Quantum Computing

If you think you can understand Quantum Mechanics, then you don't understand Quantum Mechanics.                                                                                     -Richard Feynman

Quantum Mechanics is the science of the very small, is the study of the quantum system , it's state and behavior in space and real time at the scale of subatomic and atomic particles. Quantum Mechanics is different form classical mechanics. In classical mechanics the basic information bit is the classical bit which is discrete in nature, but on the other hand in quantum mechanics, the basic information bit is the qubit(or quantum bit). It is a two-state bit and it is continuous valued. The graphical representation of qubit is done on the Bloch Sphere. This represents the state of the quantum system. Qubits can be crudely termed as a two level quantum mechanical system. A qubit cannot be wholly converted into classical bits, this is by non-teleportation theorem. It means that one qubit can't be replicated into another or one information containing qubit can't be dematerialized from one place and then again materialized into another place. Non-teleportation theorem goes hand in hand with non-cloning theorem. A qubit can't be cloned into an exact same another qubit. The information can be transported from a source to another destination by the means of quantum teleportation. The quantum analog of a bit is a quantum bit, or qubit.Quantum information can neither be copied nor destroyed called as non-cloning and non-deleting theorem respectively. Quantum mechanics including the quantum field theory describes the energy of the smallest scale of subatomic and atomic energy levels.Quantum Mechanics shows that light with other forms of radiation, comes in discrete units called photons. Photons are quantized packets of energy.

Quantum State is defined as the state of the isolated quantum mechanical system.Quantum states define the probability distribution of measured observable quantity.There are two kinds of quantum states: pure and mixed.Two quantum states can be mixed with one another to produce another quantum state, which is similar to that of the mixing of matter waves as in classical physics.

Quantum Teleportation can be defined as the transportation of information from one place to another place with the help of classical communication and with the previously shared quantum entaglement between the sending and recieving location. Here there is transfer of information and not the matter itself likewise in fiction.The latest reported record distance for quantum teleportation is 1,400 km.A certain kind of quantum channel has to be established first between the two locations for the communication of quantum information between the two.It will be accurate to say that the quantum state of an atom is teleported and not the qubit itself.Quantum channel is a communication channel between two locations between which the classical and the quantum information has to be communicated.

Quantum Entanglement(or Quantum Coherence) can be defined as the physical phenomena between two particles that interact with each other. The state of one particle is dependent on the other particle even if they are separated by a distance.Let's say, two electron waves are generated and they are mixed up. They interact/interfere with each other. They develop a link between them even if they are separated miles of distance from each other. The measurement of one particle say it's the spin of the electron is correlated with the another particle. This correlation is called entaglement. Also, the link that stretches over the distance is called non-locality.It can be simply be described as a spooky action or a non local interaction of particles separated at a distance.Entaglement produces correlation between the measurements of say two electron waves. The mutual information between these two electron waves can be exploited. The tranportation greater than the speed of the light is impossible. This is because quantum information theory, follows the classical bit theory laws, for the transportation of information from the source to the destination.The entangled particles are considered as a whole system, whose properties are dependent on each other.Two daughter particles are entangled to each other in terms of position,momentum, energy etc, this phenomena is due to the quantization of energy,which is the basic law of mechanics.Entanglement is usually created by the interaction between subatomic particles.

Quantum Realm An imagined world which is separated by the measurement barrier from the real our world. Say an single electron(sub atomic particle) can be described in the form of wave function(mathematical operation of electron). The particle nature of the electron is practically proved by the photoelectric effect, even the wave nature of the particle by the young's double slit experiment has been proved. The wave function of the electron wave is the mathematical formulation of it's amplitude, position , energy etc. To measure these few mathematical operations need to performed on the electron waves. The amplitude(or size) of the wave corresponds to the position of the electron , the momentum is described by the wavelength of the wave. The wave function gives the near probability function of the possible attained quantum states of the electrons in pre-defined specific orbits.So, let's formulate that, electrons revolutanize arounf the nucleas in certain stable predefined orbits, and also by quantum mechanics the probabiltiy of finding an electron in a particular pre-defined orbit is defined by the most occupied energy levels by the revolving electrons around the nucleus.On attaining some external energy or by thermal energy the electron jumps to another orbit emitting a subatomic spectra, which gives specific pencil lines of discrete colour, when viewed from a prism, this is observed when a gas was heated and then was viewed from the prism.This defines that certain stable and occupied states are attained by the energised electrons, which defines the emittion of a particular bare code like different coloured spectra on the detector.This all explains the quantum mechanics.

A Topological shield of entangled photons Protecting photon pairs' delicate quantum states from material defects and disorder. Entangled photons are the best candidates for the information carrying qubits. But entangled photonic quantum states are skitish things, prone to loss and other errors due to scattering. Solution to this can be topological photonics.It says that introducing a specific defect into such a system could produce a topological "edge state" that, in principle, might help correlated photon states stand up better to material defects and disorder.

Quantum Decoherence It is then loss of quantum coherence. Quantum coherence is defined as the constant phase difference and same frequency between two measurands.It is defined as the loss of information of the system into the environment due to some interaction woith the environment.