So cloning is impossible (assuming Heisenberg was right!). If we were able to clone quantum states, then from one clone we could learn the position and form the other clone we could learn the momentum. Although, we can choose one of these things to measure and reveal itself. For instance, we can’t learn both its position and its momentum.
The uncertainty principle tells us that we can’t learn everything about a quantum particle. It is easy to see that no-cloning follows from the more widely known Heisenberg uncertainty principle. Making enough copies it is highly unlikely that all copies will become damaged at the same time! However, quantum mechanics is governed by the no-cloning principle, which says that a quantum state cannot be copied. With binary data it is possible to we make many copies and store each copy in a different location.
It is actually quite remarkable that quantum error correction is possible at all. The approach allows use to extend the lifetime as long as we need, provided we use enough physical qubits (maybe hundreds or thousands will be needed). To do this we will need to use quantum error correcting codes to make a logical qubit. But for quantum computations much longer lifetimes are needed. With better technology, we might be able to push to slightly longer lifetimes. The world record for the lifetime of a qubit is 39 minutes at room temperature, after which all quantum information is lost. Controlling qubits stored in individual electrons or photons is simply much more challenging than controlling macroscopic flows of charge in traditional computers. How can we use topology to protect quantum computers from errors?Įrrors in quantum computers are unavoidable.