To further progress into the quantum age, various projects are in the works to take computing to the next level. After forming a consortium in December, EU stakeholders have launched an effort to supercharge quantum processor production.
The Quantum Large-Scale Integration with Silicon (QLSI) project and the German Quantum Computer based on Superconducting Qubits (GeQCoS) project are targeting manufacturing and design to make quantum computing possible on a larger scale.
Overview of the QLSI Project
The QLSI project is part of the EU’s FET Flagships program, emphasizing advancements in science and technology on a large scale. Any advancements in quantum integration, large or small, should have positive innovative, economic, and societal impacts.
Since quantum computing benefits could be significant, EU participants have since funneled almost €15 million into the project. With the support of universities, research institutions, and microelectronics manufacturers, the QLSI project will start with 16-qubit processors and work toward massive 1,000-qubit systems that will soon be viable by August 2024.
The QLSI project is the successor to the MOS-QUITO (MOS-based Quantum Information TechnOlogy) project—which spawned multiple cryo-CMOS demonstrations, 55 publications, and seven patents. Since the QLSI project enjoys over three times more funding, stakeholders are thrilled to see which advancements will be the most beneficial.
A quantum chip from the MOS-QUITO project. Image used courtesy of the MOS-QUITO Project.
Overcoming Production Challenges
The QLSI project’s proposition is simple: why not leverage existing manufacturing processes and resources to make quantum chips? This technique was used in the MOS-QUITO project, which took advantage of a 300-millimeter CMOS fabrication line when creating silicon-spin qubits.
Despite project MOS-QUITO’s innovations, the project coordinator Silvano De Franceschi remarked that improved fabrication processes were needed to make inroads. Fabrication issues and equipment hiccups caused some delays.
Accordingly, designing circuitry that operates effectively at temperatures approaching zero Kelvin is tricky. The quantum information stored within qubits quickly becomes unusable if the temperatures are not low enough. These electronics must withstand repeated cooling cycles—jumpstarted by injections of supercooled, liquid helium in some cases.
The quantum states achieved within a quantum chip are equivalent to traditional computer binary: 0 and 1. Quantum computers fluctuate back and forth between these states when encoding information. These states are susceptible to temperature; hence warming can essentially cause data corruption.
(A) A qubit represented in a Bloch sphere where an arrow pointing up represents the |0〉 state and pointing down it represents the |1〉 state. (B) One qubit Hadamard gate acting on an initial qubit. Image used courtesy of Clément Godfrin
Blindly crafting qubit processor prototypes isn’t the optimal way to tackle this hurdle. It’s expensive and error-prone. However, there’s evidence suggesting that quantum simulations at various temperatures can point researchers in the right direction. Designing around key performance criteria (and suitable operating conditions) will help remove the equation’s guesswork.
Lastly, silicon chip shortages due to COVID-19 and high demand have shocked many industries. While silicon remains abundant in the Earth’s crust, fabricators must balance research with their customers’ output demands. These new quantum processors will rely on existing silicon wafers.
Help from GeQCoS
There are undoubtedly production issues of quantum chips. Special considerations lying outside the realm of traditional fabrication will dictate the QLSI project’s future success. It’s much easier to make quantum processors on a small scale; however, that may soon change by streamlining qubit production.
Diagram of a qubit. Screenshot used courtesy of IBM
Thankfully, additional research stemming from Germany, in tandem with the QLSI project, is supplementing this effort. As we recently discussed, the GeQCoS (German Quantum Computer based on Superconducting Qubits) is a four-year project to improve quantum microelectronics through qubit quality, connectivity, and the connection pathways between individual qubits.
The group behind GeQCoS plans to use novel materials to boost reproducibility. Additionally, the team will place a unique emphasis on the hardware-software tandem when evaluating performance enhancements.
Electrical engineers will thus need to create chips that pair well with existing systems. Not only must production scale, but performance must also improve as quantum systems expand. Hardware specialists must balance power with manufacturing capacity while crafting the next big solution in the computing world.