The Puzzle Of Quantum Reality

Science Facebook Twitter Flipboard Email Enlarge this image Pasieka/Getty Images/Science Photo Library RF Pasieka/Getty Images/Science Photo Library RF There's a hole at the heart of quantum physics. It's a deep hole. Yet it's not a hole that prevents the theory from working. Quantum physics is, by any measure, astonishingly successful. It's the theory that underpins nearly all of modern technology, from the silicon chips buried in your phone to the LEDs in its screen, from the nuclear hearts of the most distant space probes to the lasers in the supermarket checkout scanner. It explains why the sun shines and how your eyes can see. Quantum physics works. Yet the hole remains: Despite the wild success of the theory, we don't really understand what it says about the world around us. The mathematics of the theory makes incredibly accurate predictions about the outcomes of experiments and natural phenomena. In order to do that so well, the theory must have captured some essential and profound truth about the nature of the world around us. Yet there's a great deal of disagreement over what the theory says about reality — or even whether it says anything at all about it. Even the simplest possible things become difficult to decipher in quantum physics. Say you want to describe the position of a single tiny object — the location of just one electron, the simplest subatomic particle we know of. There are three dimensions, so you might expect that you need three numbers to describe the electron's location. This is certainly true in everyday life: If you want to know where I am, you need to know my latitude, my longitude, and how high above the ground I am. But in quantum physics, it turns out three numbers isn't enough. Instead, you need an infinity of numbers, scattered across all of space, just to describe the position of a single electron. This infinite collection of numbers is called a "wave function," because these numbers Continue Reading

Quantum physics trick means we could send information twice as fast

Tech & Science Quantum Physics Information Security Our world is all about information, so perhaps it's no surprise that quantum physicists think about how they can manipulate their field to send information faster. And in a pair of recent papers, a team of quantum scientists have outlined a way to do just that—and in a way that no wannabe spy could ever listen in on. The gist of the technique feels a bit like the famous riddle in which two guards—one of whom always tells the truth and one of whom always lies—protect two doors, one of which hides a tiger. The trick is to always ask what the other guard would say: that way, it doesn't matter whether you've asked the truthful guard or the lying one, you have precisely one lie and one truth in the answer, so you can work backwards to avoid the tiger. The physicists' technique could mean information can travel twice as fast—with complete security. Leon Neal/Getty Images See all of the best photos of the week in these slideshows In the quantum communication scenario, it's not about truth and lies, it's about knowledge and uncertainty between two people. For simplicity, imagine the tiniest message possible, which includes either yes or no, no additional information. Each person knows what message they sent. Traditionally, each person would send their yes or no encoded in a particle of light and the other person would receive it based on how long light takes to bridge the distance between them: two people, two particles, twice the wait time. But here's where the new research speeds things up. Quantum physics means that the same particle can be—as one of the researchers told Live Science—essentially "in two places at the same time." Read more: Can Artificial Intelligence Help Scientists Unravel the Secrets of Colliding Black Holes? That nifty trick means two people can communicate with just one particle of light in which both people have encoded their Continue Reading

First 51-Qubit Quantum Computer Using Cold Atoms Announced In Moscow

Quantum computers hold much promise to revolutionize the computing power of machines, leaving behind the classical computing technology when it comes to solving some complex problems current computers are ill-equipped to deal with. But current quantum technology is still below the threshold of the most powerful supercomputers in the world today. Called quantum supremacy, this threshold is thought to be breached somewhere in the range of 50 qubits — quantum analogs of the classic computer bits. And the most advanced quantum computers built today are well below 20 qubits, such as the IBM machine announced in May that runs on 17 qubits. However, that may be set to change after Harvard University’s Mikhail Lukin announced at the recently concluded 4th International Conference on Quantum Technologies (ICQT) in Moscow that his team had successfully built and tested a 51-qubit quantum computer. Read: Quantum Computers Could Use Graphene To Create Stable Qubits The highlight of ICQT was supposed to be another quantum computing device, being designed by John Martinis, a professor at University of California at Santa Barbara who also works with Google toward working a scalable, practical quantum computer. On July 13, Martinis announced his team was building a 49-qubit machine, using superconductors, and hoped to have a working version in the very near future. But on the morning of the very next day — Martinis was supposed to give a public lecture about his quantum device that evening — Lukin produced quite a surprise. He said during his talk that his group, along with colleagues from the Massachusetts Institute of Technology, had successfully built and tested a 51-qubit device in his lab at Harvard, using cold atoms to achieve this feat. This achievement puts Lukin and his group at the forefront of quantum computing in the world. Mikhail Lukin in his laboratory at Harvard University. Photo: Kris Snibbe/Harvard Staff Photographer To make Continue Reading

