Australia (Commonwealth Union) – Scientific discoveries and older technologies are often enhanced and applied in modern applications. Wind power which is often viewed as a modern technological function is a basic method going back 1000s of years. Electronic vehicles are another example of an older technology that did not become widespread due to a variety of factors. However, in recent times, increased efficiency covering larger distances and reduced prices have made it a more feasible option.
Researchers at the University of New South Wales (UNSW Sydney) have shown a 20x enhancement in resetting a quantum bit to its ‘0’ state, by making use of a modern version of the ‘Maxwell’s demon’.
Quantum engineers at UNSW Sydney forwarded a procedure to reset a quantum computer, which is, to prepare a quantum bit in the ‘0’ state having greater confidence, required for reliable quantum computations. The simple procedure is associated with an older concept of ‘Maxwell’s demon’, a being capable of dividing a gas into hot and cold by observing the speed of the individual molecules.
Lead of the team, Professor Andrea Morello of UNSW, said: “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.”
“Quantum computers are only useful if they can reach the final result with 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 will be wrong too. Our digital ‘Maxwell’s demon’ gives us a 20x improvement in how accurately we can set the start of the computation,” he added.
Prof. Morello’s research team initiated the application of electron spins in silicon to encode and manipulate quantum information, indicating record-high fidelity, which is the decreased probability of errors while carrying out quantum operations. The final remaining barrier for effective quantum computations with electrons was the fidelity of preparing the electron in a known state as the initial part of the calculation.
Lead experimental author on the paper Dr Mark Johnson said: “The normal way to prepare the quantum state of an electron is go to extremely low temperatures, close to absolute zero, and hope that the electrons all relax to the low-energy ‘0’ state.”
Dr Johnson, an Electrical Engineering graduate from UNSW, applied a high-speed digital measurement instrument to ‘watch’ the state of the electron, while applying a real-time decision-making processor in the instrument to choose if to retain that electron and apply it in more computations. The impact of this method was lowering the probability of error from 20% to 1%.
The concept of ‘Maxwell’s demon’ goes back in history to the year 1867. This is when James Clerk Maxwell visualized a creature with the ability to have knowledge of the velocity of every single molecule in a gas. He had a box full of gas, with a dividing wall in the middle, and a door capable of being opened and closed instantly. Having the information of the speed of every single molecule, the demon can open the door to let the slow molecules that are cold build up on one side, and the fast hot molecules on the other.
This was the enhanced application of older idea, where many modern scientific discoveries have been based on. More research and knowledge on how specific procedures are applied have helped modern day researchers enhance many older ideas with greater knowledge and improved technology.
