Ion Milling Frequency Tuning Superconducting Qubits
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Superconducting qubits with Josephson junctions face challenges in achieving precise resonance frequencies due to fabrication imperfections, leading to unwanted coupling and frequency collisions, especially when scaling up, and existing frequency tuning methods like local laser annealing can contaminate chip surfaces.
Innovation Solution
In-situ frequency tuning of superconducting qubits using an ion beam with adjustable energy, exposure time, and oblique incidence to modify the Josephson junction properties, which also cleans the surfaces and does not significantly impact coherence times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If local laser annealing is used for frequency trimming, then the qubit frequency can be reduced, but the chip surface becomes contaminated with dirt
Solution Approach 1:
The patent replaces the thermal/optical laser annealing process with a focused ion beam (FIB) process. Instead of using laser energy to anneal and trim the Josephson junction, the invention uses physical ion bombardment to selectively remove material. This substitution of the physical mechanism eliminates the contamination issue inherent in laser-based methods while achieving the same frequency trimming objective.
Solution Approach 2:
The patent changes the fundamental parameter of the trimming process from thermal/optical interaction (laser) to physical sputtering (ion beam). By changing the interaction mechanism parameter, the process achieves frequency trimming through controlled material removal rather than through annealing, thereby avoiding surface contamination while maintaining manufacturing precision.
2Productivity
If the number of coupled qubits is increased, then the quantum computing power is enhanced, but the frequency collisions and unwanted coupling increase due to fabrication variance
Solution Approach 1:
The patent applies frequency trimming to qubits after fabrication but before final assembly and testing. By performing the ion beam trimming process as a preliminary adjustment step, the system can compensate for fabrication variances that occur during manufacturing. This preliminary action allows each qubit's frequency to be individually tuned to achieve the desired detuning, enabling larger quantum systems to be built without frequency collisions.
Solution Approach 2:
The focused ion beam process allows for localized, individual trimming of each Josephson junction. The ion beam can be precisely positioned and controlled to affect only the specific qubit being tuned, enabling independent frequency adjustment of each qubit. This local quality control ensures that frequency detuning can be optimized for each qubit pair regardless of the total number of qubits in the system.
3Reliability
If fixed frequency qubits are used, then coherence times are maintained, but the qubit frequency cannot be adjusted to compensate for fabrication deviations
Solution Approach 1:
The patent introduces a dynamic adjustment capability to fixed frequency qubits by applying ion beam trimming. While the qubits maintain their fixed frequency architecture (as opposed to flux-tunable designs), the ion beam process provides a post-fabrication dynamic adjustment mechanism. This allows the frequency to be tuned within a controlled range while preserving the coherence time benefits of fixed frequency designs, effectively combining both advantages.
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 method allows for precise frequency adjustment of superconducting qubits while maintaining coherence times, reducing the need for extensive chip screening and avoiding surface contamination, thus enhancing the performance and scalability of quantum computing systems.
Implementation Method 1
The method generates an ion beam having a beam energy. The method exposes a surface of the quantum device to the ion beam for an exposure time. The ion beam is incident onto the quantum device at an oblique angle that is less than 90 degrees as measured from the surface of the quantum device.
Implementation Method 2
Some embodiments of the invention provide a method for in-situ qubit frequency tuning with ion milling, which not only tunes the qubit frequency post fabrication, but also in some embodiments cleans the surfaces of the circuits from contamination.
Data Source
AI summary
A method of modifying a resonant frequency of a quantum device includes generating an ion beam having a beam energy and exposing a surface of the quantum device to the ion beam for an exposure time. The ion beam is incident onto the quantum device at an oblique angle that is less than 90 degrees as measured from the surface of the quantum device. The quantum device includes a Josephson junction, the ion beam exposing the quantum device proximate to the Josephson junction to modify a property of the Josephson junction, the property being associated with the resonant frequency of the quantum device.