But, and this is a very big but, for the quantum computer to work, the qubits must interact only with one another to perform calculations (via their invisible entangled “strings”). This means they must be completely isolated from their environment. The problem is that any interaction with the outside world causes the qubits to become entangled with their environment, which we can envisage as the formation of many more strings, all pulling on the qubits from different directions, competing with the strings between the qubits and therefore interfering with the calculation they are performing.
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