Nonlinear Microwave Filter for Fast Qubit Control and Longer Lifetime
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Solution Overview
Problem
In the context of superconducting qubits, coupling to a waveguide for microwave control leads to radiation relaxation, shortening the qubit's lifetime, while methods to reduce coupling also prolong gate operation times and weaken control pulses.
Innovation Solution
A nonlinear microwave filter is introduced, comprising a qubit coupled to a control waveguide with a stronger coupling than the target qubit, positioned at the waveguide end, and with a resonant frequency close to that of the target qubit, to suppress radiation relaxation and maintain high control pulse intensity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the qubit is coupled to the waveguide for microwave control, then the control pulse can be transmitted to the qubit, but the coupling causes radiation relaxation and shortens the qubit lifetime
Solution Approach 1:
The patent introduces a frequency filter as an intermediary component between the waveguide and the qubit. This filter selectively transmits the control microwave frequency while blocking other frequencies that would cause radiation relaxation. By placing this intermediary element, the system achieves both effective control pulse transmission and suppression of harmful radiation relaxation effects.
2Reliability
If the coupling between the qubit and waveguide is reduced to suppress radiation relaxation, then the qubit lifetime is extended, but the interaction between control pulse and qubit is reduced, prolonging gate operation time
Solution Approach 1:
The patent applies local quality by creating different coupling conditions at different locations along the waveguide. The qubit is positioned at a specific location where the electromagnetic field intensity is optimized for strong interaction, while frequency-selective filtering is applied locally to block radiation relaxation pathways. This spatial differentiation allows simultaneous achievement of fast gate operations and extended qubit lifetime.
3Productivity
If the control pulse intensity is increased to reduce gate operation time, then the gate velocity increases, but the thermal load on the refrigerator increases
Solution Approach 1:
The patent changes the frequency parameter of the control system by introducing a frequency filter tuned to the specific control microwave frequency. This allows the use of lower intensity control pulses since the filter ensures efficient energy transfer to the qubit, thereby reducing the thermal load on the refrigerator while maintaining fast gate operation speeds.
4Reliability
If a frequency filter is interposed to reduce coupling and suppress radiation relaxation, then the qubit lifetime is extended, but the control pulse is weakened, prolonging gate operation time
Solution Approach 1:
The frequency filter serves as an intermediary that selectively transmits the control pulse frequency while blocking other frequencies. By carefully designing the filter's transmission characteristics, the control pulse intensity is preserved at the qubit location, maintaining fast gate operation speeds while the filter blocks radiation relaxation pathways to extend qubit lifetime.
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 configuration effectively suppresses the long operation time and short lifetime of the qubit, eliminating the trade-off between extending qubit lifetime and reducing gate time, while allowing for high-speed control of the target qubit.
Implementation Method 1
a qubit, which is formed on a circuit substrate on which a target qubit, which is a qubit to be controlled in a superconducting quantum circuit, is formed, and which has a resonant frequency whose deviation from a resonant frequency of the target qubit is within a predetermined range
Implementation Method 2
a control waveguide to which the target qubit is coupled
Data Source
AI summary
This nonlinear microwave filter is provided with quantum bits that are formed on a circuit board in which target quantum bits are formed which are quantum bits controlled in a superconducting quantum circuit, and that are coupled to a control waveguide to which the target quantum bits are coupled, wherein the distance to a waveguide end in the control waveguide is within a predetermined range from semi integer times the resonant wavelength, the quantum bits have a resonant frequency in which the difference from the resonant frequency of the target quantum bits is within a predetermined range, and the coupling to the control waveguide is stronger by a predetermined value than the coupling between the target quantum bits and the control waveguide.