Michelle Simmons: Atomic-Scale Manufacturing for Quantum Computing

Michelle Simmons is a physicist known for her pioneering research in quantum computing, specifically the fabrication of atomic-scale devices in silicon. She is the founder and CEO of Silicon Quantum Computing (SQC) and a professor at the University of New South Wales (UNSW).

Early Life and Education

Simmons grew up in southeast London. She demonstrated an early aptitude for pattern recognition, notably learning to play chess by observing her father and brother. She attended a local comprehensive school and later pursued physics, eventually working at the Cavendish Laboratory at the University of Cambridge.

Move to Australia and the Centre of Excellence

In the late 1990s, Simmons sought to explore a "bottom-up" approach to atomic engineering, diverging from the traditional "top-down" methods of photolithography favored by many European institutions. In 1999, she accepted a fellowship at UNSW in Sydney, where she established the Centre of Excellence for Quantum Computation and Communication Technology (CQC²T).

The Single-Atom Transistor

Simmons's research focuses on hydrogen-resist lithography and Scanning Tunneling Microscopy (STM) to place individual phosphorus atoms into a silicon crystal.

The fabrication process involves passivating a silicon surface with a layer of hydrogen atoms. An STM tip is then used to remove specific hydrogen atoms, creating a precise template. When the surface is exposed to phosphine gas, phosphorus atoms bond to the exposed silicon sites.

In 2012, Simmons and her team published a paper in Nature Nanotechnology detailing the creation of a single-atom transistor. They successfully placed a single phosphorus atom with an accuracy of ±1 lattice spacing (0.38 nm) between atomic-scale phosphorus-doped wires. At a temperature of 4 Kelvin, the device demonstrated functional electron tunneling through the single atom's energy levels.

Silicon Quantum Computing (SQC)

In 2017, Simmons founded Silicon Quantum Computing (SQC) with backing from the Australian government, the Commonwealth Bank, and Telstra. The company aims to commercialize silicon-based quantum technologies.

Simmons advocates for building quantum computers in silicon because of its compatibility with existing semiconductor manufacturing processes and its potential for stable, long-lived qubits. In 2022, SQC demonstrated a quantum processor capable of simulating a small polyacetylene molecule by precisely aligning 10 quantum dots.

By 2025, SQC was participating in DARPA’s Quantum Benchmarking Initiative (QBI). Simmons continues to direct research toward achieving utility-scale quantum computing for applications in chemistry and materials science.