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Ansatz for the quantum phase transition in a dissipative two-qubit system
Hang Zheng1, Zhiguo Lü1, Yang Zhao2
1Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics, Shanghai Jiao Tong University, Shanghai 200240, China.
Summary
We studied quantum phase transitions in two-qubit systems using a novel ansatz. Our findings reveal critical points and explore the delocalized-localized transition, agreeing with numerical methods.
Area of Science:
- Quantum Information Science
- Condensed Matter Physics
Background:
- Understanding quantum phase transitions is crucial for quantum computing and materials science.
- Dissipative reservoirs significantly influence quantum system dynamics and ground states.
Purpose of the Study:
- To investigate quantum phase transitions in a two-qubit system coupled to a dissipative reservoir.
- To analyze the ground-state phase diagram and identify quantum critical points.
Main Methods:
- Employing a unitary transformation to propose an ansatz for studying the system.
- Analyzing the ground-state phase diagram using an analytic wave function.
- Calculating entanglement entropy and qubit-qubit correlation functions.
Main Results:
- The ground-state phase diagram was analyzed for Ohmic and sub-Ohmic baths.
- A quantum critical point was identified, marking the transition from non-degenerate to degenerate ground states.
- Calculated critical coupling strength (α(c)) shows agreement with numerical renormalization-group methods.
Conclusions:
- The study successfully characterized quantum phase transitions in a dissipative two-qubit system.
- The nature of the transition between delocalized and localized states was explored through entanglement and correlation analysis.
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