David Kirkpatrick

December 18, 2010

Science magazine’s breakthroughs of 2010

Number one is the first quantum machine.

From the link:

Physicists Andrew Cleland and John Martinis from the University of California at Santa Barbara and their colleagues designed the machine—a tiny metal paddle of semiconductor, visible to the naked eye—and coaxed it into dancing with a quantum groove. First, they cooled the paddle until it reached its “ground state,” or the lowest energy state permitted by the laws of quantum mechanics (a goal long-sought by). Then they raised the widget’s energy by a single quantum to produce a purely quantum-mechanical state of motion. They even managed to put the gadget in both states at once, so that it literally vibrated a little and a lot at the same time—a bizarre phenomenon allowed by the weird rules of quantum mechanics.

and its publisher, AAAS, the nonprofit science society, have recognized this first quantum machine as the 2010 Breakthrough of the Year. They have also compiled nine other important scientific accomplishments from this past year into a top ten list, appearing in a special news feature in the journal’s 17 December 2010 issue. Additionally, Science news writers and editors have chosen to spotlight 10 “Insights of the Decade” that have transformed the landscape of science in the 21st Century.

“This year’s Breakthrough of the Year represents the first time that scientists have demonstrated quantum effects in the motion of a human-made object,” said Adrian Cho, a news writer for Science. “On a conceptual level that’s cool because it extends quantum mechanics into a whole new realm. On a practical level, it opens up a variety of possibilities ranging from new experiments that meld quantum control over light, electrical currents and motion to, perhaps someday, tests of the bounds of quantum mechanics and our sense of reality.”

 

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August 25, 2010

Quantum entanglement and free will

A little more closely related than you might think.

From the link:

In practical terms, this means that there can be no shared information between the random number generators that determine the parameters of the experiments to be made, and the particles to be measured.

But the same also holds true for the experimenters themselves. It means there can be no information shared between them and the particles to be measured either. In other words, they must have completely free will.

In fact, if an experimenter lacks even a single bit of free will then quantum mechanics can be explained in terms of hidden variables. Conversely, if we accept the veracity of quantum mechanics, then we are able to place a bound on the nature of free will.

That’s an interesting way of stating the problem of entanglement and suggests a number of promising, related conundrums: what of systems that are partially entangled and others in which more than two particle become entangled.

Free will never looked so fascinating.

June 16, 2010

One step closer to quantum computing

Filed under: Science, Technology — Tags: , , , , — David Kirkpatrick @ 12:40 am

Alternative computing is always an fascinating topic, and the sheer processing power potential for quantum computers makes that field particularly interesting.

From the link:

Quantum computers can solve in a matter of moments problems that would take ordinary computers years to work out. But thus far, these computers exist only as state-of-the-art experimental setups in a few physics laboratories.

Now, Elena Kuznetsova, a post-doctoral researcher in UConn’s Department of Physics, has proposed a new type of quantum computer that could bring the technology one step closer to becoming a reality.

“The main excitement about quantum computers,” says Kuznetsova, “ comes from their potential ability to solve certain problems exponentially faster compared to classical computers, such as factoring a large number into its primes, which would allow us to break cryptographic codes. These problems cannot be solved using a  in the foreseeable future.”

April 18, 2010

Carbon nanotubes and new states of matter

Now this is some fascinating research on carbon nanotube properties.

From the link:

“For the first time, fields of study relating both to cold atoms and to the nanoscale have intersected,” Lene Vestergaard Hau tells PhysOrg.com. “Even though both have been active areas of research, cold atoms have not been brought together with nanoscale structures at the single nanometer level. This is a totally new system.”

Hau is the Mallinckrodt Professor of Physics and Applied Physics at Harvard University. Along with colleague J.A. Golovchenko, and graduate students Anne Goodsell and Trygve Ristroph, who are in her lab at Harvard, Hau was able to set up an experiment that allows for the observation of capture and field ionization of cold atoms. Their work can be found in : “Field  of Cold Atoms near the Wall of a Single Carbon Nanotube.”

And:

“When the electron is pulled in, it goes through a tunneling process,” Hau explains. “It has to go through areas that are classically forbidden. The process is quantum mechanical. We can observe the interaction of the atom and the nanotube as the electron is trying to tunnel, and this offers us a chance to peek at some of the interesting dynamics that happen at the nanoscale.”

