons, Fickler and his team sent a laser through a beam splitter, dividing the laser beam into two. Two photons were sent down separate optical fibers and their waves were twisted, and twisted, and twisted some more, ramping up their angular momentum — imagine a wave shaped like a spiral, spinning faster and faster. Eventually, there was enough angular momentum in the photons that their quantum numbers — the units their momentum is measured in — differed by a factor of 600, a higher value than any seen previously. The photons spinning rapidly in opposite directions, meanwhile, were still entangled. They knew this because when particles are entangled, measuring the quantum state (in this case the angular momentum and orientation) of one particle immediately tells you the quantum state of the other, no matter where it is. Since they had the ability to measure both the researchers could confirm entanglement. (Though this transfer of information between the particles is instantaneous, entanglement can’t be used for faster-than-light communication because it is impossible to set the quantum state beforehand, as you would in a message). This shows that entanglement effects can be seen at high energies, meaning closer to the macroscopic world we all know and interact with. “It means we have to take the correspondence principle with a large grain of salt,” Zeilinger said. Just as importantly, the experiment shows that the only barrier to applying certain kinds of quantum effects is technical — there is no physical reason that one shouldn’t be able to see quantum phenomena at high enough energies that they would bleed into the visible world, though that will take some time to do.

Quantum Entanglement Gets Extra ‘Twist’

Quantum physics is the science of the very small. But physicists are making it bigger, setting records for the size and energies of objects they can get to exhibit quantum effects.

Image: Here, a false-color image of a laser beam showing a superposition of entangled photons spinning in opposite directions. Copyright: Robert Fickler/University of Vienna

Now physicists at the University of Vienna in Austria have “virtually intertwined” or entangled two particles spinning faster than ever in opposite directions. Entanglement occurs when two particles remain connected so that actions performed on one affect the other, despite the distance between them.

In the new study, Anton Fickler and his colleagues entangled two photons that had a high orbital angular momentum, a property that measures the twisting of a wave of light. In quantum physics, particles such as photons can behave as particles and waves.

“It’s a stepping stone on the development of new technologies,” said Anton Zeilinger, director of the Institute for Quantum Optics and Quantum Information and a co-author of the study, which is detailed in the Nov. 5 issue of the journal Science.

Such entanglement experiments have been carried out for decades. In this case, though, the researchers did something a bit different. They created entangled photons and gave them lots of angular momentum, more than in any experiment before.

Usually the energy contained in a photon is very small: its quantum number is low. At higher energies, this changes. Quantum physics and “normal” or classical physics start to look similar when quantum numbers get high; this is called the correspondence principle, and it applies to many areas of physics.

To create entangled photons, Fickler and his team sent a laser through a beam splitter, dividing the laser beam into two. Two photons were sent down separate optical fibers and their waves were twisted, and twisted, and twisted some more, ramping up their angular momentum — imagine a wave shaped like a spiral, spinning faster and faster.

Eventually, there was enough angular momentum in the photons that their quantum numbers — the units their momentum is measured in — differed by a factor of 600, a higher value than any seen previously. The photons spinning rapidly in opposite directions, meanwhile, were still entangled.

They knew this because when particles are entangled, measuring the quantum state (in this case the angular momentum and orientation) of one particle immediately tells you the quantum state of the other, no matter where it is. Since they had the ability to measure both the researchers could confirm entanglement.

(Though this transfer of information between the particles is instantaneous, entanglement can’t be used for faster-than-light communication because it is impossible to set the quantum state beforehand, as you would in a message).

This shows that entanglement effects can be seen at high energies, meaning closer to the macroscopic world we all know and interact with. “It means we have to take the correspondence principle with a large grain of salt,” Zeilinger said.

Just as importantly, the experiment shows that the only barrier to applying certain kinds of quantum effects is technical — there is no physical reason that one shouldn’t be able to see quantum phenomena at high enough energies that they would bleed into the visible world, though that will take some time to do.

