Coherent electric field control of orbital state of a neutral nitrogen-vacancy center

At a Glance

Metadata	Details
Publication Date	2024-05-13
Journal	Nature Communications
Authors	Hodaka Kurokawa, Keidai Wakamatsu, Shintaro Nakazato, Toshiharu Makino, Hiromitsu Kato
Institutions	Yokohama National University, National Institute of Advanced Industrial Science and Technology
Citations	8
Analysis	Full AI Review Included

Technical Documentation & Analysis: Coherent Electric Field Control of NV⁰ Orbital State

This documentation analyzes the research demonstrating highly efficient electric field control of the neutral nitrogen-vacancy (NV⁰) center’s orbital state in CVD diamond, highlighting how 6CCVD’s advanced MPCVD diamond materials and fabrication services are essential for replicating and extending this critical quantum research.

Executive Summary

Core Achievement: Demonstrated coherent control of the orbital state of the neutral nitrogen-vacancy center (NV⁰) using applied electric fields in electronic-grade CVD diamond.
Efficiency Breakthrough: Orbital control requires power three orders of magnitude smaller (hundreds of µW) than conventional magnetic field methods used for spin control, enabling highly efficient manipulation.
Quantum Interface Potential: The low-power requirement and robust control make NV⁰ an ideal candidate for interfacing solid-state color centers with superconducting qubits operating in dilution refrigerators.
Key Performance Metrics: Measured orbital relaxation time (T₁) of ~138 ns (at 5.5 K) and orbital coherence time (T₂*) of 31.0 ns, comparable to SiV spin coherence times.
Material Requirements: The experiment relied on high-quality, [100]-cut single-crystal diamond (SCD) substrates combined with precise photolithography and custom Au/Ti metalization for electrode fabrication.
6CCVD Value Proposition: 6CCVD provides the necessary Optical Grade SCD substrates, ultra-smooth polishing (Ra < 1 nm), and custom metalization services (Ti/Au) required to meet the stringent material specifications for advanced quantum device engineering.

Technical Specifications

The following table extracts key quantitative data points achieved or utilized in the study concerning the NV⁰ center and device performance.

Parameter	Value	Unit	Context
Material Substrate	[100]-cut SCD	N/A	Electronic-grade CVD diamond
Operating Temperature	5.5	K	Closed-cycle optical cryostat
Ground-State Splitting	12.85	GHz	Measured via PLE spectrum
Orbital Relaxation Time (T₁)	138 ± 19	ns	Measured at 5.5 K
Orbital Coherence Time (T₂*)	31.0 ± 3.6	ns	Measured via Ramsey interference
Electric Susceptibility (d₁₁)	1.08	MHz/(V cm⁻¹)	Parallel to NV axis (DC measurement)
AC Electric Susceptibility (d^AC)	1.0	MHz/(V cm⁻¹)	Measured via Autler-Townes splitting
Rabi Frequency	87.8	MHz	At 504 µW microwave input power
Electrode Metalization Stack	Au (500 nm) / Ti (10 nm)	nm	Formed via photolithography
Required Power for Orbital Control	Hundreds of µW	N/A	Three orders of magnitude smaller than spin control

Key Methodologies

The successful demonstration of coherent NV⁰ orbital control relies on precise material preparation and advanced cryogenic measurement techniques.

Substrate Synthesis: Electronic-grade, [100]-cut single-crystal diamond (SCD) was synthesized via Chemical Vapor Deposition (CVD).
Surface Preparation: The diamond surface was cleaned and oxygen-terminated by immersion in a mixture of H₂SO₄ and HNO₃ at 200 °C for 60 minutes to remove surface contamination.
Electrode Fabrication: Custom electrodes were patterned using photolithography, followed by the deposition of a Ti (10 nm) adhesion layer and an Au (500 nm) conductive layer.
Cryogenic Setup: Experiments were conducted in a closed-cycle optical cryostat (Cryostation s50) at 5.5 K under an ambient magnetic field.
Charge State Initialization: A 637 nm red laser (200 µW, 100 µs pulse) was used to resonantly excite NV⁻, converting the charge state to the desired neutral NV⁰ state.
Optical Readout: A 575 nm yellow laser (1 µW, 1 µs pulse) was used for resonant excitation and readout of the NV⁰ transition lines.
Coherent Control: Microwave pulses (up to 16 GHz) and DC electric fields were applied to the electrodes to perform Optically Detected Electrical Resonance (ODER), Rabi oscillation, and Ramsey interference measurements.

6CCVD Solutions & Capabilities

This research underscores the critical need for high-quality diamond materials and precision fabrication for next-generation quantum technologies. 6CCVD is uniquely positioned to supply the necessary components to replicate and advance this work.

Applicable Materials

To replicate or extend this research, 6CCVD recommends the following materials:

Optical Grade Single Crystal Diamond (SCD): Required for achieving the long coherence times (T₂*) necessary for quantum operations. Our SCD material features ultra-low nitrogen and defect concentrations, minimizing spectral diffusion and maximizing quantum performance.
Custom Substrate Orientation: While the paper used [100]-cut, 6CCVD offers custom SCD substrates in various orientations (e.g., [111]) to optimize the alignment of the NV axis relative to applied electric fields, enabling tailored device geometries.
Boron-Doped Diamond (BDD): For future integration into complex quantum circuits requiring conductive layers (e.g., ground planes or integrated transmission lines), 6CCVD offers heavily Boron-Doped PCD or SCD substrates up to 500 µm thick.

Customization Potential

The success of this experiment hinges on the quality of the diamond substrate and the precision of the integrated electrodes. 6CCVD directly addresses these needs:

Research Requirement	6CCVD Capability	Specification
High-Fidelity Electrodes	In-House Metalization Services	We offer custom deposition of Ti/Au (as used in the paper), Pt/Au, Pd, W, or Cu stacks. We control thickness and adhesion critical for cryogenic stability.
Ultra-Smooth Surface	Precision Polishing	SCD substrates are polished to an industry-leading surface roughness (Ra) < 1 nm, ensuring optimal conditions for high-resolution photolithography and minimizing surface charge effects.
Custom Dimensions & Integration	Advanced Fabrication	We provide custom plates and wafers up to 125 mm (PCD) and offer precise laser cutting and shaping services to ensure substrates fit complex cryostat mounts and PCB integration, as described in the Methods section.
Thickness Control	Material Thickness Range	SCD and PCD wafers are available from 0.1 µm to 500 µm, with substrates available up to 10 mm thick, allowing flexibility for both thin-film device fabrication and robust bulk experiments.

Engineering Support

The highly-efficient control of the NV⁰ orbital state opens new avenues for hybrid quantum systems. 6CCVD’s in-house PhD team specializes in material science for quantum applications and can assist researchers with:

Material Selection: Optimizing diamond grade and orientation for similar NV⁰/SiV Orbital Control projects.
Metalization Recipe Development: Designing robust, low-loss metal stacks suitable for high-frequency microwave transmission and cryogenic operation (5.5 K and below).
Defect Engineering: Consulting on post-growth processing techniques to maximize the yield and coherence of specific color centers.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

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 − . 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.

Tech Support

Original Source

DOI: https://doi.org/10.1038/s41467-024-47973-3