Quantum Signal Conversion System for Cryogenic Loss Reduction

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Solution Overview

Problem

Quantum computing systems face challenges in efficiently converting signals between different frequency regimes, leading to increased ohmic losses and heat load in cryogenic environments, particularly as the number of qubit devices increases, which complicates signal communication and reduces system efficiency.

Innovation Solution

A quantum computing system is designed with a control system operating in one frequency regime and a quantum processing unit in another, using a signal conversion system to convert classical control signals and few-photon quantum coherent signals between these regimes, reducing the need for RF coaxial cables and other hardware components, and integrating signal conversion on a single substrate or distinct thermal stages.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the number of qubit devices is increased, then the computational capability of the quantum computing system is improved, but the ohmic losses and heat load increase due to the increased number of RF cables and interconnectors

Engineering Contradiction:

Improvecomputational capabilityVSAvoidohmic losses

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The patent replaces the mechanical/electrical RF cable system with an optical fiber communication system. Optical fibers transmit control signals from room temperature to cryogenic temperatures without the ohmic losses associated with RF cables, thereby reducing energy loss while maintaining or improving computational capability through scalable optical interconnects.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces optical fibers as an intermediary medium between the room temperature control system and the cryogenic quantum processing unit. This intermediary enables signal transmission without direct electrical connections, eliminating the need for RF cables and their associated ohmic losses while allowing for increased qubit density.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If the number of qubit devices is increased, then the computational capability is improved, but the heat load on the cryogenic environment increases due to increased RF cable connections

Engineering Contradiction:

Improvecomputational capabilityVSAvoidheat load

Core Design Contradiction:

ProductivityVSTemperature

Solution Approach 1:

The patent substitutes RF cable connections with optical fiber connections. Since optical fibers carry light rather than electrical signals, they do not conduct heat from room temperature to the cryogenic environment in the way that RF cables do, thereby reducing the heat load on the quantum processing unit while enabling higher qubit counts.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Adaptability or versatility

If RF cables and interconnectors are used for signal transmission, then the system can operate with existing hardware, but the signal transmission losses increase and system efficiency decreases

Engineering Contradiction:

Improvehardware compatibilityVSAvoidsystem efficiency

Core Design Contradiction:

Adaptability or versatilityVSProductivity

Solution Approach 1:

The patent replaces the RF cable-based electrical signal transmission system with an optical fiber-based light signal transmission system. This substitution eliminates the ohmic losses and inefficiencies of RF cable transmission while maintaining hardware adaptability through the use of standard optical communication components and interfaces.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 minimizes ohmic losses and heat load, enhances system efficiency, and addresses the scaling challenges in quantum computing by allowing for more compact and low-loss signal transmission, thereby improving the operational viability of quantum computing systems.

Implementation Method 1

the signal conversion system converts control signals between a first frequency regime (e.g., optical, terahertz, or mm-wave) and a second frequency regime (e.g., microwave or radio)

Methodology Applied

Scientific EffectFrequency conversion:

Data Source

PatentUS11983602B1Converting signals between regimes in a quantum computing system

Publication Date: 2024.05.14 RIGETTI & CO INC

AI summary

In a general aspect, signals are converted between regimes in a quantum computing system. In some cases, a quantum computing system includes: a quantum processing unit, a control system, a transmission medium, and circuitry. The quantum processing unit includes a superconducting circuit, which includes a plurality of qubit devices. The control system includes a signal generator configured to generate a first control signal and encode qubit control information in the first control signal. The transmission medium is configured to couple the signal generator with a signal conversion system. The signal conversion system is configured to: receive the first control signal generated by the signal generator; and generate a second control signal based on the qubit control information encoded in the first control signal. The circuitry is configured to deliver the second control signal to the plurality of qubit devices.