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ikenbot: Quantum Entanglement With the Past Side Note: Remember when I was going off on my ramblings about using quantum entanglement to somehow communicate with the past? Well this may not be as imaginative and hopeful about communicating with the past in our dimension as opposed to that of the quantum world but here’s an awesome article from livescience getting into this recent experiment physicists did back in April of this year, 2012. Basically they showed that in theory, it is possible to send a particle from one computer into another across vast distances long after one particle has ceased to exist, showing that quantum entanglement works both ways. A particle in the future can alter one in the past. This kind of experiment and discovery is paramount to the future of how we use our communications technology. Entanglement is a weird state where two particles remain intimately connected, even when separated over vast distances, like two die that must always show the same numbers when rolled. For the first time, scientists have entangled particles after they’ve been measured and may no longer even exist. If that sounds baffling, even the researchers agree it’s a bit “radical,” in a paper reporting the experiment published online April 22 in the journal Nature Physics. “Whether these two particles are entangled or separable has been decided after they have been measured,” write the researchers, led by Xiao-song Ma of the Institute for Quantum Optics and Quantum Information at the University of Vienna. Essentially, the scientists showed that future actions may influence past events, at least when it comes to the messy, mind-bending world of quantum physics. In the quantum world, things behave differently than they do in the real, macroscopic worldwe can see and touch around us. In fact, when quantum entanglement was first predicted by the theory of quantum mechanics, Albert Einstein expressed his distaste for the idea, calling it “spooky action at a distance.” The researchers, taking entanglement a step further than ever before, started with two sets of light particles, called photons. The basic setup goes like this: Both pairs of photons are entangled, so that the two particles in the first set are entangled with each other, and the two particles in the second set are entangled with each other. Then, one photon from each pair is sent to a person named Victor. Of the two particles that are left behind, one goes to Bob, and the other goes to Alice. But now, Victor has control over Alice and Bob’s particles. If he decides to entangle the two photons he has, then Alice and Bob’s photons, each entangled with one of Victor’s, also become entangled with each other. And Victor can choose to take this action at any time, even after Bob and Alice may have measured, changed or destroyed their photons. “The fantastic new thing is that this decision to entangle two photons can be done at a much later time,” said research co-author Anton Zeilinger, also of the University of Vienna. “They may no longer exist.” Such an experiment had first been predicted by physicist Asher Peres in 2000, but had not been realized until now. “The way you entangle them is to send them onto a half-silvered mirror,” Zeilinger told LiveScience. “It reflects half of the photons, and transmits half. If you send two photons, one to the right and one to the left, then each of the two photons have forgotten where they come from. They lose their identities and become entangled.” Zeilinger said the technique could one day be used to communicate between superfast quantum computers, which rely on entanglement to store information. Such a machine has not yet been created, but experiments like this are a step toward that goal, the researchers say. “The idea is to create two particle pairs, send one to one computer, the other to another,” Zeilinger said.”Then if these two photons are entangled, the computers could use them to exchange information.”

ikenbot:

Quantum Entanglement With the Past

Side Note: Remember when I was going off on my ramblings about using quantum entanglement to somehow communicate with the past? Well this may not be as imaginative and hopeful about communicating with the past in our dimension as opposed to that of the quantum world but here’s an awesome article from livescience getting into this recent experiment physicists did back in April of this year, 2012. Basically they showed that in theory, it is possible to send a particle from one computer into another across vast distances long after one particle has ceased to exist, showing that quantum entanglement works both ways. A particle in the future can alter one in the past. This kind of experiment and discovery is paramount to the future of how we use our communications technology.

Entanglement is a weird state where two particles remain intimately connected, even when separated over vast distances, like two die that must always show the same numbers when rolled. For the first time, scientists have entangled particles after they’ve been measured and may no longer even exist.

If that sounds baffling, even the researchers agree it’s a bit “radical,” in a paper reporting the experiment published online April 22 in the journal Nature Physics.

“Whether these two particles are entangled or separable has been decided after they have been measured,” write the researchers, led by Xiao-song Ma of the Institute for Quantum Optics and Quantum Information at the University of Vienna.

Essentially, the scientists showed that future actions may influence past events, at least when it comes to the messy, mind-bending world of quantum physics.

In the quantum world, things behave differently than they do in the real, macroscopic worldwe can see and touch around us. In fact, when quantum entanglement was first predicted by the theory of quantum mechanics, Albert Einstein expressed his distaste for the idea, calling it “spooky action at a distance.”

