Qubit? The Stuff Science Fiction Is Made of

By March 17, 2003

Wasn?t it just a few years ago that fastest CPU out there was the Intel Pentium 233MMX?

Now you can buy the Intel P4 2 Ghz with speeds later this year reaching 2.5Ghz + . Ever wonder why? I know I have.

I think I may have found an answer, a link to why processor speeds are going up and prices are going down. The future is coming, and for you super geeks out there, it might be here sooner than you think. I can use one word, ?qubit ?.

For those of you who are familiar with the term qubit, you can?t wait. For others who are thinking ? what is he talking about? ?, I?ll let you in on a little secret.

Quantum Computers. I heard that and thought to my self ?ya right? that will never happen, at least not in my life time. But according to an article by R. Colin Johnson, the NSF (National Science Foundation ) is already searching for a reliable chip-making process.

The NSF has contributed $1.6 billion dollars and a four-year effort to create such a process. At the current present only one of the leading candidates for this process has published their yields. Out of about 40 attempts, only two or three Quantum computers have actually worked at room temperature.

The aim is to have a quantum computer work at a room temperature and make it manufacturable to the public. The lead on this project is Paul R. Berger, an associate professor of electrical engineering at Ohio State University, teamed with the assistance of the University of Illinois at Urbana-Champaign, the University of Notre Dame, the University of California at Riverside, and the Naval and Air Force Research Laboratories. You didn?t think that a super computer like this wouldn?t have the governments fingers into it would you?

For those of you who are not familiar with what a Quantum computer is, here is the dirt ( I hope you have your physics hat on ).

Quantum computers use a processor much like any other computer. Except, the processor for this computer is what they call a quantum dot (now here is where the information gets thick).

A quantum dot is a small metal or semiconductor box that holds a well-defined number of electrons. The number of electrons in a dot may be adjusted by changing the dot?s electrostatic environment. Dots can be and have been made ranging from 30 nm (nanometers) to 1 micron in size, and holding from zero to hundreds of electrons (information above provided from ?The Nanoelectronics and Nanocomputing Home Page?).
Quantum dots store information in domains that are at least 10 times smaller than those typically proposed for future silicon chip technologies ? only a few square nanometers, containing 50 to 10,000 atoms per stored quantum bit (qubit). The devices work by instantaneously passing individual electrons across an insulator without taking any time to physically pass through it ? a phenomena called “tunneling” says R. Colin Johnson.

Today, those researchers who are experimenting with their own quantum chips design, build or create their own process technology without trading off manufacturability, good yields, room-temperature operation, reliability and repeatability for small size.

The ?probability wave? effects the results of tunneling into quantum dots. Because of the finite probability that an electron can turn up on the other side of the insulating barrier, quantum mechanics predicts that some electrons will turn up on one or the other side, depending on the current ?environmental? conditions.

According to the information provided by R. Colin Johnson:

?In addition to tunneling, each nanosize domain can store both a 1 and 0 simultaneously by virtue of what is called “superposition” within their qubits. Superposition?s keep the logical state of a qubit nebulous until called upon to “report” in a result. Hence, qubits simultaneously represent both 1 and 0 and can consequently perform calculations that superimpose intermediate steps atop one another in parallel, only later picking out the desired end result from multiple possible calculations.
For instance, superposition enables an 8-qubit adder to simultaneously perform all possible 8-bit additions to all possible 8-bit values. After the addition, an individual result can be picked out from among the 512 possible results that are superimposed atop each other in a single machine cycle by the qubit adder. ?
So at this point we scratch our heads and say ?Hugh, so what?s the difference between a regular desktop pc and a quantum computer??

Ok, modern computers manipulate information in what we call binary mathematics ones and zeros. That?s the fundamental basis of our current computing world. The two bits can form four combinations of ones and zeros. In a standard pc you could have 8 billion bits which will provide large potential for information.

A quantum computer performs this task differently. A qubit can attain multiple states simultaneously-each state having a probability. Each combination of ones and zeros would require a probability. The amount of combinations can grow like crazy: for n qubits there are 2^n different states, each one having a probability associated with it (Quantum).
A good example comes from Scientific American, illustrating how a modern computer and a quantum computer would find the right combination for a lock:

Take a lock with 4 numbers: 0, 1, 2, 3; and any one number needed to unlock it. A modern computer would try each number in turn: is ‘1’ correct? Is ‘2’ correct? And so on. It would potentially try all 4 numbers, until it found the correct number. A quantum computer would test multiple numbers at the same time and get a unique answer for each potential correct answer. The modern computer averages n/2 guess, whereas the quantum computer needs only the square root of n (Quantum).

Considering the enormous calculations that quantum computers can perform, the possibilities seem with out limits. Think of the computing possibilities in all fields of learning and creating. The medical field could greatly benefit from quantum computing, doctors could explore the human body and experiment on simulated environments, advancing medical research enormously. You even have the ability to calculate the prime factorization of large numbers. Prime factorization is what we know as mathematical algorithm that most organizations use for encryption.

Example by Ben Simpson,
It is very hard to calculate in reverse; a modern computer might spend millions of years trying to perform the necessary calculations, rendering any hacking attempts laughable (Quantum). A quantum computer, however, might complete the required calculations in less than a year. Now that?s a bit scary.

At this point I hope I haven?t confused you too much on this subject. As for me, I can?t wait for a Quantum computers to make their appearance. So do you think it might stand to reason that CPU manufactures would be getting worried? Once the Quantum computer comes out, it would make their systems obsolete. One question would be ?are computer manufactures researching this technology too??. I would bet my money on it.

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