Coherent electrical control of single electron spin in diamond nitrogen-vacancy center

At a Glance

Metadata	Details
Publication Date	2022-01-01
Journal	Acta Physica Sinica
Authors	Jiandong Wu, Cheng Zhi, Xiangyu Ye, Zhaokai Li, Pengfei Wang
Analysis	Full AI Review Included

Executive Summary

This research demonstrates the successful implementation of coherent electrical control (E-field) over the electron spin of a Nitrogen-Vacancy (NV) center in diamond, a critical step for integrating quantum systems with classical electronics.

Core Achievement: Coherent electrical driving of the NV electron spin, resulting in Electrically Driven Rabi Oscillations (ERabi) between the magnetic-dipole forbidden |m_s = -1> and |m_s = +1> states (a Delta m_s = ±2 transition).
Control Mechanism: The transverse alternating electric field (E_⊥) directly couples to the spin states, bypassing the need for complex, bulky magnetic field coils for this specific transition.
Scaling Law: The ERabi oscillation frequency is confirmed to be linearly proportional to the square root of the applied E-field power (f_ERabi ∝ √W), demonstrating predictable and tunable control speed.
Full Spin Manipulation: By combining the E-field control (for Delta m_s = ±2 transitions) with conventional magnetic control (for Delta m_s = ±1 transitions), full, direct coherent control over all three ground-state spin levels (|0>, |+1>, |-1>) is achieved.
Integration Potential: E-field control utilizes micro-fabricated electrodes, making it highly compatible with semiconductor chips and integrated quantum devices, overcoming the localization and shielding challenges inherent to magnetic control.
Performance Metric: A π-pulse duration of 6.65 µs was achieved at 0.28 W power, allowing for hundreds of quantum logic gate operations within the measured 1.6 ms coherence time (T₂).

Technical Specifications

Parameter	Value	Unit	Context
Diamond Material	CVD-grown, ¹²C purified	-	Used to achieve long quantum coherence time
NV Center Depth	~5	nm	Distance from surface, optimized for E-field coupling
Electron Spin Coherence Time (T₂)	1.6	ms	Measured using exponential attenuation fit
Ground State Splitting (D)	2.87	GHz	Zero-field splitting of the ³A₂ state
Applied Axial Magnetic Field (B_z)	181.47	G	Used to lift the
Transverse Electric Dipole Moment (d_⊥)	17 ± 3	Hz/(V·cm^-1)	Key coupling constant for E-field control
E-field Driven π Pulse Duration (τ_π)	6.65	µs	Achieved at 0.28 W source power
E-field Source Power (W)	0.28	W	Maximum power used for fastest ERabi
ERabi Frequency Scaling Fit	f_ERabi = 257.129√W - 0.176	kHz	Empirical relationship derived from experimental data
Electrode Gap	10	µm	Distance between surface gold electrodes
Air Breakdown Limit (Current)	~30	kV/cm	Limits current E-field strength and control speed
Diamond Breakdown Limit (Potential)	21.5	MV/cm	Theoretical maximum E-field strength if electrodes are embedded

Key Methodologies

The experiment utilized a highly purified diamond sample and specialized electrode structures integrated onto an Optically Detected Magnetic Resonance (ODMR) platform.

Material Preparation:
- Diamond was grown via Chemical Vapor Deposition (CVD) and purified to 99.999% ¹²C to maximize electron spin coherence time (T₂).
- NV centers were created via 2.5 keV ¹⁵N ion implantation, resulting in NV centers approximately 5 nm below the surface to enhance coupling with the surface electrodes.
Electrode Fabrication:
- A pair of gold (Au) electrodes were deposited directly onto the diamond surface.
- The electrode gap was approximately 10 µm, designed to generate a strong, localized alternating electric field (E-field) when driven by a microwave source (MW_E).
- A separate gold stripline, placed 10 µm away from the electrodes, was used for conventional magnetic control (MW_B).
Spin Initialization and Readout:
- A 532 nm laser was used for spin initialization (polarizing the spin to the |m_s = 0> state) and readout (measuring fluorescence intensity, where |0> is bright and |±1> is dark).
- The system was operated on a laser scanning confocal microscope platform integrated with ODMR technology.
E-field Driven Rabi Oscillation (ERabi) Sequence:
- Initialization: 532 nm laser pulse polarizes the spin to |0>.
- Preparation: A resonant microwave magnetic π-pulse (MW_B) drives the spin from |0> to the |-1> state.
- Coherent Control: An alternating E-field pulse (P_E) is applied for a variable duration (τ), driving the coherent oscillation between |-1> and |+1> (Delta m_s = ±2).
- Readout: A final MW_B π-pulse transfers the remaining population in the |-1> state back to |0> for fluorescence measurement. The resulting fluorescence contrast reveals the population transfer driven by the E-field.

