Physicists 'Entangle' Microscopic Mechanical Drum with Electrical Signals

Physicists have extended evidence of quantum behavior further into the large-scale world of everyday life. They've managed to "entangle" a microscopic mechanical drum with electrical signals. The findings could have implications for the future of quantum computers.

Entanglement is an unusual feature of the quantum world. It was once believed only to occur at atomic and smaller scales. In recent years, though, researchers have discovered entanglement in larger systems. Since it's essential for quantum computing operations such as correcting errors and for quantum teleportation of data from one place to another, entanglement has many technological uses.

In order to examine this phenomenon, the researchers took a look at the aluminum micro-drum. Just 15 micrometers in diameter and 100 nanometers thick, the drum features both mechanical properties, such as vibrations, and quantum properties, such as the ability to store and transfer individual quanta of energy. This drum is part of an electromechanical circuit that can exchange certain quantum states between the waveform of a microwave pulse and vibration in the drum.

In this case, the scientists conducted an experiment where a microwave signal "cooled" the drum to a very low energy level--just one unit of vibration--in a way analogous to some laser-cooling techniques. Then another signal caused the drum's motion to become entangled with a microwave pulse that emerged spontaneously in the system.

What was the result? The drum stored the quantum information in the form of vibrational energy for at least 10 microseconds. Then the same type of microwave signal that cooled the drum was used to transfer the state stored in the drum to a second microwave pulse.  The evidence of quantum entanglement itself came from the fact that the first microwave pulse allowed scientists to anticipate the characteristics of the second pulse with greater accuracy than would otherwise be expected. In fact, the correlations between the two pulses indicated that the first pulse was entangled with the drum and the second pulse encoded the drum's quantum state.

The findings seem to suggest that the drum has the potential to be a quantum memory device and could also be used to generate entanglement in microwaves. This could be particularly useful in future applications with quantum devices.

The findings are published in the journal Science.