. The ions interact through oscillatory motions. Researchers can manipulate the particles by training laser beams on them. )
TRAPPED-ION COMPUTERS could encode and process data with strings of ions that act somewhat like the suspended metal balls in a Newton's cradle (as seen in this artist's conception). The ions interact through oscillatory motions. Researchers can manipulate the particles by training laser beams on them.
Image: David Emmite (computer setup); George Retseck (spheres)
In Brief
- Quantum computers can store and process data using atoms, photons or fabricated microstructures. These machines may someday be able to perform feats of computing once thought to be impossible.
- The manipulation of trapped ions is at the forefront of the quantum computing effort. Researchers can store data on the ions and transfer information from one ion to another.
- Scientists see no fundamental obstacles to the development of trapped-ion computers.
More In This Article
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Infographic
Quantum Computing with Ions: The Basics
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Infographic
One Approach--Ion Strings
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Infographic
Quantum Computing with Ions: Another Approach--Linking Ions with Photons
Editor’s note (10/9/2012): We are making the text of this article freely available for 30 days because the article was cited by the Nobel Committee as a further reading in the announcement of the 2012 Nobel Prize in Physics and was also written by one of the prize winners. The full article with images, which appeared in the August 2008 issue, is available for purchase here.
Over the past several decades technological advances have dramatically boosted the speed and reliability of computers. Modern computer chips pack almost a billion transistors in a mere square inch of silicon, and in the future computer elements will shrink even more, approaching the size of individual molecules. At this level and smaller, computers may begin to look fundamentally different because their workings will be governed by quantum mechanics, the physical laws that explain the behavior of atoms and subatomic particles. The great promise of quantum computers is that they may be able to perform certain crucial tasks considerably faster than conventional computers can.
Perhaps the best known of these tasks is factoring a large number that is the product of two primes. Multiplying two primes is a simple job for computers, even if the numbers are hundreds of digits long, but the reverse process—deriving the prime factors—is so extraordinarily difficult that it has become the basis for nearly all forms of data encryption in use today, from Internet commerce to the transmission of state secrets.
In 1994 Peter Shor, then at Bell Laboratories, showed that a quantum computer, in theory, could crack these encryption codes easily because it could factor numbers exponentially faster than any known classical algorithm could. And, in 1997, Lov K. Grover, also at Bell Labs, showed that a quantum computer could significantly increase the speed of searching an unsorted database—say, finding a name in a phone book when you have only the person’s phone number.
Actually building a quantum computer, however, will not be easy. The quantum hardware—the atoms, photons or fabricated microstructures that store the data in quantum bits, or qubits—needs to satisfy conflicting requirements. The qubits must be sufficiently isolated from their surroundings; otherwise stray external interactions will halt their computations. This destructive process, known as decoherence, is the bane of quantum computers. But the qubits also have to interact strongly with one another and must ultimately be measured accurately to display the results of their calculations.
Scientists around the globe are pursuing several approaches to building the first prototype quantum computers. Our own research focuses on processing information with singly charged positive ions, atoms that have been stripped of one electron. We have trapped short strings of ions—confining the particles in a vacuum using electric fields produced by nearby electrodes—so that they can receive input signals from a laser and share data with one another. Our goal is to develop quantum computers that are scalable—that is, systems in which the number of qubits could be increased to the hundreds or thousands. Such systems would fulfill the promise of the technology by accomplishing complex processing tasks that no ordinary computer could match.
Trapping Ions
Quantum mechanics is a theory based on waves. Just as the sound waves from two or more piano strings can merge into a chord, different quantum states can be combined into a superposition. For example, an atom may be simultaneously in two locations or in two different states of excitation. When a quantum particle in a superposition state is measured, the conventional interpretation is that the state collapses to a single result, with the probability of each possible measurement given by the relative proportions of the waves in the superposition. The potential power of a quantum computer derives from these superpositions: unlike a conventional digital bit, which can have a value of either 0 or 1, a qubit can be both 0 and 1 at the same time. A system with two qubits can hold four values simultaneously—00, 01, 10 and 11. In general, a quantum computer with N qubits can simultaneously manipulate 2N numbers; a collection of only 300 atoms, each storing a quantum bit, could hold more values than the number of particles in the universe!
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19 Comments
Add CommentI^mz .... I = infinite ^ angle of mz = largest and smalles measurement programmed ga programming
Reply | Report Abuse | Link to thisIs the editor on vacation?
Reply | Report Abuse | Link to thisThis article starts minus the capital letter.
"...technological advances have dramatically boosted the..." Is that the beginning of the sentence? If so, why isn't the 't' capitalized??
Are we just throwing out the basic grammar rule book now? Shame on Sci Am. Don't publish if you aren't doing to do it right.
Quasimodo-Were you picked on a lot as a kid? The article is concise and informative. Get over yourself and take the benefit from this article that it most definitely offers. Besides I do not know what article you read but the capitalization and punctuation is fine. The sentence starts:
Reply | Report Abuse | Link to this"Over the past several decades technological advances have dramatically boosted the speed and reliability of computers."
So you have made an even bigger fool of yourself than I first assumed.
**The field of quantum information science promises to radically change the rules of computing.** As scientists still work on small size quantum gates, they cannot afford arguing about new computing rules at present. Designing the new rules simply belongs to another realm of understanding. Similarly, what evolutionism could prove so far is so inexistent that its early allegations about origin of life are boldly presumptuous. So far, origin of life is not a scientific debate.
Reply | Report Abuse | Link to thisSciMike,
Reply | Report Abuse | Link to thisProfessionals write professionally, got it? Too bad if you don't. You answered my question with a question. That's pretty unprofessional.
