Relaxation to Negative Temperatures in Double Domain Systems

Area of Science:

• Quantum physics
• Quantum information science
• Condensed matter physics

Background:

• Engineering quantum systems allows for the design of complex, composite systems.
• Coupling distinct quantum systems to a common environment can lead to unusual behaviors.

Purpose of the Study:

• Investigate the relaxation dynamics of two giant spin ensembles coupled to the same reservoir.
• Analyze the steady-state properties of such composite quantum systems.

Main Methods:

• Theoretical investigation of two collective spin ensembles.
• Analysis of systems coupled to a single, shared reservoir.
• Examination of steady-state configurations under varying ensemble sizes.

Main Results:

• The steady state of the composite system does not always reach the ground state of individual systems.
• Collective relaxation can drive a smaller spin ensemble to an excited steady state.
• Negative-temperature steady states can be achieved for a spin ensemble.

Conclusions:

• Shared environments introduce non-trivial correlations affecting quantum system relaxation.
• The size of spin ensembles plays a critical role in determining steady-state properties.
• Exploiting collective relaxation offers pathways to engineer exotic quantum states, including negative temperatures.