Datasheet for a single Qubit's memory allocation in Intel's hybrid-classical quantum computing

[newbie2]

I've found information that 20 Qubits requires at least 38MB of Random Access Memory, but for  just 1 Qubit it's enormous Input/Output data. I'd like to know more about memory allocation, so I will know what "values" are static, dynamic and/or doesn't exists at all.

[KevinR_Intel]

I'm not sure I fully understand your question, but let me elaborate on the memory requirement and perhaps that will prompt additional questions.

I believe you are referring to the table of memory need to simulate a given number of qubits using the Intel Quantum Simulator backend (IQS). That simulator uses a state-vector representation of the qubits and their quantum state. That representation grows in number of elements exponentially, i.e. proportional to 2^number of qubits. As a quantum_kernel gets run by the simulator and each instruction gets executed, the amplitudes are updated in the memory.

After the quantum_kernel completes, you can retrieve any of that data through the methods of the FullStateSimulator class and the supporting classes, QssIndex and QssMap. For some numbers of qubits, that can be a tremendous amount of data, so there are options to look at only subsets of qubits, find specific states of interest, or filter for values above a specified threshold.

Subsequent quantum_kernels that get run by the same FullStateSimulator object will use the same quantum register (so for the IQS backend, the programmer needs to reset qubits with Prep_ instructions or understand that the quantum_kernel is updating the existing quantum state of the qubits, whichever is their intention).

Lastly, the memory we have been talking about is in addition to any memory required by the classical logic of your application.

Hopefully that helps to clarify that cited RAM requirement, and please follow-up with any additional questions you have that are left unanswered.