To test the basics of quantum theory, physicists recently pulled out an antique. In a paper published today in Science, they confirmed a staple of quantum mechanics, using a test derived from a classic nineteenth century light experiment.
In particular, the researchers questioned how particles move through three slits, something previously too difficult to measure. They found that the particles behaved just like quantum theory–or more specifically the Born Rule–would have predicted.
As physicist Chad Orzel describes in his blog, that’s bad news for theorists hoping to tweak this rule to solve Nobel Prize-worthy problems related to quantum gravity or Grand Unifying Theories.
[The study is good news if] you’re the ghost of Max Born, or the author of an introductory quantum book…. This was disappointing news for some theorists, though, as there are a number of ways to approach problems … that would require some modification of the Born rule. [Uncertain Principles]
A pair of quantum entangled photons sure makes a cute couple. Of course, the two might have opposite states–one might be spin up and another spin down, for example–but they promise they’ll always stay that way.
They’re also fiercely loyal, respecting their opposite-spin preferences no matter how long-distance their relationship. (That means that by checking the state of one entangled photon, you can instantly know the state of the other, distant photon, a handy way to “teleport” information.) Unfortunately, because the couple is merely two light particles, their shining example of old romance has been too dim for our eyes to see.
Until now. As announced in their recently published Arxiv.org paper, physicists led by Nicolas Gisin at the University of Geneva in Switzerland believe they have found a way to watch this love affair unfold: by boosting the light emitted by one member of a quantum entangled pair, they think they can make this quantum effect visible to a human eye.
Measuring quantum states such as spin up or spin down is like looking at whether a switch is on or off. This closely matches the concept of a bit, a single 1 or 0, in computing. With entangled photons, physicists call these on/off states quantum bits or “qubits.” What an observer would see while observing an entangled photon is really a choice between two states. The observer could then confirm entanglement by checking to see that the photon was loyal to its partner.
In the traditional set-up, two widely separated particle detectors are used to measure the entanglement of the two photons. But Gisin and his colleagues want to let the human eye do some of the work.
A team of scientists led by Mark Raizen at the University of Texas at Austin had the gumption to take on Einstein. And according to their new paper in Science, they won. The point of contention? The lovechild of statistical mechanics and thermodynamics: Brownian motion.
Here’s how they did it.
Step 1. Learning the Moves
In the 1820s, Scottish botanist Robert Brown looked through a microscope at plant bits floating in water, and wrote [PDF]:
“I observed many of them very evidently in motion . . . [these motions] arose neither from currents in the fluid, nor from its gradual evaporation, but belonged to the particle itself.”
To make sure that the pollen wasn’t alive–actually swimming around–Brown tried it with coal dust. Dust had the same moves.
Today, we understand that Brownian motion, the random break dance of these tiny particles, comes from the water molecules bumping against them. In 1905, Einstein determined the properties of the liquid and the particles that would help describe their wanderings and the motion of molecules. But he also said that it was “impossible” to determine at any moment the speed and direction of a single particle during this dance.
Step 2. Water Into Air
The reason for Einstein’s doubt? The particles bumped around too quickly to ever measure their speed and direction:
He believed that it would be impossible in practice to track this motion, given the incredibly short timescales over which the Brownian fluctuations take place. [PhysicsWorld]
How quick is too quick? A very tiny glass sphere (think micrometers) in water would change direction almost every 100 nanoseconds (about the time it takes light to travel 30 meters). Raizen wanted to make the time between moves longer, so they didn’t use water. They put the glass beads on a dance floor with fewer partners, using a medium whose molecules are farther apart: air.
It’s become one of our favorite rituals: Researchers come out with a paper pushing the science of invisibility cloaks a little further, inspiring everyone to go giddy with visions of Harry Potter and Romulan Warbirds. This week’s study in Science is another small step, but it’s a crucial one. Scientists in Germany have created the first rudimentary “invisibility cloak” in 3D.
Invisibility cloak mania started in 2006, when a Duke University team created the technology to bend light waves around an object; since the tiny object neither absorbed nor reflected the experiment’s microwaves, it was essentially “cloaked.” (The researchers used microwaves instead of visible light because microwaves have longer wavelengths, and are therefore easier to control.) The invisibility excitement struck again two years later when researchers refined their technique to hide a nanoscale object from visible light waves.
