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Natural quantum computation

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I've been trying to understand quantum computing and despite having background in QM and computation haven't made much truck. Here's a video I've found that explains it well, by a guy who is building commercial quantum computers

D-Wave

Note this isn't a universal quantum computer, it's a specialized device made to solve a particular type of algorithm, namely simulated annealing or quantum annealing problems. These are Monte Carlo simulations where you run many simulations with a random initial state, looking for a minima which is your solution.

Anyhow hope this is helpful.
 

Analyzer

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Looks interesting, the possibilities of quantum computers are amazing.

How do you think software will be effected by quantum computers. Meaning the engineering side of it. Will it introduce in a new paradigm in programming languages, not based on boolean algebra?
 

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Looks interesting, the possibilities of quantum computers are amazing.

How do you think software will be effected by quantum computers. Meaning the engineering side of it. Will it introduce in a new paradigm in programming languages, not based on boolean algebra?

Quantum computers need to be programmed quite differently. In the example above you can see that the programming is a few vectors of numbers, but this is a speciality computer*. We don't know what programming a general purpose quantum computer would look like, because we haven't (as far as I know) been able to design a GPQC, much less define the class of problems which could be solved on one. So far we just know how to program a QC to solve monte carlo problems as above, and there's been talk of QCs being used to solve factoring problems for crypto applications.

As far as I understand QCs don't do more than can be done with computers we have today, and at the moment they do far less. The advantage is that whereas computing power goes up linearly with number of bits, it goes up exponentially (as a power) with qbits.

* In the video he mentioned using the D-wave computer for machine learning programs. Indeed, modern neural nets are computed simply by multiplying vectors and matrices, which is something their computer could handle quite well.
 

Coolydudey

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I want one...

They do offer some pretty awesome applications in the fields they specialize in, and the technology behind them is really cool. It is however unclear how far the field can advance, given its rate of progress now and the theoretical understanding of what is needed (relatively complete). Perhaps someone will make a major breakthrough allowing better scalability of quantum computers on a practical level.
 

BigApplePi

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New York Times Article on Quantum Computing
http://www.nytimes.com/2013/03/22/t...eedy-computer.html?pagewanted=1&_r=0&emc=eta1

VANCOUVER, British Columbia — Our digital age is all about bits, those precise ones and zeros that are the stuff of modern computer code.

News from the technology industry, including start-ups, the Internet, enterprise and gadgets.

Quantumjp-articleInline.jpg

Kim Stallknecht for The New York Times

Geordie Rose, left, a founder and chief technical officer of D-Wave, and Vern Brownell, the company’s chief executive.

But a powerful new type of computer that is about to be commercially deployed by a major American military contractor is taking computing into the strange, subatomic realm of quantum mechanics. In that infinitesimal neighborhood, common sense logic no longer seems to apply. A one can be a one, or it can be a one and a zero and everything in between — all at the same time.
It sounds preposterous, particularly to those familiar with the yes/no world of conventional computing. But academic researchers and scientists at companies like Microsoft, I.B.M. and Hewlett-Packard have been working to develop quantum computers.
Now, Lockheed Martin — which bought an early version of such a computer from the Canadian company D-Wave Systems two years ago — is confident enough in the technology to upgrade it to commercial scale, becoming the first company to use quantum computing as part of its business.
Skeptics say that D-Wave has yet to prove to outside scientists that it has solved the myriad challenges involved in quantum computation.
But if it performs as Lockheed and D-Wave expect, the design could be used to supercharge even the most powerful systems, solving some science and business problems millions of times faster than can be done today.
Ray Johnson, Lockheed’s chief technical officer, said his company would use the quantum computer to create and test complex radar, space and aircraft systems. It could be possible, for example, to tell instantly how the millions of lines of software running a network of satellites would react to a solar burst or a pulse from a nuclear explosion — something that can now take weeks, if ever, to determine.
“This is a revolution not unlike the early days of computing,” he said. “It is a transformation in the way computers are thought about.” Many others could find applications for D-Wave’s computers. Cancer researchers see a potential to move rapidly through vast amounts of genetic data. The technology could also be used to determine the behavior of proteins in the human genome, a bigger and tougher problem than sequencing the genome. Researchers at Google have worked with D-Wave on using quantum computers to recognize cars and landmarks, a critical step in managing self-driving vehicles.
Quantum computing is so much faster than traditional computing because of the unusual properties of particles at the smallest level. Instead of the precision of ones and zeros that have been used to represent data since the earliest days of computers, quantum computing relies on the fact that subatomic particles inhabit a range of states. Different relationships among the particles may coexist, as well. Those probable states can be narrowed to determine an optimal outcome among a near-infinitude of possibilities, which allows certain types of problems to be solved rapidly.
D-Wave, a 12-year-old company based in Vancouver, has received investments from Jeff Bezos, the founder of Amazon.com, which operates one of the world’s largest computer systems, as well as from the investment bank Goldman Sachs and from In-Q-Tel, an investment firm with close ties to the Central Intelligence Agency and other government agencies.
“What we’re doing is a parallel development to the kind of computing we’ve had for the past 70 years,” said Vern Brownell, D-Wave’s chief executive.
Mr. Brownell, who joined D-Wave in 2009, was until 2000 the chief technical officer at Goldman Sachs. “In those days, we had 50,000 servers just doing simulations” to figure out trading strategies, he said. “I’m sure there is a lot more than that now, but we’ll be able to do that with one machine, for far less money.”
D-Wave, and the broader vision of quantum-supercharged computing, is not without its critics. Much of the criticism stems from D-Wave’s own claims in 2007, later withdrawn, that it would produce a commercial quantum computer within a year.

