Physicists discover a new way to ‘see’ objects without looking at them: ScienceAlert

Physicists discover a new way to ‘see’ objects without looking at them: ScienceAlert

Physicists discover a new way to ‘see’ objects without looking at them: ScienceAlert

Usually, to measure an object, we have to interact with it in some way. Whether it’s through a poke or poke, an echo of sound waves, or a shower of light, it’s almost impossible to see without touching.

In the world of quantum physics, there are some exceptions to this rule.

Researchers at Aalto University in Finland propose a way to “see” a microwave pulse without the absorption and re-emission of light waves. It is an example of a special interaction-free measurement, where something is observed without being rattled by a mediating particle.

The fundamental concept of ‘looking without touching’ is not new. Physicists have shown that it is possible to use the wave-like nature of light to explore spaces without invoking the particle-like behavior by splitting neatly aligned light waves through different paths and then comparing their travels.

Instead of lasers and mirrorsthe team used microwaves and semiconductors, making it a standout achievement. The setup used what is known as a transmon device to detect an electromagnetic wave pulsed into a room.

Although relatively large by quantum standards, these devices mimic the multilevel quantum behavior of individual particles using a superconducting circuit.

“The interaction-free measurement is a fundamental quantum effect in which the presence of a light-sensitive object is determined without irreversible photon absorption,” the researchers write in their paper. published paper.

“Here we propose and demonstrate the concept of coherent interaction-free sensing experimentally using a three-level superconducting transmon circuit.”

The team relied on the quantum coherence produced by their custom-built system – the ability of objects to simultaneously occupy two different states, such as Schrodinger’s cat – to make the complex set-up a success.

“We had to adapt the concept to the different experimental tools available for superconducting devices,” says quantum physicist Gheorghe Sorin Paraoanufrom Aalto University in Finland.

“That’s why we also had to change the standard interaction-free protocol in a crucial way: we added an extra layer of quantum by using a higher energy level of the transmon. We then used the quantum coherence of the resulting three-level system as a resource.”

The team’s experiments were supported by theoretical models that confirmed the results. It is an example of what scientists call the quantum advantage, the ability of quantum devices to go beyond what is possible with classical devices.

In the delicate landscape of quantum physics, touching things is equivalent to breaking them. Nothing ruins a neat wave of probability like cracking reality. For cases where detection needs a softer touch, alternative detection methods – like this one – can come in handy.

Areas where this protocol can be applied include quantum computing, optical imaging, noise detection and cryptographic key distribution. In any case, the efficiency of the systems involved would be significantly improved.

“In quantum computing, our method could be applied to diagnose microwave photon states in certain memory elements,” says Paraoanu. “This can be considered a very efficient way to extract information without interfering with the operation of the quantum processor.”

The research has been published in Nature communication.

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