Photonic Link for Cryogenic Qubit Control via Optical Fiber

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Solution Overview

Problem

The scalability of quantum computing systems is limited by the heat load and space constraints of coaxial lines used to deliver microwave pulses to cryogenic environments, which compete with the limited cooling power of dilution refrigerators, restricting the number of qubits and computer power.

Innovation Solution

A photonic link system that uses an optical link to deliver microwave signals to a cryogenic environment, where they are converted back into electrical signals, allowing for the control and readout of superconducting qubits without degrading coherence, using an Electric-to-Optical (E/O) converter outside and an Optical-to-Electrical (O/E) converter within the cryogenic environment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If coaxial lines are used to deliver microwave pulses to cryogenic environments, then microwave signals can be transmitted to control and readout qubits, but heat load increases and space is consumed, limiting the number of qubits

Engineering Contradiction:

Improvequbit control and readout capabilityVSAvoidheat load

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent replaces the traditional electrical coaxial transmission line system with an optical fiber transmission system. Microwave signals are converted to optical signals for transmission through optical fibers to the cryogenic environment, where they are converted back to electrical signals. This substitution eliminates the heat conduction problem inherent in electrical cables while maintaining signal transmission capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces optical signals as an intermediary medium to transmit information from room temperature to the cryogenic environment. The microwave signals are modulated onto optical carriers for transmission through optical fibers, which have negligible thermal conductivity, thus avoiding direct heat transfer while preserving the control and readout functions.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If coaxial lines are used to deliver microwave pulses to cryogenic environments, then microwave signals can be transmitted to control and readout qubits, but space limitations are imposed that restrict system scalability

Engineering Contradiction:

Improvequbit control and readout capabilityVSAvoidspace consumption

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent replaces the bulky electrical coaxial cable infrastructure with thin optical fibers for signal transmission. This substitution dramatically reduces the space required for signal routing while maintaining the essential function of delivering control and readout signals to qubits in the cryogenic environment.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If the number of qubits is increased to improve computer power, then quantum computing capability is enhanced, but heat load from coaxial lines increases, competing with limited cooling power

Engineering Contradiction:

Improvequantum computing powerVSAvoidheat load

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The patent replaces the heat-conductive electrical transmission system with thermally-isolated optical transmission. This allows for scaling up the number of qubits and their associated control lines without proportionally increasing the heat load on the dilution refrigerator, since optical fibers conduct negligible heat compared to electrical cables.

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 reduces the heat load, maintains high fidelity of qubit operations, and enables the potential for large-scale quantum information systems with millions of qubits by leveraging low thermal conductivity and high bandwidth of optical fibers, preserving qubit coherence and readout fidelity.

Implementation Method 1

The O/E signal converter may comprise a photodetector, photodiode or another type of electro-optical device. The photodiode may utilize the photoelectric effect.

Methodology Applied

Scientific EffectPhotoelectric effect: Photoelectric Effect

Implementation Method 2

The optical link carries the optical signal generated by the E/O signal converter into the cryogenic environment.

Methodology Applied

Scientific EffectOptical fiber transmission: Optical Fibre

Data Source

PatentUS11742955B2Delivering signals to cryogenic environments via photonic links

Publication Date: 2023.08.29 THE REGENTS OF THE UNIVERSITY OF COLORADO

AI summary

An operational environment is disclosed herein that includes a cryogenic environment and a signal source. The cryogenic environment includes a signal target, an optical link, signal converter devices, and an electrical link. Outside of the cryogenic environment, the signal source generates an electric signal. An electric-to-optical converter converts the electrical signal into an optical signal. The optical link delivers the optical signal into the cryogenic environment. Inside the cryogenic environment, an optical-to-electrical converter converts the optical signal back into an electrical signal. The optical-to-electrical converter transfers the electric signal to the signal target.