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Giant resonances in atomic nuclei refer to highly collective excited states. For instance, the centre of mass of the neutron fluid can oscillate relative to the centre of mass of the proton fluid. It is called giant dipole resonance. A cluster state is also a collective state which has a few-body configuration. For instance, the famous Hoyle state in the 12C nucleus, which consists of three, loosely bound alpha particles.

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Alexis

In nuclear reactions giant resonance is a wide maximum in the reaction cross section plotted as a function of incident particle energy. Giant resonances are observed in photonuclear reactions, in reactions with incident electrons, protons, alpha particles, and in other nuclear reactions. The nature of giant resonances is explained as follows. Giant resonance is response of nucleus to electric field of incident particle. Atomic nucleus is excited by the field, and due to this oscillates. (For example in nuclei protons and neutrons oscillate relative each other, and several types of oscillation take place.) External fields can be of different nature and they have various multipolarity. Fields transfer to the nucleus the orbital angular momentum L, the spin S, and the isospin T. So giant resonances are specified by these quantum numbers L, S, T, and are classified in terms of them.

What is role of scaling in study of giant monopole  resonance ? 

Giant resonance is a high-frequency collective excitation of atomic nuclei, as a property of many-body quantum systems. In the macroscopic interpretation of such an excitation in terms of an oscillation, the most prominent giant resonance is a collective oscillation of all protons against all neutrons in a nucleus.

In quantum information and quantum computing, a cluster state is a type of highly entangled state of multiple qubits. Cluster states are generated in lattices of qubits with Ising type interactions. A cluster C is a connected subset of a d-dimensional lattice, and a cluster state is a pure state of the qubits located on C. They are different from other types of entangled states such as GHZ states or W states because it is more difficult to eliminate quantum entanglement (via projective measurements) in the case of cluster states. Another way of thinking of cluster states is as a particular instance of graph states, where the underlying graph is a connected subset of a d-dimensional lattice. Cluster states are especially useful in the context of the one-way quantum computer.