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6CCVD Research

High-Fidelity Photonic Three-Degree-of-Freedom Hyperparallel Controlled-Phase-Flip Gate

At a Glance

Section titled “At a Glance”
MetadataDetails
Publication Date2022-08-11
JournalFrontiers in Physics
AuthorsGuan-Yu Wang, Hai‐Rui Wei
InstitutionsBeijing University of Chemical Technology, University of Science and Technology Beijing
Citations4
AnalysisFull AI Review Included

Executive Summary

Section titled “Executive Summary”

The research proposes a novel method for implementing a high-fidelity photonic three-Degree-of-Freedom (3-DOF) Hyperparallel Controlled-Phase-Flip (CPF) gate, utilizing diamond Nitrogen Vacancy (NV) centers coupled to microtoroidal resonators (MTRs).

  • Core Value Proposition: Achieves simultaneous, parallel quantum computation across three independent photonic DOFs: Polarization, Spatial-Mode, and Frequency.
  • Robust Fidelity: The gate design is inherently robust, ensuring high fidelity even when using realistic, imperfect NV-cavity parameters (coupling strength, damping rates).
  • Self-Error Correction: Computation errors arising from practical NV-photon interactions are converted into detectable photon losses, which terminate the gate process, thus preventing error propagation.
  • Platform: Utilizes the practical interaction between a single photon and a diamond NV center confined within a Microtoroidal Resonator (MTR).
  • Performance: Calculated gate efficiency (η) is approximately 38.51% under experimentally demonstrated NV-cavity parameters (g/2π = 0.3 GHz, κ/2π = 26 GHz).
  • Generalizability: The methodology can be extended to construct high-fidelity photonic 3-DOF Hyperparallel CPFN gates and parity-check gates.

Technical Specifications

Section titled “Technical Specifications”

The following parameters relate to the NV center properties and the calculated performance of the hyperparallel CPF gate, based on realistic experimental conditions (Ref [55]).

ParameterValueUnitContext
NV Ground State Splitting2.88GHzZero-field splitting between ms=0 and ms=±1 levels.
NV Excited State Splitting (A2)5.5GHzMinimum splitting due to spin-orbit interaction.
NV Excited State Splitting (A2)3.3GHzMinimum splitting due to spin-spin interaction.
Coupling Strength (g/2π)0.3GHzExperimental NV-cavity coupling strength (Ref [55]).
Cavity Damping Rate (κ/2π)26GHzExperimental cavity loss rate (Ref [55]).
Total Dipolar Decay Rate (γtotal/2π)0.013GHzExperimental NV center decay rate (Ref [55]).
Zero Phonon Line (ZPL) Decay Rate (γZPL/2π)0.0004GHzExperimental ZPL decay rate (Ref [55]).
Calculated Gate Efficiency (η)38.51%Achieved under realistic conditions (κs/κ = 0.05, (ωo - ω1)/κ = 5).
ZPL Emission Rate EnhancementUp to 70%Potential enhancement using high-Q microdisks.
Required NV OperationHadamard (π/2 pulse)N/AImplemented via microwave pulses on NV centers.

Key Methodologies

Section titled “Key Methodologies”

The high-fidelity 3-DOF hyperparallel CPF gate is implemented using a two-photon system (control photon a and target photon b) interacting sequentially with three NV-cavity systems (NV1, NV2, NV3).

  1. Control Photon Injection and Splitting: The control photon (a) is injected and split by Circularly Polarizing Beam Splitters (CPBSs) based on its polarization state (|F> transmitted, |S> reflected).
  2. Frequency and Spatial-Mode Operations (NV1, NV2):
    • Wave packets interact with NV1 (frequency DOF operation) and NV2 (spatial-mode DOF operation) via the MTRs.
    • Wave-Form Correctors (WFCs) introduce specific reflection coefficients (r1, r2, r’2) derived from the practical NV-cavity interaction rules.
    • Wavelength Division Multiplexers (WDMs) and Frequency Shifters (FSs) manipulate the frequency states (ω1, ω2).
  3. Error Detection Mechanism: Single-photon detectors (D) are strategically placed. If a photon is detected (e.g., if a wave packet in the spatial-mode |a2> is in the frequency state |ω2>), it indicates a computation error, and the gate process is terminated.
  4. Polarization Operation (NV3): The control photon interacts with NV3 (polarization DOF operation) via CPBSs and HWPs.
  5. NV Center Preparation: Hadamard operations (π/2 microwave pulses) are performed on all three NV centers to prepare them for measurement.
  6. Target Photon Injection: The target photon (b) is injected, and the entire sequence (Steps 1-5) is repeated, ensuring simultaneous operation across all three DOFs.
  7. Measurement and Feed-Forward: The three NV centers are measured in the orthogonal basis ({|±>}). Based on the measurement results (Table 1), classical feed-forward operations (σzf, σzs, σzp) are applied to the control photon to complete the deterministic CPF gate.