Quantum speed limit may put brakes on quantum computers

(The Conversation is an independent and nonprofit source of news, analysis and commentary from academic experts.) Sebastian Deffner, University of Maryland, Baltimore County (THE CONVERSATION) Over the past five decades, standard computer processors have gotten increasingly faster. In recent years, however, the limits to that technology have become clear: Chip components can only get so small, and be packed only so closely together, before they overlap or short-circuit. If companies are to continue building ever-faster computers, something will need to change. One key hope for the future of increasingly fast computing is my own field, quantum physics. Quantum computers are expected to be much faster than anything the information age has developed so far. But my recent research has revealed that quantum computers will have limits of their own – and has suggested ways to figure out what those limits are. The limits of understanding To physicists, we humans live in what is called the “classical” world. Most people just call it “the world,” and have come to understand physics intuitively: Throwing a ball sends it up and then back down in a predictable arc, for instance. Even in more complex situations, people tend to have an unconscious understanding of how things work. Most people largely grasp that a car works by burning gasoline in an internal combustion engine (or extracting stored electricity from a battery), to produce energy that is transferred through gears and axles to turn tires, which push against the road to move the car forward. Under the laws of classical physics, there are theoretical limits to these processes. But they are unrealistically high: For instance, we know that a car can never go faster than the speed of light. And no matter how much fuel is on the planet, or how much roadway or how strong the construction methods, no car will get close to going even 10 percent of the speed of light. People never Continue Reading

Quantum Computing: Graphene-Based Device Theoretically Proves Existence Of Non-Abelian Anyons

Researchers from University of California, Santa Barbara, have developed a device that could prove the existence of non-Abelian anyons. These 2-dimensional quantum particles were theorized and mathematically predicted to exist but have not been synthesized till now. A study published in the journal Nature has taken the first steps toward finding conclusive evidence of the existence of non-Abelian anyons. The researchers used graphene, an atomically thin material derived from graphite, to develop “an extremely low-defect, highly tunable device in which non-Abelian anyons should be much more accessible,” said a news release published on the university website. These anyons are a type of quasiparticle that occur only in two-dimensional systems, with properties much less restricted than those of fermions and bosons. Here, when the system undergoes degeneration by exchanging two identical particles, there will be a change in state but the particles themselves will retain the same configuration. Anyons are generally classified as abelian or non-Abelian. Abelian anyons have been detected and play a major role in the fractional quantum Hall effect. Non-Abelian anyons have not been definitively detected, although this is an active area of research. In a 3D world, elementary particles can either be fermions or bosons. "The difference between these two types of 'quantum statistics' is fundamental to how matter behaves," physicist Andrea Young, author of the study said. Several fermions cannot remain in the same quantum state. This allows us to push electrons (fermion) around in semiconductors given its unique properties and also helps prevent neutron stars from collapsing, Young added. But bosons can occupy the same state and this property gives rise to pre-existing principles in physics known as the Bose-Einstein condensation and superconductivity. According to the team, if a few fermions (protons, neutrons and electrons in atoms) are Continue Reading

Quantum Computing Update: 53-Qubit Simulator, Superconducting Interconnects Bring Future Computers Closer

They are billed as machines that will change the future, but quantum computers themselves are still in the future. All the same, scientists have been working on developing a working quantum computer for years now, and the frenzied competition to be the first has yielded a new record — a 53-qubit quantum simulator. A qubit is the quantum analogue of a computer’s bit. A bit stores information as either 0 or 1, while qubits can exist as both 0 and 1 simultaneously, exponentially increasing the computing power of a system that uses them. A quantum simulator is not a general-purpose quantum computer, but one that is designed to solve a particular equation or simulate a specific problem. It does so much faster than a classic computer using bits would. The difference in speed between the two is quite phenomenal. Theoretically, the world’s fastest-existing supercomputers would be shown down by a quantum computer that uses something in the range of 50 qubits, a threshold called quantum supremacy. Working quantum computers that exist today are still below 20 qubits, and that is why the new simulator is exciting. This is an artist's depiction of a quantum simulation. Lasers manipulate an array of more than 50 atomic qubits to study the dynamics of quantum magnetism. Photo: E. Edwards/JQI Writing in a Nature paper Wednesday, titled “Observation of a many-body dynamical phase transition with a 53-qubit quantum simulator,” researchers from University of Maryland and National Institute of Standards and Technology said: “As it becomes possible to exert more control over larger numbers of qubits, such simulators will be able to tackle a wider range of problems, such as materials design and molecular modelling, with the ultimate limit being a universal quantum computer that can solve general classes of hard problems. Here we use a quantum simulator composed of up to 53 qubits to study non-equilibrium dynamics in the transverse-field Ising Continue Reading

Physicists just upended quantum theory by tracking ‘secret’ particles, a feat considered impossible

Physicists have done the seemingly impossible: found a way to track mysterious quantum particles even when those particles aren’t being directly observed.In classical physics, an object occupies only one state of being at a time; something could be either alive or dead, for example, but not both simultaneously. But quantum physics, which seeks to explain how life works at the subatomic level, isn’t so intuitive. Quantum physics differs from classical physics in that under quantum theory, objects can exist as both waves and particles, occupying both states at the same time. They only exist as either one or the other after they’ve been measured, as a press release from the University of Cambridge explains.Now, researchers from the University of Cambridge have shown that the movements of those particles actually can be tracked without measuring them first—by observing the way the particles interact with their surrounding environments, according to the press release. A paper describing the work was published in the scientific journal Physical Review A. Keep up with this story and more Think of Schrödinger’s cat, the standard paradox for illustrating this particular aspect of quantum theory. A cat in a closed box that also contains a vial of poison could be thought of as either alive or dead, so long as we can’t see inside the box, as National Geographic has explained. To see that the cat is not occupying both states simultaneously, but either one or the other, we need to directly observe it by looking inside the box. In this case, the researchers have created a way to track the quantum object (the cat) to determine if it’s either a wave or a particle (either alive or dead) without directly observing it (peeking inside the box).“This premise [of Schrödinger’s cat], commonly referred to as the wave function, has been used more as a mathematical Continue Reading

