Scale: Number of qubits
One critical factor that determines the power of a quantum computer is the number of qubits it has. Generally, the more qubits a quantum computer has, the more powerful it is. As we have learnt, one of the reason for this is that the number of possible states that can be represented by a quantum computer grows exponentially with the number of qubits. So, when the number of qubits increases, the number of computations that can be performed in parallel does as well.
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Depending on the algorithm and problem, we need a certain amount of qubits. Explore how many qubits are roughly needed to solve the following problems!
Performing a search algorithm made for quantum computers (Grover's algorithm) with 1 million elements
Simulating battery cathode material (dilithium iron silicate)
Cracking current encryption (RSA2024)
As you have probably heard, todays quantum computers haven't been applied to any problem of these sizes despite having up to a couple of hundred qubits. The reason is that the number of qubits alone does not tell the whole story.
While a certain number of qubits is an essential factor in determining the power of a quantum computer, it is not the only factor, and other parameters, such as coherence time, gate error rates, and connectivity, must also be considered.