DC SQUID Filter Switching Between Band-Pass and Band-Stop Modes

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Solution Overview

Problem

Quantum computing faces challenges in prolonging the coherence time of qubits and minimizing decoherence and noise, which limits the operational time and accuracy of quantum logic circuits, especially in large-scale quantum job executions.

Innovation Solution

A filter circuit using a direct current superconducting quantum interference device (DC SQUID) is dynamically modulated to switch between band pass and band stop filter modes, enabling selective coupling and decoupling between room temperature control electronics and cryogenic qubits, thereby suppressing noise and extending coherence time.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If quantum logic circuits operate for extended periods to complete complex quantum jobs, then productivity increases, but coherence time is exceeded causing decoherence and loss of qubit states

Engineering Contradiction:

Improvequantum job execution speedVSAvoidqubit state coherence

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent implements dynamic switching between band-pass and band-stop filter modes using a DC SQUID device. The filter circuit transitions from allowing signals through (band-pass) to blocking signals (band-stop) by adjusting the SQUID's inductance, enabling time-multiplexed operation that adapts to different computational phases

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system employs periodic switching between coupling and decoupling states. During computation phases, the filter operates in band-pass mode to allow control signals; during measurement or idle phases, it switches to band-stop mode to isolate qubits from noise, creating a rhythmic pattern of connection and isolation that extends effective coherence time

Inventive Principle:

Principle #19Periodic action

2Speed

If control electronics are continuously coupled to qubits for fast operation, then execution speed improves, but noise from room temperature electronics increases causing decoherence

Engineering Contradiction:

Improvequantum operation speedVSAvoidthermal noise from control electronics

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The filter circuit acts as an intermediary component between room temperature control electronics and cryogenic qubits. It selectively transmits or blocks signals based on the operational phase, mediating the interaction to allow fast control when needed while preventing noise transmission during isolation phases

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent extracts the noise-blocking function from the continuous coupling path by implementing a separate filter circuit with DC SQUID devices. This extracted filtering capability operates independently to remove harmful thermal noise while preserving the fast control pathway when activated

Inventive Principle:

Principle #2Taking out (Extraction)

3Duration of action of stationary object

If filter circuits are used to suppress noise, then coherence time extends, but device complexity increases

Engineering Contradiction:

Improvequbit coherence timeVSAvoidfilter circuit structure

Core Design Contradiction:

Duration of action of stationary objectVSDevice complexity

Solution Approach 1:

The patent changes the inductance parameter of the DC SQUID device dynamically to switch filter modes. By adjusting a single physical parameter (inductance) of the SQUID, the system transitions between band-pass and band-stop configurations, achieving noise suppression with minimal structural complexity

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The DC SQUID-based filter circuit serves multiple functions: it acts as a band-pass filter during computation, a band-stop filter during isolation, and provides quantum-limited sensitivity for readout. This multi-functionality reduces the need for separate dedicated components for each function

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 solution enhances the operational time and accuracy of quantum logic circuits by reducing noise and decoherence, allowing for faster and more reliable execution of quantum jobs while maintaining out-of-band performance.

Implementation Method 1

A filter circuit using a direct current superconducting quantum interference device (DC SQUID) is dynamically modulated

Methodology Applied

Scientific EffectJosephson effect: Josephson Effect

Implementation Method 2

direct current superconducting quantum interference device (DC SQUID)

Methodology Applied

Scientific EffectSuperconductivity: Superconductivity

Data Source

PatentUS11831291B2Josphson band pass to band stop filter

Publication Date: 2023.11.28 INTERNATIONAL BUSINESS MACHINE CORPORATION

AI summary

One or more systems, devices and/or methods of use provided herein relate to a device that can facilitate selective switching between band pass and band stop filter modes and/or can provide reflectionless or near reflectionless function. A device can comprise a filter circuit coupled between a pair of ports and comprising a direct current superconducting quantum interference device (DC SQUID), wherein the filter circuit is selectively activatable by varying the inductance of the DC SQUID. Applying flux bias to the DC SQUID can allow for the switching between the band pass and band stop filter modes.