Device-Independent Quantum Key Distribution With Noise Probability

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Solution Overview

Problem

Device-independent quantum key distribution requires high detection efficiencies, making practical applications on consumer devices challenging due to stringent detection efficiency requirements.

Innovation Solution

A method for generating and distributing quantum keys using entangled particles with reduced detection efficiency by introducing noise to measurement values, allowing for lower detection efficiency while maintaining device-independent security guarantees, and enabling quantum key distribution at lower detection efficiencies than previously possible.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If device-independent quantum key distribution is implemented with conventional methods, then security guarantees are maintained, but detection efficiency must be extremely high (>92%) making practical applications difficult

Engineering Contradiction:
Improvedetection efficiencyVSAvoidpractical implementability
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent changes the parameter of detection efficiency threshold from >92% to significantly lower values by introducing noise probability p as a new control parameter. This allows the system to operate with imperfect detectors while maintaining security through the modified measurement protocol that accounts for noise in the key generation process.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent introduces dynamic noise probability p that can be adjusted to optimize performance. By making the noise parameter controllable and adjustable, the system can adapt to different detector qualities and transmission conditions, enabling practical deployment on consumer devices with varying performance characteristics.

Inventive Principle:
Principle #15Dynamics

2Ease of operation

If detection efficiency requirements are reduced for consumer devices, then practical applicability improves, but security guarantees may be compromised

Engineering Contradiction:
Improvepractical applicabilityVSAvoidsecurity guarantee
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent converts the harmful effect of noise and imperfections into a beneficial feature by explicitly modeling noise probability p and incorporating it into the key generation protocol. Instead of treating noise as an adversary to be eliminated, the system uses controlled noise modeling to maintain security guarantees while accepting lower detection efficiency, thereby enabling practical consumer device implementation.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

3Reliability

If noise is introduced to measurement values to reduce detection efficiency requirements, then lower detection efficiency becomes acceptable, but key generation process becomes more complex

Engineering Contradiction:
Improvedetection efficiency thresholdVSAvoidkey generation process
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by pre-defining noise probability p and incorporating noise modeling into the measurement protocol before actual key generation. By preparing the system with known noise characteristics in advance, the complex post-processing that would otherwise be required is significantly reduced, making the overall process more manageable despite the added noise parameter.

Inventive Principle:
Principle #10Preliminary action

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 method significantly reduces the required detection efficiency, nearly doubling the admissible imperfections, making device-independent quantum key distribution feasible on everyday devices with improved security and a higher key generation rate.

Implementation Method 1

Generating a quantum mechanically entangled information pair, comprising two quantum mechanically entangled quantum moieties that have at least one degree of freedom entangled with each other

Methodology Applied
Scientific EffectQuantum entanglement:

Data Source

PatentEP4150855B1Device-independent quantum key distribution
Publication Date: 2024.10.09 ETH ZURICH
  • EP4150855B1 patent drawingFigure 1
  • EP4150855B1 patent drawingFigure 2
  • EP4150855B1 patent drawingFigure 3

AI summary

The invention relates to a method for device-independent quantum key generation and distribution between a first and a second receiver, the method comprising the steps of: a) Generating an entangled information pair, comprising two entangled quantum moieties that have at least one quantum state entangled with each other, such as a polarization, b) Transmitting a first entangled quantum moiety of the two entangled quantum moieties to the first receiver (A) and a second entangled quantum moiety of the two entangled quantum moieties to the second receiver (B), and measuring the quantum states of the entangled moieties with a set of selected detection settings chosen randomly at each receiver c) In a modification step, assigning each measurement value b1 measured with a detection setting B1 a complementary value (l)according to a noise- probability p, wherein the noise-probability p is larger than 0 and lower than 1, such that a modified plurality of measurement values (ll) is obtained, d) Generating a final shared quantum key from the modified plurality measurements values (lll) and from a plurality of measurement values α0 measured with a detection setting Ao at the first receiver (A).