External Qubit Port Measurement via Multiport Admittance Extraction
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Solution Overview
Problem
Existing superconducting quantum systems face challenges in accessing and probing internal qubit ports due to their small size, making it difficult to physically connect RF probes non-invasively, and fail to disclose how to extract internal qubit port responses from external port measurements for validating quantum Hamiltonian models.
Innovation Solution
A method and system that allow for external port measurement of qubit port responses by terminating qubit ports with different electrical connections and determining qubit port responses from external port responses, enabling the determination of multiport admittance functions for scalable qubit probing without direct access to internal ports.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If RF probes are physically connected to internal qubit ports, then qubit port responses can be directly measured, but the small size of qubit ports makes non-invasive connection difficult and device complexity increases
Solution Approach 1:
The patent introduces external ports as intermediary measurement points that are accessible from outside the quantum device. These external ports are electromagnetically coupled to the internal qubit ports through microwave resonators, allowing RF probes to connect to external ports rather than directly to the small internal qubit ports. This mediator approach enables non-invasive measurement while maintaining measurement precision.
2Measurement precision
If internal qubit ports are accessed directly, then qubit port responses can be obtained, but the invasive nature of connection affects qubit operation and scalability
Solution Approach 1:
External ports serve as non-invasive intermediaries that are electromagnetically coupled to internal qubit ports through microwave resonators. This allows measurement of qubit port responses without physically touching or interfering with the qubit terminals, thereby maintaining qubit operation reliability while enabling precise measurement through the external access points.
Solution Approach 2:
The patent replaces direct mechanical/probe-based connection to qubit ports with electromagnetic coupling through resonators. Instead of physically connecting RF probes to internal ports, the system uses electromagnetic fields to transfer signals between external ports and internal qubit ports, eliminating mechanical intrusion while preserving measurement capability.
3Productivity
If external ports are used to measure qubit responses, then scalability of qubit probing is improved, but extracting internal port responses from external measurements becomes complex
Solution Approach 1:
The patent creates a copy of the qubit port measurement capability through external ports. By designing external ports that are electromagnetically coupled to internal qubit ports via resonators, the system replicates the measurement function at accessible external locations. This copying approach enables scalable probing of multiple qubits without requiring direct access to each internal port, while the coupling physics provides a known transformation that can be mathematically inverted to extract internal port responses.
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
Enables the probing of qubits internal to a superconducting quantum device using external ports, facilitating scalable qubit probing and allowing for the determination of qubit port responses and multiport admittance functions, thus overcoming the limitations of existing systems in accessing internal ports.
Implementation Method 1
A Josephson junction generally manifests the Josephson effect of a supercurrent, where current can flow indefinitely across a Josephson junction without an applied voltage.
Data Source
AI summary
Systems, computer-implemented methods, and computer program products to facilitate external port measurement of qubit port responses are provided. According to an embodiment, a computer-implemented method can comprise terminating, by a system operatively coupled to a processor, one or more qubit ports with different electrical connections. The computer-implemented method can also comprise determining, by the system, one or more qubit port responses from external port responses based on the terminating. In some embodiments, the computer-implemented method can further comprise determining, by the system, a multiport admittance function corresponding to at least two of the one or more qubit ports.