The researchers, taking entanglement a step further than ever before, started with two sets of light particles, called photons.

The basic setup goes like this:

Both pairs of photons are entangled, so that the two particles in the first set are entangled with each other, and the two particles in the second set are entangled with each other. Then, one photon from each pair is sent to a person named Victor. Of the two particles that are left behind, one goes to Bob, and the other goes to Alice.

But now, Victor has control over Alice and Bob’s particles. If he decides to entangle the two photons he has, then Alice and Bob’s photons, each entangled with one of Victor’s, also become entangled with each other. And Victor can choose to take this action at any time, even after Bob and Alice may have measured, changed or destroyed their photons.

“The fantastic new thing is that this decision to entangle two photons can be done at a much later time,” said research co-author Anton Zeilinger, also of the University of Vienna. “They may no longer exist.”

Such an experiment had first been predicted by physicist Asher Peres in 2000, but had not been realized until now.

“The way you entangle them is to send them onto a half-silvered mirror,” Zeilinger told LiveScience. “It reflects half of the photons, and transmits half. If you send two photons, one to the right and one to the left, then each of the two photons have forgotten where they come from. They lose their identities and become entangled.”

Zeilinger said the technique could one day be used to communicate between superfast quantum computers, which rely on entanglement to store information. Such a machine has not yet been created, but experiments like this are a step toward that goal, the researchers say.

“The idea is to create two particle pairs, send one to one computer, the other to another,” Zeilinger said.”Then if these two photons are entangled, the computers could use them to exchange information.”

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Is light made of waves, or particles? This fundamental question has dogged scientists for decades, because light seems to be both. However, until now, experiments have revealed light to act either like a particle, or a wave, but never the two at once. Now, for the first time, a new type of experiment has shown light behaving like both a particle and a wave simultaneously, providing a new dimension to the quandary that could help reveal the true nature of light, and of the whole quantum world. The debate goes back at least as far as Isaac Newton, who advocated that light was made of particles, and James Clerk Maxwell, whose successful theory of electromagnetism, unifying the forces of electricity and magnetism into one, relied on a model of light as a wave. Then in 1905, Albert Einstein explained a phenomenon called the photoelectric effect using the idea that light was made of particles called photons (this discovery won him the Nobel Prize in physics). Ultimately, there’s good reason to think that light is both a particle and a wave. In fact, the same seems to be true of all subatomic particles, including electrons and quarks and even the recently discovered Higgs boson-like particle. The idea is called wave-particle duality, and is a fundamental tenet of the theory of quantum mechanics. Depending on which type of experiment is used, light, or any other type of particle, will behave like a particle or like a wave. So far, both aspects of light’s nature haven’t been observed at the same time. Now, for the first time, researchers have devised a new type of measurement apparatus that can detect both particle and wave-like behavior at the same time. The device relies on a strange quantum effect called quantum nonlocality, a counter-intuitive notion that boils down to the idea that the same particle can exist in two locations at once. “The measurement apparatus detected strong nonlocality, which certified that the photon behaved simultaneously as a wave and a particle in our experiment,” physicist Alberto Peruzzo of England’s University of Bristol said in a statement. “This represents a strong refutation of models in which the photon is either a wave or a particle.” Peruzzo is lead author of a paper describing the experiment published in the Nov. 2 issue of the journal Science.

Is light made of waves, or particles?

This fundamental question has dogged scientists for decades, because light seems to be both. However, until now, experiments have revealed light to act either like a particle, or a wave, but never the two at once.

Now, for the first time, a new type of experiment has shown light behaving like both a particle and a wave simultaneously, providing a new dimension to the quandary that could help reveal the true nature of light, and of the whole quantum world.

The debate goes back at least as far as Isaac Newton, who advocated that light was made of particles, and James Clerk Maxwell, whose successful theory of electromagnetism, unifying the forces of electricity and magnetism into one, relied on a model of light as a wave. Then in 1905, Albert Einstein explained a phenomenon called the photoelectric effect using the idea that light was made of particles called photons (this discovery won him the Nobel Prize in physics).

Ultimately, there’s good reason to think that light is both a particle and a wave. In fact, the same seems to be true of all subatomic particles, including electrons and quarks and even the recently discovered Higgs boson-like particle. The idea is called wave-particle duality, and is a fundamental tenet of the theory of quantum mechanics.

