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

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