Optical Control of a Single Nuclear Spin in the Solid State
At a Glance
Section titled āAt a Glanceā| Metadata | Details |
|---|---|
| Publication Date | 2020-04-15 |
| Journal | Physical Review Letters |
| Authors | Michael Goldman, Taylor L. Patti, David Levonian, Susanne F. Yelin, M. D. Lukin |
| Institutions | Harvard University, University of Connecticut |
| Citations | 22 |
| Analysis | Full AI Review Included |
Executive Summary
Section titled āExecutive Summaryā- Core Achievement: Demonstrated all-optical coherent control (initialization, manipulation, and readout) of a single 14N nuclear spin in a solid-state Nitrogen-Vacancy (NV) center in diamond.
- Methodology: Utilized an all-optical Raman technique mediated by the NV centerās electronic excited state level anticrossing (ESLAC).
- Performance Advantage: Optical manipulation is significantly faster and offers much higher spatial resolution compared to traditional microwave or radio-frequency control methods.
- Coherence Limitation: The coherence and speed of the optical technique are fundamentally limited by the ratio of the transverse hyperfine coupling (Aā„) to the excited state radiative decay rate (Ī³), found to be approximately 2.
- Nuclear Polarization: A novel optical pumping mechanism was developed, achieving a nuclear polarization of approximately 87%.
- Dynamics Observed: Coherent Rabi oscillations were observed for both nuclear spin-conserving and electronic-nuclear flip-flop transitions, marking the onset of coherent nuclear dynamics.
- Scalability: This approach is crucial for creating densely spaced arrays of quantum emitters integrated into nanophotonic devices for quantum networks.
Technical Specifications
Section titled āTechnical Specificationsā| Parameter | Value | Unit | Context |
|---|---|---|---|
| Quantum Emitter | Nitrogen-Vacancy (NV) Center | N/A | Host material: Diamond |
| Nuclear Spin Controlled | 14N | Spin-1 | Proximal nuclear spin |
| Operating Temperature | ~7 | K | Cryogenic conditions for Raman driving |
| Laser Wavelength | 637 | nm | Used for optical transitions |
| Raman Detuning (Ī) | ~870 | MHz | Single-photon detuning below E1 transitions |
| Axial Hyperfine Coupling (A/h) | -2.151(4) | MHz | Ground state 14N |
| Quadrupole Shift (P/h) | -4.942(9) | MHz | Ground state 14N |
| Nuclear Polarization Achieved | ~87 | % | Using targeted optical pumping |
| Excited State Radiative Decay (Ī³) | 2Ļ * 13 | MHz | Total decay rate out of 3E states |
| Transverse Hyperfine Ratio (Aā„/Ī³) | ~2 | N/A | Fundamental limit on coherence |
| Phonon-Induced Mixing Rate (ĪISC) | 2Ļ * (4.1 Ā± 1.7) | MHz | Estimated at sample temperature (14 K) |
| Electronic Zeeman Splitting | ~400 | mG | Shift observed upon cooling from 296 K to 7 K |
| Electronic Spin Projection (ms) | +1, 0, -1 | N/A | States involved in the 3A2 ground manifold |
Key Methodologies
Section titled āKey Methodologiesā- Sample and Environment: Experiments were conducted on a single NV center in diamond held at a cryogenic temperature of approximately 7 K.
- Laser System: Three external-cavity diode lasers (637 nm) were used, controlled by a combination of acousto-optic (AOM) and electro-optic modulators (EOMs).
- Raman Field Generation: The two optical driving fields required for the Raman transition were generated by modulating a single laser using an EOM, ensuring stable relative phase and precise control over the frequency difference (two-photon detuning, Ī“L).
- Electronic Initialization and Readout: The electronic spin was initialized to the |0> state using 520 nm green light. Readout was performed by exciting the |0> ā |Ey> transition and measuring the resulting fluorescence.
- Nuclear Polarization (Optical Pumping): Achieved by simultaneously pumping the |+1> ā |E1> transition and the weakly allowed |0> ā |E2> transition. This process induces a nuclear spin flip (ĪmI = +1) when the NV center decays to a different ground state.
- Raman Spectroscopy: The hyperfine structure was mapped out by sweeping the two-photon detuning (Ī“L) while applying a Raman pulse and measuring the remaining population in the |0> state.
- Coherent Dynamics Measurement: Population dynamics (Rabi oscillations) were measured by varying the duration of the resonant Raman pulse and subsequently reading out the electronic or nuclear spin population.
- Nuclear Readout: The nuclear spin state was mapped onto the electronic spin state using a nuclear spin-conserving Raman pulse, allowing the nuclear state to be read out optically via the electronic spin population.
Commercial Applications
Section titled āCommercial Applicationsā- Quantum Computing and Memory:
- Long-Lived Quantum Memory: Nuclear spins provide exceptional isolation, making them ideal candidates for robust, long-lived quantum memory elements (ancillae) in quantum registers.
- Quantum Registers: Used for building multi-qubit quantum registers by coupling the NV electronic spin to proximal 14N or 13C nuclear spins.
- Integrated Quantum Devices:
- Nanophotonic Integration: The high spatial resolution and speed of all-optical control make this technique ideal for densely spaced arrays of color centers integrated into nanophotonic circuits (e.g., waveguides or cavities).
- Quantum Repeaters: Essential for scaling up quantum networks where fast, localized control of memory qubits is required.
- Quantum Sensing:
- Enhanced Magnetometry: Techniques relying on precise nuclear spin initialization and control can enhance the sensitivity and performance of NV-based magnetometers.
- Alternative Solid-State Emitters:
- Defect Control: The methodology is readily applicable to other solid-state defects with similar excited state structures, such as Silicon-Vacancy (SiV) centers in diamond or divacancy defects in 3C-SiC, enabling their use in quantum technologies.
View Original Abstract
We demonstrate a novel method for coherent optical manipulation of individual nuclear spins in the solid state, mediated by the electronic states of a proximal quantum emitter. Specifically, using the nitrogen-vacancy (NV) color center in diamond, we demonstrate control of a proximal ^{14}N nuclear spin via an all-optical Raman technique. We evaluate the extent to which the intrinsic physical properties of the NV center limit the performance of coherent control, and we find that it is ultimately constrained by the relative rates of transverse hyperfine coupling and radiative decay in the NV centerās excited state. Possible extensions and applications to other color centers are discussed.