Quantum coupling

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Quantum Coupling is an effect in quantum mechanics in which two or more quantum systems are bound such that a change in one of the quantum states in one of the systems will cause an instantaneous change in all of the bound systems. It is a state similar to quantum entanglement but whereas quantum entanglement can take place over long distances quantum coupling is restricted to quantum scales.

Quantum coupling in action

Trapped ion quantum computers utilize the quantum coupling effect by suspending particles representing qubits in an array of ion traps. These particles are then induced into a state of quantum coupling by using optical pumping by a laser. Information can be stored in this state by coupling two or more qubits. While the individual particles may fluctuate their values, the quantum states of the two qubits remain locked in relation to each other, via Coulomb force. Any action by one of the coupled ions instantaneously alters the other to maintain the relative value. This allows the computer to hold information despite the instability of the individual particles.

Other examples

In benzene, C₆H₆, the charges of the individual carbon atoms exhibit coupling. There are three double bonds and three single bonds in alternating positions around the ring. The measurement of the energy in any individual bond will result in a puzzling result resembling an impossible "one and a half bond". This is because the bonds are in a quantum superposition of double and single bonds at any particular bond position. The coupling effect causes the charge at all points on the ring to be altered when a bond at any one point is altered, in order to maintain the relative charge between atoms. This results in an illusionary "bond and a half" bond between all 6 carbon atoms.