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“There’s no reason quantum computing shouldn’t be possible, but people talked about heavier-than-air flight for a long time before the Wright brothers solved the problem,” said Scott Aaronson, a professor of computer science at the Massachusetts Institute of Technology. D-Wave, he said, “has said things in the past that were just ridiculous, things that give you very little confidence.”

QUANTUM2-articleInline.jpg

Kim Stallknecht for The New York Times

The processor of a quantum computer at D-Wave Systems’ lab in Burnaby, British Columbia.

News from the technology industry, including start-ups, the Internet, enterprise and gadgets.

But others say people working in quantum computing are generally optimistic about breakthroughs to come. Quantum researchers “are taking a step out of the theoretical domain and into the applied,” said Peter Lee, the head of Microsoft’s research arm, which has a team in Santa Barbara, Calif., pursuing its own quantum work. “There is a sense among top researchers that we’re all in a race.”
If Microsoft’s work pans out, he said, the millions of possible combinations of the proteins in a human gene could be worked out “fairly easily.”
Quantum computing has been a goal of researchers for more than three decades, but it has proved remarkably difficult to achieve. The idea has been to exploit a property of matter in a quantum state known as superposition, which makes it possible for the basic elements of a quantum computer, known as qubits, to hold a vast array of values simultaneously.
There are a variety of ways scientists create the conditions needed to achieve superposition as well as a second quantum state known as entanglement, which are both necessary for quantum computing. Researchers have suspended ions in magnetic fields, trapped photons or manipulated phosphorus atoms in silicon.
The D-Wave computer that Lockheed has bought uses a different mathematical approach than competing efforts. In the D-Wave system, a quantum computing processor, made from a lattice of tiny superconducting wires, is chilled close to absolute zero. It is then programmed by loading a set of mathematical equations into the lattice.
The processor then moves through a near-infinity of possibilities to determine the lowest energy required to form those relationships. That state, seen as the optimal outcome, is the answer.
The approach, which is known as adiabatic quantum computing, has been shown to have promise in applications like calculating protein folding, and D-Wave’s designers said it could potentially be used to evaluate complicated financial strategies or vast logistics problems.
However, the company’s scientists have not yet published scientific data showing that the system computes faster than today’s conventional binary computers. While similar subatomic properties are used by plants to turn sunlight into photosynthetic energy in a few million-billionths of a second, critics of D-Wave’s method say it is not quantum computing at all, but a form of standard thermal behavior.
 

TimeAsylums

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http://www.scottaaronson.com/democritus/lec11.html

As the flip side, the picture also explains why it's so hard to build quantum computers: because not only are we trying to keep errors from leaking into our computer, we're trying to keep the computer from leaking into the rest of the world! We're fighting against decoherence, one of the most pervasive processes in the universe. Indeed, it's precisely because decoherence is so powerful that the quantum fault-tolerance theorem came as a shock to many physicists. (The fault-tolerance theorem says roughly that, if the rate of decoherence per qubit per gate operation is below a constant threshold, then it's possible in principle to correct errors faster than they occur, and thereby perform an arbitrarily long quantum computation.)

that's really cool
 

John_Mann

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How far we've come! We are on the verge of the very reality. Intentionally manipulating these tiny particles of matter.
 
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