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	National Time Service Center, Xi’an Jiaotong University
Analysis	Full AI Review Included

Executive Summary

Core Achievement: Demonstration of a physical model for a 1x4 optical demultiplexer based on multi-order temporal correlation interference within a Nitrogen Vacancy (NV^-) center diamond.
Mechanism: The demultiplexer utilizes the superposition of second-order (G⁽²⁾) and third-order (G⁽³⁾) temporal coherence generated by two non-degenerate pseudo-thermal fluorescence sources (Sf and SF).
Control Method: Switching between three-mode bunching and frequency beating effects is controlled by manipulating the time offset (S₀, S₁ selection lines) and the frequency difference of the incident laser beams.
High Performance: The device achieves a high channel spacing (η) of approximately 96% and an extremely fast switching speed of 17 ns, demonstrating suitability for high-speed quantum applications.
Material System: The experiment uses a low-impurity, <100> oriented crystal diamond containing NV^- centers, operating under cryogenic conditions (77 K).
Interference Tuning: The interference index (H), which measures quantum path interference, can be tuned significantly (from 0.01 to 0.9) by varying the wavelength of the pseudo-thermal source Sf.

Technical Specifications

Parameter	Value	Unit	Context
Demultiplexer Switching Speed	17	ns	Total time delay between switching outputs.
Channel Spacing (η)	96	%	Achieved for correlation curves at t₁ time offset of 2 µs.
Operating Temperature	77	K	Maintained using liquid nitrogen cryostat.
Diamond Orientation	<100>	Crystal	Sample orientation.
Nitrogen Concentration	less than 5	ppb	Impurity level in the diamond sample.
NV^- Concentration	less than 0.03	ppb	Active defect concentration.
Laser Linewidth	0.04	cm^-1	Tunable dye laser specification.
Pumping Field E₁ Wavelength	575	nm	Coupled to the _\|0> → _\|1> transition.
Pumping Field E₂ Wavelength	637	nm	Coupled to the _\|0> → _\|2> transition.
Ground State Splitting (3A₂)	2.8	GHz	Energy difference between _{\|m_s} = 0> and _{\|m_s} = ±1>.
Excited State Splitting (3E)	1.42	GHz	Energy difference between _{\|m_s} = 0> and _{\|m_s} = ±1>.
Nd/YAG Pulse Width	5	ns	Pumping laser specification.

Key Methodologies

Sample Environment: A <100> oriented crystal diamond with ultra-low nitrogen (<5 ppb) and NV^- (<0.03 ppb) concentration was mounted in a cryostat, maintaining an operating temperature of 77 K via flowing liquid nitrogen.
Excitation Setup: Two tunable dye lasers (0.04 cm^-1 linewidth) were used as pumping fields (E₁ and E₂). These lasers were pumped by an injection-locked single-mode Nd/YAG laser (10 Hz repetition rate, 5 ns pulse width).
V-Type System Coupling: The NV^- center was modeled as a V-type three-level system. E₁ (575 nm) and E₂ (637 nm) beams were coupled to the _|0> → _|1> and _|0> → _|2> transitions, respectively, generating fourth-order fluorescence (FL) signals (Sf and SF).
Second-Order Correlation Measurement (G⁽²⁾): The Sf and SF signals were passed through a non-polarizing beam splitter (BS) and detected by two detectors (D₁, D₂). The output was fed into a coincidence count system (CCC).
Third-Order Correlation Measurement (G⁽³⁾): The fluorescence signals were divided by two subsequent beam splitters (BS₁ and BS₂) and detected by three detectors (D₁, D₂, D₃) to measure the three-mode intensity noise correlation.
Demultiplexer Control: The 1x4 demultiplexer function was realized by defining the time offsets (t₁ and t₂) as selection lines (S₀ and S₁). By adjusting these offsets (e.g., 0 µs, 1 µs, 2 µs), the interference between two- and three-mode bunching was controlled, resulting in distinct “Logic 1” (bright peak) and “Logic 0” (dark/no peak) outputs (O₁-O₄).
Frequency Tuning: The frequency difference between the pseudo-thermal sources (Sf and SF) was varied (e.g., changing Sf wavelength from 575 nm to 578 nm) to enhance the frequency beating term, increasing the number and sharpness of interference peaks.

Commercial Applications

Quantum Computing: The NV^- center serves as a robust solid-state qubit system. This demultiplexer model provides a high-speed, integrated mechanism for routing and logic processing of quantum information.
Quantum Communication Networks: The high channel spacing (96%) and rapid switching speed (17 ns) are critical for developing fast, low-crosstalk optical demultiplexers necessary for quantum key distribution (QKD) and quantum internet infrastructure.
Integrated Photonics and Quantum Circuits: The demonstration provides a physical model for creating diamond-based integrated optical components (switches, routers) that operate based on quantum interference principles.
High-Speed Signal Processing: The ability to control signal output based on temporal correlation and frequency beating offers a novel approach for ultra-fast signal processing and multiplexing in non-quantum domains.
Quantum Sensing: The underlying research into coherence and interference in dressed NV^- states contributes directly to improving the sensitivity and control of NV-based magnetic and electric field sensors.

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]