| Metadata | Details |
|---|
| Publication Date | 2020-04-29 |
| Journal | Physical Review Letters |
| Authors | Thomas Kornher, Da-Wu Xiao, Kangwei Xia, Fiammetta Sardi, Nan Zhao |
| Institutions | University of Stuttgart, Beijing Computational Science Research Center |
| Citations | 31 |
| Analysis | Full AI Review Included |
- Platform Validation: Successfully demonstrated coherent control and spin spectroscopy of individual Cerium (Ce3+) electron spins embedded in a Yttrium Orthosilicate (YSO) host crystal.
- Extended Coherence: Achieved a long electron spin coherence time (T2 = 124 Āµs) despite the presence of a dense 89Y nuclear spin bath, enabling detailed spin environment analysis.
- Individual Spin Sensing: The Ce3+ electron spin was used as a sensor to detect and isolate signatures of individual, proximal 29Si nuclear spins (4.7% natural abundance) located less than 6 Angstrom away.
- Methodology: Dynamic Decoupling (DD) sequences, specifically Carr-Purcell-Meiboom-Gill (CPMG), were employed to distill the weak 29Si signal from the noisy 89Y bath background.
- Quantum Memory Resource: The coupled environmental nuclear spins (29Si and 89Y) serve as potential long-lived quantum memory resources, overcoming the limitations of the electron spin T2.
- Scalability: This work motivates the realization of controllable multi-spin quantum registers in rare-earth ion systems, essential for quantum error correction and scalable quantum networks.
| Parameter | Value | Unit | Context |
|---|
| Electron Spin Coherence Time (T2) | 124 Ā± 5 | Āµs | Measured via Hahn Echo sequence |
| Free Induction Decay Time (T2*) | 310 | ns | Measured via Ramsey sequence (inhomogeneous broadening) |
| Spin Relaxation Time (T1) | 610 | Āµs | Measured at T = 7.8 K (heat exchanger) |
| Spin Relaxation Time (T1) | 280 | Āµs | Measured at T = 8.5 K (heat exchanger) |
| Magnetic Field Strength (B) | 970 | Gauss | Applied parallel to the optical beam (YSO b-axis) |
| Ce3+ Magnetic Resonance Frequency | 1930.5 | MHz | Optically Detected Magnetic Resonance (ODMR) |
| ODMR Linewidth (Ī) | 2.2 | MHz | Typical range for individual Ce3+ ions |
| Rabi Oscillation Frequency | 5.6 | MHz | Under strong Microwave (MW) driving |
| Rabi Oscillation Decay Time | 2 | Āµs | Exponential fit to Rabi oscillations |
| Ce3+ Initialization Fidelity | 5 to 15 | % | Achieved via optical pumping |
| 29Si Natural Abundance | 4.7 | % | Isotope used for nuclear spin sensing |
| 29Si Detection Distance | Less than 6 | Angstrom | Distance from Ce3+ ion (nearest neighbor shell) |
| Sample Temperature (Tsample) | ~8 | K | Estimated actual temperature during experiment |
| Excitation Wavelength | 355 | nm | Picosecond pulsed laser |
| Zero-Phonon Line (ZPL) | 371 | nm | Characteristic Ce3+:YSO fluorescence |
- Material and Defect Creation:
- Host Material: Ultra-pure Yttrium Orthosilicate (Y2SiO5, YSO) crystal.
- Dopant: Trivalent Cerium (Ce3+) substituting Y3+ at the 7-oxygen-coordinated site (C1 symmetry).
- Microscopy and Setup:
- Setup: Laser Scanning Confocal Microscopy within a cold-finger cryostat (T ā 8 K).
- Resolution Enhancement: Solid Immersion Lenses (SILs) fabricated on the sample surface via Focused Ion Beam (FIB) milling to resolve individual Ce3+ ions.
- Optical Spin Initialization and Readout:
- Initialization: Off-resonant excitation using a 355 nm picosecond pulsed laser, combined with Ļ+ circularly polarized light, to pump the Ce3+ electron spin into an optically ādarkā state.
- Readout: Optically Detected Magnetic Resonance (ODMR) used to monitor fluorescence changes induced by resonant Microwave (MW) radiation (1930.5 MHz).
- Coherent Spin Control:
- Rabi Oscillations: Demonstrated using strong MW driving to confirm coherent manipulation capability.
- T2 Measurement: Hahn spin echo sequence (Ļ/2 - Ļ - Ļ - Ļ - Ļ/2) used to measure the electron spin coherence time (T2 = 124 Āµs).
- Nuclear Spin Spectroscopy (Dynamic Decoupling):
- Technique: Carr-Purcell-Meiboom-Gill (CPMG-N) sequences (N=1, 2, 5 Ļ-pulses) applied to the Ce3+ electron spin.
- Purpose: Decoupling the electron spin from the slow noise of the dense 89Y bath, allowing the detection and isolation of the hyperfine coupling signature from proximal 29Si nuclear spins.
- Theoretical Modeling:
- Simulation Method: Cluster-Correlation Expansion (CCE) method used to numerically calculate the decoherence of the Ce3+ ion subjected to the YSO nuclear spin bath Hamiltonian.
- Quantum Information Processing (QIP):
- Quantum Memory: Utilizing the long-lived 29Si and 89Y nuclear spins as robust storage nodes, interfaced by the optically active Ce3+ electron spin.
- Quantum Error Correction (QEC): The ability to control and couple multiple local nuclear spins provides the necessary architecture for implementing QEC protocols.
- Quantum Networking and Repeaters:
- Telecom Interface: Rare-earth ions (REIs) are key candidates for quantum repeaters, as their optical transitions can be engineered to match telecom wavelengths, enabling long-distance entanglement distribution.
- Solid-State Qubit Development:
- Host Material Validation: Confirms YSO as a viable, low-noise host for Kramers rare-earth ions, extending applicability to other commercially relevant qubits like Erbium (Er3+) and Gadolinium (Gd3+).
- High-Resolution Quantum Sensing:
- Local Environment Probing: The Ce3+ electron spin acts as an ultra-sensitive magnetometer capable of detecting and localizing single nuclear spins in complex solid-state environments, useful for material characterization.
View Original Abstract
Rare-earth related electron spins in crystalline hosts are unique material systems, as they can potentially provide a direct interface between telecom band photons and long-lived spin quantum bits. Specifically, their optically accessible electron spins in solids interacting with nuclear spins in their environment are valuable quantum memory resources. Detection of nearby individual nuclear spins, so far exclusively shown for few dilute nuclear spin bath host systems such as the nitrogen-vacancy center in diamond or the silicon vacancy in silicon carbide, remained an open challenge for rare earths in their host materials, which typically exhibit dense nuclear spin baths. Here, we present the electron spin spectroscopy of single Ce^{3+} ions in a yttrium orthosilicate host, featuring a coherence time of T_{2}=124 Ī¼s. This coherent interaction time is sufficiently long to isolate proximal ^{89}Y nuclear spins from the nuclear spin bath of ^{89}Y. Furthermore, it allows for the detection of a single nearby ^{29}Si nuclear spin, native to the host material with ā¼5% abundance. This study opens the door to quantum memory applications in rare-earth ion related systems based on coupled environmental nuclear spins, potentially useful for quantum error correction schemes.
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