Commercial Applications

The ability to coherently control NV center spins using localized electric fields is crucial for the development and commercialization of solid-state quantum technologies.

Industry/Field	Application	Technical Relevance
Quantum Computing	Solid-State Qubit Control, Quantum Logic Gates	E-field control allows for fast, localized, and scalable qubit addressing, essential for dense integration on semiconductor platforms.
Quantum Sensing (Electromagnetism)	High-Resolution Electric Field Sensing	The demonstrated strong coupling between the E-field and the spin state forms the basis for highly sensitive, nanoscale E-field sensors.
Quantum Simulation	Integrated Quantum Systems	Enables the study of complex quantum phenomena in solid-state environments using highly controllable, integrated NV centers.
Micro/Nano-Electronics	Hybrid Quantum-Classical Devices	E-field control is inherently compatible with CMOS fabrication, facilitating the integration of NV quantum sensors directly onto classical electronic circuits.
Precision Measurement	Temperature and Strain Sensing	While the paper focuses on E-field, the underlying NV platform is used for high-precision measurement of temperature, strain, and magnetic fields (as demonstrated by the related articles). E-field control enhances the speed and fidelity of these sensing protocols.

View Original Abstract

The nitrogen-vacancy (NV) color center quantum system in diamond has shown great application potential in the fields of solid-state quantum computing and quantum precision measurement because of its unique advantages such as single-spin addressing and manipulation and long quantum coherence time at room temperature. The precise manipulation technology of single spin is particularly important for the development of the application of NV center. The common spin manipulation methods used in NV center quantum system are to drive and manipulate the electron spin by resonant alternating magnetic field. In recent years, the electrical control of quantum spin has attracted extensive attention. In this paper, using the alternating electric field to control the electron spin of NV center is studied. The alternating electric field generated by the electrode successfully drives the Rabi oscillation of the NV center spin between the <inline-formula><tex-math id=“M4”>\begin{document}$\Delta m_{\rm{s}}=\pm2$\end{document}</tex-math><alternatives><graphic xmlns:xlink=“http://www.w3.org/1999/xlink” xlink:href=“11-20220410_M4.jpg”/><graphic xmlns:xlink=“http://www.w3.org/1999/xlink” xlink:href=“11-20220410_M4.png”/></alternatives></inline-formula> magnetic-dipole forbidden energy levels of <inline-formula><tex-math id=“M5”>\begin{document}$|m_{\rm{s}}=-1\rangle$\end{document}</tex-math><alternatives><graphic xmlns:xlink=“http://www.w3.org/1999/xlink” xlink:href=“11-20220410_M5.jpg”/><graphic xmlns:xlink=“http://www.w3.org/1999/xlink” xlink:href=“11-20220410_M5.png”/></alternatives></inline-formula> and <inline-formula><tex-math id=“M6”>\begin{document}$|m_{\rm{s}}=+1\rangle$\end{document}</tex-math><alternatives><graphic xmlns:xlink=“http://www.w3.org/1999/xlink” xlink:href=“11-20220410_M6.jpg”/><graphic xmlns:xlink=“http://www.w3.org/1999/xlink” xlink:href=“11-20220410_M6.png”/></alternatives></inline-formula>. Further studies show that the frequency of the electrically driven Rabi oscillation is controlled by the power of the driven electric field but independent of the resonant frequency of the electric field. The combination of spin electric control and magnetic control technology can realize the full manipulation of the direct transition among the three spin energy levels of NV center, thus promoting the development of the researches and applications of NV quantum system in the fields of quantum simulation, quantum computing, precision measurement of electromagnetic field, etc.

Tech Support

Original Source

DOI: https://doi.org/10.7498/aps.70.20220410