Either answer my question, or hush up. My question had Nothing to do with the actual facts put forth in the body of the article. Grow up and smell the decade.
I have a question, if anyone here can help me out on this. Considering qubits that are based on the magnetic orientation of a trapped ion, as I understand it, in order to make a particle (say a proton) "flip" in a magnetic field from one orientation to another, we need to apply an amount of energy (by using a wave of particular frequency) that is exactly equivalent to the energy gap between the two spin states (orientations). So, how exactly is it possible to make the particle be in the superposition state? Do we apply half the energy or twice as much (which doesn't make sense), or what exactly do we do? I guess this is the whole point of quantum mechanics...but I dont really get it.
Reply | Report Abuse | Link to thisOh yeah, and something else regarding logic gates....maybe I misunderstood, but how is it possible to form classic logic gates like AND and OR gates using qubits? I mean, these gates are based on determinable deductive logic, but in quantum mechanics, there is always uncertainty (heisenberg's principle) and logic is based on probability (am I right?), so how is that possible?
Reply | Report Abuse | Link to thisIt is of certain intrigue how the evolutionary procedure of this technological branch would reach the ironic imminence of its possible outcomes, which will set forward a whole new perspective on the computational processes within modern electronics. But considering the constant repression the elite has over the introduction of ideas that can potentially compromise their agenda, this technology would still be far from reaching consumer applications.
Reply | Report Abuse | Link to thisOh yeah, and something else regarding logic gates....maybe I misunderstood, but how is it possible to form classic logic gates like AND and OR gates using qubits? I mean, these gates are based on determinable deductive logic, but in quantum mechanics, there is always uncertainty (heisenberg's principle) and logic is based on probability (am I right?), so how is that possible?
Reply | Report Abuse | Link to thisQuantum dot: Are you trying to understand how the gates work or are you just asking how classical gates can be used at all? If you are asking how a classical logic gate works in this situation I will explain that. The logic behind the gates (as I see it) works on a basic principle of quantum mechanics: when you measure something, it changes. Uncertainty doesn't apply in this instance. I see this as a similarity to the double slit experiment where a physical medium is used to measure a quantum state, which forces it to choose and orientation.
ID-based COMPLEX GATES : ID global approach holds the overall answer (God), to be verified in subsequent details. Conversely, evolutionism starts from details (fossils), with no serious intention of reaching a significant answer(Void). Similarly, quantum gates computing rules are determined from software design, while Hardware approach deals with details void of meaning. For instance, the elementary quantum gate described here may get two meanings: CNOT (already described) and XOR. Let us call D1, D2 respectively the first and second data of the gate and A the XOR result. If D1 is 1 and D2 is 1, D2 holds the result as 0: A=D2=0**D1=1, D2=0: A=D2=1** D1=0, D2=1: A=D2=1 **D1=0, D2=0: A=D2=0 ** It is therefore software level interpretation (as XOR or CNOT) that gives the gate its actual meaning, hardware approach simply describing the gate maravellous potential.
Reply | Report Abuse | Link to thisQuasimodo , I find it hilarious that your incorrect rant about an error in their article, is followed with this statement by you:
Reply | Report Abuse | Link to this"Shame on Sci Am. Don't publish if you aren't doing to do it right. "
Hilarious! Shame on you, don't comment if you aren't going to do it correctly!
Kevino819, thank you for your response. You mentioned the basic quantum mechanical principle of: when we measure something, it changes, but what I was trying to say is I just don't understand how its possible to run an algorithm or a program, or to program the logic gates themselves, when the outcome is unknown and based on the measurement, there is no expected result, do you see what I'm trying to say? I mean, its like trying to use logic gates for something where there is no logic.
Reply | Report Abuse | Link to thisWith the AND and OR gates, you'd do it kinda like it's done like it's done in a normal computer. AND: measure two qubits. if they're both in the 1 state, then your AND thing gets a 1 as a return. for the OR gate you'd do the same thing but return a 1 if either qubit was a 1.
Reply | Report Abuse | Link to thisOh, and i think that the qubits can use any of their properties as the data carrying ones, it doesn't have to be their magnetic alignment, it can be anything.
Something that would be very cool about this technology (if i'm assuming correctly) is that you could entangle particals and seperate them between a pair of machines, creating a wireless connection between the two of infinite range. It would work in a tunnel, underground, on the moon! Or, you could go a stage further and link all the processors of all Quantum computers in the world so that they share their computing power amongst all the users!
I will be the first one implements commercial Qcomputer
Reply | Report Abuse | Link to thisI will be the first one implements commercial Qcomputer.
Reply | Report Abuse | Link to thisIt is a very nice thing to see your excellent work and I like your article very much. With your rich knowledge, we can learn more from your wonderful post. Thanks so much.
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What's most interesting is how conditional programs might be able to use probabilistic results of conditional tests - will this be accomplished through probabilistic branch functions? 'If taxable income >72% Then 48% Perform tax calculation...'
Reply | Report Abuse | Link to thisQuasi, SciMike was right. You were and are wrong. And, oddly, you persisted in being wrong.
Reply | Report Abuse | Link to thisI have been puzzled of late. With the Higgs Boson "found" does that mean we have M-theory to ponder. I mean the standard model is vindicated and there is a bridge to quantum effects within the standard model. If this is correct the M-theory is valid; please correct me if I have strayed. What I want to know is what does an electron, for instance, look like in any of the other 7 dimensions and can that be computed using this method. Can we develop sensors and emitters to augment our simple four dimensions? Does that form the basis of what dark matter is? This has had me in a transfixed state since the Higgs was defined. If anyone can elucidate more please feel free!
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