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Questions tagged [quantum-process-tomography]

For all questions regarding quantum process tomography or derivatives thereof (like gate-set tomography). In quantum process tomography, processes that are performed on qubits are characterized rather than the state of the qubits themselves; see quantum state tomography for this.

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11 votes
1 answer
2k views

What is the relationship between Choi and Chi matrix in Qiskit?

I'm struggling with the framework for quantum process tomography on Qiskit. The final step of such a framework is running fit method of ...
Daniele Cuomo's user avatar
5 votes
1 answer
1k views

How to perform Quantum Process Tomography for three qubit gates?

I am trying to perform Quantum process tomography (QPT) on three qubit quantum gate. But I cannot find any relevant resource to follow and peform the experiment. I have checked Nielsen and Chuang's ...
Pralekh Dubey's user avatar
5 votes
2 answers
333 views

Why does the $\chi$ matrix have $d^4-d^2$ independent parameters?

In the section on Quantum process tomography, Page 391, Chapter 8, Quantum Computation and Quantum Information by Nielsen and Chuang. it is given that In general, $\chi$ will contain $d^4−d^2$ ...
Sooraj S's user avatar
  • 821
3 votes
1 answer
164 views

Does any quantum channel satisfy ${\rm Tr}(\mathcal E^\dagger \mathcal E) \in[0, d^2]$?

I am reading the paper "Direct Fidelity Estimation from Few Pauli Measurements". According to the paper, the entanglement fidelity between the a unitary channel $\mathcal U$ and a quantum ...
Michael.Andy's user avatar
2 votes
0 answers
98 views

What is the best method for estimating average channel fidelity?

This thesis shows an efficient way to estimate average channel fidelity (in chapter 4). However, it is somewhat old (from 2005). Are there any better methods out there? By better I mean: are there ...
Quantum Guy 123's user avatar
2 votes
1 answer
744 views

How to find the Kraus operators from the process matrix?

I am trying to find the Kraus operator from process matrix. For instance, suppose that for single qubit identity gate, I have the following process matrix: ...
quest's user avatar
  • 636
1 vote
0 answers
197 views

In quantum process tomography for one and two qubit, why can we express the $\chi$ matrix in this form?

I'm reading Nielsen and Chuang and I read quantum tomography process given by N&C (box 8.5), which provides an algorithm for determining $\chi$ in terms of block matrices and density matrices. And ...
username9's user avatar
1 vote
1 answer
86 views

Why is $\chi$ not uniquely determined by $\sum_{mn}\beta_{jk}^{mn}\chi_{mn}=\lambda_{jk}$?

The mathematical construct of the Quantum process tomography is given in Page 391, 392, Chapter 8, Quantum Computation and Quantum Information by Nielsen and Chuang, as follows Let a fixed set of ...
Sooraj S's user avatar
  • 821
1 vote
1 answer
250 views

How to derive the number of independent parameters in the $\chi$ matrix from the Choi matrix?

In the section on Quantum process tomography, Page 391, Chapter 8, Quantum Computation and Quantum Information by Nielsen and Chuang. it is given that In general, $\chi$ will contain $d^4−d^2$ ...
Sooraj S's user avatar
  • 821