Scientists just measured a mechanical quantum system without destroying it

(ORDO NEWS) — There is a key aspect of quantum computing that you may not have thought about before. Called “quantum non-destructive measurements”, they refer to the observation of certain quantum states without destroying them in the process.

If we want to assemble a functioning quantum computer so that it does not break every second during operation. calculations would obviously be useful. Now scientists have described a promising new technique for recording quantum measurements without destroying them.

In this case, the study involved mechanical quantum systems – objects that are relatively large in terms of quantum computing. but extremely small for us. They use mechanical motion (such as vibration) to control the necessary quantum magic, and they can also be combined with other quantum systems.

“Our results open the door to even more complex quantum algorithms using mechanical systems. , such as quantum error correction and multimode operations,” the researchers write in their published paper.

For the purposes of this study, the team assembled a thin strip of high-quality sapphire, just under half a millimeter thick.

A thin piezoelectric transducer has been used to excite acoustic waves, moving units of energy such as phonons, which could theoretically be subjected to quantum computing processes. Technically, this device is known as an acoustic resonator.

This was the first part of the installation. For the measurement, the acoustic resonator was connected to a superconducting qubit, those basic building blocks of a quantum computer that can contain the values ​​1 and 0 at the same time, and from which companies like Google and IBM have already built the simplest quantum computers.

By putting the status of a superconducting qubit in dependence on the number of phonons in the acoustic resonator, scientists were able to read this number of phonons that do not actually interact with them and do not transfer any energy.

They describe it as playing the theremin, a strange musical instrument that doesn’t need to be touched to produce sound.

Creating the equivalent of quantum computing was not an easy task: quantum states are usually very short-lived, and part of the innovation in this technique was that these states were stretched out for a longer time.

The team did this partly through the choice of materials and partly through a superconducting aluminum resonator that provided electromagnetic shielding.

In further experiments, they managed to extract the so-called “parity measure” of a mechanical quantum system. .

The measure of parity is critical to various quantum technologies, especially when it comes to correcting errors in systems, and no computer can work properly if it regularly makes mistakes.

“By coupling mechanical resonators with superconducting circuits, quantum circuit acoustic dynamics can make available many important tools for controlling and measuring moving quantum states,” the researchers wrote.

All this is very high-level from the point of view of quantum physics. physics, but the bottom line is that this is an important step forward in one of the technologies that could eventually become the basis for future quantum computers, especially in terms of combining different types of systems. ms together.

A hybrid qubit-resonator device like the one described in this study potentially offers the best of two different areas of research: the computational capabilities of superconducting qubits and the stability of mechanical systems. Now scientists have shown that information can be extracted from such a device in a non-destructive way.

There is still a lot of work to be done – once the task of measuring states is refined and completed, these states are then so that they can be exploited and manipulated to gain real benefits, but the huge potential of quantum computing systems can become one step closer.

“Here we demonstrate direct measurements of the phonon number distribution and parity of non-classical mechanical states,” the researchers write.

“These measurements are one of the main building blocks for creating acoustic quantum storage devices and processors.”


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