Question

What is actually quantum state mean ?

Answer 1

go to the link
http://en.wikipedia.org/wiki/Quantum_state

Answer 2

From WIKI, your answer is - "In physics, a quantum state is a set of mathematical variables that fully describes a quantum system. For example, the set of 4 numbers;


defines the state of an electron within a hydrogen atom and are known as the electron's quantum numbers. Other examples could be some "given direction and energy, or some other given condition"[1], when we are talking about scattering. More generally, the state of the system is represented by a single vector known as a ket.

Typically, one postulates some experimental apparatus and procedure which "prepares" this quantum state; the mathematical object reflects the operations performed by this apparatus. Quantum states can be either pure or mixed. Pure states cannot be described as a mixture of others. Mixed states correspond to an experiment involving a random process that blends pure states together.[2]

When performing a particular measurement on a quantum state, the result is usually described by a probability distribution, and the form that this distribution takes is completely determined by the quantum state and the observable describing the measurement. These probability distributions are necessary for both mixed states and pure states: It is impossible in quantum mechanics (unlike classical mechanics) to have any state whose properties are all fixed and certain. This is exemplified by the Heisenberg uncertainty principle, and reflects a core difference between classical and quantum physics.

Mathematically, a pure quantum state is typically represented by a vector in a Hilbert space, which is a generalization of our more usual three dimensional space. In a Hilbert space the co-ordinates are complex numbers, a complex kind of distance between points is defined, and infinite series of numbers are made to converge. In physics, bra-ket notation is often used to denote such vectors. Linear combinations (superpositions) of vectors can describe interference phenomena. Mixed quantum states are described by density matrices.

In a more general mathematical context, quantum states can be understood as positive normalized linear functionals on a C* algebra; see GNS construction."

Answer 3

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