# TLDR: The Complete Guide to Quantum Computing

## By Hacker Noon

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**The complete guide to Quantum Computing**

*Everything you need to know about computing’s next wave, in laymen’s terms…*Hacker Noon >>> Annotote

**“ **light is composed of tiny particles called photons, and each photon has energy. In general, quantum mechanics deals with the behaviour of matter and its interactions with energy on the scale of atoms and subatomic particles.

**“ **With the advent in quantum mechanics, Newtonian Mechanics (or Classical Mechanics) begin to subside at fundamental levels.

**“** the Bohr model, in which he narrates atom as a small, positively charged nucleus surrounded by electrons that travel in circular orbits around the nucleus — similar to structure of the Solar System. Each orbit corresponds to a different energy level. Changes of energy, such as the transition of an electron from one orbit to another around the nucleus of an atom, is done in discrete quanta. The term quantum leap refers to the abrupt movement from one discrete energy level to another, with no smooth transition. There is no “in between’’. [The electron] just disappeared from one orbit and appeared in the next orbit with no intermediate state and emitted (or absorbed) a specific amount of energy.

**“ **So, in general, the energy of electron in an atom is quantized.

**“ **matter can exhibit both particle and wave nature same as that of light. And the wave nature of electrons insist them to obtain certain wave lengths which are allowed for them to fit in an orbit. But with in that orbit electron can exists at all places, not just at a particular spot, due to the wave nature of electron.

**“ **Since matter with higher mass, like us humans, have high momentum and the wave length of such matters will be considerably smaller as mass is inversely proportional

**“ **Heisenberg’s uncertainty principle which sates that the position and the velocity of a particle cannot both be measured exactly, at the same time

**“** This is Quantum superposition, the normal material universe has meaning only at the moment of measurement [i.e. in a static snapshot, as opposed to dynamic].

**“** Quantum entanglement is the phenomenon by which more than one particle, generated together or closely interacted, can start a relationship and the quantum state of each particle cannot be described independently … they become a connected system and measuring one will affect the state of another. This property will be preserved even when they are separated by a large distance too.

**“ **In classical computer, we transforms any data to zeros and ones, so called bits. Actually to high voltage and low voltage for processing, then pass them through a series of gates called logic gates which can manipulate the data to figure out result. Logic gates like AND, OR, NOT, XOR, etc. can be arranged in different ways to process the bits and produce the output.

**“ **In quantum computing, the basic computational unit is a Qubit which can represent information. A qubit have some similarities to normal bit such as it can be measured to either zero or one. But the power of qubit lies in its quantum mechanical properties like superposition and entanglement. A qubit can be in both zero state and one state at the same time.

**“ **Even if the amount of information required to describe the super position grows exponentially with number of qubits we will not be able to access all this information because of the fundamental limits of quantum measurement.

**“ **That means in order to use full potential of quantum computer we need develop quantum algorithms which explore the existence of huge amount of information stored in super position of qubits

**“ **Current implementation of quantum computers are based on semi-conductors. The qubits generated from these semi-conductors should be kept away from any external interference. Other wise the quantum mechanical properties of these qubits will be lost. So the temperature of these quantum computers are kept very near to absolute zero and the set up for this along with calculations at microscopic levels can make quantum computers extremely expensive. Precise microwave/electromagnetic waves can be used to modify the states of qubites. It is often the case that a classical computer is used along with a quantum computer to help with processing.

**“ **IBM Q is an industry-first initiative to build commercially available universal quantum computers for business and science.

**“ **D-Wave products are widely used by companies like Google to run Quantum Artificial Intelligence Lab and NASA for their research.

**“ **Further more, it can be used for Quantum teleportation which was reported by Chinese scientists that they had transmitted the quantum state of a photon on Earth to another photon on a satellite in low Earth orbit.

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