Depending on which type of experiment is used, light, or any other type of particle, will behave like a particle or like a wave. So far, both aspects of light’s nature haven’t been observed at the same time.

Now, for the first time, researchers have devised a new type of measurement apparatus that can detect both particle and wave-like behavior at the same time. The device relies on a strange quantum effect called quantum nonlocality, a counter-intuitive notion that boils down to the idea that the same particle can exist in two locations at once.

“The measurement apparatus detected strong nonlocality, which certified that the photon behaved simultaneously as a wave and a particle in our experiment,” physicist Alberto Peruzzo of England’s University of Bristol said in a statement. “This represents a strong refutation of models in which the photon is either a wave or a particle.”

Peruzzo is lead author of a paper describing the experiment published in the Nov. 2 issue of the journal Science.

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sklogw: The scanning single-electron transistor (SET) microscope head, seen through a viewport into the microscope vacuum chamber. The image shows the SET tip above a graphene sample. (Courtesy: Yacoby lab) Graphene offers up another quantum surprise Physicists in the US and Germany have discovered yet another surprising property of the “wonder material” graphene – it displays a fractional quantum Hall effect (FQHE) that is different to that seen in conventional materials. The finding will be important for studying correlations among relativistic particles and may even help in the development of quantum computers in the future. The FQHE occurs when charge carriers like electrons are confined to a 2D plane, as in graphene, and are subjected to a perpendicular magnetic field in the Z-direction. If a current flows in the X-direction, a voltage – the Hall voltage – occurs in the Y-direction. At very low temperatures, this voltage is quantized in distinct steps or Hall states. Read More →

sklogw:

The scanning single-electron transistor (SET) microscope head, seen through a viewport into the microscope vacuum chamber. The image shows the SET tip above a graphene sample. (Courtesy: Yacoby lab)

Graphene offers up another quantum surprise

Physicists in the US and Germany have discovered yet another surprising property of the “wonder material” graphene – it displays a fractional quantum Hall effect (FQHE) that is different to that seen in conventional materials. The finding will be important for studying correlations among relativistic particles and may even help in the development of quantum computers in the future.

The FQHE occurs when charge carriers like electrons are confined to a 2D plane, as in graphene, and are subjected to a perpendicular magnetic field in the Z-direction. If a current flows in the X-direction, a voltage – the Hall voltage – occurs in the Y-direction. At very low temperatures, this voltage is quantized in distinct steps or Hall states.

Read More →

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occupyallstreets: An Unhackable Baby Quantum Internet Was Born Yesterday Years from now it may be said that the quantum Internet was born today. When the baby system matures, it will be able to process unfathomable amounts of data and never be hacked. The system only has two nodes, but the Internet’s birth started in a similar way back in the late 1960s. The developers — physicists led by Stephan Ritter and Gerhard Rempe of the Max Planck Institute of Quantum Optics in Germany — published their work in this week’s issue of the journal “Nature.” The quantum network was built using two atoms of rubidium that exchange photons, or particles of light. Each atom is placed inside a cavity with highly reflecting mirrors on each side, and at a very short distance from each other. The two so-called optical cavities are connected by an optical fiber. Scientists aim a laser at the first atom, causing the atom to emit a single photon. That photon zooms along the optical fiber to other optical cavity containing the other atom. That’s where the mirrors come in — ordinarily it’s difficult to get an atom and a photon to interact reliably. But by bouncing the photon off the mirrors in the cavity thousands of times, it’s more likley to hit the atom and be absorbed by it. That absorbtion is what transmits the information about the first atom’s quantum state to the second atom. Besides sending information, the two atoms were entangled, meaning that the atoms were linked. If the first node is in quantum state A, for example, the second node will also be in quantum state A. In this experiment, the atoms were entangled for 100 microseconds — a long time in quantum physics. This entanglement is what makes hacking into a quantum computer and eavesdropping on impossible. As as soon as a hacker tapped into a quantum network, the states of the atoms wouldn’t match up — a big red flag that something was awary. It’s a long way yet to a truly large-scale quantum network, but this is a first step. Source

occupyallstreets:

An Unhackable Baby Quantum Internet Was Born Yesterday

Years from now it may be said that the quantum Internet was born today. When the baby system matures, it will be able to process unfathomable amounts of data and never be hacked.

