Quantum control and Berry phase of electron spins in rotating levitated diamonds in high vacuum

At a Glance

Metadata	Details
Publication Date	2024-06-13
Journal	Nature Communications
Authors	Yuanbin Jin, Kunhong Shen, Peng Ju, Xingyu Gao, Chong Zu
Institutions	Purdue University West Lafayette, Sandia National Laboratories
Citations	19
Analysis	Full AI Review Included

Technical Documentation & Analysis: Quantum Control in Levitated Diamond

Research Paper Analyzed: Quantum control and Berry phase of electron spins in rotating levitated diamonds in high vacuum (Nature Communications, 2024)

This analysis highlights the critical role of high-quality diamond materials in advancing quantum spin-mechanics and precision sensing, directly correlating the experimental requirements with 6CCVD’s MPCVD diamond capabilities.

Executive Summary

This research represents a significant breakthrough in interfacing mechanical rotation with spin qubits, establishing a robust platform for quantum gravity studies and sensitive gyroscopes.

High Vacuum Stability: Achieved stable levitation of nanodiamonds in high vacuum (< 10^-5 Torr) using an integrated surface ion trap, overcoming previous stability limitations caused by laser heating and trap design.
Extreme Rotation Speed: Demonstrated record-breaking mechanical rotation speeds up to 20 MHz (1.2 x 10⁹ rpm), which is three orders of magnitude faster than previous motor-mounted diamond experiments.
Quantum Control in Motion: Successfully performed Optically Detected Magnetic Resonance (ODMR) measurements and achieved quantum control (Rabi oscillations) of NV centers in a fast-rotating levitated nanodiamond.
Berry Phase Observation: Observed the effect of the Berry phase generated by the coupling between mechanical rotation and embedded NV electron spins, crucial for building sensitive gyroscopes.
Cryogenic Cooling: Cooled the Center-of-Mass (CoM) motion of the levitated particle down to a minimum effective temperature of 1.2 K along the x-direction using feedback cooling.
Platform Potential: The stable, high-vacuum, high-rotation platform is ideal for exploring massive quantum superpositions and developing advanced rotational matter-wave interferometers.

Technical Specifications

Hard data extracted from the experimental results:

Parameter	Value	Unit	Context
Stable Levitation Pressure	< 10^-5	Torr	Internal temperature stable at $\sim$350 K.
Maximum Rotation Frequency ($\omega_{r}/2\pi$)	20	MHz	Limited by waveform generation bandwidth.
Equivalent Rotation Speed	1.2 x 10⁹	rpm	Surpasses typical NV spin dephasing rates.
AC Trapping Voltage Amplitude	$\sim$200	V	Applied at 20 kHz frequency.
Internal Nanodiamond Temperature	$\sim$350	K	Stable temperature below 5 x 10^-5 Torr.
Zero-Field Splitting (D)	2.8650 - 2.8694	GHz	Used for internal temperature calculation.
Minimum CoM Temperature (x-direction)	1.2 $\pm$ 0.3	K	Achieved via FPGA-implemented feedback cooling.
CoM Temperature (y-direction)	3.5 $\pm$ 0.4	K	Achieved via FPGA-implemented feedback cooling.
Nanodiamond Radius (Estimated)	$\sim$264	nm	Based on Power Spectrum Densities (PSDs).
NV Excitation Laser Intensity (532 nm)	0.030	W/mm²	Used for ODMR measurements.
NV Absorption Coefficient (532 nm)	111	cm^-1	Estimated from heating/cooling balance.

