Silicon has been the semiconductor industry’s workhorse for more than half a century, but Delft startup Groove Quantum believes its cousin germanium is better positioned to support large-scale quantum computers. The race to build a practical quantum computer is often portrayed as a contest between competing qubit technologies. Superconducting circuits currently dominate in qubit count, trapped ions excel in coherence and photonic approaches promise room-temperature operation. And there’s the spin qubit approach, looking to stay as close as possible to conventional chip manufacturing to facilitate scaling by leveraging decades of investment in semiconductor technology. Most startups subscribing to this strategy are betting that it won’t be necessary to trade in the semicon industry’s dominant substrate, silicon. These firms believe the only significant change necessary is swapping classic transistors for ‘quantum switches.’ Groove Quantum is taking a different view. As well-understood as silicon may be, the Delft-based startup claims that its cousin germanium is a much better match for quantum chips. Groove founders Anne-Marije Zwerver and Nico Hendrickx. Credit: Marc Blommaert Neighbors Groove’s roots spring from Qutech, the quantum research institute in Delft. Around 2017, Anne-Marije Zwerver and her eventual cofounder Nico Hendrickx began PhDs there. While Zwerver’s work helped prove that silicon spin qubits could be fabricated on real semiconductor production lines, Hendrickx started pioneering work in germanium. The work on germanium quickly caught up with a decade of silicon progress. By the time both researchers were well into their postdocs, it was clear that germanium qubits had hit every basic milestone required for a scalable quantum computing platform. Encouraged and supported by their thesis advisors, Zwerver and Hendrickx quit their jobs and founded Groove Quantum to push germanium spin qubits from academic curiosity to industrial technology. Zwerver, now Groove’s CEO, explains that one of germanium’s most important advantages stems from basic semiconductor physics. “Charge carriers in germanium have a lower effective mass than electrons in silicon. That allows their quantum wavefunctions to spread over a larger region, giving designers significantly more flexibility when laying out qubits on a chip.” This deserves a bit of unpacking. The effective mass of charge carriers – electrons or holes – is a measure of how easily these particles move through the crystal lattice of a material. In classic semiconductor technology, this higher mobility translates into faster chips. Interestingly, since charge carriers in germanium have a lower effective mass than those in silicon, germanium is the superior substrate for microchips in that respect. That silicon nonetheless came out on top has practical reasons. In quantum chips, charge carriers don’t have to zip through the lattice. Their lower effective mass matters for a different reason: They can ‘feel’ their neighbors better. One way to think about this is to imagine quantum chips as an array of charge carriers, each of them confined to a tiny area on the chip. To perform quantum computing magic, these qubits need to interact with their neighbors. The better the wavefunction spreads out, the stronger this interaction between adjacent qubits. Bits&Chips’ Dutch state of semicon 2026 This article is part of the Bits&Chips special edition on the Dutch state of semicon, published on 23 October 2026. Order your hard copy of the special at info@techwatch.nl. Tiny So, how does this germanium property translate into better quantum chips? “It means we can place qubits farther apart, to a spacing of 200-250 nanometers,” says Zwerver. For an industry accustomed to manufacturing transistors far smaller, the ability to relax the pitch of quantum chips hardly seems relevant. But that comparison misses the point, Zwerver points out. “The larger spacing creates valuable process margin.” Qu