Cryogenic Vector Signal Generator With Josephson Resonator Control
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Solution Overview
Problem
Conventional methods for generating microwave signals of desired frequency, amplitude, and phase for cryogenically cooled nano-electronic circuits are bulky, costly, and suffer from thermal noise and latency issues, particularly as the complexity of nano-electronic circuitry increases.
Innovation Solution
A vector signal generator integrating a tunable-frequency microwave source, resonator with controllable quality factors, and a 2π phase shifter, utilizing Josephson junctions and SINIS structures to generate signals internally within the cryostat, reducing thermal loading and enabling scalable operation with low output noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional baseband signal generators and microwave mixers are used at room temperature, then signals can be generated with desired frequency, amplitude, and phase, but the equipment becomes bulky and costly
Solution Approach 1:
The patent extracts the microwave signal generation function from room-temperature equipment and relocates it to the cryogenic environment by integrating a microwave resonator and Josephson junction directly on the cryoCMOS chip, eliminating the need for external baseband generators and mixers
Solution Approach 2:
The patent merges multiple functions (signal generation, signal distribution, and control) into a single integrated cryoCMOS chip that operates at cryogenic temperatures, combining what were previously separate room-temperature components into one unified cryogenic system
2Measurement precision
If signals are transmitted through coaxial cables from room temperature, then signal distribution is achieved, but thermal noise occurs on the transmission lines
Solution Approach 1:
The patent removes the source of thermal noise by generating microwave signals directly at cryogenic temperatures within the cryostat, eliminating the need for long coaxial cable transmissions from room temperature that introduce thermal noise
Solution Approach 2:
The patent introduces cryoCMOS circuitry as an intermediary that generates and distributes microwave signals entirely within the cryogenic environment, serving as a mediator between the quantum circuit and external control systems while maintaining low thermal noise
3Adaptability or versatility
If conventional signal generation methods are used, then signals can be provided to multiple channels, but the number of required signal channels increases significantly with circuit complexity
Solution Approach 1:
The integrated cryoCMOS chip provides universal signal generation and distribution capabilities that can serve multiple quantum circuit elements simultaneously, reducing the overall system complexity despite increasing circuit scale
Solution Approach 2:
The patent combines multiple signal generation and distribution functions into the integrated cryoCMOS chip, allowing a single chip to handle what would otherwise require multiple separate signal channels and components
4Measurement precision
If signals are generated at room temperature and transmitted to cryostat, then signal generation is achieved, but latency occurs in feedback control loops
Solution Approach 1:
The patent extracts the microwave signal generation function from room-temperature equipment and relocates it to the cryogenic environment, enabling real-time feedback control without the latency introduced by temperature transitions and long transmission lines
Solution Approach 2:
The integrated cryoCMOS chip enables fast feedback control loops by providing real-time signal generation and processing capability directly at the quantum circuit, allowing rapid measurement and control iterations without external latency
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 allows for efficient, low-noise generation of microwave signals at desired frequencies and phases, improving the operation fidelity of quantum circuits and reducing thermal noise, while simplifying connections between cryogenic and room temperature environments.
Implementation Method 1
a first Josephson junction or junction array coupled to the microwave resonator for emitting microwave signals into the microwave resonator
Implementation Method 2
a second biasing circuit for applying a second bias to said SINIS structure, to control the rate at which electrons absorb microwave photons from said resonator in tunneling across said SINIS structure
Data Source
AI summary
A vector signal generator is capable of operating on microwave frequencies. It comprises a microwave resonator, an output for coupling microwave photons out of said microwave resonator, and a Josephson junction or junction array coupled to the microwave resonator for emitting microwave signals into the microwave resonator. A biasing circuit is provided for applying a bias to the Josephson junction or junction array. A tunable attenuator is coupled to said microwave resonator.