Gaussian Thermal Operations and The Limits of Algorithmic Cooling.

Area of Science:

• Quantum thermodynamics
• Quantum information theory
• Statistical mechanics

Background:

• Investigating quantum states and nanoscale thermal machines requires understanding thermal operations.
• Existing models often exclude continuous variable systems and bilinear system-environment interactions.

Purpose of the Study:

• To characterize general Gaussian thermal operations on bosonic modes.
• To derive conditions for state transformations in single-mode Gaussian systems.
• To assess the feasibility of algorithmic cooling using Gaussian operations.

Main Methods:

• Focusing on Gaussian quantum states and channels.
• Characterizing general Gaussian thermal operations on multiple bosonic modes.
• Analyzing state transformations under single-mode Gaussian operations.
• Investigating the impact of system-environment interactions.

Main Results:

• A complete characterization of general Gaussian thermal operations was achieved.
• These operations are embeddable in Markovian dynamics.
• Conditions for state transformations in single-mode squeezed states were derived.
• Algorithmic cooling below environmental temperature was proven impossible.

Conclusions:

• Gaussian thermal operations are fundamentally constrained.
• It is impossible to reduce system entropy below environmental temperature using Gaussian operations and unitaries.
• These findings set limits on using Gaussian resources in quantum thermodynamics.