What is a Quantum computer?.
How does it differ from classical computers?
First let’s see, how classical computers
work.
A classical computer works with the Binary
numbering system, and the computer is not
convenient with the Decimal numbering system.
Binary system has only two digits.
And it is very easy to process the “Yes”
or “No” based logics.
Decimal system has 10 digits so the “Yes”
or “No” based logics would be more difficult
to process, so it wouldn’t work.
All arithmetic operations are done by the
binary system based logic.
See an example of adding two single digit
binary numbers using yes or no logic.
Turn the first bit on, if any one of the bit
is on.
(that is exclusive OR).
Turn the second bit on if both the bits are
on.
(that is AND).
For example, 1+0 is equal to 1.
So the logic for the first bit is that if
any one of the bit is on, then “Set the
first bit on”. so the first bit is 1.
The logic for the second bit is that if both
the bits are on “Set the second bit on”.
so the second bit is 0.
It gives the answer 1.
Another example 1+1.
We can use electrical-switches as an input
device and lights as output device.
Transistors can be used for binary-logic based
operations and turning on or off the lights
based on the switch settings.
Transistors can be inter connected in particular
way to pass the electric-current by “XOR”
and “AND” operations with two switches.
This is a half-adder to add two single digits.
1 + 0 is 1.
1 + 1 is 10.
This is full adder to add multi bit numbers.
This is the connections of 8 Full-adders to
add two 8 digit binary numbers.
So computer computes by binary-state gates.
A mobile phone has millions of transistors
inside.
A computer has billions of transistors inside.
So, Computer doesn’t like the Decimal state.
Computer likes binary stat.
How about the Quantum state which has the
stat of both 0 and 1 at the same time?
It will become crazy, isn’t it?.
Binary Bit state may be 0 or 1.
Quantum Qubit state will be both 0 and 1 at
the same time.
See how the result of Qubit number addition
will be.
As individual digits of input numbers have
all possible ways, the result will also have
all possible values.
Yes two single digit Qubit numbers addition
will make 4 possible combinations and return
3 possible values.
Two double digit Qubit numbers addition will
make16 possible combinations and so on.
This kind of computation is done by all types
of arithmetic operations.
So Quantum computer computes all possible
ways in parallel.
But classical computer computes only one at
a time.
See this example.
This is the room entrance and it has a maze
inside.
The entrance is split into multiple paths
and has only one exit.
The task of computer is to find the correct
path which leades to the exit.
Classical computer has to travel each path
to find the exit.
But Quantum computer can travel all paths
simultaneously and find the exit immediately.
It computes all possible combinations simultaneously
and choosing the best one.
Database search from Billions of records can
be done in a single search attempt.
Any type of Encrypted data can be cracked
in fractions of second.
Robots can move and walk like human, by studying
all possible movement and learning best moves.
Simulating and studying complicated biological
formatted data.
Classical computer uses Transistors to create
binary based Logic-Gates .
What does quantum computer use for qubit based
logic-gates?
This is the answer all Quantum physicists
and researchers are still searching for.
The research is still going on.
Let us see the possible choices given by Quantum
Mechanics.
Introduction to Quantum Mechanics.
Subatomic particles such as electrons and
photons behave in a very strange way.
Electron has a property of Spin.
The Spin state may be Up, Down, Right or left.
The spin state will be both Up and Down or
Right and Left simultaneously in particular
scenario.
Such a state is called super position state.
Photon has a property of Polarization.
The Polarization state may be Horizontal,
Vertical.
The Polarization state will be both horizontal
and vertical simultaneously in particular
scenario.
Light has strange behavior in the Double-slit
experiment.
Light without any slit shows normal pattern.
Light passing through single slit is spread
out, because of Qunatum uncertainty behavior.
Light passing through double slit shows interference
pattern because of the wave behavior of light.
Passing single photon at a time in single
slit hits random place, accumulates and shows
the same spread pattern over the time period.
Passing single photon at a time in double
slit hits random place, accumulates and shows
the same interference pattern over the time
period.
How can a single photon which is not a wave,
show interference pattern?
.
Actually it splits in to two photons, passing
through slits simultaneously, interferes with
itself and shows interference pattern.
The photon is in superposition state of passing
both slits.
The spread-pattern of single slit is also
the super position state of a photon is in
all position simultaneously.
The photon is in all places, not in all places,
is in one place only, is in two places ….
it resides in this area with the possibility
of all combinations.
This super position state can be used to create
Qubits which is used in Quantum computers.
Super position of Particle Spin can be used
to create Quantum Logic gates.
Super position of Photon Polarization can
be used.
Super position of Photon in two slit can be
used.
Super position of Photon in particular area
can be used.
this is Quantum Computing.
At present human cannot utilize such an enormous
computational power.
These are all just fundamental Ideas for Quantum
computer.
The exact method of Quantum computer is still
at the research level.
The major problem is that, the super position
is collapsed and turned in to definite state
when it gets measured.
Here may be a possibility that the Quantum
Computer can process all possible logics,
choose the best one, self train, self study,
self program, evolve and eventually acquire
intelligence.
Somebody is going to open Pandora the Box
soon.
Cyberdyne, John Connor and Terminator are
can be expected.
Canada based DWave Inc has steped in to Quantum
computer world.
They have announced that they are selling
commercial Quantum computers.
It is not full Quantum Mechanic Based computer
but based on the Subset of Quantum-Mechanic,
called Quantum Annealing.
You can see this reliability as Google and
NASA have bought this 10 Million dollar DWave
Quantum Computer.
