Dephasing and relaxational polarized sub-Ohmic baths acting on a two-level system

Area of Science:

• Quantum physics
• Quantum information science
• Condensed matter physics

Background:

• Quantum systems interact with their environments through baths.
• Understanding these interactions is crucial for quantum technologies like superconducting qubits.
• Two common bath types are dephasing and relaxational baths.

Purpose of the Study:

• To investigate the effects of cooling a quantum two-level system coupled to two independent baths.
• To analyze how bath polarization influences system dynamics.
• To provide insights for optimizing cooling protocols in quantum devices.

Main Methods:

• Theoretical modeling of a quantum two-level system.
• Analysis of system behavior under sub-Ohmic dephasing and Ohmic/sub-Ohmic relaxational baths.
• Investigating the impact of bath polarization on system asymmetry and oscillation frequency.

Main Results:

• Cooling a two-level system inevitably polarizes one of its baths.
• A polarized relaxational bath induces asymmetry, which can be mitigated by dephasing noise.
• A polarized dephasing bath causes a significant shift in the system's oscillation frequency, largely independent of other noise sources.

Conclusions:

• Bath polarization is a key consequence of cooling quantum systems.
• The interplay between dephasing and relaxational baths affects system properties.
• Findings are relevant for enhancing cooling strategies in superconducting phase qubits and other quantum electronic devices.