Resonator Switch Structure for Qubit Isolation and Purcell Loss Reduction

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Solution Overview

Problem

Current quantum devices face challenges in efficiently shifting the frequency of resonators to isolate qubits from external components, which affects coherence and reduces processing efficiency due to limitations in existing switch technologies.

Innovation Solution

A switch device is implemented across the resonator, comprising a bridge or cantilever structure that shifts the resonance frequency by moving between open and closed positions, allowing for isolation of qubits and improved coherence through radio frequency shorts or grounds, thereby facilitating reduced Purcell loss and enhanced quantum computing performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a mechanical switch is used to shift resonator frequency, then qubit isolation from external components is achieved, but device complexity increases

Engineering Contradiction:
Improvequbit isolationVSAvoidswitch device structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces mechanical switch structures with a superconducting quantum interference device (SQUID) loop array that uses magnetic flux control to achieve frequency tuning. This substitution eliminates mechanical moving parts while maintaining the ability to isolate qubits from external components through frequency detuning, thereby reducing device complexity while preserving reliability.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the operating parameter from mechanical position to magnetic flux through the SQUID loops. By applying external magnetic flux, the inductance of the SQUID array is modulated, which directly tunes the resonator frequency. This parameter change enables frequency shifting for qubit isolation without requiring complex mechanical switch structures.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If frequency shifting is implemented to reduce Purcell loss, then coherence is improved, but energy consumption increases

Engineering Contradiction:
ImprovecoherenceVSAvoidenergy for frequency tuning
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The SQUID-based frequency tuning mechanism utilizes the inherent quantum interference properties of superconducting loops. The magnetic flux control is achieved through Josephson junctions that naturally respond to flux changes, enabling frequency tuning without requiring additional active energy input mechanisms. The system leverages its own quantum properties to achieve the desired frequency shifting for reducing Purcell loss.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent exploits the phase transition properties of superconducting materials and the quantum phase interference in SQUID loops. By controlling the magnetic flux through the SQUID array, the system induces phase changes in the superconducting state that directly modulate the resonator frequency. This phase-based control mechanism enables coherent frequency tuning with minimal energy dissipation compared to resistive or mechanical alternatives.

Inventive Principle:
Principle #36Phase transitions

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 switch device effectively shifts the resonance frequency of resonators from λ/2 to λ/4, isolating qubits and reducing dephasing, leading to improved coherence and processing efficiency in quantum devices.

Implementation Method 1

A switch device is implemented across the resonator, comprising a bridge or cantilever structure that shifts the resonance frequency by moving between open and closed positions

Methodology Applied
Scientific EffectResonance: Resonance

Data Source

PatentEP4073844B1A switch device facilitating frequency shift of a resonator in a quantum device
Publication Date: 2024.04.24 INTERNATIONAL BUSINESS MACHINE CORPORATION
  • EP4073844B1 patent drawingFigure 1
  • EP4073844B1 patent drawingFigure 2A~2B
  • EP4073844B1 patent drawingFigure 3A~3B

AI summary

Devices, systems, methods, computer-implemented methods, apparatus, and/or computer program products that can facilitate a switch device that shifts frequency of a resonator in a quantum device are provided. According to an embodiment, a device (102) comprises a readout resonator (104) coupled to a qubit. The device can further comprise a switch device (108) formed across the readout resonator that shifts frequency of the readout resonator based on position of the switch device. According to another embodiment, a device comprises a bus resonator coupled to a plurality of qubits. The device can further comprise a switch device formed across the bus resonator that shifts frequency of the bus resonator based on position of the switch device.