Even D-Wave’s detractors are starting to feel like quantum computers are getting close, though only for some applications.
Category: quantum physics – Page 998
Are the Laws of Physics Really Universal?
Can the laws of physics change over time and space?
As far as physicists can tell, the cosmos has been playing by the same rulebook since the time of the Big Bang. But could the laws have been different in the past, and could they change in the future? Might different laws prevail in some distant corner of the cosmos?
“It’s not a completely crazy possibility,” says Sean Carroll, a theoretical physicist at Caltech, who points out that, when we ask if the laws of physics are mutable, we’re actually asking two separate questions: First, do the equations of quantum mechanics and gravity change over time and space? And second, do the numerical constants that populate those equations vary?
Upgrading the quantum computer
Theoretical physicists have proposed a scalable quantum computer architecture. The new model, developed by Wolfgang Lechner, Philipp Hauke and Peter Zoller, overcomes fundamental limitations of programmability in current approaches that aim at solving real-world general optimization problems by exploiting quantum mechanics.
Within the last several years, considerable progress has been made in developing a quantum computer, which holds the promise of solving problems a lot more efficiently than a classical computer. Physicists are now able to realize the basic building blocks, the quantum bits (qubits) in a laboratory, control them and use them for simple computations. For practical application, a particular class of quantum computers, the so-called adiabatic quantum computer, has recently generated a lot of interest among researchers and industry. It is designed to solve real-world optimization problems conventional computers are not able to tackle. All current approaches for adiabatic quantum computation face the same challenge: The problem is encoded in the interaction between qubits; to encode a generic problem, an all-to-all connectivity is necessary, but the locality of the physical quantum bits limits the available interactions.
“The programming language of these systems is the individual interaction between each physical qubit. The possible input is determined by the hardware. This means that all these approaches face a fundamental challenge when trying to build a fully programmable quantum computer,” explains Wolfgang Lechner from the Institute for Quantum Optics and Quantum Information (IQOQI) at the Austrian Academy of Sciences in Innsbruck.
‘Zeno effect’ verified: Atoms won’t move while you watch
One of the oddest predictions of quantum theory — that a system can’t change while you’re watching it — has been confirmed in an experiment by physicists.
Simulation Shows Time Travel Is Possible
Australian scientists created a computer simulation in which quantum particles can move back in time. This might confirm the possibility of time travel on a quantum level, suggested in 1991. At the same time, the study revealed a number of effects which are considered impossible according to the standard quantum mechanics.
Using photons, physicists from the University of Queensland in Australia simulated time-traveling quantum particles. In particular, they studied the behavior of a single photon traveling back in time through a wormhole in space-time and interacting with itself. This time-traveling loop is called a closed timelike curve, i.e. a path followed by a particle which returns to its initial space-time point.
The physicists studied two possible scenarios for a time-traveling photon. In the first, the particle passes through a wormhole, moving back in time, and interacts with its older self. In the second scenario, the photon passes through normal space-time and interacts with another photon which is stuck in a closed timelike curve.
Quantum Theory: ‘Spooky Action at a Distance’ confirmed
In one of my first articles for Lifeboat,* I provided an experimental methodology for demonstrating (or proving) the instantaneous ‘communication’ between quantum entangled particles. Even though changes to one particle can be provably demonstrated at its far away twin, the very strange experimental results suggested by quantum theory also demonstrate that you cannot use the simultaneity for any purpose. That is, you can provably pass information instantly, but you cannot study the ‘message’ (a change in state at the recipient), until such time as it could have been transmit by a classical radio wave.
Now, scientists have conducted an experiment proving that objects can instantaneously affect each other, regardless o the distance between them. [continue below]
[From The New York Times—Oct 21, 2015]:
Sorry Einstein.
Quantum Study Suggests ‘Spooky Action’ is RealIn a landmark study, scientists at Delft University of Technology in the Netherlands reported that they had conducted an experiment that they say proved one of the most fundamental claims of quantum theory — that objects separated by great distance can instantaneously affect each other’s behavior.
The finding is another blow to one of the bedrock principles of standard physics known as “locality,” which states that an object is directly influenced only by its immediate surroundings. The Delft study, published Wednesday in the journal Nature, lends further credence to an idea that Einstein famously rejected. He said quantum theory necessitated “spooky action at a distance,” and he refused to accept the notion that the universe could behave in such a strange and apparently random fashion.
