Quantum Network Node Charge State Resetting for Fidelity Preservation

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Solution Overview

Problem

In quantum network operations, the loss of the wanted state of electron spin hosts leads to significant dephasing and ionization issues, affecting the coherence and fidelity of data qubits, particularly in systems like diamond-based quantum networks where NV-defects are used.

Innovation Solution

A method that includes charge state resetting of electron spin hosts from unwanted to wanted states using resonant electromagnetic radiation, such as resonant laser light, without affecting the data qubit, thereby maintaining high fidelity and coherence, and accounting for dephasing dynamics by varying electron spin states during entanglement protocols.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If repeated operation of entanglement primitive is performed, then entanglement generation is achieved, but electron spin host transitions to unwanted state causing dephasing of data qubit

Engineering Contradiction:

Improveentanglement generation rateVSAvoiddata qubit coherence

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies preliminary action by performing charge state resetting of the electron spin host before it transitions to the unwanted state, thereby preventing dephasing of the data qubit. The reset operation is executed in advance to maintain the electron spin host in the wanted state throughout the entanglement generation process.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements feedback by monitoring the charge state of the electron spin host and dynamically adjusting the reset operation. When the electron spin host transitions to the unwanted state, the system detects this change and initiates a reset sequence to return it to the wanted state, thereby maintaining data qubit coherence.

Inventive Principle:

Principle #23Feedback

2Reliability

If charge state resetting is performed to maintain electron spin host in wanted state, then data qubit coherence is preserved, but additional time and energy are consumed

Engineering Contradiction:

Improvedata qubit coherenceVSAvoidreset operation time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies periodic action by implementing charge state resetting at specific intervals during the entanglement generation process. The reset operation is performed periodically to prevent the electron spin host from remaining in the unwanted state for extended periods, thereby balancing coherence preservation with time consumption.

Inventive Principle:

Principle #19Periodic action

3Productivity

If electron spin host is reset from unwanted to wanted state, then entanglement operations can continue, but fidelity loss occurs due to dephasing during unwanted state occupation

Engineering Contradiction:

Improveentanglement operation continuityVSAvoidentanglement fidelity

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent converts the harmful effect of unwanted state occupation into a beneficial process by utilizing the time spent in the unwanted state for charge state resetting. The reset operation, which would otherwise be a separate step, is integrated into the entanglement generation cycle, thereby converting a potential fidelity loss into an opportunity for state restoration without significant additional time penalty.

Inventive Principle:

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

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 effectively mitigates the effects of ionization and dephasing, allowing for reliable entanglement operations with fidelity loss less than 5%, preferably below 1%, and preserves the quantum state of data qubits with high probability, enabling longer coherence times and improved network performance.

Implementation Method 1

resetting a charge state of the electron spin host from the unwanted charge state to the wanted charge state using resonant electromagnetic radiation

Methodology Applied

Scientific EffectResonant electromagnetic radiation: Electromagnetic Induction

Implementation Method 2

application of radiation resonant to a particular transition of the electron spin host for controlling the electron spin and/or for electron—photon entanglement

Methodology Applied

Scientific EffectElectron-photon entanglement: Electromagnetic Induction

Data Source

PatentUS20250013903A1Method and system for operating a quantum network node

Publication Date: 2025.01.09 TECH UNIV DELFT

AI summary

Method for operating a quantum network node comprising an electron spin host providing an electron spin for a communication qubit and a nuclear spin host providing a nuclear spin for a data qubit. The method comprises: data qubit state preparation; entanglement, comprising subjecting the electron spin to a protocol comprising multiple repetitions of a primitive for entangling with another quantum system; and data qubit state use, comprising performing operations on and/or readout of the data qubit state or causing entanglement between the data qubit state and a further quantum system. When the wanted (unwanted) state of the electron spin host is a wanted (an unwanted) charge state, the protocol comprises charge state resetting. The method may also or alternatively comprise determining an average unwanted state electron spin value when the electron spin host is in the unwanted state, and further steps in the entanglement protocol.