Non-Markovianity-assisted high-fidelity Deutsch–Jozsa algorithm in diamond

At a Glance

Metadata	Details
Publication Date	2018-01-08
Journal	npj Quantum Information
Authors	Yang Dong, Yu Zheng, Shen Li, Cong Cong Li, Xiang-Dong Chen
Institutions	University of Science and Technology of China, CAS Key Laboratory of Urban Pollutant Conversion
Citations	46
Analysis	Full AI Review Included

High-Fidelity Quantum Algorithms in Diamond: Leveraging Non-Markovian Dynamics for Enhanced QIP

Material Science and Engineering Analysis Document Source Paper: Non-Markovianity-assisted high-fidelity Deutsch-Jozsa algorithm in diamond

This document provides a technical analysis of the reported research, focusing on the material requirements, methodologies, and direct connection to 6CCVD’s capabilities in high-purity Single-Crystal Diamond (SCD) and Polycrystalline Diamond (PCD) synthesis and device fabrication.

Executive Summary

This research demonstrates a critical advance in solid-state quantum information processing (QIP) by achieving an unprecedented high fidelity in the Deutsch-Jozsa algorithm (RDJA) utilizing synthetic diamond Nitrogen-Vacancy (NV) centers.

High-Fidelity QIP: Achieved a Probability of Success (POS) exceeding 97% for the refined Deutsch-Jozsa algorithm (RDJA) using a single NV center electron spin qubit at room temperature.
Non-Markovian Resource: The performance enhancement was directly attributed to the active utilization of non-Markovian memory effects in the spin bath, confirming that memory effects can function as an important physical resource for QIP.
Dynamical Decoupling (DD) Integration: Dynamical Decoupling (specifically, spin echo sequences) was employed not only to mitigate decoherence but also to successfully extract and leverage the beneficial effects of the non-Markovian environment.
Environment Engineering: The study demonstrated full environmental control by successfully inducing a transition from complex non-Markovian dynamics (bidirectional information flow) to simpler Markovian dynamics (monotonical decay) through the application of a DC magnetic field (> 35 mT).
Material Platform Validation: The experiment utilized high-quality, type-IIa single-crystal synthetic diamond, validating its position as a superior, robust platform for studying complex quantum dynamics and implementing high-fidelity quantum algorithms in a solid-state environment.
Methodology: The device utilized impedance-matched gold coplanar waveguides (CPW) deposited directly onto the diamond substrate for precise microwave (MW) pulse delivery to the implanted NV center.

Technical Specifications

The core experimental results and material parameters are summarized below.

Parameter	Value	Unit	Context
Material Host	Type-IIa Synthetic Diamond	N/A	Single-Crystal Diamond (SCD)
Operating Environment	Room Temperature	°	Realistic solid spin system
Target Qubit	NV Center Electron Spin	S = 1	Encoded states $
Max RDJA Success Rate	> 97	%	Achieved with Dynamical Decoupling (DD)
Non-Markovianity Measure (N)	1.96 ± 0.14	N/A	Confirms memory effects (N > 0 implies non-Markovian)
Implantation Energy	30	keV	Used for nitrogen ion creation of NV centers
Implantation Dosage	10¹¹	/cm²	Nitrogen ion density
Estimated NV Depth	20	nm	Near-surface depth for quantum sensing/QIP
DD Sequence Duration	700	ns	Total sequence length for spin echo
Markovian Transition Field	≥ 35	mT	Magnetic field required to suppress non-Markovianity
Qubit Excitation Wavelength	532	nm	Diode laser for initialization and readout
MW Delivery Structure	Gold Coplanar Waveguide (CPW)	N/A	Impedance-matched, deposited on diamond

Key Methodologies

The experiment successfully combined high-quality material processing, precise microwave control, and advanced quantum measurement techniques to study and exploit non-Markovian dynamics.

Material Selection and Preparation: A Type-IIa single-crystal synthetic diamond, characterized by low nitrogen and defect concentrations, was selected to maximize the coherence time of the NV electron spin.
NV Center Creation: NV centers were generated near the surface using targeted nitrogen ion implantation (30 keV energy, 10¹¹/cm² dosage), resulting in an average NV depth of approximately 20 nm.
Microwave (MW) Device Integration: An impedance-matched gold Coplanar Waveguide (CPW) was deposited directly onto the diamond surface to enable efficient and precise delivery of MW pulses for spin control.
Qubit Control and Encoding: The NV center electron spin ($m_s = 0$ and $m_s = +1$ states) was defined as the qubit. Qubit initialization and readout utilized 532 nm laser pulses. Quantum gates (rotation and phase-controlled) were implemented using highly synchronized MW pulse sequences ($\pi/2$, $\pi$, etc.) via a multichannel pulse generator.
Non-Markovian Characterization: The environment’s memory effects were quantified by measuring the non-Markovianity (N) using the trace distance method based on the evolution of optimal state pairs, confirming bidirectional information flow between the qubit and the spin bath.
Performance Enhancement via DD: The success probability of the RDJA was boosted to over 97% by incorporating a single $\pi$ pulse (spin echo) into the sequence, enabling the utilization of the non-Markovian memory effects during the algorithm execution.
Environmental Tuning: A transition from non-Markovian to Markovian dynamics was experimentally realized by applying a static magnetic field (≥ 35 mT) along the NV symmetry axis, polarizing the surrounding nuclear spin bath.

6CCVD Solutions & Capabilities

6CCVD is uniquely positioned to supply the advanced diamond materials and integrated solutions required to replicate and extend this research on non-Markovian quantum dynamics and high-fidelity QIP.

Research Requirement	6CCVD Material/Capability	Value to Researcher
High-Purity Host Material	Optical Grade Single Crystal Diamond (SCD): Custom wafers up to 125 mm. SCD with ultra-low residual nitrogen concentration (sub-ppb) and minimal strain.	Provides the required material baseline for long spin coherence times (T₂) necessary for complex, multi-pulse algorithms.
Near-Surface NV Creation	Advanced Polishing (Ra < 1 nm for SCD): Highly polished surfaces and minimized sub-surface damage (SSD) following etching or implantation.	Ensures high-quality surface termination crucial for creating shallow, highly coherent NV centers, necessary for optimal spin readout and control.
MW Device Integration	Custom Metalization Services: In-house deposition capabilities including Ti, Au, Pt, Pd, and Cu. Specialization in creating high-frequency structures like impedance-matched Coplanar Waveguides (CPW).	Delivers ready-to-use substrates with integrated microwave components, accelerating device fabrication time and ensuring high-fidelity MW pulse delivery.
Custom Wafer Geometry	Custom Dimensions and Thickness: SCD wafers from 0.1 µm to 500 µm thickness; substrates up to 10 mm. Precision laser cutting for complex device layouts.	Enables scalable QIP designs or non-standard configurations required for customized optical access or integration into specific cryostats/magnets.
Environmental Engineering	Boron-Doped Diamond (BDD): Control over material conductivity and spin bath density is achievable via tailored SCD or PCD doping.	Provides engineered diamond hosts for experiments requiring specific electrical properties or controlled spin environments for advanced dynamics studies.

Engineering Support: 6CCVD’s in-house PhD team can assist with material selection for similar Solid-State Quantum Dynamics and High-Fidelity Quantum Algorithm projects, including specifications for nitrogen purity, orientation, and metalization schemes compatible with high-frequency control. We ensure that the diamond substrate is an asset, not a limitation, to your quantum research.

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/s41534-017-0053-z