Atomic state that is a coherent superposition?

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• meyol99
In summary, the conversation is about the meaning of the k vector and a specific equation involving the wave number and a Stokes amplitude. The participants ask for clarification and a reference is provided for the quoted material. The reference is a paper titled "Quantum repeaters based on atomic ensembles and linear optics" published in 2011.

meyol99

Can someone explain the meaning of the k vector and the general meaning of this equation?

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1) k is the wave number ##2\pi\over \lambda##
2) difficult if you don't show where this is appearing. Some Stokes amplitude ? In particular: what the ##| g_j\rangle_n## stand for.

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@meyol99 please give a reference for what you are quoting from.

Nicolas Sangouard, Christoph Simon, Hugues de Riedmatten, and Nicolas Gisin
"Quantum repeaters based on atomic ensembles and linear optics",
Rev. Mod. Phys. 83, 33 – Published 21 March 2011

meyol99 said:
Nicolas Sangouard, Christoph Simon, Hugues de Riedmatten, and Nicolas Gisin
"Quantum repeaters based on atomic ensembles and linear optics",
Rev. Mod. Phys. 83, 33 – Published 21 March 2011

Here it is:

https://arxiv.org/abs/0906.2699

1. What is meant by an "atomic state that is a coherent superposition"?

An atomic state that is a coherent superposition refers to a quantum state in which an atom or particle exists in multiple states at the same time. This is a fundamental principle of quantum mechanics known as superposition, which allows particles to exist in a combination of multiple states until they are observed or measured.

2. How is a coherent superposition different from a classical state?

In classical physics, a particle can only exist in one state at a time. However, in quantum mechanics, particles can exist in a superposition of states, meaning they can exist in multiple states simultaneously. This is a key difference between classical and quantum systems.

3. What causes an atomic state to enter a coherent superposition?

An atomic state can enter a coherent superposition through a process called quantum interference. This occurs when the wave-like nature of an atom or particle interferes with itself, resulting in a superposition of states. Additionally, external factors such as temperature, pressure, or electromagnetic fields can also cause an atomic state to enter a coherent superposition.

4. Can a coherent superposition be observed in real life?

Yes, coherent superpositions have been observed in various experiments, such as the famous double-slit experiment. In this experiment, particles were observed to behave as both waves and particles, existing in a superposition of states until they were observed or measured.

5. What are the practical applications of coherent superpositions?

Coherent superpositions have many practical applications, particularly in quantum computing and cryptography. They are also important in the development of new technologies, such as quantum sensors and quantum communication systems. Additionally, understanding and controlling coherent superpositions is crucial in furthering our understanding of the quantum world and developing new technologies based on quantum mechanics.