A Divide-and-Conquer Approach to Dicke State Preparation

Journal Article · 12 May 2022 · IEEE Transactions on Quantum Engineering

DOI: https://doi.org/10.1109/tqe.2022.3174547 · OSTI ID:1871751

Aktar, Shamminuj  ^[1]; Bartschi, Andreas  ^[2]; Badawy, Abdel-Hameed A.  ^[3]; Eidenbenz, Stephan  ^[2]

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1. New Mexico State University, Las Cruces, NM (United States); Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
3. New Mexico State University, Las Cruces, NM (United States)

We present a divide-and-conquer approach to deterministically prepare Dicke states |$$D^n_k \rangle$$ (i.e., equal-weight superpositions of all n-qubit states with Hamming weight k) on quantum computers. In an experimental evaluation for up to n=6 qubits on IBM Quantum Sydney and Montreal devices, we achieve significantly higher state fidelity compared to previous results. The fidelity gains are achieved through several techniques: our circuits first “divide” the Hamming weight between blocks of n/2 qubits, and then “conquer” those blocks with improved versions of Dicke state unitaries (Bärtschi et al. FCT’2019). Due to the sparse connectivity on IBM’s heavy-hex-architectures, these circuits are implemented for linear nearest neighbor topologies. Further gains in (estimating) the state fidelity are due to our use of measurement error mitigation and hardware progress.

• Research Organization: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA); USDOE Laboratory Directed Research and Development (LDRD) Program
• Grant/Contract Number: 89233218CNA000001; 20200671DI; LA-UR-21-31138
• OSTI ID: 1871751
• Alternate ID(s): OSTI ID: 1873362
• Report Number(s): LA-UR-21-31138
• Journal Information: IEEE Transactions on Quantum Engineering, Vol. 3; ISSN 2689-1808
• Publisher: IEEECopyright Statement
• Country of Publication: United States
• Language: English