Building quantum computers atom-by-atom with Michelle Simmons

Michelle Simmons operates in a world where the smallest vibration is a catastrophe. In the basement of the University of New South Wales, she navigates a silence so absolute it borders on the supernatural. Her "opponents" are not people, but the jittering atoms of the universe-the thermal noise that threatens to scramble the delicate quantum information she spends her life protecting. Her pieces are even smaller: single phosphorus atoms, positioned with the surgical precision of a god.

In 2012, Simmons and her team achieved what many in the global scientific community called a physical impossibility. They didn't just build a transistor; they built the world’s first single-atom transistor. By manually placing an individual phosphorus atom into a silicon crystal with an accuracy of better than half a nanometer, she proved that Moore’s Law-the decade-long drumbeat of doubling transistor density-wasn't just a trend; it was a countdown to the atomic limit.

"The things most worth doing in life are nearly always hard to do," Simmons often says. It is her personal mantra and the operational doctrine of her company, Silicon Quantum Computing (SQC).

In a world where Silicon Valley giants like Google and IBM are betting on "superconducting loops"-giant, noisy machines the size of chandeliers-Simmons is the ultimate minimalist. She believes the future of the human race won't be found in massive exotic structures, but in the same material that powered the 20th century: silicon. She isn't just trying to build a computer; she is trying to rewrite the architecture of reality, one atom at a time.

To understand why a world-leading physicist left the elite halls of Cambridge for the "frontier" of Australia, and why she spends her life staring into the tip of a scanning tunneling microscope, you have to go back to a silent chess match in a London suburb and a "disastrous" school where academic success was viewed as a survival trait.

Part I: The Silent Move

Michelle Simmons did not grow up in the gilded corridors of the British establishment. She grew up in Lee, a tough, working-class suburb of south-east London.

Her household was a place of quiet, intense observation. Her father was a policeman, her mother a bank manager. But the true intellectual arena was the family chessboard. For months, eight-year-old Michelle sat silently by the table, watching her father and older brother, Gary, play. She didn't ask questions. She just absorbed the patterns-the way a Knight’s move could bypass a defensive line, the way a sacrifice could lead to a strategic checkmate.

One afternoon, she finally spoke. "I want to play," she told her father.

He was dismissive. He didn't believe she knew the rules, let alone the strategy. He sat down, chatting casually with her mother, barely looking at the board as he made his moves.

Michelle didn't say a word. She was intensely focused, seeing the board not as a collection of wood, but as a grid of logical constraints. To her father’s shock, she didn't just play; she won.

"I remember that feeling of proving someone wrong," Simmons recalls. "It wasn't about the game. It was about the fact that expectations are just a baseline. You can always go beyond them if you see the patterns they don't."

This desire to "see the patterns" drove her through a local comprehensive school that she later described as "academically a disaster." Out of several hundred students in her year, only two passed their A-levels. Simmons was one of them. She learned early that if you wanted to achieve something difficult, you couldn't wait for the environment to support you. You had to create your own sterile environment. You had to be your own cleanroom.

Part II: The "One-Way Ticket" Epiphany

By the late 1990s, Simmons was a rising star at the University of Cambridge, working at the prestigious Cavendish Laboratory. She was at the heart of the scientific world. But she felt a growing friction.

The establishment in the UK and Europe was focused on "top-down" engineering-using massive, expensive machines to etch smaller and smaller circuits. Simmons wanted to go "bottom-up." She wanted to build from the atom up.

She realized that Australia, a country often dismissed by the Northern Hemisphere as a "scientific backwater," offered something the elite universities couldn't: the freedom of the frontier.

"In Australia, they don't tell you why something can't be done," she said. "They just ask how much it will cost and how long it will take."

In 1999, she took a gamble that horrified her colleagues. She accepted a fellowship at UNSW in Sydney. Her brother Gary, who used to tease her about her relentless intensity, joked that he would buy her a "one-way ticket to Australia" just to get some peace.

She took the joke literally. She moved to Sydney, founded the Centre of Excellence for Quantum Computation and Communication Technology (CQC²T), and began the "euphoric struggle" of her life.

Part III: The Atomic Forge and the 2012 Breakthrough

Simmons wasn't just building a lab; she was building a new kind of physics. She abandoned the traditional photolithography used by Intel and TSMC. Instead, she turned to Scanning Tunneling Microscopy (STM) and a process known as "hydrogen-resist lithography."

