Scientists create optical-mechanical quantum memory that can become basis of quantum Internet

A group of scientists from the Niels Bohr Institute (Denmark) has announced the development of an unusual quantum memory called a "quantum drum". This opto-mechanical memory stores quantum states of photons in the mechanical (acoustic) vibrations of a ceramic membrane - essentially a drum. Such a device can act as a repeater for transmitting entangled quantum states over a network, making the quantum internet a reality.

The "quantum drum" is a ceramic plate made of a glass-like material. In previous studies, scientists have demonstrated that a specially treated ceramic plate can preserve the quantum states of laser light (photons) hitting it. The remarkable aspect is not only the conversion of quantum states of light into sound (phonons), but also that the quantum device is represented by a tangible component - the quantum micro-world is embodied on a macroscopic level, making it usable.

The drum retains the quantum state until it can be transmitted further through the network as photons. This is temporary memory and is essential for organizing repeaters. It is well known that the main advantage of quantum communication networks is their sensitivity to message interception. Any interception of "charged" photons with quantum states disrupts them, serving as an indicator of transmission compromise.

Purely quantum repeaters are a modern challenge, and developing them further or proposing something new, such as "quantum drums" developed at the Niels Bohr Institute, is an important step in the development of quantum communication networks. Without such devices, a global quantum network is unimaginable. The Danes have taken a confident step forward, demonstrating in the laboratory under room temperature conditions that the lifetime of a quantum signal in the membrane reaches 23 milliseconds with an effective extraction probability of 40% for classical coherent pulses.

"We expect that storing quantum light will become possible under moderate cryogenic conditions (T≈10 K). Such systems may find applications in new quantum networks, where they can serve as long-lived optical quantum memories, storing optical information in a sound mode," explain the developers in an article published in the journal Physical Review Letters.