快猫短视频

A design for a quantum engine that uses two entangled quantum bits and is powered by measuring their properties has been tested in the lab for the first time.

At the quantum scale, measuring an object鈥檚 property can change its energy. In 2021, at Grenoble Alpes University聽in France and her colleagues for an engine that could be powered using only this energy change. Now, Bresque and other colleagues have tested this design in the lab.

The engine consists of two quantum bits or qubits 鈥� like those used to carry information in quantum computers 鈥� encoded into a single particle of light, or photon. The qubits are quantum entangled, meaning that measuring the state of one changes the state of the other.

To encode the qubits into the photon, the researchers directed it through a series of devices including lenses, filters and semi-transparent pieces of glass. A key property these devices changed was polarisation, which describes how light oscillates as it travels, like up or down or left or right.

鈥淚n the classical world, measurements just obtain some information, but for a quantum engine, measurements also input energy,鈥� says co-author at Anhui University in China. He says that this increase in energy was measured in the experiment although the team didn鈥檛 go as far as to use it. In principle, the additional energy could amplify or speed up the way light-based quantum computers process information.

Bresque says that quantum engines powered by measurements have been built in experiments before, but not with entangled qubits. Measuring the state of one qubit always changes the state of its entangled pair,聽so the entanglement could allow聽the new engine design聽to聽gain more energy after fewer measurements, she says.

Using measurements instead of adding fuel to power an engine is an idea that has no equivalent in classical physics, says at the University of Exeter in the UK. Until recently, such engines were only theoretical, but studies like the new experiment have now begun to prove that they can exist, she says.

Reference: Physical Review Research,