A Quantum Machine That Vibrates And Remains Still At The Same Time Has Been Created By British Physicists

The quantum mechanics is crazy. In the realm of particles, objects can be in two places at the same time or behave in one way and the other way at the same time., defying our common sense. This counterintuitive behavior is generally limited to the microscopic realm, but could the same thing happen in everyday objects, the ones we see with our own eyes? A team of British and Australian researchers has taken a key step in understanding the boundary between the quantum world and our own, enabling a drumstick made of light to make a drum barely visible to the naked eye vibrate and stand still at the same time. That is, a man-made object responds to the laws of small things, such as molecules, atoms, and subatomic particles.

The first successful experiment of this kind won the title of scientific breakthrough of the year in 2010 from the prestigious journal Science. So physicists at the University of California, Santa Barbara, chilled a tiny quantum drumstick, about 30 micrometers long but visible to the human eye, that vibrates when placed in motion in a range of frequencies. Then they connected the drumstick to a superconducting electrical circuit so that it reached the quantum state. Then, due to the strange rules of quantum mechanics, they managed to set the drumstick in motion ... while holding still. The stick was vibrating and it wasn't at the same time. The researchers showed that the principles of quantum mechanics can be applied to everyday objects.

The First Quantum Drum Test - Imperial College London

Now, a team from Imperial College London has developed a new technique to generate this type of quantum behavior in the movement of a small drum barely visible to the naked eye. Details of their research are published in the "New Journal of Physics."

Mechanical vibrations, like those that create the sound of a drum, are an important part of our everyday experience. Striking a drum with a drumstick causes it to move rapidly up and down, producing the sound we hear.

In the strange quantum world, things work differently and a drum can vibrate and be still at the same time. However, generating such a quantum motion is very challenging. "You need a special kind of drumstick to make a quantum vibration with our little drum," explains Martin Ringbauer of the University of Queensland.

Towards quantum gravity

These experiments have made the first observation of mechanical interferences fringes, which is a crucial step forward for the field.

In the experiment, the fringes were at a classical level due to thermal noise, but motivated by this success, the team are now working hard to improve their technique and operate the experiments at temperatures close to absolute zero where quantum mechanics is expected to dominate.

These future experiments may reveal new intricacies of quantum mechanics and may even help light the path to a theory that links the quantum world and the physics of gravity.

Schrödinger's cat

In recent years, the emerging field of quantum optomechanics has come a long way toward the goal of a quantum drum that uses laser light as a type of drumstick. However, many challenges remain, which is why the present study takes an unconventional approach. "We adapted a trick from optical quantum computing to help us beat the quantum drum. We use a measurement with individual photons of light particles to adapt the properties of the stick", explains the researcher. "This provides a promising route to making a mechanical version of Schrödinger's cat , where the drum vibrates and stops at the same time," he adds.

Future experiments may reveal new complexities in quantum mechanics and may even help illuminate the way to a theory linking the quantum world and the physics of gravity. Furthermore, "these systems offer significant potential for the development of powerful new technologies with quantum enhancements, such as ultra-precise sensors and new types of transducers," explains Michael Vanner of the Quantum Measurement Lab at Imperial College and lead author of the project.

Reference: Quantum Measurement Lab at Imperial CollegeNew Journal of Physics.

Generation of Mechanical Interference Fringes by Multi-Photon Counting’ by M Ringbauer, T J Weinhold, L A Howard, A G White & M R Vanner is published in New Journal of Physics 20, 053042 (2018)

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