# How can quantum decoherence be managed?

I've stumbled myself upon this article on Wikipedia, which says:

Decoherence can be viewed as the loss of information from a system into the environment (often modeled as a heat bath), since every system is loosely coupled with the energetic state of its surroundings.

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Decoherence represents a challenge for the practical realization of quantum computers, since such machines are expected to rely heavily on the undisturbed evolution of quantum coherences. Simply put, they require that coherent states be preserved and that decoherence is managed, in order to actually perform quantum computation.

(emphasis mine)

So I am wondering how can this loss of information be managed? Does this mean that it should be prevented completely, or is it necessary for quantum computing to actually allow some information loss in order to compute?

A coin has two states, and makes a good bit but a poor qubit because it cannot remain in superposition of head and tail for very long as it is a classical object. A single nuclear spin can be a very good qubit, because superposition of being aligned with or against an external magnetic field can last for a long time, even days. But it can be difficult to build a quantum computer from nuclear spins because their coupling is so small that it is hard to measure the orientation of a single nuclei. The observation that the constraints are opposing in general: a quantum computer has to be well isolated in order to retain its quantum properties, but at the same time its qubits have to be accessible so that they can be manipulated to perform computation and read out the results. A realistic implementation must strike a balance between these constraints.