Scientists Just Measured a Mechanical Quantum System Without Destroying It

You may not have considered a critical element of quantum computing previously. Quantum non-detruction measurements relate to detecting quantum states without destroying them.

If we want to build a working quantum computer, not having it crash every second while computations are being performed is obviously beneficial. Scientists have now detailed a promising new approach for capturing quantum non-demolition data.

Mechanical quantum systems - items that are reasonably large in quantum computing terms but extremely small for humans – were the focus of this study. They manage the required quantum magic with mechanical motion (such as vibration), and they may also be integrated with other quantum systems.

"Our results open the door for performing even more complex quantum algorithms using mechanical systems, such as quantum error correction and multimode operations," the researchers write in their article.

The researchers created a narrow strip of high-quality sapphire that was just under half a millimeter thick for this experiment. A tiny piezoelectrical transducer was utilized to generate acoustic waves, which are energy units that may be pushed through quantum computing operations in principle. An acoustic resonator is the technical term for this device.

That was the first step in the process. The acoustic resonator was paired with a superconducting qubit — the basic quantum computer building parts that can simultaneously contain both a 1 and a 0 value and on which businesses like Google and IBM have previously constructed primitive quantum computers – to do the measurements.

The scientists were able to read the number of photons in the acoustic resonator without actually interacting with them or transmitting any energy by making the state of the superconducting qubit dependent on their quantity.

They compare it to playing a theremin, a bizarre musical instrument that produces sound without being touched.

It was a difficult undertaking to put together the quantum computing equivalent: The way these phases were extended out for longer was part of the technique's uniqueness. This was accomplished in part via material selection and in part through the use of a superconducting aluminum chamber for electromagnetic shielding.

They were able to obtain the mechanical quantum system's 'parity measure' in subsequent trials.

The parity measure is important in a range of quantum technologies, especially when it comes to repairing system mistakes — because no computer can function effectively if it makes errors all the time.

"By interfacing mechanical resonators with superconducting circuits, circuit quantum acoustodynamics can make a variety of important tools available for manipulating and measuring motional quantum states," the researchers claim.

This is all very high-level quantum physics, but the bottom line is that this is a significant step forward in one of the technologies that might potentially serve as the foundation for future quantum computers, particularly in terms of mixing multiple sorts of systems.

A hybrid qubit-resonator device like the one reported in this paper might combine the best of two fields of research: superconducting qubit processing capability and mechanical system stability. Scientists have now demonstrated that information can be retrieved from such a gadget without causing damage.

There is still much more work to be done – once the process of measuring states has been improved and accomplished, these states must then be exploited and controlled to be of practical value – but quantum computing systems may have just taken another step closer to realizing their enormous promise.

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

"These measurements are some of the basic building blocks for constructing acoustic quantum memories and processors."