Posted in | Quantum Physics

Novel Nanomechanical Gadget Opens Door Towards Future Quantum Internet

Based on quantum-mechanical vibrations of a nanomechanical gadget, a collaborative team of researchers from the University of Vienna and the TU Delft have formulated a primary step towards a universal quantum link.

A stylization of the researcher’s nanomechanical device. By way of vibrating back-and-forth, the hole-filled silicon beam converts quantum particles of light into quantum vibrations, and later back into light (Copyright: Jonas Schmöle, The Aspelmeyer Research group, Faculty of Physics, Vienna Center for Quantum Science and Technology (VCQ), University of Vienna).

It is a challenge to realize interconnectivity between various types of quantum systems, but this is crucial to futuristic quantum computing architectures.

Numerous new quantum technologies are scientifically based on quantum physics. The new innovations are likely to revolutionize the way people communicate, and improve the performance of many powerful computers and sensors.

Making various quantum technologies communicate to each other for practical is one of the open challenges faced by researchers, as today many quantum devices are not compatible with each other, preventing emerging technologies from connecting or linking to one another. As a solution researchers have proposed to construct nanometer-sized mechanical objects with the capability to vibrate back and forth, identical to a miniature vibrating tuning fork.

It is possible to engineer these “nanomechanical devices” so that their vibrations act as a mediator between different quantum systems. Mechanical gadgets capable of converting their mechanical vibrations into light could link themselves and other gadgets to the optical fiber networks around the world to form the Internet.

Constructing a nanomechanical gadget capable of converting quantum-mechanical vibrations to quantum-level light has been a challenge in quantum physics. A resolution of the challenge would facilitate the connecting of quantum devices to a quantum Internet of the future. Markus Aspelmeyer led the research team at the University of Vienna, while Simon Gröblacher headed the team at TU Delft. Together they have created a nanomechanical gadget with the required capabilities. The gadget can convert photons into phonons or quantum-mechanical vibrations, and then transform them again into photons. This collaborative research has been reported in the Nature journal.

The possibility of converting a photon into a phonon has been very small to be of any use. However, the research team used a trick. The nanomechanical gadget created a “signaling” photon when the gadget first converted a photon to a phonon. The researchers were able to know precisely when their nanomechanical gadget had achieved the conversion, first by searching for the signaling photon, which had converted into quantum-mechanical vibrations of the nanomechanical gadget. With the aid of lasers, the researchers then used their gadget to emit a photon by converting the phonon into light.

Finally, the researchers counted the signaling photons and the emitted photons, illustrating that the whole conversion process occurred at the quantum level, which means a single particle at a time.

Not only is this exactly what is necessary to convert and store quantum bits; what I also find amazing. Is the implications for fundamental physics. We normally think of mechanical vibrations in terms of waves, like waves traveling across a lake, as water vibrates up and down. But our measurements are clear evidence that mechanical vibrations also behave like particles. They are genuine quantum particles of motion. It’s wave-particle duality, but with a nano-sized tuning fork.

Ralf Riedinger, Lead Author

The nanomechanical device is a small silicon beam measuring only half a micrometer wide. It contains a standard pattern of holes, which capture mechanical vibrations and light in the same region. The beam vibrates back and forth billions of times per second. Prof. Gröblacher’s team fabricated it on a silicon chip, and utilized infrared wavelengths of light similar to emerging photonic circuits, industry-standard fiber optic networks, and integrated electronic.

We clearly also see the long-term technological potential. Such quantum mechanical vibrations could eventually be used as a ‘memory’ to temporarily store quantum information inside quantum networks or computers.

Simon Gröblacher, TU Delft

Going forward, the team hope to create a quantum Internet, where quantum bits rather than classical bits are processed across the world. Similar to the Internet available today, light will be applied for worldwide exchange of quantum data.

The next challenge would be to determine how it could be converted to a large number of different quantum gadgets, which can be used for computation and storage.

Our research indicates that nanomechanical devices are a promising candidate to form this link.

Simon Gröblacher, TU Delft

The Foundation for Fundamental Research on Matter (FOM) Projectruimte program supports the TU Delft research. The European Research Council (ERC) Consolidator Grant Program, the Vienna Science and Technology Fund WWTF, the European Commission, the Austrian Science Fund FWF, and the DOC fellowship program of the Austrian Academy of Sciences supported the research activities carried out at University of Vienna.

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