Quantum algorithms with local particle-number conservation: Noise effects and error correction

Quantum circuits with local particle-number conservation restrict the quantum computation to a subspace of Hilbert space qubit register. In noiseless or fault-tolerant computation, such quantities are preserved. presence noise, however, evolution's symmetry could be broken and nonvalid states sampled at end computation. On other hand, restriction in ideal case suggests possibility more resource-efficient error-mitigation techniques for preserving symmetries that not possible general circuits. Here, we analyze probability staying symmetry-preserved subspaces under providing an exact formula depolarizing noise. We apply our findings benchmark, robustness XY alternating operator Ansatz, which has conserving is special Ansatz. also influence choice encoding problem on algorithm discuss simple adaption bit-flip code correct symmetry-breaking errors reduced resources.