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Scientists create single-atom bit, smallest memory in the world

Scientists create single-atom bit, smallest memory in the world | Quantum Physics | Scoop.it

Karlsruhe Institute of Technology (KIT) researchers have taken a big step towards miniaturizing magnetic data memory down to a single-atom bit: they fixed a single atom on a surface so the magnetic spin remained stable for ten minutes.

 

“A single atom fixed to a substrate is [typically] so sensitive that its magnetic orientation is stable only for less than a microsecond,” said Wulf Wulfhekel of KIT.

 

A compound of several million atoms has been needed to stabilize a magnetic bit longer than that. That’s because the magnetic moments of these atoms are normally easily destabilized by interactions with electrons, nuclear spins, and lattice vibrations of the substrate.

 

The finding opens up the possibility of designing more compact computer memories and could also be the basis for quantum computers, Wulfhekel said.

 

In their experiment, the researchers placed a single holmium atom onto a platinum substrate. At temperatures close to absolute zero (about 1 degree Kelvin), the atom was nearly vibration-free. They measured the magnetic orientation of the atom using the fine tip of a scanning tunneling microscope. The magnetic spin changed after about 10 minutes — “about a billion times longer than that of comparable atomic systems,” Wulfhekel said.

 

Reference: 

Toshio Miyamachi et al., Stabilizing the magnetic moment of single holmium atoms by symmetry, Nature, 2013, DOI: 10.1038/nature12759


Via Dr. Stefan Gruenwald
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Decoherence and the Quantum to Classical Transition - The Fun Is Real

Decoherence and the Quantum to Classical Transition - The Fun Is Real | Quantum Physics | Scoop.it
Conflating Science with Pseudoscience The spreading of misinformation and misconceptions about the quantum world can be lumped into two different categories.
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I take on some of the myths and misconceptions about the relationship between quantum and classical phenomena and how quantum transitions to classical

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The Wholeness of Quantum Reality: An Interview with Physicist Basil Hiley | Critical Opalescence, Scientific American Blog Network

The Wholeness of Quantum Reality: An Interview with Physicist Basil Hiley | Critical Opalescence, Scientific American Blog Network | Quantum Physics | Scoop.it
One night in 1952, Richard Feynman and David Bohm went bar-hopping in Belo Horizonte. Louisa Gilder reconstructs the night in her brilliant book on the history ...
Warren Huelsnitz's insight:

Very excellent article.  George Musser interviewed Physicist Basil Hiley.  Hiley worked with David Bohm on de Broglie-Bohm pilot wave theory and algebraic expressions of QM.  This is a very insightful and intriguing conversation.  Provides insights into the physics and the thoughts of Bohm and Hiley.  The article provides evidence for the prejudice and suppression of ideas and theories that did not conform with the Copenhagen Interpretation.  This includes suppression of Bohms papers as well as suppression of Hiley's curiosity.

 

I discussed similar suppression and neglect of investigations into foundations of quantum theory in a blog article a few weeks ago:

http://www.thefunisreal.com/2013/08/contrary-to-popular-belief-einstein-was-not-mistaken-about-quantum-mechanics/.

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Gary Bamford's curator insight, November 4, 2013 10:58 PM

When I was starting our in my physics career I read an article in the New Scientist about David Bhom's theory. Which I didn't quite follow but though it sounded really interesting. He was at Birkbeck at the time. I thought 'oh well ' I'll write to him with my questions thats the only way I will get to understand this. Not believing I would really get a reply - but to my amasement I got a hand written note back from him outlining the elements of the pilot wave theory. Well impressed - and I still like the positioning of the theory even thoug its out of favour!

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New Experiments to Pit Quantum Mechanics Against General Relativity | Simons Foundation

New Experiments to Pit Quantum Mechanics Against General Relativity | Simons Foundation | Quantum Physics | Scoop.it
Physicists have devised experiments that can probe the interface between quantum mechanics and general relativity.
Warren Huelsnitz's insight:

If they succeed, the greek phrase "Audaces Fortuna Juvat" will be applicable to these experimentalists (Fortune Favors the Bold).

 

It's not clear to me that it is actually "Pitting the two experiments against each other".  But, experiments that can show gravitational effects and quantum effects simultaneously will be very interesting and important.   Some time ago, I read a paper about a proposed experiment to combine gravitational time-dilation and the double slit experiment (in the form of an interferometer).  The idea is to have the two paths of the interferometer at different heights.  The different rates of time should then impact the phases of each path when they reach the re-combination point.  Unfortunately, I have not been able to re-locate the paper.

 

One of the basic properties of quantum mechanics is that a particle (or quantum system made up of a group of particles) can act as if it is in a superposition of possible outcomes.  The most common example is the story of Schrodinger's cat: a cat is sealed in a box; also in the box is a radioactive isotope, a hammer, and a vial of poison; if an atom decays in a certain period of time, the hammer breaks the vial and the cat is killed.  So the cat is in a superposition of dead and alive states. 

