Microwave Sum-Frequency Circuit for Multipair-Filtered Entanglement

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing quantum communication technologies face challenges in maintaining entanglement fidelity and compatibility with device-independent quantum key distribution schemes due to inherent multipair emission from spontaneous parametric down-conversion sources and detection loopholes in linear optical elements, which reduce the reliability of entanglement swapping protocols.

Innovation Solution

A sum frequency generator circuit in the microwave domain, utilizing a Josephson ring modulator and resonators, up-converts input photons to a sum frequency, enabling remote entanglement of qubits and serving as a nonlinear filter to enhance entanglement swapping and quantum communication reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If spontaneous parametric down-conversion sources are used for quantum communication, then photon pair generation is achieved, but multipair emission reduces entanglement fidelity

Engineering Contradiction:

Improveentanglement fidelityVSAvoidmultipair emission

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent extracts and removes the harmful multipair emission component from the spontaneous parametric down-conversion process by using a sum frequency generator to filter and select only single photon pairs, thereby eliminating the harmful effect while preserving the useful photon generation

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The sum frequency generator acts as an intermediary device between the down-conversion source and the detection system, mediating the photon pairs by filtering out multipair emissions and allowing only valid single photon pairs to pass through for entanglement verification

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If linear optical elements are used for detection, then photon detection is achieved, but detection loopholes reduce protocol reliability

Engineering Contradiction:

Improveprotocol reliabilityVSAvoiddetection loopholes

Core Design Contradiction:

ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent replaces the traditional linear optical detection system with a sum frequency generation-based detection mechanism that operates in the microwave domain, substituting the problematic optical detection approach with a more reliable superconducting quantum interference device-based measurement system that closes detection loopholes

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Adaptability or versatility

If sum frequency generator circuit is implemented with Josephson ring modulator and resonators, then up-conversion of photons is achieved, but device complexity increases

Engineering Contradiction:

Improvefrequency up-conversion capabilityVSAvoidcircuit structure

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent merges the sum frequency generation functionality with the existing Josephson ring modulator architecture, combining multiple functions (frequency conversion, photon filtering, and quantum state manipulation) into a single integrated circuit structure, thereby reducing overall system complexity while maintaining adaptability

Inventive Principle:

Principle #5Merging (Combining)

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

The sum frequency generator circuit effectively heralds entanglement of distant photons, improving entanglement fidelity and compatibility with device-independent quantum key distribution schemes, thereby enhancing the reliability of quantum communication protocols.

Implementation Method 1

a sum frequency generator circuit in the microwave domain, utilizing a Josephson ring modulator and resonators, up-converts input photons to a sum frequency

Methodology Applied

Scientific EffectSum frequency generation: Second Harmonic Generation

Implementation Method 2

utilizing a Josephson ring modulator

Methodology Applied

Scientific EffectJosephson effect: Josephson Effect

Implementation Method 3

a first resonator connected to a Josephson ring modulator (JRM), where the first resonator is configured to receive a first photon at a first frequency. The circuit includes a second resonator connected to the JRM

Methodology Applied

Scientific EffectResonance: Resonance

Data Source

PatentUS9680452B1Sum frequency generator in the microwave domain for quantum communication and computation applications

Publication Date: 2017.06.13 INTERNATIONAL BUSINESS MACHINE CORPORATION

AI summary

A technique relates to a circuit for a sum frequency generator. A first resonator is connected to a Josephson ring modulator (JRM), and the first resonator is configured to receive a first photon at a first frequency. A second resonator is connected to the JRM, and the second resonator is configured to have a first harmonic and no second harmonic. The second resonator is configured to receive a second photon at a second frequency, and the first resonator is configured to output an up-converted photon. The up-converted photon has an up-converted frequency that is a sum of the first frequency and the second frequency.