Errors in quantum computers are a major obstacle to their widespread use. But a group of scientists say they may have found a way to stop them using an antimony atom and the Schrödinger's Cat thought experiment. Scientists have used the famous Schrödinger's Cat thought experiment to find a way to eliminate errors from future quantum computers.
The new method encodes quantum information on an antimony atom, which has eight possible states, allowing for more secure data storage than in a standard two-state qubit, or quantum bit. The breakthrough is a vital step in reducing the likelihood of errors in quantum systems and, when they do occur, making them easier to detect and correct, a key obstacle to the development of quantum computers. The researchers published their findings Wednesday (Jan. 14) in the journal Nature Physics.
First developed by physicist Erwin Schrödinger in 1925, his thought experiment vividly describes the strange rules of the quantum world by imagining a cat placed inside an opaque box containing a bottle of poison, the opening mechanism of which is controlled by radioactive decay—a completely random quantum process.
Schrödinger argued that until the box was opened and the cat observed, the rules of quantum mechanics meant that the unfortunate feline would exist in a superposition of states, simultaneously dead and alive.
In the case of a qubit, quantum information, which corresponds to the 0 or 1 states of a classical computer, can be encoded in the “spin up” and “spin down” states of an atom—spin is the atom’s own angular momentum. a fundamental particle. But if noise in a quantum computer causes a sudden change in spin (as is often the case), the quantum state will be lost, creating an error and destroying the information inside.
To get around this problem, the researchers in the new study embedded an antimony atom, which has eight different spin directions, into a silicon quantum chip. The antimony atom’s six additional spin directions (given by the compound nature of the atom, which adds several individual spins) mean that, unlike a system with two spin states, one mistake is not enough to destroy the encoded information. “As the saying goes, a cat has nine lives. One small scratch is not enough to kill it,” co-author Benjamin Wilhelm, a doctoral student in electrical and telecommunications engineering at the University of New South Wales (UNSW) in Australia, said in a statement. “Our metaphorical ‘cat’ has seven lives: it would take seven consecutive mistakes to turn a ‘0’ into a ‘1’!”
With this system, the researchers say they will now work to demonstrate a method for detecting and correcting errors in their chip, a feat considered the "Holy Grail" in the field of quantum computing.
“If there’s an error, we can detect it immediately and fix it before it accumulates further. Continuing the Schrödinger’s cat metaphor, it’s like seeing our cat come home with a big scratch on its face,” said lead author Andrea Morello, a professor of electrical engineering and quantum physics at UNSW, in a statement. “He’s far from dead, but we know he got into a fight; we can go and find out who started the fight before it happens again and our cat gets even more injured.”