| Date | 20th, Jan 2023 |
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Quantum computing is a type of computing that uses quantum-mechanical phenomena, such as superposition and entanglement, to perform operations on data. It has the potential to solve certain problems much faster than classical computers and has applications in areas such as cryptography, drug discovery, and artificial intelligence.
Researchers at UNSW Sydney have created a new technique for resetting quantum computers with a high level of accuracy. This process, known as preparing a quantum bit in the ‘0’ state, is crucial for accurate quantum computations. The method is based on the principle of “Maxwell’s demon,” a hypothetical creature that can separate hot and cold molecules by observing their speed. This innovative solution is simple yet effective in ensuring the reliability of quantum computations.
“Here we used a much more modern ‘demon’ – a fast digital voltmeter – to watch the temperature of an electron drawn at random from a warm pool of electrons. In doing so, we made it much colder than the pool it came from, and this corresponds to a high certainty of it being in the ‘0’ computational state,” says Professor Andrea Morello of UNSW, who led the team.
“Quantum computers are only useful if they can reach the final result with a very low probability of errors. And one can have near-perfect quantum operations, but if the calculation started from the wrong code, the final result would be wrong too. Our digital ‘Maxwell’s demon’ gives us a 20x improvement in how accurately we can set the start of the computation.”
The research was published in Physical Review X, a journal published by the American Physical Society.
Prof. Morello’s team has pioneered the use of electron spins in silicon to encode and manipulate quantum information and demonstrated record-high fidelity – that is, a very low probability of errors – in performing quantum operations. The last remaining hurdle for efficient quantum computations with electrons was the fidelity of preparing the electron in a known state as the starting point of the calculation.
“The normal way to prepare the quantum state of an electron is to go to extremely low temperatures, close to absolute zero, and hope that the electrons all relax to the low-energy ‘0’ state,” explains Dr. Mark Johnson, the lead experimental author on the paper. “Unfortunately, even using the most powerful refrigerators, we still had a 20 percent chance of preparing the electron in the ‘1’ state by mistake. That was not acceptable, we had to do better than that.”