Another possibility is that this combination of cold atoms with  could lead to new states of matter. “Since we now know how to suck atoms into orbit at such high spin rates, it could lead to a new state of cold-atomic matter that could be super interesting to study,” Hau points out.

Practical applications?:

Practically, this new system has potential as well. “We could make very sensitive detectors,” Hau says. “Things like ‘atom sniffers’ that detect trace gases could be an application for this work. Additionally, the possibility of single nanometer precision means super high spatial resolution. This system could be used in interferometers — interferometers built on a single chip and based on , which would be of importance for navigation, for example.”

For the raw material, here’s the release the linked article sprung from.

September 2, 2009

Blame quantum amnesia for lack of time travel

Filed under: et.al., Science, Technology — Tags: , , , , , — David Kirkpatrick @ 2:54 pm

Via KurzweilAI.net — And if quantum amnesia is a real phenomena without a solution time travel would be a one-way affair. I’m not sure if anyone would sign up for a one=way ticket to an uncertain future.

Quantum amnesia gives time its arrow

NewScientist Physics & Math, Aug. 26, 2009

The forward-only direction of time is the result of quantum-mechanical amnesia that erases any trace thattime has moved backwards, says Lorenzo Maccone of MIT.

Read Original Article>>

April 30, 2009

Quantum cryptography becoming practical

Looks like things are moving that direction. Very cool.

The release:

Computer hackers R.I.P. — making quantum cryptography practical

Quantum cryptography, a completely secure means of communication, is much closer to being used practically as researchers from  and Cambridge University’s Cavendish Laboratory have now developed high speed detectors capable of receiving information with much higher key rates, thereby able to receive more information faster.

Published as part of IOP Publishing’s New Journal of Physics‘ Focus Issue on ‘Quantum Cryptography: Theory and Practice’, the journal paper, ‘Practical gigahertz quantum key distribution based on avalanche photodiodes’, details how quantum communication can be made possible without having to use cryogenic cooling and/or complicated optical setups, making it much more likely to become commercially viable soon.

One of the first practical applications to emerge from advances in the often baffling study of quantum mechanics, quantum cryptography has become the soon-to-be-reached gold standard in secure communications.

Quantum mechanics describes the fundamental nature of matter at the atomic level and offers very intriguing, often counter-intuitive, explanations to help us understand the building blocks that construct the world around us. Quantum cryptography uses the quantum mechanical behaviour of photons, the fundamental particles of light, to enable highly secure transmission of data beyond that achievable by classical encryption.

The photons themselves are used to distribute keys that enable access to encrypted information, such as a confidential video file that, say, a bank wishes to keep completely confidential, which can be sent along practical communication lines, made of fibre optics. Quantum indeterminacy, the quantum mechanics dictum which states that measuring an unknown quantum state will change it, means that the key information cannot be accessed by a third party without corrupting it beyond recovery and therefore making the act of hacking futile.

While other detectors can offer a key rate close to that reported in this journal paper, the present advance only relies on practical components for high speed photon detection, which has previously required either cryogenic cooling or highly technical optical setups, to make quantum key distribution much more user-friendly.

Using an attenuated (weakened) laser as a light source and a compact detector (semiconductor avalanche photodiodes), the researchers have introduced a decoy protocol for guarding against intruder attacks that would confuse with erroneous information all but the sophisticated, compact detector developed by the researchers.

As the researchers write, “With the present advances, we believe quantum key distribution is now practical for realising high band-width information-theoretically secure communication.”

Governments, banks and large businesses who fear the leaking of sensitive information will, no doubt, be watching closely.

 

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September 25, 2008

Quantum computing and more

We’re getting closer to harnessing quantum mechanics to create supercomputers and other devices.

From the link:

The brave new world of quantum technology may be a big step closer to reality thanks to a team of University of Calgary researchers that has come up with a unique new way of testing quantum devices to determine their function and accuracy. Their breakthrough is reported in today’s edition of Science Express, the advanced online publication of the prestigious journal Science.

“Building quantum machines is difficult because they are very complex, therefore the testing you need to do is also very complex,” said Barry Sanders, director of the U of C’s Institute for Quantum Information Science and a co-author of the paper. “We broke a bunch of taboos with this work because we have come up with an entirely new way of testing that is relatively simple and doesn’t require a lot of large and expensive diagnostic equipment.”