The process was agonizingly slow. Her team would take a clean silicon crystal and passivate the surface with a single layer of hydrogen atoms. This acted as a "resist"-a atomic-level shield. Then, using a microscopic STM tip, they would selectively "punch out" individual hydrogen atoms, creating a precise template in the silicon lattice.

Once the pattern was etched, they would dose the surface with phosphine gas. The phosphorus atoms would land exactly where the hydrogen was missing, bonding to the silicon.

For a decade, the skeptics circled. They said the phosphorus atoms would "wander" or "segregate" when they tried to bury them under a fresh layer of silicon. They said the electrical signals from a single atom would be too weak to measure against the background noise of the universe.

Simmons ignored them. She worked 80-hour weeks, often sleeping in the lab, obsessing over the "incorporation" process-the exact thermal window where a phosphorus atom replaces a silicon atom in the lattice without moving.

In 2012, the proof was published in Nature Nanotechnology.

The device featured a single phosphorus atom, placed with an accuracy of ±1 lattice spacing (0.38 nm), connected to source and drain electrodes made of atomic-scale phosphorus-doped wires less than 20 nanometers apart.

When they cooled the device to 4 Kelvin-just above absolute cold-and applied a voltage, the results were undeniable. The current didn't flow in a continuous stream; it tunneled through the discrete quantum energy levels of that single atom. They hadn't just reached the end of Moore’s Law; they had turned the end into a new beginning.

"We proved that we can build a functional device where the active component is a single atom," Simmons said. "The era of the 'atomic computer' had begun."

Part IV: The Industrialization of the Impossible

Success in the lab was only the first half of the game. Simmons realized that if quantum computing remained an academic curiosity, it would never change the world. She needed to build a factory.

In 2017, she founded Silicon Quantum Computing (SQC). It was a unique hybrid-a commercial company born inside the university, backed by $150 million from the Australian government, the Commonwealth Bank, and Telstra.

While Google’s Sycamore and IBM’s Osprey made headlines with "Quantum Supremacy," Simmons focused on "Quantum Utility." She didn't want to build a machine that could solve a useless mathematical puzzle. She wanted to build a machine that could solve chemistry.

In 2022, her team achieved another world first: a quantum processor made of atomic-scale circuits that could simulate the behavior of a small molecule. By placing 10 "quantum dots" (clusters of phosphorus atoms) in a specific 1.5-nanometer alignment, they created a "Quantum Twin" of a polyacetylene molecule.

"We aren't just calculating the properties of the molecule," Simmons explained. "We are building a physical system that mimics the molecule at the same scale. The computer is the chemistry."

This breakthrough led to "Watermelon"-a quantum machine learning system that uses the unique physics of silicon to identify patterns in data that classical AI can't see. By 2025, SQC was selected for DARPA’s Quantum Benchmarking Initiative (QBI), a high-stakes U.S. government program to identify the only technologies capable of building a "utility-scale" quantum computer by 2033.

Part V: The Architecture of the Atom

Today, Michelle Simmons is a Companion of the Order of Australia (AC) and a global icon of the "frontier spirit." Her company is no longer just a research lab; it is the cornerstone of the "Australian Quantum Alliance," a multi-billion dollar effort to turn Sydney into the "Silicon Valley of the Southern Hemisphere."

While the rest of the world debates the "safety" of AI software, Simmons is focused on the "integrity" of the hardware.

"If you don't control the hardware at the atomic level, you don't really control the computer," she argues.

Her vision is "d/acc" (Defensive/Decentralized Acceleration) in its purest physical form. By building quantum computers in silicon-the same material as our existing world-she is ensuring that the quantum revolution is compatible with human infrastructure. She is building tools for molecular and materials discovery-systems that can find new catalysts for carbon capture or new room-temperature superconductors.

In 2026, as she leads the race toward the first million-qubit processor, Michelle Simmons still looks at the world through the lens of that eight-year-old girl at the chessboard.

The universe is a grid of constraints. Most people see the barriers. Michelle Simmons just sees the atoms that need to be moved.

"Don't do what's easy," she tells the next generation of engineers. "Run towards the hard problems. Because that’s where the future is hiding."