Error mitigation for variational quantum algorithms through mid-circuit measurements

Understand

Noisy Intermediate-Scale Quantum (NISQ) algorithms require novel paradigms of error mitigation.

• To obtain noise-robust quantum computers, each logical qubit is equipped with hundreds or thousands of physical qubits.
• However, it is not possible to use memory-consuming techniques for current quantum devices having at most hundreds or at best thousands of physical qubits on their own.
• For specific problems, valid quantum states have a unique structure as in the case of Fock states and W-states where the Hamming weight is fixed, and the evolution takes place in a smaller subspace of the full Hilbert space.