Now, researchers have created a cloak that not only works in infrared light wavelengths that are close to humans’ visual range, but also in 3D, too. Previous devices have been able to hide objects from light travelling in only one direction; viewed from any other angle, the object would remain visible [BBC News].
The team from Karlsruhe Institute of Technology didn’t exactly make the Statue of Liberty disappear. The “bump” made invisible is a spot in a layer of gold that’s 0.00004 inches high by 0.00005 inches wide. That hasn’t dampened lead researcher Tolga Ergin’s excitement, though. “In principle, the cloak design is completely scalable; there is no limit to it,” Ergin said. Developing the fabrication technology so that the crystals were smaller could “lead to much larger cloaks” [The Independent].
The sci-fi kind of cloaking will be harder to achieve, since visible wavelengths of light are shorter than infrared and thus harder to control. But Ergin’s 3D cloak is another step toward humanity’s ultimate dream: not being bothered by other humans.
One small step for flashing bacteria, one giant leap for synthetic biology. In a new Naturestudy, molecular biologist Jeff Hasty and his team say they have created a line of E. coli bacteria that flash in fluorescent light and keep time like a clock.
Previously, scientists had engineered only single cells to become oscillators — devices that could count time by performing a particular activity on a cyclical schedule [Nature News]. Back in 2008, Hasty and his team created an oscillator for single cells that could be set to temperature or chemical triggers. But now the researchers have induced a whole host of bacteria to work together to keep time by taking advantage of the way they collaborate naturally: quorom sensing.
Scientists have figured out a way to switch brain cells on and off like light bulbs, but instead of using a clapper, they’re using microbial proteins and lasers. Ed Boyden, a neuroscientist at the Massachusetts Institute of Technology, has developed a way to shut down parts of a brain just by shining light on them. When the light is turned off, the brain switches back on [Forbes].
The research team says their technology will help neuroscientists probe the brain’s circuitry by silencing certain regions and studying the effects. The technique, which was described in the journal Nature, could one day be used to shut down overactive regions of the brain often found in people with epilepsy, depression, Parkinson’s disease, and blindness.
Scientists say that a thousand-year quest–one that you probably didn’t even know about–has accidentally come to an end. Painters and fabric makers can rest easy because Mas Subramanian and his research team at Oregon State University have created a near-perfect blue pigment. Blue pigments of the past have often been expensive (ultramarine blue was made from the gemstone lapis lazuli, ground up), poisonous (cobalt blue is a possible carcinogen and Prussian blue, another well-known pigment, can leach cyanide) or apt to fade (many of the organic ones fall apart when exposed to acid or heat) [The New York Times].
The new pigment popped up when the researchers were mixing manganese oxide, which is black, with other chemicals and then heating them up to high temperatures to study their electronic properties. One day, Subramanian was poking around in his lab when he noticed a graduate student removing a sample from the furnace that was brilliant blue.
The 2,000-degree-Fahrenheit furnace created a crystal structure that allowed the manganese ions to absorb red and green wavelengths of light while reflecting blue wavelengths. White yttrium oxide and pale yellow indium oxide are also required to stabilize the crystal structure. Subramanian said the pigment is safe, but far from cheap, since indium is quite costly, so they are trying to substitute cheaper oxides for indium. “Basically, this was an accidental discovery,” said Subramanian. “We were exploring manganese oxides for some interesting electronic properties they have, something that can be both ferroelectric and ferromagnetic at the same time. Our work had nothing to do with looking for a pigment” [UPI]. Regardless, their research appears in the Journal of the American Chemical Society.
New results are in from the Fermi Space Telescope, which settled into orbit in the summer of 2008, and the findings seem to prove Albert Einstein right once again. Man, that guy was good.
The telescope detected and studied a gamma ray burst, one of the massively bright and powerful explosions that occurs when stars go supernova in distant galaxies. Astronomers were interested in the gamma rays of differing energies and wavelengths that were generated by the explosion, and that raced each other across the universe. After a journey of 7.3 billion light-years, they all arrived within nine-tenths of a second of one another in a detector on NASA’s Fermi Gamma-Ray Space Telescope, at 8:22 p.m., Eastern time, on May 9 [The New York Times].
