Thermodynamics of a Minimal Algorithmic Cooling Refrigerator

Area of Science:

• Quantum thermodynamics
• Solid-state quantum computing

Background:

• Algorithmic cooling is a technique to improve qubit polarization.
• Heat-bath refrigerators utilize thermal reservoirs to extract heat.
• Three-qubit systems offer a minimal platform for studying quantum refrigeration.

Purpose of the Study:

• To theoretically and experimentally investigate the thermodynamic performance of a three-qubit heat-bath algorithmic cooling refrigerator.
• To analyze the coefficient of performance, cooling power, and qubit polarization under realistic conditions.
• To determine the fundamental upper bounds of these parameters and their experimental feasibility.

Main Methods:

• Analytical computation of thermodynamic parameters for an arbitrary number of cycles.
• Inclusion of realistic experimental imperfections in theoretical models.
• Experimental implementation using a three-qubit system in a nitrogen-vacancy center in diamond.

Main Results:

• The coefficient of performance, cooling power, and target qubit polarization were analytically derived.
• Fundamental upper bounds for these parameters were determined in the ideal reversible limit.
• Experimental results demonstrated that the system can approach these theoretical limits.

Conclusions:

• The three-qubit heat-bath algorithmic cooling refrigerator exhibits promising thermodynamic performance.
• The system's ability to approach ideal limits highlights its potential for practical quantum applications.
• Nitrogen-vacancy centers in diamond provide a viable platform for realizing advanced quantum cooling refrigerators.