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Public Seminar of RPg Student:
Preliminary Study on Quantum Control with Smooth Entropy


Speaker:Mr. Kwok Chung Joseph NG
Affiliation:The University of Hong Kong
Date:May 4, 2018 (Friday)
Time:3:30 p.m.
Venue:Rm 522, 5/F, Chong Yuet Ming Physics Building, HKU

Abstract
 

Quantum control, the quantum counterpart of classical control theory which concerns the control of machines in the field of engineering, aims at obtaining a desired target state from a given initial state, by varying the external parameters. It has found applications in a wide range of disciplines, including physical chemistry, molecular physics, and quantum optics. It is also important to the development of quantum information theory, in which the quantum states have to be controlled precisely.

In this research, I investigate quantum control in the case of an open quantum system, that is, a quantum system which is subjected to disturbances and uncertainties from the environment. In order to handle such noises, I look into robust quantum control, whose goal is the minimization of the adverse effects from these uncertainties. Since these noises are of an indeterministic nature, I propose to, instead of requiring the state to approach the target state every time, consider only the cases when the state is evolved close enough to the target state with a high probability. This notion of proximity to a certain state with high likeliness has already been developed in the field of quantum information theory, namely, smooth entropy, which I plan to borrow to the field of quantum control theory.

In order to handle the effects of the environment, which is competing with the control mechanics to exert influence on the quantum state, I will apply the uncertainty principle formulated in terms of smooth entropies to examine to what extent the environment sways the state.

Apart from investigating the impact from the external disturbances, I also wish to introduce feedback control method that is analogous to quantum error correction in quantum information theory.

Anyone interested is welcome to attend.