The problem with allowing the engineers who create a program also write its Help and Tutorials is that you get people who cannot write, writing Help for people who do not need help. ~Mark Rector

Quantum ComputersNishit Shankar(4th yr, ECE)

 

Why Quantum Computers ?

Quantum Computer Promises To:-
1. Increase the storage area by 100,000 times & processing speed exponentially as compared to classical computers.
2. Solve the NP hard problems that must consider the combination of a vast number of events.
3. Make Teleporting possible in another 4 to 5 decades.
4. Can compute Prime Factors of big numbers easily which the supercomputers of today will
take years to solve.
5. Secure communications based on quantum
Cryptography.

World’s First Commercial Quantum Computer

VANCOUVER, B.C. or MT. VIEW, CA – February 13, 2007 – The world’s first
Commercially viable quantum computer was unveiled and demonstrated at the Computer History Museum in Silicon Valley by D-Wave Systems, Inc., a privately-held Canadian firm
Headquartered near Vancouver. The world’s fastest computer uses the 16-Qubit Orion
Processor.

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Fig1: Demonstration of World’s 1st Quantum Computers

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Fig2: The 16-Qubit Orion Processor

 What are Qubits

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Fig3: A Qubit

Bit versus Qubit: A bit is the base of computer information. A qubit has some similarities to a classical bit, but is overall very different. Like a bit, a qubit can have only two possible values -
Normally a 0 or a 1. The difference is that whereas a bit must be either 0 or 1, a qubit can be 0, 1, or a superposition of both
Representation
The states a qubit may be measured in are known as basis states (or vectors). As is the tradition with any sort of quantum states, Dirac, or bra-ket notation is used to represent them. This means that the two computational basis states are conventionally written as and (pronounced: 'ket 0' and 'ket 1').
Qubit states

A pure qubit state is a linear superposition of those two states. This means that the qubit

can be represented as a linear combination of q4 and  q5 :
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where α and β are probability amplitudes and can in general both be complex numbers.
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since the total probability is always 1.

Fig4: Qubit Basics
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QUANTUM ENTANGLEMENT

Einstein termed it "spooky action at a distance." Quantum entanglement is a quantum mechanical phenomenon in which the quantum states of two or more objects have to be described with reference to each other, even though the individual objects may be spatially separated. This leads to correlations between observable physical properties of the systems.
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Fig6: Quantum Entanglement

As a result, measurements performed on one system seem to be instantaneously influencing other systems entangled with it. But quantum

entanglement does not enable the transmission of classical information faster than the speed of light. Quantum entanglement has applications in the emerging technologies of quantum computing and quantum cryptography, and has been used to realize quantum teleportation experimentally.

5 Things Every Quantum Computer Needs:
1. You must be able to set all the qubits to 0 at the start of a calculation.
2. You must be able to read the answer when the calculation is done.
3. The qubits must last long enough to run a program of a decent size.
4. The computer must be able to perform the two fundamental gate operations required for calculations.
5. The system’s basic architecture must be able to handle large number of qubits.

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Source- SPECTRUM