Coherent electric field control of orbital state of a neutral nitrogen-vacancy center
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2024-05-13 |
| Journal | Nature Communications |
| Authors | Hodaka Kurokawa, Keidai Wakamatsu, Shintaro Nakazato, Toshiharu Makino, Hiromitsu Kato |
| Institutions | National Institute of Advanced Industrial Science and Technology, Yokohama National University |
| Citations | 8 |
| Analysis | Full AI Review Included |
Executive Summary
Section titled âExecutive SummaryâThis research demonstrates the coherent electric field control of the orbital state of the neutrally-charged nitrogen-vacancy center (NV0) in diamond, establishing a pathway for ultra-low-power quantum manipulation.
- Core Achievement: Coherent control (Rabi oscillation and Ramsey interference) of the NV0 orbital state using applied AC electric fields (microwaves).
- Power Efficiency: The required microwave power for orbital control is three orders of magnitude smaller than that needed for conventional magnetic field spin control in similar color centers.
- System Suitability: NV0 is proposed as an ideal system due to its ground-state spin-orbit splitting (~10 GHz, allowing direct microwave access) and a relatively long orbital relaxation time (T1 ~138 ns at 5.5 K).
- Electric Susceptibility: The measured AC electric susceptibility (dAC = 1.0 MHz/(V cm-1)) is comparable to the excited state of the negatively charged NV- center.
- Coherence Metrics: Orbital Rabi oscillations were observed at 87.8 MHz, and the orbital coherence time (T2*) was measured to be 31.0 ns at 5.5 K.
- Future Interface: The low-power requirement is critical for interfacing solid-state color centers with high-impedance superconducting qubits operating in dilution refrigerators, potentially achieving single-photon coupling in the tens of kilohertz range.
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| Operating Temperature | 5.5 | K | Closed-cycle optical cryostat |
| NV0 Ground-State Splitting | 12.85 | GHz | Measured via PLE/ODER |
| Orbital Relaxation Time (T1) | 138 (±19) | ns | At 5.5 K, limited by thermal phonons |
| Orbital Coherence Time (T2*) | 31.0 (±3.6) | ns | Measured via Ramsey interference |
| Orbital Rabi Frequency | 87.8 | MHz | Measured at 504 ”W input microwave power |
| Power Reduction Factor | 103 | N/A | Orbital control power vs. spin control power |
| DC Electric Susceptibility (dparallel) | 1.08 | MHz/(V cm-1) | Parallel to NV axis |
| AC Electric Susceptibility (dAC) | 1.0 | MHz/(V cm-1) | Estimated from Autler-Townes splitting |
| Rabi Frequency Slope | 3.86 (±0.03) | MHz/”W1/2 | Dependence on square root of microwave power |
| Charge Initialization Laser | 637 | nm | Converts NV- to NV0 (200 ”W power) |
| Readout/Excitation Laser | 575 | nm | Resonant with NV0 Zero-Phonon Line (ZPL) |
| Electrode Materials | Au (500 nm)/Ti (10 nm) | N/A | Formed on diamond substrate |
Key Methodologies
Section titled âKey MethodologiesâThe experiment relies on high-quality diamond material processing and cryogenic optical/electrical control:
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Diamond Substrate Preparation:
- Used [100]-cut electronic-grade single-crystal diamond synthesized via Chemical Vapor Deposition (CVD).
- Surface cleaned using a mixture of H2SO4 and HNO3 at 200 °C for 60 minutes to remove contamination and achieve oxygen termination.
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Electrode Fabrication:
- Au (500 nm) and Ti (10 nm) electrodes were formed on the substrate using photolithography processes.
- Electrodes were connected to a Printed Circuit Board (PCB) using gold wire bonds for electrical access.
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Cryogenic Confocal Microscopy:
- All measurements were performed in a closed-cycle optical cryostat at 5.5 K under an ambient magnetic field.
- A home-built confocal microscope was used for optical excitation and collection.
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Charge State Initialization:
- The NV center was initialized to the neutral state (NV0) using a 637 nm red laser pulse (100 ”s duration, 200 ”W power), achieving a charge initialization fidelity greater than 97.0%.
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Orbital State Control and Readout:
- DC Field Measurement: DC voltages were applied to estimate strain parameters and electric susceptibility via Photoluminescence Excitation (PLE) frequency shifts.
- AC Field Control: Microwave pulses (up to 16 GHz) were applied via the electrodes for Optically Detected Electrical Resonance (ODER), Rabi oscillation, and Ramsey interference measurements.
- Readout: The 575 nm yellow laser was used to observe the NV0 ZPL transition and measure population changes via Photoluminescence (PL) counts.
Commercial Applications
Section titled âCommercial ApplicationsâThe demonstrated low-power, coherent orbital control of NV0 centers is highly relevant for next-generation quantum technologies:
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Quantum Computing and Networking:
- Hybrid Qubit Interfaces: NV0 serves as a robust solid-state quantum memory interface, communicating with superconducting qubits (e.g., transmon) via electric fields in a dilution refrigerator environment.
- Quantum Network Nodes: Enables efficient generation of entanglement between remote color centers by tuning the Zero-Phonon Line (ZPL) frequency using electric fields.
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Quantum Sensing:
- Electric Field Sensing: The strong coupling between the orbital degree of freedom and electric fields allows for highly sensitive, localized electric field sensing.
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Cryogenic Electronics:
- Low-Power Control Systems: The three-orders-of-magnitude reduction in required control power is crucial for scaling up quantum processors operating at millikelvin temperatures, minimizing heat load in dilution refrigerators.
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Diamond Material Engineering:
- Strain Engineering: Provides a platform for studying the effects of strain and electric fields on quantum defects across a wide parameter range, informing the design of future group-IV color centers (e.g., SiV, GeV).
View Original Abstract
Abstract The coherent control of the orbital state is crucial for realizing the extremely-low power manipulation of the color centers in diamonds. Herein, a neutrally-charged nitrogen-vacancy center, NV 0 , is proposed as an ideal system for orbital control using electric fields. The electric susceptibility in the ground state of NV 0 is estimated, and found to be comparable to that in the excited state of NV â . Also, the coherent control of the orbital states of NV 0 is demonstrated. The required power for orbital control is three orders of magnitude smaller than that for spin control, highlighting the potential for interfacing a superconducting qubit operated in a dilution refrigerator.