Constructing a virtual two-qubit gate by sampling single-qubit operations

2019/09/30 by Kosuke Mitarai, Keisuke Fujii · 2 citations
Computer Science · Mathematics · Physics and Astronomy · #Algorithm #Combinatorics #Computer science #Mathematics #Observable #Pauli exclusion principle #Physics #Quantum #Quantum Computing Algorithms and Architecture #Quantum Information and Cryptography #Quantum circuit #Quantum computer #Quantum error correction #Quantum gate #Quantum many-body systems #Quantum mechanics #Qubit #Swap (finance) #Topology (electrical circuits) #quant-ph

paper · pdf · doi:10.1088/1367-2630/abd7bc

published as New Journal of Physics 23, 023021 (2021)

openalex publication_date 2020/12/31 · openalex created_date 2021/01/05 · arxiv created 2021/01/06 · arxiv updated 2022/03/14 · openalex updated_date 2026/08/05

Abstract

We show a certain kind of non-local operations can be simulated by sampling a set of local operations with a quasi-probability distribution when the task of a quantum circuit is to evaluate an expectation value of observables. Utilizing the result, we describe a strategy to decompose a two-qubit gate to a sequence of single-qubit operations. Required operations are projective measurement of a qubit in Pauli basis, and π/2 rotation around x, y, and z axes. The required number of sampling to get an expectation value of a target observable within an error of ε is roughly O(9^k/ε²), where k is the number of "cuts" performed. The proposed technique enables to perform "virtual" gates between a distant pair of qubits, where there is no direct interaction and thus a number of swap gates are inevitable otherwise. It can also be utilized to improve the simulation of a large quantum computer with a small-sized quantum device, which is an idea put forward by [Peng, et al., arXiv:1904.00102]. This work can enhance the connectivity of qubits on near-term, noisy quantum computers.

Citations

• Simulating Large Quantum Circuits on a Small Quantum Computer
• Simulating Quantum Computation by Contracting Tensor Networks
• Elementary gates for quantum computation
• A variational eigenvalue solver on a photonic quantum processor
• Characterizing quantum supremacy in near-term devices
• Tensor Networks in a Nutshell
• A blueprint for demonstrating quantum supremacy with superconducting qubits
• Unsupervised Machine Learning on a Hybrid Quantum Computer
• Quantum Computing in the NISQ era and beyond
• Ground-state energy estimation of the water molecule on a trapped ion quantum computer

Cited by

• How Much Reconstruction Does Quantum Machine Learning Need? Late Fusion of Independently Trained Quantum Subcircuits
• Scalable Circuit Cutting: A Framework for Combined Gate and Wire Cuts Using Gate Groups