Engineers at the University of New South Wales (UNSW) achieved a milestone in quantum computing by demonstrating Schrödinger's famous thought experiment using an antimony atom. The study, recently published in the journal Nature, demonstrates the maturity and universality of high-dimensional quantum computing, according to Science Daily.
In their research, Professor Andrea Morello's team used an atom of antimony, a heavy element with a complex nuclear spin, to represent a quantum superposition and store data for quantum computations. This makes the information better protected from errors than in a standard qubit, as reported by Phys.org.
"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," said Professor Morello from UNSW, according to Newsweek.
Schrödinger's cat is a famous thought experiment that illustrates one of the most puzzling principles of quantum mechanics: superposition. In this paradox, a cat inside a box can be both alive and dead at the same time, depending on the decay of a radioactive particle, emphasizing the concept that quantum systems can exist in multiple states simultaneously until observed. The notion serves as the foundation for quantum computing, where qubits can be in superposition, representing both '0' and '1' at the same time.
An antimony atom possesses eight different spin directions due to its composite nature, adding multiple individual spins. Xi Yu, the lead author of the study, explained, "The spin of antimony can take eight different directions instead of two. This may not seem like much, but it completely changes the behavior of the system," as reported by Phys.org.
The researchers addressed the challenge of error correction in quantum computing by using the antimony atom's eight spin states to represent information, which provides greater protection against errors. "In case of an error, we detect it straight away, and we can correct it before further errors accumulate," said Morello.
"As the proverb says, a cat has nine lives. A small scratch is not enough to kill it. Our metaphorical 'cat' has seven lives: seven consecutive errors would be needed to turn '0' into '1'. This is the sense in which the superposition of antimony spin states in opposite directions is 'macroscopic'—because it is happening on a larger scale and realizes a Schrödinger's cat," Xi Yu explained, according to Newsweek.
The team at UNSW and the University of Melbourne integrated the antimony atom into a silicon quantum chip, leveraging methods similar to those used to build current computer chips. "Hosting the 'cat' in silicon means that, in the long term, this technology can be scaled using methods similar to those we already adopt to build the computer chips we have today," added Danielle Holmes, according to Science Daily.
The researchers applied magnetic fields and microwaves to induce and control quantum superposition in the nuclear spins, achieving control over the quantum state of the antimony atom. This advancement opens new perspectives for the future of quantum computation, with profound consequences for scientists working on building a quantum computer using the nuclear spin of an atom as the basic building block, as well as for error-proofing quantum computers.
Quantum technology has the potential to radically transform the capabilities and applications of computing devices due to its extraordinary computing speed, enhanced by the ability of qubits to exist in superposition, allowing them to process multiple possibilities simultaneously.
"By hosting the atomic 'Schrödinger's cat' within a silicon chip, we gain extraordinary control over its quantum state, or, if you prefer, over its life and death," concluded Holmes, according to Science Daily.
The article was written with the assistance of a news analysis system.