Observing Information Backflow from Controllable Non-Markovian Multichannels in Diamond

At a Glance

Metadata	Details
Publication Date	2020-05-27
Journal	Physical Review Letters
Authors	Ya-Nan Lu, Yu-Ran Zhang, Gang‐Qin Liu, Franco Nori, Heng Fan
Institutions	University of Michigan, University of Chinese Academy of Sciences
Citations	44
Analysis	Full AI Review Included

Technical Documentation and Analysis: Controllable Non-Markovian Dynamics in Diamond NV Centers

This analysis connects the material requirements and experimental methodologies of the research paper, “Observing information backflow from controllable non-Markovian multi-channels in diamond,” directly to the advanced Single Crystal Diamond (SCD) capabilities offered by 6ccvd.com.

Executive Summary

The research successfully demonstrates the engineering and control of non-Markovian quantum dynamics in a solid-state system using the Nitrogen-Vacancy (NV) center in high-purity diamond. This achievement relies critically on ultra-stable, highly coherent diamond substrates.

System Control: The NV electron spin acts as the open quantum system, while nearby ¹⁴N and ¹³C nuclear spins serve as precisely controllable dissipative channels.
Non-Markovian Witness: Quantum Fisher Information (QFI) flow is utilized as a metric to characterize quantum coherence and metrologically useful entanglement, clearly demonstrating information backflow (non-Markovianity).
Material Necessity: The experiment mandates ultra-low nitrogen concentration (< 5 p.p.b.) Single Crystal Diamond (SCD) to achieve the necessary coherence time ($T_2$* $\approx$ 2.9 µs).
Hybrid Solid-State Register: The NV center, host ¹⁴N spin, and proximal ¹³C spin form a robust three-qubit register, paving the way for scalable quantum computing and sensing in solids.
Optical Enhancement: Photon collection efficiency was enhanced using Solid Immersion Lenses (SILs) etched onto the diamond surface, requiring exceptional material quality and precise surface polishing (e.g., Ra < 1nm).

Technical Specifications

The following critical parameters, extracted from the research, define the material quality and experimental conditions required for successful quantum metrology in this NV system.

Parameter	Value	Unit	Context
Diamond Purity (N concentration)	< 5	p.p.b.	Ultra-high purity SCD required to minimize electron spin decoherence.
NV Center Depth	10	µm	Below the diamond surface, optimized for coupling and optical access.
Laser Excitation Wavelength	532	nm	Used for NV polarization and readout.
Laser Excitation Power	240	µW	Power level achieving high photon detection rates.
Photon Detection Rate	450	kcps	Enhanced via etched Solid Immersion Lenses (SILs).
External Magnetic Field ($B_z$)	482	Gauss	Applied along the NV symmetry axis for spin polarization (ESLAC).
Nearby ¹³C Hyperfine Coupling ($A_c$)	12.8	MHz	Strong coupling; utilized as a controllable channel.
Host ¹⁴N Hyperfine Coupling ($A_n$)	-2.16	MHz	Strong coupling; utilized as a controllable channel.
NV Electron Spin Coherence Time ($T_2$*)	$\approx$ 2.9	µs	Fundamental performance metric for the quantum register.
QFI Measurement Duration	0 to 600	ns	Temporal window for observing non-Markovian information backflow.

Key Methodologies

The experiment uses a multi-stage approach combining highly specialized diamond material processing with complex quantum control sequences.

Material Selection & Preparation:
- High-purity bulk Single Crystal Diamond (SCD) with N concentration < 5 p.p.b. was used to ensure minimal decoherence.
- NV centers were located approximately 10 µm below the polished surface.
- Surface Enhancement: Solid Immersion Lenses (SILs) were etched onto the diamond surface to significantly enhance 532 nm photon collection efficiency.
Spin Polarization:
- An external magnetic field ($B_z = 482$ Gauss) was applied along the NV symmetry axis.
- A short 532 nm laser pulse was used to simultaneously polarize the NV electron spin and the host ¹⁴N and nearby ¹³C nuclear spins via excited state level anti-crossing (ESLAC).
Coherent Manipulation:
- The electron spin and nuclear spins were controlled using resonant Microwave (MW) and Radio-Frequency (RF) pulses (e.g., 13.284 MHz and 2.929 MHz RF pulses).
- Pulse sequences (quantum circuits) were executed to prepare the system in specific initial states (e.g., maximally entangled states).
State Tomography & Readout:
- The state of the open system (electron qubit, or electron/¹³C pair) was reconstructed using single-qubit or two-qubit state tomography techniques.
- Measurements involved collecting fluorescence photon counts ($L_x, L_y, L_z$) after pulse sequences to calculate the Bloch vector components and determine the Quantum Fisher Information (QFI).

6CCVD Solutions & Capabilities

6CCVD is uniquely positioned to supply and engineer the high-performance diamond materials required to replicate and advance this cutting-edge research in non-Markovian quantum dynamics and solid-state quantum registers.

Applicable Materials

To replicate the demonstrated $T_2$* coherence times and control stability, researchers require the highest quality, low-strain SCD.

Material Required: Optical Grade Single Crystal Diamond (SCD).
- Purity Match: 6CCVD guarantees N concentrations well below the required < 5 p.p.b., minimizing magnetic noise and maximizing $T_2$* coherence times.
- Thickness Control: We provide SCD wafers with precise thickness control, essential for subsequent processing steps, including the required 10 µm NV center depth relative to the surface. SCD can be manufactured from 0.1 µm up to 500 µm thickness.

Customization Potential

The experimental setup necessitates precision engineering of the diamond substrate for optimal performance.

Ultra-Polishing for SILs: The use of etched Solid Immersion Lenses (SILs) demands an atomically smooth starting surface. 6CCVD provides ultra-low roughness polishing (Ra < 1 nm) on SCD, ensuring minimal optical scatter and maximized photon collection efficiency during laser excitation (532 nm).
Custom Metalization and Circuitry: Implementing the MW and RF control pulses requires electrodes adjacent to the NV centers. 6CCVD offers internal, custom metalization services (Ti, W, Cu, Pt, Au, Pd) for direct integration of microwave strip lines or RF antennas onto the diamond surface, streamlining experimental setup for precise spin control.
Custom Dimensions: While the paper implies a bulk sample, 6CCVD can supply custom dimensions for specialized lab setups, including plates/wafers up to 125 mm (PCD), and custom laser cutting services for specific geometries.

Engineering Support

NV-based quantum experiments are inherently sensitive to material defects and processing variations.

In-House PhD Expertise: 6CCVD’s in-house PhD team provides authoritative support in material selection, NV implantation strategies (if required for deterministic placement, though natural centers were used here), and surface engineering necessary for high-coherence solid-state quantum metrology projects.
Consultation on Doping: For future extensions of this work requiring integrated sensors or on-chip electronics, we offer consultation on Boron-Doped Diamond (BDD) integration as high-performance electrodes or thermal management layers.

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

View Original Abstract

The unavoidable interaction of a quantum open system with its environment leads to the dissipation of quantum coherence and correlations, making its dynamical behavior a key role in many quantum technologies. In this Letter, we demonstrate the engineering of multiple dissipative channels by controlling the adjacent nuclear spins of a nitrogen-vacancy center in diamond. With a controllable non-Markovian dynamics of this open system, we observe that the quantum Fisher information flows to and from the environment using different noisy channels. Our work contributes to the developments of both noisy quantum metrology and quantum open systems from the viewpoints of metrologically useful entanglement.

Tech Support

Original Source

DOI: https://doi.org/10.1103/physrevlett.124.210502