Questions tagged [quantum-metrology]

The study of making high-resolution and highly sensitive measurements of physical parameters using quantum theory to describe the physical systems, particularly exploiting quantum entanglement and quantum squeezing.

7 questions with no upvoted or accepted answers
Filter by
Sorted by
Tagged with
5 votes
0 answers
124 views

Why is the quantum Fisher information $J_f=[f(\frac43-f)]^{-1}$ for maximally entangled qubit pairs?

I am reading paper Channel Identification and its Impact on Quantum LDPC Code Performance where the authors discuss the scenario where the decoder of a Quantum LDPC code uses an estimation of the ...
Josu Etxezarreta Martinez's user avatar
2 votes
0 answers
36 views

Fisher information of parametric channel

Suppose $\Phi_\theta$ is a quantum channel whose action can be written for any state $\rho\in \mathcal S(\mathcal H_S)$ in the Stinespring representation as $\Phi_\theta(\rho)= \text{Tr}_E(U_\theta (\...
Quantastic's user avatar
2 votes
0 answers
102 views

What happens in the Cramer-Rao bound if the quantum Fisher information is zero?

The famous Cramer-Rao bound is $$\Delta\theta\ge\frac{1}{\sqrt {F[\rho,H]}}$$ But what happens if the denominator vanishes, i.e., $F[\rho,H]=0$ ($F[\rho,H]$ here stands for the quantum fisher ...
narip's user avatar
  • 2,984
1 vote
0 answers
63 views

What are the similarity and difference between quantum fidelity estimation and parameter estimation problem?

Quantum fidelity (1) estimation is to estimate the similarity between two quantum states or process. Could quantum fidelity be viewd as a parameter? And what are the similarity and difference between ...
Michael.Andy's user avatar
1 vote
0 answers
53 views

In quantum metrology, how do we achieve unbiased estimator in the local unbiased formalism?

In quantum metrology, the main goal is to estimate some unknown parameter to the limit of quantum mechanics. Suppose there's a unitary quantum channel $U_{\theta}=e^{-i\theta \sigma _z}$ with $\theta$ ...
narip's user avatar
  • 2,984
1 vote
0 answers
54 views

How is quantum metrology realized in experiment?

Are there some lists of the method to realize quantum metrology, or rather, utilizing quantum resources to enhance the precision of parameter estimation. The experimental method I've know is listed as ...
narip's user avatar
  • 2,984
0 votes
0 answers
18 views

Calculation of QCRB from QCRB

On page 3 of Zhuang et al. (2018), they found the quantum Cramér-Rao bound (QCRB) of the parameter using the quantum fisher information matrix. See Equations $(15)$ and Eq $(16)$. The problem is ...
Samo Yass's user avatar