Now, superposition does not really work with something as large as a cat, it decoheres to a classical state too quickly due to interactions of all the particles it is made of, with the environment.  That is why they have to use a tiny system in this experiment.

So, in this experiment, the "ball" will be in a superposition of having been struck and not struck by a photon.  The scientists are trying to design an experiment that is sensitive enough to measure the curvature of space-time due to the vibrating ball.  They want to see if space-time is also in a superposition of curved and not curved by the vibrating (and not vibrating) ball.

What makes this so immensely challenging is that the vibrating quantum system has to be very small so that the superposition can be maintained.  And that makes it very, very hard to measure the teeny-tiny effect on space-time.  The cool thing about these experiments is they will be directly observing quantum and gravitational effects simultaneously, both affecting the outcome of the experiment.  This could provide input to theorists who are trying to reconcile quantum mechanics with general relativity and come up with a theory of quantum gravity.

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Japanese Telco Smashes Entanglement Distance Record - MIT Technology Review

Japanese Telco Smashes Entanglement Distance Record - MIT Technology Review | Quantum Physics | Scoop.it
Japanese Telco Smashes Entanglement Distance Record
MIT Technology Review
Entanglement makes possible all kinds of exotic phenomena that cannot occur in the ordinary, non-quantum world.
Warren Huelsnitz's insight:

Using superconducting photon detectors, they have been able to distribute entangled photons over 300 km.  But, the data rate of 1 bit every 10 million seconds needs some improvement; so if you are considering a job in quantum computing or quantum communications, there is still more work to be done.

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“Other Universes are Pulling on Our Universe” — New Planck Data Triggers Controversy

“Other Universes are Pulling on Our Universe” — New Planck Data Triggers Controversy | Quantum Physics | Scoop.it
Is our universe merely one of billions? Evidence of the existence of 'multiverse' revealed for the first time by a cosmic map of background radiation data gathered by Planck telescope. The fi

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Persuading light to mix it up with matter

Persuading light to mix it up with matter | Quantum Physics | Scoop.it
Scientists have documented a never-before-seen coupling of photons with electrons on the surface of an exotic crystal.

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Hydrodynamic Quantum Analogs - The Fun Is Real

Hydrodynamic Quantum Analogs - The Fun Is Real | Quantum Physics | Scoop.it
Hollywood and Black Hole Analogs The Big Bang Theory’s end-of-season cliff-hanger referred to a similarity between the equations of hydrodynamics and the equations of black holes, and the usefulness of hydrodynamic simulations to understand black ...
Warren Huelsnitz's insight:

New blog article on experimental investigations of quantum physics using hydrodynamic quantum analogs.  A lot of good info in the article and the embedded links; as well as some cool video clips.

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Physicists aim to make transition to quantum world visible

Physicists aim to make transition to quantum world visible | Quantum Physics | Scoop.it
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Researchers are designing an experiment to study the transition from quantum to classical behaviors.

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Quantum Erasure

Quantum Erasure | Quantum Physics | Scoop.it
When I posted congratulating the winner of this year’s Nobel betting pool, I received a gentle reminder in email that I’m a Bad Person and still haven’t done one of the posts I owe to the 2011 winners.
Warren Huelsnitz's insight:

Excellent article about delayed choice quantum eraser experiments (modifications to the double slit experiment that highlight the wierdness of quantum physics).

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Quantum Experiment Shows How Time ‘Emerges’ from Entanglement

Quantum Experiment Shows How Time ‘Emerges’ from Entanglement | Quantum Physics | Scoop.it
When the new ideas of quantum mechanics spread through science like wildfire in the first half of the 20th century, one …

Via Apmel
Warren Huelsnitz's insight:

A significant contribution in the debate over whether time is fundamental, or emergent. 

 

Emergent typically means like temperature or pressure, for example.  Temperature and pressure are undefined for a single particle.  It's only for distributions of many-particle systems that temperature or pressure makes sense.  Could it be that way for time?  Does an isolated particle not experience time; only systems of entangled particles? 

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Professor's quantum teleportation theory to be tested on space station - Phys.Org

Professor's quantum teleportation theory to be tested on space station - Phys.Org | Quantum Physics | Scoop.it
Professor's quantum teleportation theory to be tested on space station Phys.Org Professor Bernstein is now part of a team of experimental quantum mechanics investigators, led by physics professor Paul Kwiat at the University of Illinois at...
Warren Huelsnitz's insight:

I scooped this article because it is an example of articles that I hate.  It is all "fluff" and no "stuff".  It goes on and on about Super dense teleportation that is going to be tested on the space station.  But it never tells you how super dense teleportation works, what is different about the method compared to regular teleportation, how it is going to be tested on the space station, etc.  Popular science writers out there: if you are going to take the time to write, and expect people to take the time to read, teach them something!