The system only has two nodes, but the Internet’s birth started in a similar way back in the late 1960s. The developers — physicists led by Stephan Ritter and Gerhard Rempe of the Max Planck Institute of Quantum Optics in Germany — published their work in this week’s issue of the journal “Nature.”

The quantum network was built using two atoms of rubidium that exchange photons, or particles of light. Each atom is placed inside a cavity with highly reflecting mirrors on each side, and at a very short distance from each other. The two so-called optical cavities are connected by an optical fiber.

Scientists aim a laser at the first atom, causing the atom to emit a single photon. That photon zooms along the optical fiber to other optical cavity containing the other atom. That’s where the mirrors come in — ordinarily it’s difficult to get an atom and a photon to interact reliably. But by bouncing the photon off the mirrors in the cavity thousands of times, it’s more likley to hit the atom and be absorbed by it. That absorbtion is what transmits the information about the first atom’s quantum state to the second atom.

Besides sending information, the two atoms were entangled, meaning that the atoms were linked. If the first node is in quantum state A, for example, the second node will also be in quantum state A. In this experiment, the atoms were entangled for 100 microseconds — a long time in quantum physics.

This entanglement is what makes hacking into a quantum computer and eavesdropping on impossible. As as soon as a hacker tapped into a quantum network, the states of the atoms wouldn’t match up — a big red flag that something was awary.

It’s a long way yet to a truly large-scale quantum network, but this is a first step.

Source

(via anarcho-queer)

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thequantumlife: Replica of Trojan asteroids fits in single atom In a paper published in the journal Physical Review Letters, the Rice University team showed they could cause an electron in an atom to orbit the nucleus in precisely the same way that Jupiter’s Trojan asteroids orbit the sun. The findings uphold a prediction made in 1920 by famed Danish physicist Niels Bohr about the relationship between the then-new science of quantum mechanics and Isaac Newton’s tried-and-true laws of motion. Using atoms to model the solar system. Badass.

thequantumlife:

Replica of Trojan asteroids fits in single atom

In a paper published in the journal Physical Review Letters, the Rice University team showed they could cause an electron in an atom to orbit the nucleus in precisely the same way that Jupiter’s Trojan asteroids orbit the sun.

The findings uphold a prediction made in 1920 by famed Danish physicist Niels Bohr about the relationship between the then-new science of quantum mechanics and Isaac Newton’s tried-and-true laws of motion.

Using atoms to model the solar system.

Badass.

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Quantum computing device hints at powerful future | BBC →

It uses the strange “quantum states” of matter to perform calculations in a way that, if scaled up, could vastly outperform conventional computers.

The 6mm-by-6mm chip holds nine quantum devices, among them four “quantum bits” that do the calculations.

The team said further scaling up to 10 qubits should be possible this year.

Rather than the ones and zeroes of digital computing, quantum computers deal in what are known as superpositions - states of matter that can be thought of as both one and zero at once.

[Read More]

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Entangled diamonds blur quantum-classical divide | NewScientist →

Two diamonds as wide as earring studs have been made to share the spooky quantum state known as entanglement. The feat, performed at room temperature, blurs the divide between the classical and quantum worlds, since typically the quantum link has been made with much smaller particles at low temperatures.

Entanglement is one of the weird aspects of quantum mechanics, where the fates of two or more particles are intertwined – even when they are physically far apart. Electrons, for example, have been entangled, so that changing the quantum spin of one affects the spins of its entangled partners.

Macroscopic objects, on the other hand, are supposed to mind their own business – flipping one coin shouldn’t force a neighbouring flipped coin to come up heads.

But that’s just what happened with two 3-millimetre-wide diamonds on a lab bench at the University of Oxford. Physicists there led by Ka Chung Lee andMichael Sprague were able to show that the diamonds shared one vibrational state between them.

