Demultiplexer of Multi-Order Correlation Interference in Nitrogen Vacancy Center Diamond

At a Glance

Metadata	Details
Publication Date	2021-11-09
Journal	Materials
Authors	Xinghua Li, Faizan Raza, Yufeng Li, Jinnan Wang, Jinhao Wang
Institutions	Chinese Academy of Sciences, National Time Service Center
Analysis	Full AI Review Included

Technical Documentation & Analysis: NV Center Demultiplexer

Executive Summary

This research successfully demonstrates a physical model for a high-speed optical demultiplexer utilizing the multi-order temporal correlation interference of pseudo-thermal sources generated within a Nitrogen Vacancy (NV^-) center in diamond. This breakthrough leverages the unique quantum properties of diamond for applications in quantum computing and communication.

Core Achievement: Realization of a 1x4 optical demultiplexer model based on second- and third-order temporal correlation functions in the NV^- center.
Material Requirement: The experiment relies critically on ultra-high purity, low-strain Single Crystal Diamond (SCD) with extremely low nitrogen (< 5 ppb) and NV^- concentration (< 0.03 ppb) to ensure isolated, stable quantum emitters.
Performance Metrics: The device achieved a high channel spacing (η) of 96% and an ultra-fast switching speed of 17 ns.
Mechanism: Demultiplexing is controlled by manipulating the time offset and frequency difference of the incident laser beams (575 nm and 637 nm), enabling quantum path interference.
6CCVD Value Proposition: 6CCVD specializes in providing the necessary Electronic Grade SCD substrates, grown via MPCVD, with guaranteed ultra-low impurity levels and precise crystal orientation (<100> or <111>) required for scalable quantum device fabrication.
Application Focus: The proposed model has immediate potential for integration into quantum registers, quantum communication networks, and high-fidelity quantum logic processing.

Technical Specifications

The following hard data points were extracted from the research paper detailing the material requirements and performance metrics of the NV^- diamond demultiplexer.

Parameter	Value	Unit	Context
Crystal Orientation	<100>	N/A	Sample used in experiment
Nitrogen Concentration (N)	< 5	ppb	Required for high-purity, low-strain material
NV^- Concentration	< 0.03	ppb	Required for isolated NV^- centers
Operating Temperature	77	K	Cryostat temperature (liquid nitrogen flow)
Input Beam E₁ Wavelength	575	nm	Coupled to transition
Input Beam E₂ Wavelength	637	nm	Coupled to transition
Ground State Splitting (D)	2.8	GHz	³A₂ fine-structure level difference
Excited State Splitting (D)	1.42	GHz	³E fine-structure level difference
Channel Spacing (η)	96	%	Achieved demultiplexer performance
Switching Speed	17	ns	Total time delay between switching outputs

Key Methodologies

The experimental realization of the NV^- demultiplexer relied on precise material selection, cryogenic stabilization, and controlled laser excitation to manipulate quantum interference effects.

Material Selection: Use of a <100> oriented crystal diamond characterized by ultra-low impurity levels (N < 5 ppb, NV^- < 0.03 ppb) to minimize decoherence and ensure isolated NV^- centers.
Cryogenic Stabilization: The diamond sample was held in a cryostat maintained at 77 K (liquid nitrogen flow) to stabilize the NV^- electronic spin and reduce phonon-related decoherence (Γ_phonon).
Excitation Source: Two tunable dye lasers, pumped by an injection-locked single-mode Nd/YAG laser (10 Hz repetition rate, 5 ns pulse width), were used to generate the pumping fields E₁ and E₂.
V-Type System Coupling: E₁ (575 nm) and E₂ (637 nm) were coupled to the V-type three-level system transitions (|0> → |1> and |0> → |2>) within the NV^- center.
Correlation Measurement: Fourth-order fluorescence (FL) signals (S_f and S_F) were measured using a three-mode coincidence count system (CCC) after passing through non-polarizing beam splitters (BS₁, BS₂).
Control Mechanism: The demultiplexer output (O₁-O₄) was controlled by manipulating the time offset (S₀, S₁) and the power of the incident beams (E₁ power varied from 1 mW to 5 mW) to switch between three-mode bunching and frequency beating effects.

