I'm doing a university thesis using IBM's quantum backends. In my analysis I am making some considerations on what differentiates one backend from another other than the number of qubits and quantum volume.

The parameters that come into play are:

  • Frequency: the difference in energy between the ground and exicted states
  • Readout Error: the error in measuring qubit
  • T1: the relaxation time
  • T2: the coherence time
  • CNOT error: the error on operating the 2-qubit gate
  • Sqrt-x (sx) error: ?
  • Anharmonicity: ?
  • Gate time: ?

The last three I have not yet understood.

Is each single qubit powered individually or does it follow the topological configuration of the backend?

For example if I used a 5 qubit system and used the linear configuration 0-1-2-3-4 and used 0-1 and 3-4. Does the current have to go from 2 to get to 3-4? Or are they powered individually?

I tried to look for articles and information on the internet that gave me these answers but I did not find anything, if you have any material that may be useful to me, please link it to me!

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    $\begingroup$ Just note that T2 is dephasing time (i.e. a time during it a quantum phase does not change). T1 and T2 are together considered as parameters describing decoherence. $\endgroup$ Jan 31, 2021 at 7:25
  • $\begingroup$ Hi Marco, could you tell me exactly what you mean by "powered qubit" and what "individually powered" means? I have never seen this expression, I'm curious $\endgroup$
    – Lena
    Feb 5, 2021 at 9:42
  • $\begingroup$ @Lena I mean if the current passes through certain qubits according to the topology or if a current generator is connected to each qubit $\endgroup$ Feb 6, 2021 at 9:13


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