qiskit.ignis.characterization.t2_circuits

t2_circuits(num_of_gates, gate_time, qubits, n_echos=1, phase_alt_echo=False)

Generate circuits for T2 (echo) measurement, by a CPMG sequence.

Each circuit consists of:

• $Y90-t-Y-[t-t-X/Y]^m-t-Y90$
• $n_{echos} = n+1$
• if phase_alt_echo then the X/Y alternate, if phase_alt_echo=False tthen he pulses are always Y

Standard T2* echo is $n_echos=1$

Parameters

• num_of_gates (Union[List[int], array]) – Each element of the list corresponds to a circuit. num_of_gates[i] is the number of identity gates in each section “t” of the pulse sequence in circuit no. i. Must be in an increasing order.
• gate_time (float) – time of running a single identity gate.
• qubits (List[int]) – indices of the qubits whose T2*‘s are to be measured.
• n_echos (int) – number of echo gates (X or Y).
• phase_alt_echo (bool) – if True then alternate the echo between X and Y.

Return type

Tuple[List[QuantumCircuit], array]

Returns

• Generated circuits
• Delay times, i.e., gate_time multiplied by the numbers in num_of_gates

Raises

ValueError – If n_echos is less than 1