6CCVD Solutions & Capabilities

6CCVD is uniquely positioned to supply the specialized diamond materials required to replicate, scale, and advance this quantum demultiplexer research. The successful operation of this device hinges on the quality and purity of the SCD substrate, which is our core expertise.

Applicable Materials

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

Electronic Grade Single Crystal Diamond (SCD): Essential for achieving the ultra-low nitrogen concentration (< 5 ppb) and low NV^- background (< 0.03 ppb) necessary for long coherence times (T₂*) and stable quantum operation at 77 K.
Optical Grade Polishing: Required for the input and output faces to minimize scattering losses for the 575 nm and 637 nm laser beams. 6CCVD guarantees SCD polishing to Ra < 1 nm.

Customization Potential

The integration of this demultiplexer into a functional quantum chip requires precise material engineering and fabrication capabilities, all available in-house at 6CCVD.

Research Requirement	6CCVD Customization Service	Technical Advantage
Precise Orientation (<100> used)	Custom SCD Crystal Orientation	We supply SCD wafers grown specifically along the <100> axis (or <111> for alternative NV alignment) to optimize spin initialization and readout fidelity.
Device Integration (Need for contacts/waveguides)	In-House Metalization	We offer custom deposition of thin films (Au, Pt, Ti, Pd, W, Cu) for creating electrodes, microwave lines, or surface contacts necessary for controlling the NV^- center.
Scalable Dimensions (For chip fabrication)	Custom Dimensions and Thickness	We provide SCD plates in custom dimensions and thicknesses, ranging from 0.1 µm to 500 µm (SCD) and up to 125 mm (PCD), suitable for integration into complex cryostat and photonic setups.
Surface Preparation (Minimizing loss)	Advanced Polishing Services	Guaranteed surface roughness of Ra < 1 nm on SCD, ensuring minimal optical loss and high-fidelity coupling for the 575 nm and 637 nm excitation beams.

Engineering Support

The successful implementation of NV^- based quantum devices requires deep expertise in material science and quantum physics. 6CCVD’s in-house PhD team specializes in MPCVD growth parameters optimized for quantum applications. We can assist researchers with:

Material Selection: Determining the optimal nitrogen doping level (or lack thereof) and crystal orientation for specific NV^- based quantum computing and communication projects.
Post-Processing: Consultation on NV creation techniques (e.g., implantation and annealing) to achieve desired NV concentration profiles while maintaining low strain.
Integration Design: Advising on metalization schemes and surface preparation for coupling the diamond chip to external photonic or electronic circuitry.

Call to Action: For custom specifications or material consultation regarding high-purity SCD for quantum demultiplexers, quantum registers, or advanced sensing applications, visit 6ccvd.com or contact our engineering team directly. We ship globally (DDU default, DDP available).

View Original Abstract

We reported the second- and third-order temporal interference of two non-degenerate pseudo-thermal sources in a nitrogen-vacancy center (NV−). The relationship between the indistinguishability of source and path alternatives is analyzed at low temperature. In this article, we demonstrate the switching between three-mode bunching and frequency beating effect controlled by the time offset and the frequency difference to realize optical demultiplexer. Our experimental results suggest the advanced technique achieves channel spacing and speed of the demultiplexer of about 96% and 17 ns, respectively. The proposed demultiplexer model will have potential applications in quantum computing and communication.

Tech Support

Original Source

DOI: https://doi.org/10.3390/ma14226745

References

1966 - The Feynman Lectures on Physics [Crossref]
2018 - Bunching and antibunching in four wave mixing NV center in diamond [Crossref]
2007 - Biphoton generation in a two-level atomic ensemble [Crossref]
2008 - Narrowband biphoton generation near atomic resonance [Crossref]
1986 - Interference between independent photons [Crossref]
1963 - Coherent and incoherent states of the radiation field [Crossref]
1965 - Coherence properties of optical fields [Crossref]
2013 - Conditions for two-photon interference with coherent pulses [Crossref]
2006 - Two-photon interference with two independent pseudothermal sources [Crossref]