Characterizing Noisy Non-Clifford Gates Through Partial Pauli Twirling or Through Alternating Pauli Twirling

A computer-implemented method, comprising:

• generating, by a system comprising a processor, a quantum circuit comprising a series of one or more instances of a quantum gate of interest, and having each instance of the quantum gate of interest being bounded by a pair of Pauli gates, wherein each pair of Pauli gates comprises two of the same bounding Pauli gate;
• randomly selecting, by the system, separately for each instance of the quantum gate of interest, the bounding Pauli gate to employ for each instance of the quantum gate of interest;
• inserting, by the system, according to a determined probability, an initial Pauli gate, that is based on an initial quantum state of the quantum circuit, into the quantum circuit prior to the series of one or more instances of the quantum gate of interest;
• and
• based on one or more parameters of a curve, to which an expectation value, resulting from a measurement outcome of execution of the quantum circuit at a quantum system, is fitted, generating, by the system, an element characterizing noise of the quantum gate of interest.

A computer program product facilitating a process to characterize a noisy quantum gate, the computer program product comprising a computer readable storage medium having program instructions embodied therewith, the program instructions executable by a processor to cause the processor to:

• generate, by the processor, a quantum circuit comprising a series of one or more instances of a quantum gate of interest, and having each instance of the quantum gate of interest being bounded by a pair of Pauli gates, wherein each pair of Pauli gates comprises two of the same bounding Pauli gate;
• randomly select, by the processor, separately for each instance of the quantum gate of interest, the bounding Pauli gate to employ for each instance of the quantum gate of interest;
• insert, by the processor, according to a determined probability, an initial Pauli gate, that is based on an initial quantum state of the quantum circuit, into the quantum circuit prior to the series of one or more instances of the quantum gate of interest;
• and
• based on one or more parameters of a curve, to which an expectation value, resulting from a measurement outcome of execution of the quantum circuit at a quantum system, is fitted, generate, by the processor, an element characterizing noise of the quantum gate of interest.