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An influential article in Nature Physics recently argued that “Quantum materials,” is fast becoming “a common thread linking disparate communities of researchers” (The rise of quantum materials, 2016). This effect is important, according to the article, despite the authors’ concession of the “trivial” fact that “all materials exist thanks to the laws of quantum mechanics”.
Simply put, all materials may be considered quantum when observed or manipulated at their smallest possible interacting – or quantum – scale of size. However, quantum materials behave in particularly useful or interesting ways at this scale. This usefulness or interestingness of certain materials connects various areas of both academic and industrial research and development.
Disparate Communities Connected by Experimentation
These connected areas operate at the frontiers of modern science. Quantum physics – both experimental and theoretical – has turned the laws of classical mechanics, known as fact since Isaac Newton’s time, on their heads.
Quantum tunneling is observed when particles pass through matter like disappearing through a brick wall. Quantum superposition shows how a particle can occupy two mutually exclusive states at once (made famous by the Schroedinger’s cat thought experiment).
Perhaps the most exploited by the growing quantum materials industry is quantum entanglement. This describes how two discrete particles can become entangled so that a stimulus on one affects the other in predictable ways, despite the distance between them.
Advanced microscopy methods have enabled the smallest interactions in our universe. Such as those between particles of matter, subatomic particles, and pieces of energy such as electrons and photons to be observed, studied and manipulated. Quantum tunneling, for example, is observable in Raman spectroscopy and atomic force microscopy (AFM) and is only possible due to our understanding of atomic forces operating on the quantum scale.
Nanotechnology has applied these peculiar behaviors in increasingly unique and useful ways. The recent discovery of graphene, for example, is gaining attention for its potential in many applications. From wearable technology to energy generation and distribution, to superfast quantum computing.
Techniques Behind Quantum Materials
Just a few of the techniques the quantum materials industry use to observe, study, fabricate and manipulate the quantum behaviors of particles of matter are outlined below.
Ultrafast spectroscopy uses rapidly pulsing lasers to emit light on the specimen matter. The matter’s subsequent interactions with the light are recorded as valuable data plotting changes in the material’s state over nanoseconds in time.
The various techniques of ultrafast spectroscopy are used in quantum materials to understand things like the energy conversion efficiency of new synthetic or newly discovered organic photovoltaic materials for the solar energy industry.
Atomic Force Microscopy (AFM)
AFM is an advanced microscopy technique that utilizes an extremely sensitive cantilever connected to a nanometer-sharp pointer. The pointer is scraped over the specimen material and minute deviations caused by atomic forces operating between the material’s surface and the pointer are measured.
AFM measures various quantum materials’ topographies. This information is essential for the successful use of these materials, especially when considering the bonds and connections to other materials in a new technology or process.
The self-assembly of quantum materials – otherwise known as bottom-up manufacturing, especially in nanotechnology – is rife with experimental techniques that rely on the understanding and application of the latest developments in quantum chemistry, condensed-matter physics, and materials science.
Here, a material like graphene can be induced to “grow” as part of a natural electrochemical process. This experimental technique can much cheaper than conventional “bottom-down” manufacturing processes, removing the need for extremely precise fabrication machines.
References and Further Reading
- Orenstein, J. (2012). Ultrafast spectroscopy of quantum materials. Physics Today. 65 (9), pp.44–50. doi:10.1063/PT.3.1717
- The rise of quantum materials. (2016). Nature Physics, 12(2), pp.105–105. doi:10.1038/nphys3668