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Building a Better Quantum State - Physics

Building a Better Quantum State
Physics
All quantum technologies, from cryptography to computing, rely on the precise preparation and characterization of quantum states, i.e., the wave functions of a particle or an ensemble of particles.
Warren Huelsnitz's insight:

Mapping the wave function via quantum topography.  Not many years ago, this was not even believed possible (for technical as well as philossophical reasons).  Now, experiementalists are doing it all the time.  See http://arxiv.org/pdf/1306.4191.pdf for the paper the article discusses.

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Quantum 'world record' smashed

Quantum 'world record' smashed | Quantum Physics | Scoop.it

A fragile quantum memory state has been held stable at room temperature for a "world record" 39 minutes - overcoming a key barrier to ultrafast computers.


Via Szabolcs Kósa
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luiy's curator insight, November 16, 2013 9:48 AM

"Qubits" of information encoded in a silicon system persisted for almost 100 times longer than ever before.

 

Quantum systems are notoriously fickle to measure and manipulate, but if harnessed could transform computing.

 

The new benchmark was set by an international team led by Mike Thewalt of Simon Fraser University, Canada.

Continue reading the main story“Start Quote

"39 minutes may not seem very long. But these lifetimes are many times longer than previous experiments”

Stephanie SimmonsOxford University

"This opens the possibility of truly long-term storage of quantum information at room temperature," said Prof Thewalt, whose achievement is detailed in the journal Science.

In conventional computers, "bits" of data are stored as a string of 1s and 0s.

 

But in a quantum system, "qubits" are stored in a so-called "superposition state" in which they can be both 1s and 0 at the same time - enabling them to perform multiple calculations simultaneously.

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Science and Its Skeptics

Science and Its Skeptics | Quantum Physics | Scoop.it
What science needs is enthusiasm for those willing to invest the time to try to sort truth from hype.
Warren Huelsnitz's insight:
 Great article by Gary Marcus.  I think criticism of how science is practiced (as is done in the John Horgan article that Gary refers to) is legitimate.  But you have to be careful not to generalize too much.  For example, I think the root causes (and consequences) of the string theory fiasco are significantly different than the problem of lack of repeatability in the medical sciences.  Marcus calls for more people willing to take the time to separate the truth from the hype: "What science really needs is greater enthusiasm for those people who are willing to invest the time to try to sort the truth from hype and bring that to the public. Academic science does far too little to encourage such voices." I am trying to separate the truth from the hype in the field of quantum physics; see my blog at www.thefunisreal.com.
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Quantum reality more complex than previously thought

Quantum reality more complex than previously thought | Quantum Physics | Scoop.it
Imagine you order a delivery of several glass vases in different colors. Each vase is sent as a separate parcel.

Via Ioannis
Warren Huelsnitz's insight:

Changing the photon's polarization along one leg of an interferometer impacts the interference at the output of the interferometer.  Photon's are pretty sneaky...

 

The double slit experiment is the quintessential experiment that shows quantum interference: how a single particle can interfere with itself by (apparently) traveling through both slits and striking a detection screen.  Modern versions are done with interferometers because they are more sensitive and easier to include modifications (beam splitters, reflectors, polarizers, etc.).  So, you have a photon that travels two paths simultaneously to a detector and then interferes with itself.

The interference between the two paths depends on the phase of the wave function for each photon (or electron, or whatever particle you are using; the experiment in the paper used photons).  And the phase of the wave functions depends on the path lengths (and also the number of reflections, and so on.)  But, you can build the interferometer so that the two paths interfere constructively or destructively.  If they interfere destructively, the photon is not detected.

The bizarre thing about QM is that if you somehow measure which path the photon actually took (or which slit  in the double-slit experiment), the interference is not observed.  It is as if by peeking under the sheets to see what is going on, the split personality of the particle goes away.

What this experiment showed is that if you modify the polarity of the photon along one of the paths, the interference goes away.  Polarity means the direction that the EM field oscillates for the photon (vertical or horizontal for example).  If you change this for one path, it acts as if you have tagged the photon and the interference goes away.   The weird thing is you have not physically disturbed the photon or applied a force to it that would (by any classical means) disrupt the interference.

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New Experiments to Pit Quantum Mechanics Against General Relativity | Simons Foundation

New Experiments to Pit Quantum Mechanics Against General Relativity | Simons Foundation | Quantum Physics | Scoop.it
Physicists have devised experiments that can probe the interface between quantum mechanics and general relativity.
Warren Huelsnitz's insight:

If they succeed, the greek phrase "Audaces Fortuna Juvat" will be applicable to these experimentalists (Fortune Favors the Bold).

