Microwave Qubit Filter Topology for Spontaneous Emission Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Superconducting qubits in microwave circuitry face a significant challenge due to spontaneous emission through the microwave transmission line, which negatively impacts the qubit's lifetime during state measurement.
Innovation Solution
A microwave device with a filter comprising at least two resonant elements, positioned along the transmission line to limit transmission at the qubit frequency while maintaining good transmission at the resonator frequency, effectively reducing spontaneous emission and extending the qubit's lifetime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the qubit is coupled to a microwave transmission line for state measurement, then the resonance frequency can be probed to read the qubit state, but the qubit lifetime is reduced due to spontaneous emission through the transmission line
Solution Approach 1:
A filter is introduced as an intermediary component between the qubit and the transmission line. This filter selectively blocks spontaneous emission at the qubit frequency while allowing probe signals at the resonator frequency to pass through, thus enabling measurement while protecting the qubit from decay
Solution Approach 2:
The filter is designed with frequency-selective properties that create a stopband at the qubit frequency while maintaining passband transmission at the resonator frequency. This local quality differentiation allows the system to simultaneously achieve measurement capability and qubit protection at different frequency bands
2Duration of action of moving object
If a filter is added to reduce spontaneous emission, then the qubit lifetime is extended, but the device complexity increases due to additional components
Solution Approach 1:
The harmful spontaneous emission channel is extracted and blocked by the filter, separating the measurement function from the decay pathway. This allows the qubit to be protected from decay while maintaining the transmission line for measurement purposes
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
The implementation of the filter significantly reduces qubit decay, thereby enhancing the qubit's lifetime and improving the accuracy of quantum state measurement by creating a stopband around the qubit frequency, ensuring better preservation of quantum information.
Implementation Method 1
A first resonant element has a first resonance frequency f1 and is positioned along the transmission line between the first port and the qubit. A second resonant element has a second resonance frequency f2 different from f1 and is positioned along the transmission line between the first resonant element and the qubit.
Data Source
AI summary
There is described a microwave device and methods of operating same. The device comprises at least one superconducting qubit coupled to a transmission line defining a first port, and a filter. The filter comprises a first resonant element having a first resonance frequency f1, positioned along the transmission line between the first port and the qubit, and a second resonant element having a second resonance frequency f2 different from f1 and positioned along the transmission line between the first resonant element and the qubit.