Quantum speed limit based on the bound of Bures angle.

Area of Science:

• Quantum information science
• Open quantum systems
• Quantum thermodynamics

Background:

• Quantum speed limits (QSLs) define the fastest possible rate of quantum evolution.
• Open quantum systems interact with their environment, leading to decoherence and affecting evolution speed.
• The Bures angle provides a metric for distinguishability of quantum states, relevant for QSLs.

Purpose of the Study:

• To investigate a unified bound for quantum speed limit time in open quantum systems.
• To apply this bound to specific models like the damped Jaynes-Cummings model and the dephasing model.
• To analyze the influence of environmental factors, such as white noise and non-Markovianity, on QSL time.

Main Methods:

• Utilizing the modified Bures angle to establish a unified bound for quantum speed limit time.
• Deriving analytical expressions for quantum speed limit time in the damped Jaynes-Cummings model and the dephasing model.
• Examining the impact of initial states, including coherent states with white noise, on the calculated QSL time.

Main Results:

• The quantum speed limit time in both non-Markovian and Markovian regimes can be reduced by white noise compared to pure states.
• For the dephasing model, quantum speed limit time is influenced by the initial state's coherence and non-Markovianity.
• The population of the initial excited state also plays a role in the quantum speed limit time for the dephasing model.

Conclusions:

• A unified bound for quantum speed limit time in open systems is established and applied effectively.
• White noise is shown to accelerate quantum evolution by decreasing the quantum speed limit time.
• The findings highlight the complex interplay between environmental noise, system coherence, and the fundamental limits of quantum dynamics.