Phononic Waveguides for Directional Quantum State Transfer

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Solution Overview

Problem

Current quantum circuits face challenges in efficiently transferring quantum states between qubits while being immune to thermal mechanical noise, and existing technologies lack scalable solutions for directional and internal quantum state transfer.

Innovation Solution

The use of phononic waveguides coupled with spin-mechanical resonators on a diamond membrane, which allow for directional transfer of quantum states between qubits and internal state transfer within resonators, utilizing periodic variations in acoustic impedance to define non-overlapping frequency bands for acoustic coupling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If phononic waveguides are used to enable directional quantum state transfer between qubits, then quantum state transfer efficiency is improved, but device complexity increases due to the need for alternating frequency bandgap structures

Engineering Contradiction:

Improvequantum state transfer efficiencyVSAvoidwaveguide structure complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The waveguide structure is segmented into alternating high and low acoustic impedance regions with different periodicities, creating distinct frequency bandgaps. This segmentation allows the waveguide to selectively pass specific frequency ranges while blocking others, enabling directional quantum state transfer between qubits operating at different frequencies without requiring complete structural redesign for each qubit pair.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The phononic waveguide structure serves multiple functions simultaneously: it acts as a transmission medium for quantum states, provides frequency filtering through bandgaps, enables directional coupling between different qubit types, and maintains quantum coherence. This multi-functionality reduces the need for separate components for each function, thereby managing complexity while improving transfer efficiency.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If alternating frequency bandgap waveguides are implemented for frequency-selective coupling, then quantum state transfer selectivity is improved, but manufacturing precision requirements increase

Engineering Contradiction:

Improvefrequency selectivityVSAvoidhole periodicity precision

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The waveguide structure utilizes changes in acoustic impedance parameters through alternating material regions or geometric variations (such as hole size and periodicity) to create frequency bandgaps. By carefully controlling these physical parameters during fabrication, the system achieves frequency-selective coupling between qubits while the parameter variations themselves provide a fabrication roadmap that can be implemented with standard manufacturing tolerances.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If multiple acoustic waveguides with different frequency ranges are coupled to a mechanical resonator, then quantum network scalability is improved, but loss of energy increases due to additional coupling interfaces

Engineering Contradiction:

Improvequantum network scalabilityVSAvoidenergy loss at coupling interfaces

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

Multiple acoustic waveguides with different frequency ranges are merged into a single integrated phononic waveguide structure that supports multiple frequency bandgaps. This unified structure reduces the number of separate coupling interfaces compared to using independent waveguides for each frequency range, thereby minimizing energy loss while maintaining the ability to couple multiple qubits at different frequencies to the same mechanical resonator.

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

This approach enables robust and scalable quantum state transfer, immune to thermal mechanical noise, by using phononic waveguides to couple spin qubits at specific frequencies, enhancing the stability and efficiency of quantum computations.

Implementation Method 1

The first acoustic waveguide includes a periodic variation in acoustic impedance so as to attenuate acoustic propagation between the first and second mechanical resonators at an acoustic frequency associated with a period of the periodic variation

Methodology Applied

Scientific EffectPhononic bandgap: Phononic Crystal

Implementation Method 2

a first acoustic waveguide coupled to the first mechanical resonator in a first acoustic frequency range

Methodology Applied

Scientific EffectAcoustic resonance: Resonance

Data Source

PatentUS11113622B2Phononic quantum networks of solid-state spins with alternating and frequency-selective waveguides

Publication Date: 2021.09.07 UNIVERSITY OF OREGON

AI summary

Spin qubits are situated in mechanical resonators that are acoustically coupled with acoustic waveguides. The acoustic waveguides provide frequency dependent phonon propagation selected so that mechanical resonators adjacent to a selected mechanical resonator are acoustically coupled to the selected mechanical resonator in different acoustic frequency ranges. This configure permits directional transfer of quantum states between spins in spin-mechanical resonator and provides a scalable platform for spin-based quantum computing.