The researchers were wondering if certain gamma rays with both high energies and short wavelengths would arrive last, at the back of the pack. That would suggest that they had violated one of the principles set out in Einstein‘s theory of relativity: that the speed of light is always constant. If researchers could detect a significant lag in some gamma rays, it would also give fresh hope to those ambitious researchers searching for a theory of everything.
In a lab in Nanjing, China, two researchers are mucking about with what could be called the world’s first artificial black hole–but there’s no reason for alarm. The researchers, Qiang Cheng and Tie Jun Cui, haven’t created a doomsday device, but rather a nifty experiment that harnesses the strange properties of metamaterials. Physicists have already learned how to steer light around an object within a metamaterial to create an invisibility cloak…. Now Qiang and Tie have created a metamaterial that distorts space so severely that light entering it (in this case microwaves) cannot escape [Technology Review].
The lab experiment simulates a cosmological black hole, where the intense gravity curves space-time, sucking in any matter or radiation that gets too close. Not even light can escape a black hole (hence the name). The researchers couldn’t duplicate the intense gravity, but they could build a metamaterial with a physical structure that would make light curve into its central core, never to return. The device they built works only with microwaves so far, but the researchers say a visible light black hole is the next step.
Three scientists who mastered light through technology have been awarded this year’s Nobel Prize for physics, for breakthroughs that the prize committee said “helped to shape the foundations of today’s networked societies.” Half of the $1.4 million prize goes to Charles Kao (pictured), for his work on fiber optics, while the other half will be divided between Willard Boyle and George Smith, two retired researchers from Bell Labs who invented the first imaging technology using a digital sensor instead of film, paving the way for the creation of digital cameras.
Kao’s discovery in fiber optics set the stage for the technological revolution that underpins today’s global communication systems, powering broadband internet connections and carrying data transmissions around the world. In 1966, he figured out how to transmit light for more than 100 kilometers using optical glass fibers, five times the length of the most advanced fibers then available [Bloomberg]. Fiber optics have become ubiquitous in today’s wired, networked world; the Nobel committee noted that if all the optical cables in use today were unraveled, it would equal a single thread more than a billion kilometers long, enough to circle the globe 25,000 times.
A $40 price tag for a single light bulb may seem ridiculous to most consumers. But the Dutch company Lemnis Lighting hopes people will listen to all the arguments for their high-tech LED bulb, and consider it a bargain. [W]hat if it used 90% less electricity than a standard incandescent bulb, cut greenhouse gas emissions and saved you about $280 over its 25-year life span? [Los Angeles Times].
LEDs — light-emitting diodes — are semiconductors that glow and are considered one of the great hopes for slashing carbon emissions from lighting, which consumes about 19% of energy production worldwide [Los Angeles Times]. LEDs are already used in commercial lighting and electronic displays, but the cold, invariable glow has not caught on for household fixtures. Lemnis says its Pharox60 bulb, which just came on the market in the United States, is a major improvement, as it casts a warm glow similar to that of a standard 60-watt incandescent bulb and works in any normal light socket. The company also says this bulb is the first that’s compatible with dimmer switches. Finally, unlike curly compact fluorescent bulbs, LED bulbs don’t contain toxic mercury and can be recycled.
Scientists now know how the iridescent green scarab beetle‘s shell get its iridescent hue: A molecular arrangement that reflects light, with the reflected light’s magnetic field oriented like a corkscrew, according to a study published in Science.
The beetles don’t appear green due to pigments, which give flowers and plants their colors. Instead, they get their hue from structural color, or molecular structures that reflect light in a certain manner–the same way birds and butterflies do. Light hitting the shell is reflected by the microstructures, and these reflections create an electric field that forms a clockwise helix. Humans cannot see this property — known as left-handed circular polarization — but can see a green hue [ScienceNews]; some organisms, however, can actually see circular polarization itself. The molecular structure consists of three shapes: pentagons, hexagons, and seven-sided heptagons.
Researchers have created a fabric that acts like a camera, made of tiny light-sensitive fibers that turn light waves into images. Says lead researcher Yoel Fink: “While the current version of these fabrics can only image nearby objects, it can still see much farther than most shirts can” [LiveScience].