Key Methodologies

The experiment successfully integrated micro-fabrication, high-vacuum physics, and quantum optics:

Trap Fabrication: An integrated surface ion trap was fabricated on a sapphire wafer using photolithography, designed with a Q-shaped stripline for simultaneous AC high voltage and microwave delivery.
Particle Charging and Levitation: Nanodiamonds (estimated radius $\sim$264 nm) were charged via electrospray (typically > 1000 e) and delivered to the trap, achieving a trapping depth of > 100 eV.
High-Speed Rotation: A rotating electric field was generated by applying AC voltage signals (A sin($\omega$t + $\phi$)) with $\pi$/2 phase differences between neighboring corner electrodes, driving the nanodiamond up to 20 MHz.
Spin Readout (ODMR): Optically Detected Magnetic Resonance (ODMR) was performed using a 532 nm laser for NV center excitation and a 1064 nm laser to monitor CoM motion. The zero-field splitting was used to determine the internal temperature.
Quantum Control: Rabi oscillations were measured by synchronizing GHz microwave pulses with the rotation phase of the levitated nanodiamond, demonstrating quantum state control in a rotating frame.
Feedback Cooling: Center-of-Mass (CoM) motion was cooled using an FPGA-implemented feedback loop that applied electric forces proportional and opposite to the particle’s velocity, achieving 1.2 K in the x-direction.

6CCVD Solutions & Capabilities

This research validates the need for high-quality, customizable MPCVD diamond materials and integrated fabrication services. 6CCVD is uniquely positioned to supply the foundational materials and engineering support required to replicate and extend this work toward commercial quantum gyroscopes and advanced sensing platforms.

Applicable Materials

Application Requirement	6CCVD Material Recommendation	Technical Justification
High-Coherence Spin Qubits	Optical Grade Single Crystal Diamond (SCD)	Provides the lowest defect density and highest purity necessary for maximizing NV center spin coherence times (T₂), critical for quantum sensing and superposition experiments. Available in thicknesses from 0.1 µm to 500 µm.
Integrated Trap Substrates	Custom SCD/PCD Wafers	The experiment requires a substrate with high optical transparency (for 532 nm and 1064 nm lasers) and excellent thermal properties. 6CCVD supplies custom diamond plates (PCD up to 125 mm) that offer superior heat dissipation compared to sapphire.
Advanced Microwave/RF Circuitry	Precision Metalized Diamond	The surface ion trap relies on complex Q-shaped striplines for microwave delivery. 6CCVD offers in-house metalization using Au, Pt, Pd, Ti, W, and Cu directly patterned onto diamond surfaces for low-loss, high-frequency operation up to GHz ranges.
Conductive/Charge Dissipation Layers	Heavy Boron-Doped Diamond (BDD)	For future experiments requiring enhanced AC magnetic field sensing or minimizing surface charging effects on the trap electrodes, 6CCVD provides BDD films with tunable conductivity.

Customization Potential

The success of this experiment hinges on the precise integration of the diamond material with the surface ion trap geometry. 6CCVD offers comprehensive customization services:

Custom Dimensions: We provide SCD and PCD plates/wafers up to 125 mm in diameter, allowing researchers to scale up the integrated trap design for arrayed sensors or larger particle levitation.
Precision Polishing: To minimize surface charge accumulation and laser scattering—key challenges in high-vacuum levitation—6CCVD guarantees ultra-smooth surfaces: Ra < 1 nm for SCD and Ra < 5 nm for inch-size PCD.
Metalization and Patterning: We can replicate the complex electrode patterns (e.g., Q-shaped striplines and corner stabilization electrodes) using our internal metalization capabilities (Ti/Pt/Au stacks are standard) to ensure optimal microwave and AC field delivery.
Substrate Thickness: We offer custom diamond substrate thicknesses up to 10 mm, providing mechanical stability for high-vacuum chamber integration.

Engineering Support

6CCVD’s in-house team of PhD material scientists and engineers specializes in MPCVD growth parameters optimized for quantum applications. We can assist researchers with material selection, NV center creation strategies, and integration challenges for similar Quantum Spin-Mechanics and Gyroscope projects.

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

Tech Support

Original Source

DOI: https://doi.org/10.1038/s41467-024-49175-3