Entangled Web: The optical components on this lab bench, such as mirrors and filters, allow researchers in Prem Kumar’s lab at Northwestern University to direct and manipulate light. In Kumar’s most recent work, he has created a quantum logic gate within an optical fiber; such gates could eventually enable networks of quantum computers.
Prem Kumar
A quantum logic gate in an optical fiber could lay the foundation for a quantum computer network.
The promise of quantum computers is tantalizingly great: near-instantaneous problem solving, and perfectly secure data transmission. For the most part, however, small-scale demonstrations of quantum computation remain isolated in labs throughout the world. Now, Prem Kumar, a professor of electrical engineering and computer science at Northwestern University, has taken a step toward making quantum computing more practical. Kumar and his team have shown that they can build a quantum logic gate--a fundamental component of a quantum computer--within an optical fiber. The gate could be part of a circuit that relays information securely, over hundreds of kilometers of fiber, from one quantum computer to another. It could also be used on its own to find solutions to complicated mathematical problems.
A logic gate is a device that receives an input, performs a logic operation on it, and produces an output. The type of gate that Kumar created, called a controlled NOT gate, has a classical-computing analogue that flips a bit registering a "1" to "0," and vice versa. Quantum logic gates like Kumar's have been built before, but they worked with laser beams that passed through the air, not through fiber. The new gate lays the foundation for experiments that demonstrate the abilities of quantum computers in fiber, says Kumar. "The exciting thing here is that an application is within reach," he says. Within the next year, Kumar and his team plan to test the gate in a specific application: conducting a complex auction over a secure quantum network.
Researchers at IBM, MIT, and many other corporations and universities have been working on quantum computers since they were first proposed in the 1980s. A quantum computer is a device that processes bits of information by exploiting the weird quantum-mechanical properties of particles such as electrons and photons. A quantum computer is theoretically able to process exponentially more information than classical computers can. The unit of information in a classical computer is the bit, which represents either a "1" or a "0"; but in a quantum computer, it's the qubit, which can represent both a "1" and a "0" at the same time. Since qubits compute with multiple values at once, the processing power of a quantum computer doubles with each additional qubit. This characteristic would enable a quantum computer with only a couple hundred qubits to significantly outperform today's best supercomputers.
Kumar's group makes qubits out of photons that are "entangled." That means that their physical characteristics, such as polarization, are linked in such a way that if one photon assumes a particular physical state, the matching photon instantly assumes a corresponding state. A few years ago, Kumar demonstrated that optical fiber itself could cause photons to become entangled, and that they would remain entangled over a distance of 100 kilometers. His recent work, described in Physical Review Letters, goes one step further, creating a logic gate that entangles photon pairs.
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No no, the end result of the gate would have to be 100% entangled, I would imagine for total security in the environment. And the X^2 binary we know would double, becase the quibit it both a "1" and "0" at the same time. So it would be x^4
I don't know much about quantum computation. However the article says that quantum computers can deal with exponentially more information than classical computers. x^2, x^3, x^4 are all polynomials. Exponential implies something of the form a^x, with constant a.
Yeah, I think the original poster probably meant the 2^x binary we know, since the number of possible values that can be expressed by x bits is 2^x. So x qubits can express all those values simultaneously; a calculation performed using eight qubits, for instance, is the equivalent of 256 separate calculations on a classical computer.
http://www.cs.caltech.edu/~westside/quantum-intro.html
This article really helped me wrap my head around the basics of quantum computers. And this article is just a bit more challenging but provides a great basis:
http://antoine.frostburg.edu/chem/senese/101/quantum/
Enjoy :)
Indeed, quantum computers will be affecting our lives directly, even though they rely on quantum phenomena, so it's much easier to understand what's going on in that weird world.
This article defines qubit just a bit inaccurately. A qubit is 1, 0, and a superposition between 1 and 0. So it isn't that it is 1 and 0 at the same time, it embodies all values between as well. At least, from my reading, that is how I understand it.
This just in ... Comcast researchers discover a way to increase rates on a quantum level by acting as internet gate keepers. Comcast calls this the "Quantum Net", and promises to charge every website a toll per visitor, thus Quantumly enhancing their profits and decreasing user satisfaction simultaneously.
Wow!, some progress ... finally. This article does give hope that I'll someday have some kind of Apple computer device in my arthritic hands for my Alzheimered mind to play with before I croak. Though I suppose I'll probably be long gone dead when the throw the switch to turn on the first commercial fusion engine. I mean, talk about snail's pace.
When was the word quantum first uttered in relation to the atomic world? More than eighty years ago?
Geez, let's get going, fellas! God forbid some Bangladeshi, or heavens to Mergatroid, a North Korean brilliantly writes the paper of Papers ...! The humiliation we'll pass on to future generations, and it'll never lie down.
Don't worry too much, we've got them all working in our research labs already, so we can just take the credit when they find something.
Unfortunately, quantum computing is one of the areas I've started to allow other people to learn about instead of taking it on myself. I may be able to wrap my head around it all with enough effort but I'm beginning to realize how little impact I have on the subject compared with other areas. The amount of effort it takes to become an expert in this particular field is better left to someone more passionate about it than myself. It's basically become the next subject ignored in a line that started with Greek Tragedy.
Manufacturing in the United States is in trouble. That's bad news not just for the country's economy but for the future of innovation.
This document is part of the “How-To Guide for Most Common Measurements” centralized resource portal. This tutorial provides a detailed guide for measurement and device considerations to take temperature measurements using thermocouples. Get an introduction to thermocouples, which are inexpensive sensing devices widely used with PC-based data acquisition systems. Also review some specific thermocouple examples and learn how thermocouples work and ways to integrate them into a data acquisition measurement system.
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Shiladie
56 Comments
Reliability
I'm assuming that the chance of the photons not being entangled would have to be lowered before this can be put into a production environment.
also, with the qubit, is it simply taking the X^2 of binary we know and love and making it X^3 by adding a 3rd option? or is there more that I'm not understanding?
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brunascle
65 Comments
Re: Reliability
with the qubit, is it simply taking the X^2 of binary we know and love and making it X^3 by adding a 3rd option?
not really. from what i understand, a qubit is kind of like a bunch of regular bits blurred together. each of those bits can only be a 1 or 0.
and a quantum computer is kind of like a bunch of classical (binary) computers blurred together, all running the same algorithm at the same time. each one comes up with a different answer, and if the algorithm is set up right, the one answer you're looking for will stand out above the rest.
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