The IBM Quantum team recently announced a community built, open-source computer automated design and analysis toolfor hardware engineers and theorists working on quantum hardware. If you've ever tried to design quantum hardware or novel qubits on your own, you know that this process takes way too much work. I thought you might appreciate a taste of what this program is and how it works.
State of Quantum Chip Design
But first, for those of you who aren't already quantum engineers: What you may or may not know is that before a quantum processor chip can ever be fabricated, someone has to design and simulate it across numerous software programs, and on top of that, do quantum analysis. Fabrication is a lengthy process, taking months in some labs. Once created, a chip can also take more months to measure and figure out if anything went wrong, so it is crucial to have accurate and predictive modeling techniques.
As a grad student, simulation and design took up an enormous chunk of my own life. The process would begin with an idea and a rough sketch of how I wanted the circuit to look. When I felt confident, I would draw it as a 3-D object in Ansys® HFSS (High Frequency Structure Simulator), a third-party classical physics simulator originally designed for microwave antenna. Inevitably I would forget to add units every single time, and the program would assume I meant gigameters and send the object flying off to the ends of the earth never to be seen again. When I finally had a first draft, I'd simulate, iterate, adjust, simulate again.... and repeat. Once I had a design with good electrical and quantum properties, I would extract it into a standard file format such as GDS file in order for it to be fabricated—sometimes realizing that the import had skipped key design elements, sending me back to the drawing board. All this work was just for a single-qubit chip. What if I wanted to build something bigger? In this field, innovation is still key, so freeing up time for one to think about new, creative ideas is important to propel us forward.
What is Qiskit Metal
The team, started and led by Zlatko Minev, Research Scientist at IBM Quantum, is debuting a new branch of the Qiskit software development stack, codenamed Qiskit Metal, for people with struggles like mine. The vision of this open-source software and integration process is to develop a community-driven universal toolkit capable of orchestrating quantum chip development from concept to fabrication in a streamlined, scalable, and open framework. Like all of Qiskit, Metal is user-intuitive and based in Python. Qiskit Metal will add a whole new hardware dimension to the Qiskit stack. Like the software side of Qiskit Metal will have multiple branches, each focused on different aspects of hardware design such as design automation and analysis.
As an example of the design process using Metal, we will walk through how to create a 4 qubit (transmon) chip.
4 Transmon Example
First, python scripts are used to generate the basic layout which becomes visible in the design GUI:
This was all created from the built-in library of quantum components that only takes a dozen lines of code, and just 10 minutes to set up from scratch. Custom components are also possible; simply follow one of the tutorials or templates.
From the GUI it is possible to easily and quickly change features' shapes or positions. Once you are happy with the layout, we aim to make it simple to export the design directly into your favorite co-simulation tool, such as Ansys ® HFSS , Sonnet ® or AWR Design Environment. Here, I am using HFSS.
Here the chip can be simulated exactly as the design layout seen in the GUI. If changes need to be made to the design in the GUI, it can automatically be redrawn. All objects are drawn natively instead of being imported, as this can often lead to problems with mesh edges around corners. From HFSS, we can extract the crucial device parameters such as qubit frequencies, coupling strengths, and dissipative parameters, in order to create our ideal chip.
Here is a close-up image of one of the transom elements in HFSS to better understand how this step works:
Image (A) shows the transmon as is, prior to any simulation. (B) shows the transmon with its overlayed mesh. In HFSS, the physics of the system is calculated at finite steps across the object. Every time one of these mesh lines intersect at a node, the physical equations are solved there. More mesh leads to mode nodes which leads to more precise simulation. (C) shows the transmon after the simulation has been run with this mesh. It is plotting the magnitude of the electric field in dB units.
Once all aspects of the chip design have been considered, Metal makes it easy to export the layout directly to a GDS file (here shown in KLayout) which is the type of file processed by fabrication software.
Now you have everything you need in order to begin creating your quantum device without spending hours drawing anything by hand.
OK, So, What Next?
You can learn more about Metal here, sign up to stay in touch, or even better, try it out for your next quantum hardware design yourself by singing up for the early-access program. An early version of the alpha code will be shared with some early access community members in November. This is a very early version of the code (v0.0.2), and we aim to share it with those who frequently use tools like HFSS, Microwave Office, AutoCad, or Sonnet, in order to gather input and open it up to contributions from the community. If that sounds like you, you can sign up for early access here.
Over the course of the next year, we'll slowly be offering access to our early version of the code to the wider community. Qiskit Metal has a lot of work before it's the complete electronic automated design tool we want it to be. But as the team has been saying internally: if Metal can't do what you want it to do, go in and build it! The Metal team is hoping that grad students, as well as electronics engineers, quantum hardware specialists, and others will be excited about joining the community and trying out this software.
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