Decoherence of quantum local fisher and uncertainty information in two-qubit NV centers
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2025-10-02 |
| Journal | Scientific Reports |
| Authors | H. Allhibi, Fahad Aljuaydi, AbdelâBaset A. Mohamed, H. A. Hessian |
| Institutions | Princess Nourah bint Abdulrahman University, Al Baha University |
| Analysis | Full AI Review Included |
Executive Summary
Section titled âExecutive Summaryâ- Core System Robustness: The study confirms that two-qubit Nitrogen-Vacancy (NV) centers in diamond possess a high intrinsic capability to generate strong quantum correlations (Local Quantum Fisher Information (LQFI), Local Quantum Uncertainty (LQU), and Concurrence) even under weak intrinsic decoherence.
- Correlation Enhancement: Increasing the external electric control field (Ex) and the dipole-dipole coupling (Î) significantly strengthens the generation of LQFI, LQU, and Concurrence by increasing oscillation amplitudes and frequencies.
- Correlation Weakening: The ability of the system to generate correlations is weakened by increasing the external magnetic field (Bz) and the zero-field splitting fields (Dk), which accelerate state transitions and limit quantum information exchange.
- Decoherence Impact: Strong intrinsic decoherence (large coupling 1/Îł) causes rapid exponential degradation of all correlations, leading the system quickly toward low-amplitude, quasi-dependent stationary states.
- Wigner-Yanase-Fisher Correlation: LQFI and LQU generally exhibit the same oscillatory dynamics, defining a âWigner-Yanase-Fisher correlation,â which is maintained except during intervals characterized by strong Concurrence (entanglement).
- Entanglement Dynamics: Concurrence is generally more robust against decoherence than LQFI and LQU. Under strong electric fields, the system exhibits sudden-death and sudden-birth phenomena in entanglement over short time intervals.
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| System Type | Two-qubit | N/A | Nitrogen-Vacancy (NV) centers in diamond. |
| Initial State M(0) | 1A1B><1A1B | ||
| Gyromagnetic Factor (Ď) | 0.5 | N/A | Dimensionless parameter used in simulations. |
| Inter-qubit Distance (r) | 1 | N/A | Unit vector (0, 1, 0) used for dipole-dipole calculation. |
| Zero-Field Splitting (DA) | 0.8 to 2.5 | N/A | Varied to study correlation dynamics (Fig. 1). |
| Zero-Field Splitting Difference (DB - DA) | -0.3 | N/A | Fixed difference used in simulations. |
| External Magnetic Field (Bz) | 0.5 (baseline), 2, 7 | N/A | Varied to study correlation degradation (Fig. 2, 6a). |
| External Electric Field (Ex) | 2 (baseline), 4, 8 | N/A | Varied to study control field effects (Fig. 3, 6b). |
| Dipole-Dipole Coupling (Î) | 0.4 (baseline), 0.8, 1.5 | N/A | Varied to study interaction strength (Fig. 4, 6c). |
| Weak Intrinsic Decoherence (1/Îł) | 5 x 10-5 | N/A | Used for baseline oscillatory dynamics (Fig. 1-4). |
| Strong Intrinsic Decoherence (1/Îł) | 5 x 10-3, 5 x 10-2 | N/A | Used to model rapid correlation degradation (Fig. 5, 6). |
| Correlation Bounds (L, U, C) | 0 to 1 | N/A | LQFI, LQU, and Concurrence are bounded by 0 < L(t) ⤠1. |
Key Methodologies
Section titled âKey Methodologiesâ- System Hamiltonian Formulation: The physical model defined two coupled NV centers (A and B) in diamond, incorporating zero-field splitting (Dk), Zeeman interaction (Bz), external electric control (Ex), and dipole-dipole coupling (Î). The total Hamiltonian (H) was constructed as a 4x4 matrix in the two-qubit basis.
- Intrinsic Decoherence Modeling: Decoherence was modeled using the Milburn intrinsic decoherence model (pure dephasing), which describes non-unitary evolution of the density matrix M(t) governed by the intrinsic coupling parameter Îł.
- Time Evolution Calculation: The time evolution of the density matrix M(t) was computed analytically using the Hamiltonian eigenvalues (Ek) and eigenstates (|Ek>), incorporating both unitary interaction (Xmn(t)) and exponential decoherence (Ymn(t)) terms.
- Initial State Preparation: The system was initialized in a maximally excited-state triplet M(0) = |1A1B><1A1B|, representing an uncorrelated starting point (L(0) = U(0) = C(0) = 0).
- Correlation Quantification: Dynamics were numerically simulated by calculating three key quantum correlation metrics:
- Local Quantum Fisher Information (LQFI, L(t)): Quantifies interferometric power beyond entanglement.
- Local Quantum Uncertainty (LQU, U(t)): Minimum Wigner-Yanase skew information.
- Concurrence (C(t)): Standard measure of entanglement.
- Parameter Sweep Analysis: The dynamics of LQU, LQFI, and Concurrence were systematically analyzed by increasing the values of Dk, Bz, Ex, Î, and the decoherence coupling 1/Îł to determine their respective effects on correlation generation and degradation.
Commercial Applications
Section titled âCommercial Applicationsâ| Industry/Application | Relevance to NV Center Technology |
|---|---|
| Room-Temperature Quantum Computing | NV centers are prime candidates for scalable quantum processors due to their long coherence times, even at room temperature. This research provides engineering guidelines for optimizing external control fields (Ex, Bz) to maximize qubit correlation and minimize decoherence. |
| Quantum Metrology and Sensing | The realization and robust estimation of Quantum Fisher Information (QFI) and LQFI are crucial for enhancing the precision limits of quantum sensors, particularly those based on NV centers for magnetic or electric field detection. |
| Solid-State Quantum Memory | Understanding how intrinsic decoherence (Îł) and internal couplings (Î) affect correlation stability is essential for designing robust quantum memory architectures based on NV center spin systems. |
| Quantum Communication and Cryptography | The ability to generate and maintain strong two-qubit correlations (Concurrence) is a prerequisite for implementing secure quantum key distribution (QKD) and quantum teleportation protocols. |
| Materials Engineering for Qubits | Provides specific data on how material parameters, such as zero-field splitting (Dk) and dipole-dipole interaction (Î), must be controlled during diamond synthesis and device fabrication to optimize quantum performance. |