Entanglement Degradation in Two Interacting Qubits Coupled to Dephasing Environments

Area of Science:

• Quantum Information Science
• Quantum Computing
• Atomic Physics

Background:

• Decoherence, caused by qubit-environment interaction, leads to loss of quantum entanglement, hindering quantum computation.
• Asymmetric two-level atoms (qubits) and various dephasing environments are crucial factors in quantum system stability.

Purpose of the Study:

• To investigate the dynamics of entanglement in a system of two interacting asymmetric qubits under pure and correlated dephasing.
• To analyze how qubit asymmetry (frequency and coupling strength differences) and initial states influence entanglement decay.

Main Methods:

• Simulating a two-qubit system with varying interaction strengths, relative frequencies, and environmental coupling.
• Analyzing entanglement evolution for different initial states, including disentangled, Werner, and Bell states.
• Comparing the effects of pure (uncorrelated) and correlated dephasing environments.

Main Results:

• Qubit asymmetry significantly affects entanglement decay, with rates depending on the initial state and anisotropy.
• Increased frequency differences enhance entanglement decay for disentangled and Werner states, showing more persistence with higher anisotropy.
• Correlated dephasing can enhance entanglement for certain initial states (disentangled, anti-correlated Bell, Werner) but decay for others (correlated Bell).

Conclusions:

• Qubit asymmetry and dephasing environment characteristics critically influence quantum entanglement dynamics.
• Understanding these effects is vital for designing robust quantum computing architectures.
• Tailoring qubit properties and environment interactions can potentially preserve or even enhance entanglement.