Inside Silicon Quantum Computing: an interview with Komal Pahwa
Michelle Simmons is probably the most famous scientist in Australia today. She's delivered hundreds of speeches and presentations, including the Australia Day address and the Boyer Lectures – the most prestigious annual series hosted by the national broadcaster. She's won a stack of awards, including the Feynman Prize, the Royal Society Bakerian medal, and the Eureka Prize for leadership in science. She's even featured in a documentary by news channel France24.
In 2018 she was recognised with the ultimate national accolade: Australian of the Year.
It's a remarkable status for an academic with the day job of professor of quantum science at the University of New South Wales. Not since the days of Bohr and Planck has the media taken such an interest in a quantum personality.
Simmons is more than an academic. She's the founder of Silicon Quantum Computing, a Sydney-based company with a mission to create the world's highest-performing quantum computer. It's where her 400 co-authored research papers intersect with the world of commerce. SQC claims an impressive list of breakthroughs: the only company in the world to manufacture devices with atomic precision, the highest fidelity and fastest spin read-out in semiconductor qubits, the lowest charge noise, fastest two qubit gate and first integrated circuit made with atomic precision.
Intellectual property like this is more than valuable. It is potentially the building block of an entirely new era of computer science. This is where Simmons needs serious support – the breakthroughs at SQC mean little if they can't be protected. The job of defending the IP of this remarkable company falls to senior IP counsel and patent attorney Komal Pahwa – in what must be one of the most challenging jobs in law, anywhere in the world.
“It's amazing working with this team on a daily basis,” says Pahwa.
“We are working on technology which could take over the world in the next 10-20 years. And I get daily inspiration from Michelle!”
Pahwa is more than up to the job. She graduated as a master of physics from Guru Nanak Dev University, winning a gold medal for outstanding performance, then did her PhD in physics at the University of Birmingham studying laser cooling and trapping of potassium atoms.
“I am one of those lucky people who can apply their education in their current job,” says Pahwa. “My work looked at using lasers to cool atoms. If you shine a laser of the right frequency on an atom, the atom can absorb high-energy photons and later emit low-energy photons, leading to the removal of energy from the system. Shine from all six sides along 3D axes at the right frequency and you cool the atom down very close to zero Kelvin. The cooled atoms can then be trapped using another laser beam.”
Atoms this close to absolute zero enter Bose-Einstein condensate, the fifth state of matter along with solid, liquid, gas, and plasma. They can lose their individuality and enter a collective quantum state. The approach is the core mechanism in quantum technologies made by the likes of Infleqtion, recently profiled by Mewburn Ellis. Her background in this area gives Pahwa a detailed understanding of how quantum effects are generated and controlled.
A unique vision for quantum processors
SQC is pursuing a unique approach. It is building a quantum processor by precisely embedding phosphorus atoms in a silicon substrate. It's a unique method, which harnesses Simmon's lifetime of research in the field.
“We are working with phosphorus donors in silicon, a platform that has provided record-long quantum coherence times. We are using advanced STM technology, which stands for scanning tunnelling microscope,” says Pahwa. “We pick silicon as the base of the chip, and then we place individual phosphorus atoms at desired locations within the silicon crystal to create qubits, wires, sensors and the complete circuit to address the qubits. It's really precise.” The approach is completely novel, with a philosophically pure approach to quantum computing. The general rule is the smaller the qubit the more stable and noise-free. Controlling the placement of single atoms and their electrons had never been achieved before the project started, but the results are predicted to create the highest-performance quantum processors. “It's not just about the number of qubits,” says Pahwa. “It's the quality that matters. Our qubits have a very long coherence time. The noise level in our devices is exceptionally low. If another platform needs, say, a million qubits to achieve a result, we can achieve a similar or better result with far less.” The goal of SQC is to deliver a 100-qubit quantum processor, with error correction, by 2028. A full commercial launch of an error-corrected and scalable quantum computer is roughly estimated for 2033. These dates may look a little distant at a time when IBM is launching the Kookaburra quantum chip with 1,386 qubits in 2025, but as Pahwa says, the race will be won by stable and noise-free qubits, rather than merely the most numerous.
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