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Is the Higgs boson real? Imaged Above: A collision event recorded by Atlas at the LHC. Bloggers report rumours that evidence of the Higgs boson will be announced next Tuesday. Photograph: Cern/PA A couple of blogs, including viXra and Peter Woit’s Not Even Wrong, have now posted rumours that the Atlas and CMS teams see Higgs-like signals around 125GeV, though they say the evidence is not robust enough to claim an official discovery.

Is the Higgs boson real?

Imaged Above: A collision event recorded by Atlas at the LHC. Bloggers report rumours that evidence of the Higgs boson will be announced next Tuesday. Photograph: Cern/PA

A couple of blogs, including viXra and Peter Woit’s Not Even Wrong, have now posted rumours that the Atlas and CMS teams see Higgs-like signals around 125GeV, though they say the evidence is not robust enough to claim an official discovery.

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More Evidence Found for Quantum Physics in Photosynthesis Physicists have found the strongest evidence yet of quantum effects fueling photosynthesis. Multiple experiments in recent years have suggested as much, but it’s been hard to be sure. Quantum effects were clearly present in the light-harvesting antenna proteins of plant cells, but their precise role in processing incoming photons remained unclear. In an experiment published Dec. 6 in Proceedings of the National Academy of Sciences, a connection between coherence — far-flung molecules interacting as one, separated by space but not time — and energy flow is established. “There was a smoking gun before,” said study co-author Greg Engel of the University of Chicago. “Here we can watch the relationship between coherence and energy transfer. This is the first paper showing that coherence affects the probability of transport. It really does change the chemical dynamics.”

More Evidence Found for Quantum Physics in Photosynthesis

Physicists have found the strongest evidence yet of quantum effects fueling photosynthesis.

Multiple experiments in recent years have suggested as much, but it’s been hard to be sure. Quantum effects were clearly present in the light-harvesting antenna proteins of plant cells, but their precise role in processing incoming photons remained unclear.

In an experiment published Dec. 6 in Proceedings of the National Academy of Sciences, a connection between coherence — far-flung molecules interacting as one, separated by space but not time — and energy flow is established.

“There was a smoking gun before,” said study co-author Greg Engel of the University of Chicago. “Here we can watch the relationship between coherence and energy transfer. This is the first paper showing that coherence affects the probability of transport. It really does change the chemical dynamics.”

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‘Scientists at Chalmers have succeeded in creating light from vacuum - observing an effect first predicted over 40 years ago. In an innovative experiment, the scientists have managed to capture some of the photons that are constantly appearing and disappearing in the vacuum.’ Our concept of a vacuum is something that has no matter which, in most cases, is a good enough definition. However, modern physics states that this vacuum is filled with virtual particles which come in and out of existence for such short periods of time that they cannot be detected (and if they are detected, they are no longer virtual particles). Most of the time, virtual particles are produced in pairs with a virtual antiparticle so that they annihilate each other fairly quickly. The dynamic Casimir effect (not the static one which has been investigated in more depth) occurs when a mirror is brought to speeds near that of light. If a virtual photon collides with this fast-moving mirror, it can often be separated from its virtual antiparticle. This leaves us with light!  Rather than having a mirror travelling at speeds near that of light (which is impossible for our current standards) the scientists used a rapidly changing magnetic field to cause a superconductor to vibrate at a fourth of the speed of light which works to the same effect.

‘Scientists at Chalmers have succeeded in creating light from vacuum - observing an effect first predicted over 40 years ago. In an innovative experiment, the scientists have managed to capture some of the photons that are constantly appearing and disappearing in the vacuum.’

Our concept of a vacuum is something that has no matter which, in most cases, is a good enough definition. However, modern physics states that this vacuum is filled with virtual particles which come in and out of existence for such short periods of time that they cannot be detected (and if they are detected, they are no longer virtual particles). Most of the time, virtual particles are produced in pairs with a virtual antiparticle so that they annihilate each other fairly quickly.

The dynamic Casimir effect (not the static one which has been investigated in more depth) occurs when a mirror is brought to speeds near that of light. If a virtual photon collides with this fast-moving mirror, it can often be separated from its virtual antiparticle. This leaves us with light! 

Rather than having a mirror travelling at speeds near that of light (which is impossible for our current standards) the scientists used a rapidly changing magnetic field to cause a superconductor to vibrate at a fourth of the speed of light which works to the same effect.

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