scholarly journals Comment on “Fisher information of a vector potential for time‐dependent Feinberg–Horodecki equation”

2021 ◽  
Author(s):  
João P. G. Nascimento ◽  
Vanderley Aguiar ◽  
Raimundo N. Costa Filho ◽  
João Milton Pereira Jr
Keyword(s):  
Fisher Information ◽  
Vector Potential ◽  
Time Dependent

TIME-DEPENDENT DENSITY FUNCTIONAL THEORY BEYOND THE ADIABATIC APPROXIMATION

2001 ◽  
Vol 15 (10n11) ◽  
pp. 1714-1723 ◽  
Author(s):  
G. VIGNALE
Keyword(s):  
Density Functional Theory ◽  
Quantum Wells ◽  
Vector Potential ◽  
Density Functional ◽  
Time Dependent ◽  
Viscous Force ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Functional Theory ◽  
Dependent Density

I review recent advances in understanding the physical character of the exchange-correlation (xc) potential in time-dependent density functional theory. I show that in an electron gas of slowly varying density the dynamical part of the xc potential is an extremely nonlocal functional of the density. This difficulty can be circumvented by introducing an xc vector potential that is a function of the local current density. The form of this vector potential is entirely specified by symmetry. Its physical effects are analogous to those of the viscous force in the Navier-Stokes equation of classical hydrodynamics. Recent applications of the xc vector potential to the calculation of infrared absorption linewidths in quantum wells are described.

Magnetic Aharonov-Bohm effect under time-dependent vector potential

2000 ◽  
Vol 26 (5) ◽  
pp. 392-393 ◽  
Author(s):  
A. N. Ageev ◽  
S. Yu. Davydov ◽  
A. G. Chirkov
Keyword(s):  
Vector Potential ◽  
Time Dependent ◽  
Dependent Vector ◽  
Bohm Effect ◽  
Aharonov Bohm

scholarly journals Shortcut-to-Adiabaticity-Like Techniques for Parameter Estimation in Quantum Metrology

Entropy ◽  
2020 ◽  
Vol 22 (11) ◽  
pp. 1251
Author(s):  
Marina Cabedo-Olaya ◽  
Juan Gonzalo Muga ◽  
Sofía Martínez-Garaot
Keyword(s):  
Parameter Estimation ◽  
Quantum Mechanics ◽  
Adaptive Control ◽  
Fisher Information ◽  
Upper Bound ◽  
Point Of View ◽  
Time Dependent ◽  
Precision Measurements ◽  
Quantum Metrology ◽  
Unitary Transformations

Quantum metrology makes use of quantum mechanics to improve precision measurements and measurement sensitivities. It is usually formulated for time-independent Hamiltonians, but time-dependent Hamiltonians may offer advantages, such as a T4 time dependence of the Fisher information which cannot be reached with a time-independent Hamiltonian. In Optimal adaptive control for quantum metrology with time-dependent Hamiltonians (Nature Communications 8, 2017), Shengshi Pang and Andrew N. Jordan put forward a Shortcut-to-adiabaticity (STA)-like method, specifically an approach formally similar to the “counterdiabatic approach”, adding a control term to the original Hamiltonian to reach the upper bound of the Fisher information. We revisit this work from the point of view of STA to set the relations and differences between STA-like methods in metrology and ordinary STA. This analysis paves the way for the application of other STA-like techniques in parameter estimation. In particular we explore the use of physical unitary transformations to propose alternative time-dependent Hamiltonians which may be easier to implement in the laboratory.

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