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This is a question that I asked on Qiskit ignis section of slack, with a very interesting answer by A Kapila, but I also need to get a short answer in nanoseconds.

I want to evaluate decoherence in function of a waiting time introduced by adding identity gates before the measurement phase (using barriers before and after the series of id gates) enter image description here For instance for the Essex device, I can obtain the id gate length value using the following code:

device = provider.get_backend('ibmq_essex')

properties = device.properties()

from qiskit.providers.aer.noise.device.parameters import gate_length_values

gate_times_out = gate_length_values(properties)

print(gate_times_out[0])

  ('id', [0], 64.0)

Note that this method of creating a delay was used in a published paper about decoherence.

https://arxiv.org/pdf/1712.07080.pdf

In the methods section the authors give the following description:

« A delay τ is realized via the application of multiple identity operations. Each identity operation has the same duration as a single-qubit rotation gate (80 ns) and is followed by a 10-ns buffer time, which corresponds to a total delay of 90 ns per identity operation. »

For the circuit presented here, the waiting time is 4 * 64 ns = 256 ns plus four times the additional buffer time between gate for the device.

I can find the buffer times in older descriptions of some devices, like the Yorktown (see: https://github.com/Qiskit/ibmq-device-information/blob/master/backends/yorktown/V1/version_log.md). But I cannot find it for the Essex device.What is it? Or where can I find it? Or maybe the waiting time is already included in the gate length values?

Thanks by advance for helping.

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