VW, Google cooperate on quantum computing in tech push

Volkswagen AG plans three research projects on a Google quantum computer as part of the German automaker’s push to develop new digital features for cars and broaden its technological heft beyond manufacturing and selling vehicles.The projects include refining traffic-management systems, simulating the structure of electric-car batteries and other materials as well as artificial intelligence for autonomous driving, Wolfsburg-based Volkswagen said Tuesday in a statement.“Quantum computer technology opens new dimensions for us,” Chief Information Officer Martin Hofmann said in the statement. “We from Volkswagen want to be among the first to use quantum computing as a company as soon as this technology is commercially available.”The world’s largest automaker has stepped up spending on electric vehicles and new digital services like ride hailing as part of a comprehensive overhaul in the wake of its diesel-emissions scandal. The strategy is part of seismic shift across the auto industry to virtually connected, battery-powered cars that can drive themselves.Google will be providing access to powerful devices that use the principles of quantum mechanics to process information in a wider variety of ways than a conventional computer, which uses just a binary system to identify data. VW started its first quantum-computing project in March in China to optimize traffic for 10,000 taxis in Beijing, using another technology supplier.“We’re looking forward to explore together how quantum computing could change and bring forward the automobile industry,” Hartmut Neven, development head at Google Quantum Artificial Intelligence Laboratory, said in the statement. Continue Reading

Australia researchers say find new way to build quantum computers

By Jeremy Wagstaff SINGAPORE (Reuters) - Researchers in Australia have found a new way to build quantum computers which they say would make them dramatically easier and cheaper to produce at scale.  Quantum computers promise to harness the strange ability of subatomic particles to exist in more than one state at a time to solve problems that are too complex or time-consuming for existing computers. Google, IBM and other technology companies are all developing quantum computers, using a range of approaches.  The team from the University of New South Wales say they have invented a new chip design based on a new type of quantum bit, the basic unit of information in a quantum computer, known as a qubit. The new design would allow for a silicon quantum processor to overcome two limitations of existing designs: the need for atoms to be placed precisely, and allowing them to be placed further apart and still be coupled.  Crucially, says project leader Andrea Mello, this so-called "flip-flop qubit" means the chips can be produced using the same device technology as existing computer chips. "This makes the building of a quantum computer much more feasible, since it is based on the same manufacturing technology as today's computer industry," Mello said. That would allow chips for quantum computers to be mass-manufactured, a goal that has so far eluded other researchers. IBM's quantum computer in the United States has 16 qubits, meaning it can only perform basic calculations. Google's computer has nine qubits.   A desktop computer runs at gigaflops. The world’s fastest supercomputer, China’s Sunway TaihuLight, runs at 93 petaflops, but relies on 10 million processing cores and uses massive amounts of energy.In theory, even a small 30-qubit universal quantum computer could run at the equivalent of a classic computer operating at 10 teraflops.          The researchers' paper will Continue Reading

Nobel Prize goes to French-American duo for quantum physics

STOCKHOLM — A French-American duo shared the 2012 Nobel Prize in physics Tuesday for inventing methods to observe the bizarre properties of the quantum world, research that has led to the construction of extremely precise clocks and helped scientists take the first steps toward building superfast computers. Serge Haroche of France and American David Wineland opened the door to new experiments in quantum physics by showing how to observe individual quantum particles while preserving their quantum properties. A quantum particle is one that is isolated from everything else. In this situation, an atom or electron or photon takes on strange properties. It can be in two places at once, for example. It behaves in some ways like a wave. But these properties are instantly changed when it interacts with something else, such as when somebody observes it. Working separately, the two scientists, both 68, developed "ingenious laboratory methods" that allowed them to manage and measure and control fragile quantum states, the Royal Swedish Academy of Sciences said. "Their ground-breaking methods have enabled this field of research to take the very first steps towards building a new type of superfast computer based on quantum physics," the academy said. "The research has also led to the construction of extremely precise clocks that could become the future basis for a new standard of time." Christophe Lebedinsky/AP This 2009 photo shows French physician Serge Haroche, right, and his aide Igor Dotsenko in Paris. Haroche is a professor at the College de France and Ecole Normale Superieure in Paris. Wineland is a physicist at the National Institute of Standards and Technology, or NIST, and the University of Colorado in Boulder, Colorado. The two researchers use opposite approaches to examine, control and count quantum particles, the academy said. Wineland traps ions — electrically charged atoms — and measures them with light, while Continue Reading