Similar to any electronic or mechanical device, building a quantum machine requires a thorough understanding of how each part operates and interacts with other parts if the finished product is going to work properly. In the quantum realm, scientists have been struggling to find ways to accurately determine the properties of individual components as they work towards creating useful quantum systems. The U of C team has come up with a highly-accurate method for analyzing quantum optical processes using standard optical techniques involving lasers and lenses.

June 11, 2008

Quantum cryptography

Move over one-time pad, there’s a new kid on the cryptographic block — quantum cryptography. This is one amazing application for the weirdness that is quantum mechanics and quantum effects. And one cool way to transmit secret messages.

Today’s KurzweilAI.net newsletter had a link to a Scientific American story on space-based quantum codes used for cryptography.

Over at Bad Astronomy, Phil Plait wrote about this on Monday. He offers a cool short-version explanation of the quantum mechanics involved, and his comment section has even more detail provided by BABlog readers.

Here’s the KurzweilAI  short:

Space Station Could Beam Secret Quantum Codes by 2014
ScientificAmerican.com, June 9, 2008

University of Vienna researchers hope to send an experiment to the International SpaceStation (ISS) by the middle of the next decade that would pave the way for transcontinental transmission of secret messages encoded using quantum entanglement.


(European Space Agency

In addition to potential use for secure communications, the “Space-QUEST” project would give researchers a chance to test the theory that entanglement should be unlimited in range.

 
Read Original Article>>

 

Here’s an excerpt from the Scientific American link found above at “Read Original Article”:

Researchers hope to send an experiment to the International Space Station (ISS) by the middle of the next decade that would pave the way for transcontinental transmission of secret messages encoded using the mysterious quantum property of entanglement.

When two particles such as photons are born from the same event, they emerge entangled, meaning they can communicate instantaneously no matter how far apart they are. Transmitting entangled pairs of photons reliably is the backbone of so-called quantum key distribution—procedures for converting those pairs into potentially unbreakable codes. Quantum cryptography, as it is known, could appeal to banks, covert government agencies and the military, and was tested in a 2007 Swiss election

Here’s some of Phil Plait’s commentary at Bad Astronomy:

So some European scientists came up with the idea of using the International Space Station (I know! Using ISS for science! Wow!) to test this out. They can create a small setup with a laser which can create entangled photons. The entangled photons are then sent simultaneously to two different ground stations, widely separated on the surface of the Earth, so that both have a copy of the entangled photons. In addition, two quantum keys are created based on the photons; this is essentially a code based on the state of the photons — like winning a bet is based on which way a coin lands. The two keys are different, and one each is sent to the two ground stations. So both stations have a pair of entangled photons (identical to the other station’s) and a different key.

Each key is actually a long chain of 1s and 0s. The two keys are then compared on the ISS to create what’s called a bitwise XOR — for example, if two coins both land heads then the XOR operation yields a 0, but if they land differently (one heads and one tails) then it yields a 1 — it’s just telling you whether they are the same or different. So for each place in the key, the two numbers are compared, and if they’re the same (both 1s or both 0s) then a 0 is written down. If they are different then a 1 is put there. When this is done, you get a third string of 1s and 0s, representing a comparison of the two keys.

Still with me? Yeah, me neither, but we’re almost done. So now the ISS has this long number string which represents whether the keys are alike or different. It then transmits this to one of the two stations on Earth.

So? What does this mean? This means that now the two ground stations can create a code between them based on their keys, a code that is known only to them and no one else. Furthermore, this code cannot be cracked by anyone, anywhere, because it’s based on entangled photons that cannot be known to anyone else! Because of entanglement, they know what the other station has because they can look at their key and figure it out. But no one else can.

February 27, 2008

Nanotechnology advances in quantum computing

Filed under: Science, Technology — Tags: , , , , , — David Kirkpatrick @ 11:52 pm

More cool nanotech. This time from the KurzweilAI.net newsletter. For reference, a qubit is a unit of quantum information.

Physicists Demonstrate Qubit-Qutrit Entanglement
PhysOrg.com, Feb. 26, 2008An international team of physicists entangled a qubit with its 3D equivalent, the “qutrit,” demonstrating a new way to handle higher-dimensional quantum information carriers.

Qubit-qutrit entanglement could lead to advantages in quantum computing, such as increased security and more efficient quantum gates, and enable novel tests of quantum mechanics. A qutrit is the quantum informationanalogue of the classical trit and carries more information: it exists in superpositions of its three basics states, while a qubit can exist in superpositions of its two states.
Read Original Article>>