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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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What is quantum tomography useful for?

First time poster and just started with quantum computing for my master thesis, so I'm sorry if the question seems obvious. I understand that the tomography is used to reconstruct the state and/or ...
Oliver Müller's user avatar
5 votes
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What is the best quantum process tomography method?

This question is somewhat related to this question. What is currently the best method for quantum process tomography? By best I mean, the one that can achieve the best accuracy of estimation per qubit ...
Quantum Guy 123's user avatar
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Why use 576 configurations for two-qubit process tomography?

In the paper "Efficient Measurement of Quantum Dynamics via Compressive Sensing" Shabani Et. al (2011) [arXiv:0910.5498], The full process tomography of two-photon is performed as: ...
karry's user avatar
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2 votes
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Problem with orthogonal traceless Hermitian matrices

In the compressive QPT method, the trace-preserving constraint of the process matrix is $\sum_{n, m} \chi_{n m} \Upsilon_m^{\dagger} \Upsilon_n=1$. In this paper:https://arxiv.org/abs/1404.2877, as $\...
karry's user avatar
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2 votes
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Quantum Process Tomography for 2 qubits

I need clarification on a few aspects related to Box 8.5 and Exercise 8.34 from the book Quantum Computation and Quantum Information by Nielsen & Chuang . While attempting Exercise 8.34, I ...
Sachindra Kumar's user avatar
2 votes
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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
1 vote
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Non-local $CNOT$ By means of Ising gates

Consider the circuit below. This is almost the same as the standard protocol to perform a non-local $CNOT_{0,3}$. The only difference is that I decomposed the upper local $CNOT_{0,1}$ into one Ising ...
Daniele Cuomo's user avatar
1 vote
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Prove $\beta=\Lambda\otimes\Lambda$, where $\Lambda=\dfrac{1}{2}\begin{bmatrix}I&X\\X&-I\end{bmatrix}$ for single qubit tomography

In the Section on single qubit quantum process tomography, Box 8.5, Page 393, Chapter 8, Quantum Computation and Quantum Information by Nielsen and Chuang, and in Prescription for experimental ...
Sooraj S's user avatar
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1 vote
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How to extract the entanglement fidelity from an arbitrary quantum operation?

I have an arbitrary process matrix that does an entangling operation (a controlled-pi/2 rotation) plus some additional phase rotations that are not of interest. I am curious to find a way to extract a ...
t4tuin's user avatar
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1 vote
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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
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How to merge logical computation with encoding-decoding schemes

Usually QEC is treated in two different ways. Definition of a logical computation with a non-destructive QEC scheme Definition of a encoding-decoding scheme with destructive measurement after ...
Daniele Cuomo's user avatar
1 vote
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Why the chi-matrix fidelity of the process is the fidelity of the chi-matrix noise map

I am following this paper, and I am stuggling with a derivation. Basically, I consider an orthonormal basis $\{B_i \}$ with respect to Hilbert-Schmidt scalar product, on the density matrix space $\...
Marco Fellous-Asiani's user avatar
1 vote
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Is it possible to partial trace the $\chi$-matrix of $4$ qubits $q_0,q_1,q_2,q_3$ to obtain a description of what happens to $q_1$?

Considering a $\chi$-matrix of a circuit with, say, 4 qubits, is it possible to trace out 3 of them from $\chi$ - for example qubits $q_0$, $q_2$ and $q_3$ - thus gaining the process matrix describing ...
Daniele Cuomo's user avatar
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Optimising Tomography on logical computation

I already got part of the answer in thread. Which says that if I want to perform a state tomography on a known state, the estimation can be simplified. In the case of "GHZ-class", citing ...
Daniele Cuomo's user avatar
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Process Tomography for Blind Quantum Computation

Process Tomography can identify the quantum channel, while Blind Quantum Computation strives to hide the inputs using quantum gates. Given the user executes the same blind circuit multiple times (of ...
Aritra's user avatar
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