Quantum Readout Isolation Using Non-Reciprocal Frequency Conversion
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Solution Overview
Problem
The readout chain of a quantum computer requires bulky and expensive circulators to isolate the quantum processing unit from back action noise, which present a large thermal mass and take up mechanical space, and existing alternatives face issues with reliability, impedance matching, dynamic range, and sensitivity to external factors.
Innovation Solution
Implement non-reciprocal frequency conversion combined with frequency filtering before and after the conversion, utilizing components like traveling wave parametric amplifiers and tunable phase shifters to suppress back-action noise without magnetic components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If circulators are used to isolate the quantum processing unit from back action noise, then electromagnetic isolation is improved, but the device complexity and thermal mass increase
Solution Approach 1:
The patent extracts the isolation function from traditional circulator components and implements it through frequency conversion. The readout signal is upconverted to a higher frequency band where noise from room temperature electronics does not overlap, effectively separating the quantum processing unit from harmful back-action noise without requiring bulky circulator components
Solution Approach 2:
The patent replaces the mechanical circulator system with an electronic frequency conversion system. Instead of using physical circulators with moving parts and large thermal mass, the invention uses frequency converters to achieve isolation through frequency domain separation, eliminating the need for mechanical isolation components
2Object-affected harmful factors
If circulators are used for electromagnetic isolation, then back action noise is reduced, but the area and volume occupied increase
Solution Approach 1:
The isolation function is extracted from physical circulator components and implemented through frequency domain separation. The readout signal is upconverted to a higher frequency band, allowing noise filtering without requiring large physical isolation components, thereby reducing the area occupied in the cryostat
3Object-affected harmful factors
If Hall effect devices are used for isolation, then alternative isolation is achieved, but reliability and impedance matching deteriorate
Solution Approach 1:
The patent replaces unreliable Hall effect devices with frequency conversion technology. The frequency converters use well-established mixing and filtering techniques to achieve isolation, providing superior reliability and impedance matching compared to Hall effect-based isolation devices
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 effectively isolates the quantum processing unit from back-action noise while maintaining signal integrity and coherence, achieving the quantum limit for noise in amplification and reducing the need for circulators.
Implementation Method 1
non-reciprocal frequency conversion may be effectively used for isolation for a quantum computing circuit
Implementation Method 2
frequency filtering before and after the frequency conversion
Data Source
AI summary
Disclosed is an apparatus and a method for facilitating a first frequency filtering and a second frequency filtering together with non-reciprocal frequency conversion for electromagnetic isolation.