[Read John Markoff’s full article in The New York Times]
* The original Lifeboat article—in which I describe an experimental apparatus in lay terms—was reprinted from my Blog, A Wild Duck.
5 REAL Possibilities for Interstellar Travel | Space Time | PBS Digital Studios
Tweet at us! @pbsspacetime.
Facebook: facebook.com/pbsspacetime
Email us! pbsspacetime [at] gmail [dot] com.
Comment on Reddit: http://www.reddit.com/r/pbsspacetime
The prospect of interstellar travel is no longer sci-fi. It COULD be achievable within our lifetime! But, how would an interstellar rocket-ship work? On this week’s episode of Space Time, Matt talks options for interstellar travel — from traditional rocket fuel to antimatter drives, could we travel to other star systems? Watch this episode of Space Time to find out!
“Quantum Entanglement & Spooky Action at a Distance”:
https://www.youtube.com/watch?v=ZuvK-od647c
“The Real Meaning of E=Mc²”:
https://www.youtube.com/watch?v=Xo232kyTsO0
“Could You Fart Your Way To The Moon”:
Engineered viruses provide quantum-based enhancement of energy transport
How cool is this!
Rendering of a virus used in the MIT experiments. The light-collecting centers, called chromophores, are in red, and chromophores that just absorbed a photon of light are glowing white. After the virus is modified to adjust the spacing between the chromophores, energy can jump from one set of chromophores to the next faster and more efficiently. (credit: the researchers and Lauren Alexa Kaye)
MIT engineers have achieved a significant efficiency boost in a light-harvesting system, using genetically engineered viruses to achieve higher efficiency in transporting energy from receptors to reaction centers where it can be harnessed, making use of the exotic effects of quantum mechanics. Emulating photosynthesis in nature, it could lead to inexpensive and efficient solar cells or light-driven catalysis,
This achievement in coupling quantum research and genetic manipulation, described this week in the journal Nature Materials, was the work of MIT professors Angela Belcher, an expert on engineering viruses to carry out energy-related tasks, and Seth Lloyd, an expert on quantum theory and its potential applications, and 15 collaborators at MIT and in Italy.
A New Experiment May Determine Whether Gravity Is Quantized
In physics there are two broad ways to look at the world. One is the classical realm of Newton and Einstein, where objects have definite form and interact in clearly determinate ways. The other is the quantum realm, where objects seem nebulous, with a strange mix of particle-like and wave-like behavior. The classical view gives us a wonderfully accurate description of everything from planets to baseballs. The quantum view is necessary to accurately describe the behavior of light and atoms. The classical world dominates on the scale of our daily lives, but nature seems to be rooted in quantum theory at its most basic level.
While both the classical and quantum approach are extremely accurate in their respective regimes, what happens in the intersection of the two regimes is still unclear. We don’t have a rigorous theory combining our classical and quantum models. We also don’t have certain key observational evidence, particularly in the nexus of quantum theory and gravity. But as quantum experiments increasingly study more massive objects and gravity experiments become increasingly sensitive, we’re approaching the point where “quantum gravity” experiments could be made. That’s the goal of a recently proposed experiment.
Since there isn’t yet a unified theory of quantum gravity, folks have instead focused on approximate approaches. One such approach is to add gravity to quantum theory a little bit at a time. This perturbative approach quantizes objects and their gravitational fields, and it works well for weak gravitational fields. One of the predictions of this approach is the existence of gravitons as the field quanta of gravity, much like photons are the field quanta of electromagnetism. However with stronger gravitational fields the approach becomes problematic. Basically, perturbative gravity builds upon itself in a way that is unphysical, so the model breaks down.
Researchers use engineered viruses to provide quantum-based enhancement of energy transport
Nature has had billions of years to perfect photosynthesis, which directly or indirectly supports virtually all life on Earth. In that time, the process has achieved almost 100 percent efficiency in transporting the energy of sunlight from receptors to reaction centers where it can be harnessed—a performance vastly better than even the best solar cells.
One way plants achieve this efficiency is by making use of the exotic effects of quantum mechanics—effects sometimes known as “quantum weirdness.” These effects, which include the ability of a particle to exist in more than one place at a time, have now been used by engineers at MIT to achieve a significant efficiency boost in a light-harvesting system.
Surprisingly, the MIT researchers achieved this new approach to solar energy not with high-tech materials or microchips—but by using genetically engineered viruses.