Error suppression by a virtual two-qubit gate
Sparse connectivity of a superconducting quantum computer results in the
large experimental overheads of SWAP gates. In this study, we consider
employing a virtual two-qubit gate (VTQG) as an error suppression technique.
The VTQG enables a non-local operation between a pair of distant qubits using
only single qubit gates and projective measurements. Here, we apply the VTQG to
the digital quantum simulation of the transverse-field Ising model on an IBM
quantum computer to suppress the errors due to the noisy two-qubit operations.
We present an effective use of VTQG, where the reduction of multiple SWAP gates
results in increasing the fidelity of the output states. The obtained results
indicate that the VTQG can be useful for suppressing the errors due to the
additional SWAP gates. Additionally, by combining a pulse-efficient
transpilation method with the VTQG, further suppression of the errors is
observed. In our experiments, we have observed one order of magnitude
improvement in accuracy for the quantum simulation of the transverse-field
Ising model with 8 qubits.
Takahiro Yamamoto Ryutaro Ohira