Entanglement loss in molecular quantum-dot qubits due to interaction with the environment

Area of Science:

• Quantum Information Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Quantum entanglement is crucial for quantum computing.
• Environmental interactions can cause entanglement loss (decoherence).
• Understanding decoherence in complex nanoscale systems is vital for quantum technologies.

Purpose of the Study:

• To investigate quantum entanglement loss in a two-qubit system (electrons in double quantum dots) interacting with a complex environment.
• To analyze the time evolution of entanglement using Bell operators (CHSH and BPRV).
• To determine disentanglement times in realistic molecular double-dot systems.

Main Methods:

• Modeling a two-qubit system (electron in double quantum dot) initially in a Bell state.
• Simulating environmental interaction using surrounding double quantum dots with random positions and orientations.
• Calculating the unitary evolution of the joint system and environment.
• Examining the time dependence of bipartite Bell operators (CHSH and BPRV).

Main Results:

• Entanglement loss was studied in a complex, geometrically varied environment.
• The transition to local realism was explored via Bell operator expectation values.
• A universal behavior in disentanglement was observed, scalable with system parameters.
• Disentanglement times were determined for realistic molecular double-dot parameters.

Conclusions:

• Environmental geometry influences entanglement dynamics but a universal scaling behavior emerges.
• The study provides crucial insights into decoherence mechanisms in nanoscale quantum systems.
• Quantified disentanglement times are relevant for designing robust molecular quantum computing architectures.