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Universal quantum Otto heat machine based on the Dicke model.
He-Guang Xu1, Jiasen Jin1, G D M Neto2
1School of Physics, Dalian University of Technology, 116024 Dalian, China.
Researchers developed a universal quantum heat machine (UQHM) using qubits and a bosonic field. This quantum engine can act as an engine, refrigerator, heater, or accelerator, with performance enhanced near phase transitions.
Area of Science:
- Quantum thermodynamics
- Quantum information science
- Condensed matter physics
Background:
- Quantum thermal machines offer novel ways to harness quantum phenomena for energy conversion.
- The Dicke model describes interacting quantum systems, relevant for understanding collective effects.
Purpose of the Study:
- To investigate the creation of a universal quantum heat machine (UQHM) using N qubits coupled to a bosonic field within the open Dicke model.
- To analyze the machine's functionality as an engine, refrigerator, heater, or accelerator by controlling system parameters.
Main Methods:
- Modeling a quantum Otto thermal machine with N qubits interacting with a bosonic field and a reservoir (open Dicke model).
- Calculating heat and work exchanges considering atom number, coupling regimes, and reservoir temperature ratios.
- Analyzing quantum features like entanglement and second-order correlation.
Main Results:
- Demonstrated the UQHM's ability to function in multiple modes (engine, refrigerator, heater, accelerator).
- Showed that quantum resources (entanglement, correlation) do not impact UQHM efficiency or performance.
- Identified improved efficiency and performance near the critical value of the Dicke model's phase transition parameter.
Conclusions:
- A universal quantum heat machine is achievable using the open Dicke model.
- Quantum correlations do not enhance the performance of this specific UQHM.
- Optimal performance is linked to the proximity of the system's phase transition.

