Soorya Rethinasamy

Logarithmic-Depth Quantum Circuits for Hamming Weight Projections

Physical Review A (Phys. Rev. A), 2024

Abstract

A pure state of fixed Hamming weight is a superposition of computational basis states such that each bitstring in the superposition has the same number of ones. Given a Hilbert space of the form H=(C2)n, or an n-qubit system, the identity operator can be decomposed as a sum of projectors onto subspaces of fixed Hamming weight. In this work, we propose several quantum algorithms that realize a coherent Hamming weight projective measurement on an input pure state, meaning that the post-measurement state of the algorithm is the projection of the input state onto the corresponding subspace of fixed Hamming weight. We analyze a depth-width trade-off for the corresponding quantum circuits, allowing for a depth reduction of the circuits at the cost of more control qubits. For an n-qubit input, the depth-optimal algorithm uses O(n) control qubits and the corresponding circuit has depth O(log(n)), assuming that we have the ability to perform qubit resets. Furthermore, the proposed algorithm construction uses only one- and two-qubit gates.

BibTeX

			
@article{PhysRevA.110.052401,
    title = {Logarithmic-depth quantum circuits for Hamming weight projections},
    author = {Rethinasamy, Soorya and LaBorde, Margarite L. and Wilde, Mark M.},
    journal = {Phys. Rev. A},
    volume = {110},
    issue = {5},
    pages = {052401},
    numpages = {14},
    year = {2024},
    month = {Nov},
    publisher = {American Physical Society},
    doi = {10.1103/PhysRevA.110.052401},
    url = {https://link.aps.org/doi/10.1103/PhysRevA.110.052401}
}