London: Researchers at the University of Bristol, UK, have designed a blueprint for the world’s smallest refrigerator that could help keep quantum computers run smoothly by keeping them chilled.
According to New Scientist, Noah Linden and her colleagues suggest that the fridge would consist of two quantum bits, or qubits, which interact with a third qubit in such a way that it would cool.
Each qubit has two possible energy states: high, or "1", and low, or "0". The team found that when first qubit is attached to a heat bath, they interact on a quantum level with the unexpected consequence that the probabilities flip, making the 010 state more likely. As the probability of the third qubit being in state 0 increases, its temperature falls. Increasing the probability is easy: turn up the heat on the first qubit.
So, the fridge could be used to chill the qubits in a quantum computer, cutting out the thermal noise that can upset their delicate quantum properties. However, to reach super-cool temperatures within a quantum computer the fridge would need a super-hot heat bath.
Raymond Laflamme`s team at the University of Waterloo in Ontario, Canada, has made a quantum refrigeration system that runs on similar principles to the Bristol team`s blueprint, but the cooling is driven by an external magnet acting on the qubits rather than heat. They have used their fridge to cool a carbon atom to -95°C, but they intend to approach absolute zero in future experiments.
The results are published in Physical Review Letters.