Robotics Reference
In-Depth Information
an electronic computer. To put this into perspective, one thousand bil-
lion of these computers would fit into a teardrop and almost ten million
on the full stop at the end of this sentence. This breakthrough in size
points the way to tiny medical “nanosubs” that hunt down tumours and
germs before delivering their drugs, in much the same way as in the 1966
movie
Fantastic Voyage,
in which a submarine is shrunk by military re-
searchers and dispatched to destroy a blood clot threatening the life of a
key scientist.
The Quantum Computer
A full explanation of the meaning of “quantum computing” would reach
far beyond the scope of this topic, but the brief description in this section
conveys the general idea. Quantum computing is a new field in computer
science, one that has been developed as a result of mankind's increased
understanding of the science of the structure and functions of atoms,
a science known as quantum physics or quantum mechanics. In the
electronic computers we all know and love, the basic unit of information
is a
bit
(coined from “binary digit”). A binary digit is a 0 or a 1 and all
binary numbers are made up of a string of 0s and 1s. The bit employed
in the computers of today can therefore be in only one of two states.
In quantum computing the basic unit of information—the equiva-
lent of a bit—is called a
qubit
(quantum bit), and can be in both states
at the same time.
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It has been shown that a sub-atomic particle can
have different states simultaneously because when the momentum of a
particle is measured, that momentum appears different to different ob-
servers and thus the particle has several different states simultaneously.
This has been shown to be true for particles moving very fast, close to the
speed of light. Because one subatomic particle can have different states at
the same time, a combination of qubits holds very much more informa-
tion than a combination of the same number of bits.
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So by replacing
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If you want to know more about how this is possible, read up on quantum physics.
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Using the classical binary representation, three bits can be employed to represent any of the
numbers from 0 to 7, one at a time: 000, 001, 010, 011, 100, 101, 110, 111. If we now consider
three qubits, we can see that if each bit is in what is called the
coherent state
, i.e., 0 and 1 simul-
taneously, they can represent all the numbers from 0 to 7
simultaneously
, because each of the three
bits can be a 0 and a 1 simultaneously! A processor that can use memory locations to store qubits
will, in effect, be able to perform calculations using all the possible values of the qubits in a memory
location simultaneously, a phenomenon called quantum parallelism. By processing data in parallel
rather than sequentially, the computational process is speeded up enormously.