Fink notes that the technology does away with one of the most basic camera components: the lens. Just like in an eye, cameras use a curved lens to focus the light waves reflected off an object, but the system contains an Achilles’ heel: Damage the lens, and you lose or diminish the ability to see [ScienceNOW Daily News]. By getting rid of the lens, researchers say they can develop a technology that is less vulnerable to damage–if one part of the fabric gets damaged, the rest can still function. “We are saying, ‘instead of a tiny, sensitive object [for capturing images], let’s construct a large, distributed system,’” Fink said [LiveScience].
The European Space Agency’s Planck observatory has reached its operating temperature of a mere tenth of a degree above the lowest temperature theoretically possible given the laws of physics, known as absolute zero. That means it’s ready for its mission: Observing the oldest light in the universe, known as the cosmic microwave background, or CMB, to create the clearest picture yet of what the young universe looked like.
Although scientists have achieved temperatures closer than this to absolute zero in the laboratory, the spacecraft is likely the coldest object in space. Such low temperatures are necessary for Planck’s detectors to study the Cosmic Microwave Background by measuring its temperature across the sky. Over the next few weeks, mission operators will fine-tune the spacecraft’s instruments. Planck will begin to survey the sky in mid-August [SPACE.com], and the first batch of data is expected to be released next year. Planck was launched May 14 and will observe the CMB from a spot more than 930,000 miles from Earth.
Computers powered by frickin’ laser beams just came a step closer. Light-based, or photonic, computers would theoretically be much faster and smaller than the electronic computers we use today, but researchers have had a hard time putting theory into action. Now, a new study has shown that two laser beams can be harnassed to turn a single molecule into a transistor. However, the specialized conditions necessary for the trick to work mean that computer stores won’t have photonic sections anytime soon.
Conventional computers are based on transistors, which allow one electrode to control the current moving through the device and are combined to form logic gates and processors. The new component achieves the same thing, but for laser beams, not electric currents. A green laser beam is used to control the power of an orange laser beam passing through the device [New Scientist]. In the study, published in Nature, the green beam could make the orange beam either weak or strong, which is analagous to an electronic transistor turning a current on or off.
80beats is DISCOVER's news aggregator, weaving together the choicest tidbits from the best articles on the day's most compelling topics.
80beats is written by Veronique Greenwood and Valerie Ross. This team darts through each day's science news faster than the ruby-throated hummingbird that beats its wings 80 times per second. Send ideas, tips, suggestions, and complaints to [azeeberg at discovermagazine dot com].
To test the basics of quantum theory, physicists recently pulled out an antique. In a paper published today in Science, they confirmed a staple of quantum mechanics, using a test derived from a classic nineteenth century light experiment.
A pair of quantum entangled photons sure makes a cute couple. Of course, the two might have opposite states–one might be spin up and another spin down, for example–but they promise they’ll always stay that way.
A team of scientists led by 
It’s become one of our favorite rituals: Researchers come out with a paper pushing the science of 
Scientists have figured out a way to switch brain cells on and off like light bulbs, but instead of using a clapper, they’re using microbial proteins and 
Scientists say that a thousand-year quest–one that you probably didn’t even know about–has accidentally come to an end. Painters and fabric makers can rest easy because Mas Subramanian and his research team at Oregon State University have created a near-perfect blue pigment. 
New results are in from the 
In a lab in Nanjing, China, two researchers are mucking about with what could be called the world’s first artificial black hole–but there’s no reason for alarm. The researchers, Qiang Cheng and Tie Jun Cui, haven’t created a doomsday device, but rather a nifty experiment that harnesses the strange properties of metamaterials. Physicists have already learned how to
Three scientists who mastered light through technology 
A $40 price tag for a single light bulb may seem ridiculous to most consumers. But the Dutch company 
Scientists now know how the iridescent green scarab 
Researchers have created a fabric that acts like a camera, made of tiny light-sensitive fibers that turn 
The European Space Agency’s 
Computers powered by frickin’ laser beams just came a step closer. Light-based, or photonic, computers would theoretically be much faster and smaller than the electronic 
