Chip 'cat' aids quantum tech
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A cat that is both alive and dead might save computers from their own mistakes.
Quantum engineers at the University of New South Wales (UNSW) have replicated a renowned quantum thought experiment - Schrödinger’s cat - on a silicon chip.
The development is a critical step towards creating reliable quantum computers.
The “Schrödinger’s cat” metaphor represents a system existing in two contradictory states simultaneously - a cat that is both dead and alive until observed.
UNSW’s team has realised this concept using an antimony atom embedded in a silicon quantum chip. This innovation advances quantum error correction, a significant challenge in the field.
“No one has ever seen an actual cat in a state of being both dead and alive at the same time, but people use the Schrödinger’s cat metaphor to describe a superposition of quantum states that differ by a large amount,” says lead researcher Professor Andrea Morello.
The experiment uses antimony, a heavy atom with an unusually large nuclear spin, enabling it to possess eight spin directions.
This complexity makes antimony far more robust than conventional quantum bits, or “qubits”, which typically operate in two states: “0” (spin down) and “1” (spin up).
“A single error is not enough to scramble the quantum code. As the proverb goes, a cat has nine lives. Our metaphorical ‘cat’ has seven lives: it would take seven consecutive errors to turn the ‘0’ into a ‘1’,” said lead author Xi Yu.
This resilience stems from the multiple quantum states that separate the antimony spin’s superposition branches, making it a practical choice for scalable and fault-tolerant quantum computing.
The antimony atom is embedded within a silicon chip, aligning quantum technologies with existing silicon-based manufacturing infrastructure.
This compatibility allows for future scalability, paving the way for broader applications.
“Hosting the ‘cat’ in silicon means that, in the long term, this technology can be scaled up using similar methods as those we already adopt to build the computer chips we have today,” says Dr Danielle Holmes, a UNSW researcher involved in chip fabrication.
UNSW’s breakthrough strengthens the potential for quantum error detection and correction, long regarded as the ‘Holy Grail’ of the field.
“If an error occurs, we detect it straight away and correct it before further errors accumulate,” said Professor Morello.
The project involved collaboration with researchers from the University of Melbourne, NASA Ames, Sandia National Laboratories, and the University of Calgary.
The full paper is accessible here.
