Quantum reference frames and their applications to thermodynamics

Area of Science:

• Quantum Physics
• Quantum Information Science
• Thermodynamics

Background:

• Implementing arbitrary quantum transformations is challenging under conservation laws.
• Existing methods often struggle with back-action from conserved quantities.
• Quantum reference frames are crucial for quantum information processing.

Purpose of the Study:

• To construct a quantum reference frame capable of implementing unitary transformations despite conserved quantities.
• To develop a system that absorbs back-action from conservation laws.
• To apply this framework to quantum thermodynamics with multiple conserved quantities.

Main Methods:

• Construction of a quantum reference frame using subsystems similar to the target system.
• Interaction design involving two-body terms coupling system and reference frame.
• Absorption of back-action from conservation laws by the reference frame.

Main Results:

• A physically intuitive and implementation-friendly quantum reference frame was constructed.
• The reference frame functions as a battery for conserved quantities.
• Arbitrary unitary transformations can be approximately implemented in systems with conserved quantities.

Conclusions:

• The developed quantum reference frame provides a practical solution for implementing quantum transformations in systems with conserved quantities.
• This framework enables the definition of explicit batteries for quantum thermodynamic systems.
• The work contributes to the foundations of quantum mechanics and its societal impact.