What's the fastest computer in
the world? If you've seen the new Apple
advertisement, you may say the iMac G5. Some of
you may say a supercomputer at NASA and others
may even say a mainframe at the pentagon. Well
those answers are good, but they aren't close
enough. The fastest computer in the world is
"The Earth Simulator" in Japan. This computer is
so fast that it can perform 35.86 trillion
calculations per second - more than 4 times
greater than the next-fastest machine.
Especially considering that a trillion is a
thousand billions or a million million. now what
if I told you that, a "Quantum Computer" can be
at least billion times faster than "The Earth
Simulator" in Japan?
A Quantum computer is a special
type of a computer that is based on quantum
physics and not on conventional physics like out
current digital computers. The reliance on
quantum physics makes a quantum computer
amazingly fast. But quantum before you start
taking out your credit card in the hopes that
you can but this baby, think again. A Quantum
computer does not exist in reality. The
fundamental idea behind quantum computers has
been laid down on paper. It's just a matter of
time before we have the technology to build the
first quantum computer.
**How it works:**
You see a conventional computer
hasn't changed in its fundamental principle over
its life span. Sure, there have been drastic
changes in computer technology since the early
pioneering days of Charles Babbage (1791-1871),
with mechanical gears leading to vacuum values
to transistors and finally to integrated
circuits boards. Although computers have become
more compact and considerably faster in
performing their task, the task remains the
same: to manipulate and interpret an encoding of
binary bits into a useful computational results.
A bit is a fundamental unit of information,
classically represented as ones or zeroes in
your digital computer. Each classical bit is
physically realized through a macroscopic
physical system, such as the magnetization on a
hard disk or the charge on a capacitor. Here
lies a key difference between your classical
computer and a quantum computer. Where a
classical computer obeys the well understood
laws of classical physics, a quantum computer is
a device that harnesses physical phenomenon
fundamentally new mode of information
processing.
In a quantum computer, the
fundamental unit of information (called a
quantum bit or qubit), is not binary but rather
more quaternary in nature. in other words, a
qubit can exist in more than one state. This
coexistence in multiple states is a function of
quantum physics. A simple analog to this can be
given by looking at any analog clock and
comparing it to a digital clock. The digital
clock is very distinct in its hours,
minutes and seconds. The digital watch "jumps"
from one minute to the next. It is either 31
minutes past the hour or 32 minutes. There is no
in between, there is no compromise. However
compare that to an analog clock. See how there
are "infinite" number of possibilities between
the 31 minute maker and the 32 minute maker.
These infinite number of possibilities represent
the state of the clock, but we can't measure it
precisely. That's why we say, "It's half past
the hour." But unlike humans, in quantum
computers, we can measure the multiple states of
qubits, and we can measure than accurately. This
is what makes quantum computers, we can measure
the multiple states of qubits, and we can
measure them very accurately. This is what makes
quantum computers so powerful. So unlike a
digital computer, where Boolean logic is applied
to information represented as ones and zeros,
quantum computers can apply gates to qubits and
process nearly infinite amounts of information
with one action. This fundamental difference is
what makes quantum computer so much faster than
conventional computers.
The idea of computational device
based on quantum mechanics was first explored in
1970's and early 1980's by physicists and
computer scientists. The problem was put forward
after realizing that technology developments in
this field will shrink computer parts down to
the atomic level. At the atomic scale the
physical laws that govern the behavior and
properties of the circuit and inherently quantum
mechanical in nature, not classical. This then
raised the question of whether a new kind of
computer could be devised based on the
principles of quantum physics.
Till now, no full-fledged quantum
computer has been built and most researched in
the field agree that such a device lies still
many years or decades in the future. Much
progress has been promising for the
implementation of a quantum computer. These
systems must consist of a collection of
well-defined distinct qubits. The qubits must be
isolated from the environment but yet
controllable from the computers perspective.
This is the hardest to achieve in reality and no
one has come close to accomplishing this.
**Quantum and Cryptography:**
Even though no real quantum
computer has been created, much research into
quantum information processing has been done.
One such research was carried out by Peter Shor
of AT&T's Bell Laboratories in New Jersey. Shor
circulated in 1994 a preprint of a paper in
which he set out a method for using quantum
computers to crack an important problem in
number theory, namely factorization. This in
turn opened a new can of worms - of
cryptographs. Cryptography is used to secure
important transmission of data, such as
financial transactions, government and corporate
information. Conventional cryptography is based
on public key distribution; which uses prime
numbers to make it next to impossible to break
the code. However Shor's algorithm challenged
the belief that conventional cryptography was
unbreakable.
Ironically, this cryptography
problem can also be solved by quantum mechanics.
The foundation of quantum mechanics is based on
a principle which states that observation of a
quantum system unavoidably disturbs this system.
In other words, every time you open the
lid of the box to look in, the contents of the
box change. The more you peek in, the more
change happens. This natural phenomenon can be
used to guarantee secret key distribution in
quantum cryptography. Imagine you have a dozen
leaping frogs in a shoebox. The size, weight,
and texture of the frogs represent some code,
which your friend knows from before. You mail
this shoebox to your friend through the post.
Now on its way to your friend, the mailman
carrying the shoebox gets curious and open the
shoebox. He finds leaping frogs in the box and
some manage to jump out before he closes the
lid. He delivers the box to your with a few
missing frogs. You know from before that your
friend mailed you a dozen frogs and since
someone are missing, you can guess that the
security of the box has been compromised.
That's exactly how quantum
cryptography works. Two communicating parties
agree on a random key by exchanging and
manipulating quantum systems in such a way that
the law of physics guarantee that an
eavesdropper will either reveal themselves with
near certainly or gain nearly no information
about the key. Quantum key distribution is the
most advanced applications of quantum
information theory. There have been many
successful experiments in realistic
circumstances. In all these experiments the
two-state quantum systems exchanged by the
communicating parties and realized by photons,
the qubit being for example encoded in the
polarization of the photon. Most experiments to
date uses optical fibers to transmit the
photons. Currently, distances over ten of
kilometers have been achieved at many places,
for example at Los Alamos (USA), BT Labs (UK),
the University of Geneva (CH).
**2020 and beyond:**
The pioneering field of quantum
information has already achieved a
multitude of exciting and surprising insights -
both in the foundations to problems of
communication and computation. With many
dedicated groups now working in this area, more
surprises and breakthroughs are expected.
Unfortunately, a quantum computer will not be
emerging anytime within the next decade or so.
Especially considering that quantum hardware
still remains to be an developing field. It may
be a matter of time before quantum computers
will emerge as the superior computational
devices at the very least, and perhaps one day
make today's modern computer obsolete. Till then
we have to make do with super computers as "The
Earth Simulator" in Japan or our iMac G5. |