 

One of the basic properties of quantum mechanics is that a particle (or quantum system made up of a group of particles) can act as if it is in a superposition of possible outcomes.  The most common example is the story of Schrodinger's cat: a cat is sealed in a box; also in the box is a radioactive isotope, a hammer, and a vial of poison; if an atom decays in a certain period of time, the hammer breaks the vial and the cat is killed.  So the cat is in a superposition of dead and alive states. 

Now, superposition does not really work with something as large as a cat, it decoheres to a classical state too quickly due to interactions of all the particles it is made of, with the environment.  That is why they have to use a tiny system in this experiment.

So, in this experiment, the "ball" will be in a superposition of having been struck and not struck by a photon.  The scientists are trying to design an experiment that is sensitive enough to measure the curvature of space-time due to the vibrating ball.  They want to see if space-time is also in a superposition of curved and not curved by the vibrating (and not vibrating) ball.

What makes this so immensely challenging is that the vibrating quantum system has to be very small so that the superposition can be maintained.  And that makes it very, very hard to measure the teeny-tiny effect on space-time.  The cool thing about these experiments is they will be directly observing quantum and gravitational effects simultaneously, both affecting the outcome of the experiment.  This could provide input to theorists who are trying to reconcile quantum mechanics with general relativity and come up with a theory of quantum gravity.

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Skepticblog » Quantum Medicine

Quantum Medicine uses the principles of quantum physics such as non-locality, tangled hierarchy, and discontinuous leap in consciousness to better understand medicine. How will attendees ... as a marketing strategy.
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Well written, brief article criticising quantum quackery.

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Entangled toy universe shows time may be an illusion - physics-math - 25 October 2013 - New Scientist

Entangled toy universe shows time may be an illusion - physics-math - 25 October 2013 - New Scientist | Quantum Physics | Scoop.it
Pairs of entangled photons that act as clocks demonstrate for the first time how the passage of time might be an illusion
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"It's a visualisation of the phenomenon, it's not a proof," Genovese says of the experiment. "You should look to the universe itself for that."

 

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Cool Physics: Time and Entanglement...

Cool Physics: Time and Entanglement... | Quantum Physics | Scoop.it
Warren Huelsnitz's insight:

Nice summary by @Cool_Physics, of the recent paper about time and quantum entanglement.

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Light propagation, the classical way

Light propagation, the classical way | Quantum Physics | Scoop.it
Light propagation, the classical way
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Attempt at an explanation using classical physics and wave nature of light, to explain apparent photon trajectories that come out of weak measurements.  Weak measurements are not defined in the article; but essentially they are observations on a large ensemble of systems, done so as not to disturb the system too much, but to reveal the wave function.

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The Reins of Casimir: Engineered Nanostructures Could Offer Way to Control Quantum Effect ... Once a Mystery Is Solved

The Reins of Casimir: Engineered Nanostructures Could Offer Way to Control Quantum Effect ... Once a Mystery Is Solved | Quantum Physics | Scoop.it
You might think that a pair of parallel plates hanging motionless in a vacuum just a fraction of a micrometer away from each other would be like strangers passing in the night—so close but destined never to meet.
Warren Huelsnitz's insight:

The casimir effect is such a cool phenomenon. Easy to understand yet it displays amazing properties of the "vacuum"

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H Bar

The Quantum Bar - a short film produced for and shown during the Origins 2013 Live Webcast in Geneva, CERN, Globe of Science and Innovation, on European Rese...
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This is what happens when physicists try too hard to be cool.

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Google Has Turned Minecraft Into A Quantum Physics Simulator - Inventorspot

Google Has Turned Minecraft Into A Quantum Physics Simulator - Inventorspot | Quantum Physics | Scoop.it
Google Has Turned Minecraft Into A Quantum Physics Simulator
Inventorspot
We've seen faithful recreations of entire worlds, fully-functional assembly lines, even working computers.
Warren Huelsnitz's insight:

Writers and editors: Please stop calling it a simulation of quantum physics.  Google does not consider it that, and neither do any real physicists.  As Google states, it is a fun way to expose people to analogies that reflect quantum physics.  From qCraft.org: "qCraft is not a simulation of quantum physics (this is v1 after all) but it does provide ‘analogies’ that attempt to show how quantum behaviors are different from everyday experience."

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Can a game teach kids quantum mechanics?

Can a game teach kids quantum mechanics? | Quantum Physics | Scoop.it
Five months ago, I received an email and then a phone call from Google's Creative Lab Executive Producer, Lorraine Yurshansky. Lo, as she prefers to be called, is not your average thirty year-old. ...
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Quantum Mechancis mod for Minecraft!  More info at http://qcraft.org/. ; I may just have to learn to play MInecraft!

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