Commercial Applications

Section titled “Commercial Applications”

This technology, leveraging robust, high-fidelity quantum gates based on diamond NV centers, is highly relevant to several advanced engineering and commercial sectors.

  • Fault-Tolerant Quantum Computation: The self-error-corrected nature of the gate is crucial for building scalable, reliable quantum processors, particularly those based on photonic qubits.
  • Hyperparallel Quantum Communication: Utilizing multiple DOFs (polarization, spatial-mode, frequency) significantly increases the channel capacity for quantum key distribution (QKD) and quantum teleportation.
  • Diamond Quantum Sensing: NV centers are leading solid-state qubits for sensing magnetic fields, temperature, and strain. High-fidelity control gates are essential for complex quantum sensing protocols.
  • Integrated Photonics and Quantum Hardware: The use of MTRs and integrated optical components (WDMs, FSs, CPBSs) points toward scalable, on-chip quantum circuit fabrication.
  • CVD Diamond Substrates: The underlying material platform requires high-purity, low-strain Chemical Vapor Deposition (CVD) diamond substrates for optimal NV center creation and coherence time.
  • Quantum Machine Learning: Parallel processing capabilities enabled by hyperparallel gates can accelerate complex quantum algorithms used in machine learning applications.
View Original Abstract

Encoding computing qubits in multiple degrees of freedom (DOFs) of a photonic system allows hyperparallel quantum computation to enlarge channel capacity with less quantum resource, and constructing high-fidelity hyperparallel quantum gates is always recognized as a fundamental prerequisite for hyperparallel quantum computation. Herein, we propose an approach for implementing a high-fidelity photonic hyperparallel controlled-phase-flip (CPF) gate working with polarization, spatial-mode, and frequency DOFs, through utilizing the practical interaction between the single photon and the diamond nitrogen vacancy (NV) center embedded in the cavity. Particularly, the desired output state of the gate without computation errors coming from the practical interaction is obtained, and the robust fidelity is guaranteed in the nearly realistic condition. Meanwhile, the requirement for the experimental realization of the gate is relaxed. In addition, this approach can be generalized to complete the high-fidelity photonic three-DOF hyperparallel CPF N gate and parity-check gate. These interesting features may make the present scheme have potential for applications in the hyperparallel quantum computation.

Tech Support

Section titled “Tech Support”

Original Source

Section titled “Original Source”

References

Section titled “References”
  1. 2000 - Quantum Computation and Quantum Information
  2. 1993 - Teleporting an Unknown Quantum State via Dual Classical and Einstein-Podolsky-Rosen Channels [Crossref]
  3. 1992 - Communication via One- and Two-Particle Operators on Einstein-Podolsky-Rosen States [Crossref]
  4. 2002 - General Scheme for Superdense Coding between Multiparties [Crossref]
  5. 1991 - Quantum Cryptography Based on Bell’s Theorem [Crossref]
  6. 1992 - Quantum Cryptography without Bell’s Theorem [Crossref]
  7. 1999 - Quantum Secret Sharing [Crossref]
  8. 2002 - Theoretically Efficient High-Capacity Quantum-Key-Distribution Scheme [Crossref]
  9. 2003 - Two-step Quantum Direct Communication Protocol Using the Einstein-Podolsky-Rosen Pair Block [Crossref]
  10. 2007 - Quantum Secure Direct Communication with Quantum Memory [Crossref]

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