Dipole-Coupled Defects for On-Chip Entangled Photon Sources

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Solution Overview

Problem

Current methods for generating entangled photon pairs, such as semiconductor quantum dots, face challenges in scalability and efficiency due to inconsistent synthesis and on-chip integration difficulties, while alternative approaches like spontaneous parametric down-conversion have low pair generation efficiency.

Innovation Solution

A device comprising dipole-coupled defects in a solid-state material, where two electric-dipole coupled defects with orthogonal transition dipole moments are prepared in a symmetric superposition state, emitting entangled photon pairs through radiative decay, enabling deterministic and on-demand production of polarization-entangled photons.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If semiconductor quantum dots are used to generate entangled photon pairs, then entanglement can be achieved, but scalability and synthesis consistency deteriorate

Engineering Contradiction:

Improveentanglement qualityVSAvoidsynthesis consistency

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent transitions from semiconductor quantum dots to color centers in diamond, changing the material parameter to achieve better synthesis consistency while maintaining entanglement quality. The diamond color centers provide deterministic positioning and uniform optical properties that resolve the manufacturing inconsistency issue.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention uses a composite system combining diamond host material with nitrogen-vacancy color centers, leveraging the stability of diamond and the quantum properties of the color centers to achieve both reliable entanglement and manufacturability.

Inventive Principle:

Principle #40Composite materials

2Reliability

If spontaneous parametric down-conversion is used to generate entangled photon pairs, then entanglement can be achieved, but pair generation efficiency deteriorates

Engineering Contradiction:

Improveentanglement qualityVSAvoidpair generation efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent replaces the spontaneous parametric down-conversion process with direct excitation of dipole-coupled color centers, substituting a low-efficiency spontaneous process with a deterministic on-demand emission mechanism that achieves high pair generation efficiency.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The dipole-coupled color center system inherently generates entangled photon pairs through its natural radiative decay process when excited, eliminating the need for additional conversion steps and achieving direct, efficient entanglement generation.

Inventive Principle:

Principle #25Self-service

3Productivity

If quantum emitters are integrated on-chip, then scalability can be improved, but integration difficulty increases

Engineering Contradiction:

ImprovescalabilityVSAvoidintegration difficulty

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent creates localized dipole-coupled color center pairs within the diamond crystal lattice, where each pair serves as an independent entanglement source. This local approach simplifies integration compared to global quantum dot arrays, as each color center pair can be independently addressed and controlled.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The system divides the quantum emitter population into discrete dipole-coupled pairs, with each pair functioning as an independent unit for entanglement generation. This segmentation enables modular scaling and simplified on-chip integration compared to continuous quantum dot structures.

Inventive Principle:

Principle #1Segmentation

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach provides a scalable, on-chip, and chemically stable entanglement generator for quantum technologies, offering flexible integration and tunable emission properties, with optimized Bell state fidelity and efficiency, suitable for quantum information processing and networking.

Implementation Method 1

Each of the first and second quantum emitters has a ground state and at least a first and a second excited states, wherein the at least first and second excited states have transition dipole moments with respect to the ground state

Methodology Applied

Scientific EffectRadiative decay: Luminescence

Implementation Method 2

the at least first and second quantum emitters being dipole-dipole coupled

Methodology Applied

Scientific EffectDipole-dipole coupling:

Implementation Method 3

Dipole moments are said to be orthogonal when the electromagnetic waves emitted due to a transition from the first excited state to the ground state and a transition from the second excited state to the ground state are orthogonally polarized

Methodology Applied

Scientific EffectOrthogonal polarization: Polarisation

Data Source

PatentUS11387915B2Dipole-coupled defects as entangled photon pair sources

Publication Date: 2022.07.12 PRESIDENT & FELLOWS OF HARVARD COLLEGE

AI summary

Devices comprising dipole-coupled defects for use as entangled photon pair sources are provided.