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Questions tagged [gate-fidelity]

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5 votes
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Is there a concentration inequality for the quantum gate fidelity $F(C,U)$ for a channel $C$ such that $\int dU F(C,U)=X$?

For a fixed quantum channel $N$ and a unitary channel $U$, we define $N$'s gate fidelity as $$ F(N,U) = \int \langle \psi| U \, N(| \psi \rangle \langle \psi |) \, U^\dagger| \psi \rangle d\mu_H(\psi)$...
Davide Li Calsi's user avatar
2 votes
1 answer
86 views

What is the relationship between gate fidelity and norm?

I've seen a lot of analyses on quantum circuit error bound based on the norm difference $\Vert U - V \Vert$. On the other hand, I've also seen a lot of papers that use the gate fidelity $\frac{1}{2^n}\...
user185671631's user avatar
4 votes
1 answer
197 views

Can you compute the average fidelity of two qubits by averaging over a finite number of states?

For a single qubit and a quantum operation, the fidelity $$ F_{|\psi\rangle\!\langle \psi|} = \mathrm{Tr}\bigg(U | \psi \rangle\!\langle \psi | U^\dagger \mathcal M\big(| \psi \rangle\!\langle \psi |\...
Omar Nagib's user avatar
1 vote
1 answer
115 views

Calculate average fidelity of QobjEvo

I am using QuTip to simulate a quantum gate, and I want to calculate the average fidelity of the gate. I have the Hamiltonian, the interaction time, and Liouvillian modeling the decoherence. Is there ...
user26199's user avatar
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
1 vote
0 answers
57 views

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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4 votes
0 answers
251 views

Qiskit NoiseModel.from_backend gives wrong gate error

According to the Qiskit documentation, a gate error is simulated by a thermal relaxation channel followed by a depolarisation channel, where the parameter of the depolarisation channel is adjusted so ...
siserman's user avatar
  • 161
4 votes
0 answers
221 views

How can I get fidelity of a gate from randomized benchmarking?

I found (page 33) the method of finding fidelity from fit by "interleaved and reference decay" according to the sequence fidelity formula: $$F_{ref}=Ap_{ref}^{m}+B,$$ where $p_{ref}^{m}$ is ...
Curious's user avatar
  • 259
2 votes
1 answer
64 views

What are the "higher moments" of the gate fidelity?

Reading the paper Gate fidelity fluctuations and quantum process invariants I came across the concept of higher moments of the gate fidelity, for example in the following excerpt from the introduction:...
epelaez's user avatar
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8 votes
3 answers
7k views

What does quantum gate fidelity mean?

The formal definition states that it's the distance between two quantum states. What does that mean experimentally? Does distance here mean the distance between two states on the Bloch Sphere? I am a ...
Maxx's user avatar
  • 161
5 votes
2 answers
2k views

What is a difference between error rates and qubit/gate fidelity?

What is a difference between error rates and qubit/gate fidelity? A bit of maths in the explanation is fine but I am an A Level student doing a research project so definitions would be preferred.
980emma's user avatar
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