Figure 1 shows. When metals and semiconductors are combined, they form Schottky junctions, creating regions of space charge. In this region, the density of charged particles undergoes fluctuations that affect the behavior of the interface. Using the external bias potential (V), we can change the properties of the junction (see Figure 2). When the bias potential is zero (V=0), the ideal band plot of the Schottky junction. The work functions of metals and semiconductors are expressed in h m and h s, respectively. where Ec is the lowest energy of the conduction band, Ev is the highest energy of the valence band, Ef is the fermi energy of the junction, Eg = (Ec−Ev) is the energy band gap of the semiconductor, Hbn is the Schottky junction barrier, and χs is the electron affinity energy of the semiconductor. Photo credit: Kosala Herath, Sarath D. Gunapala and Malin Premaratne
Imagine a field where light can be carefully controlled and manipulated on extremely small scales, unlocking the unprecedented potential of nanotechnology and quantum information technology. Recent breakthroughs in quantum research have brought us closer to a reality that may be more achievable than before.
In this article, we delve into the realm of surface plasmons (SPPs) and the enormous possibilities they offer in the revolution in the field of quantum optics.
Surface plasmons (SPPs)
Imagine a tranquil lake on a sunny day. When you throw a small stone into the water, it makes gentle ripples on the surface of the water. Now, think of light as those undulating ripples. When light encounters the interface of metal and dielectric material, it has the ability to generate waves, like ripples on the surface of a lake. This phenomenon is even more interesting because these light waves can interact with the microscopic components of metals, such as electrons. It is worth noting that the oscillations of light waves and electrons are synchronized, producing SPP waves.
This new wave travels gracefully along the metal surface, reminiscent of the ripples of a lake, but infused with the essence of light. SPPs have special properties because they can navigate through tiny gaps in metal surfaces, similar to moving through a maze. Because SPPs have unique properties and abilities beyond ordinary light waves, scientists are committed to studying them. The ability to traverse such tiny spaces has facilitated the development of nanoscale electronics, including data processing units and sensors. These advances pave the way for cutting-edge quantum technology, heralding a future full of endless possibilities.
Schottky knot
Traditional SPPs, which occur at the interface of metals and dielectric materials, have shown significant potential in nanophotonics. However, scientists have recently made an interesting discovery that adds a new dimension to the phenomenon.
When metals and semiconductors come together to form a Schottky junction (Figure 1), a separate space charge region appears at this junction due to the difference in carrier density between the metal and the semiconductor, which is an extraordinary thing [1]. This area changes the properties of the interface, resulting in a shift in SPP behavior. This is similar to discovering a completely new wave on this special interface.
Figure 2. Within the Schottky junction, metal regions encounter two different types of incident light: a linear polarization dressing field from the top and a circular polarization dressing field from the bottom. Through quantum descriptions, we can show that this phenomenon allows us to actively manipulate the motion of surface plasmons (SPPs) along the interface. Photo credit: Kosala Herath, Sarath D. Gunapala and Malin Premaratne
Schottky junction quantum description based on disguised SPPs
Our research team has developed a comprehensive theoretical framework based on quantum theory [2] that can accurately predict the SPP behavior at the Schottky junction when subjected to external electromagnetic fields [Figure 2]. We published our findings in Scientific Reports.
By applying quantum principles, we derive the expression of the "dress up" metal dielectric function. But what exactly does "dressing" mean in this context? Recent scientific breakthroughs have shown that using Floquet engineering, external electromagnetic fields have the ability to "modify" or change the properties of metals [3,4,5]. It must be emphasized that these observations can only be understood and interpreted within the framework of quantum theory.
Now, here's the really exciting part: this trimming farm provides an effective tool to control and enhance the reproduction of SPPs. It changes the metal's magnetic susceptibility and permittivity functions, which in turn changes its interaction with light and other electromagnetic waves. By adjusting the intensity, frequency, and polarization of this outer field, we can finely adjust the mobility of electrons inside the metal. Our findings suggest that by doing so, we can extend the distance SPPs travel without dissipating energy. This progress is of great significance to the development of nanoscale data processing equipment in practical applications.
What does all this mean for our world? Let your imagination soar and imagine a future where incredibly tiny circuits harness the power of light to fuel our devices. These circuits will exhibit extraordinary efficiency and process information at breakneck speeds. This breakthrough in controlling and enhancing the propagation of light at the nanoscale opens up many possibilities for the future of quantum information technology.
The ability to finely control light waves paves the way for the development of advanced quantum photonic circuits and devices that surpass the capabilities of current electronic components. Imagine smartphones that are faster, smaller, and more powerful than ever before, and can handle complex tasks effortlessly. Imagine that fast data processing and sharing systems will revolutionize the telecommunications, computing, and healthcare industries.
With these advances, the landscape of technology and various sectors will change profoundly. These breakthroughs have the potential to reshape our world, with significant advances in communications, computing, and healthcare.
[1] Malin Premaratne and Govind P. Agrawal, Theoretical Foundations of Nanoscale Quantum Devices, Cambridge University Press (2021). DOI: 10.1017 / 9781108634472
[2] Zhang Jianjun, Zhang Jianjun, Zhang Jianjun, et al. Optimization Design Method of Surface Plasma Waveguide, Acta Photonica Sinica (Natural Science Edition) (2009). DOI: 10.1038 / s41598 - 023 - 37801 - x
[3] Wang Xiaoming, et al. Generalized models of charge transport properties in quantum Hall systems, Acta Physica Sinica(B)(2010). DOI: 10.1103 / PhysRevB.105.035430
[4] Zhang Xiaoming, Zhang Xiaoming, et al. Study on the polarization effect of plasma waveguide, Acta Optica Sinica(Natural Science Edition), 2012(4). DOI: 10.1117/12.2635710
[5] Wang Xiaoming, et al. Study on surface plasmon mode in plasma waveguide,Acta Physica Sinica,2002,21(5):555-557. DOI: 10.1103 / PhysRevB.106.235422
BIOS:
Kosala Herath, PhD candidate, is a member of the Advanced Computing and Simulation Laboratory (qdresearch.net) for Electrical and Computer Systems Engineering, Monash University, Australia. He received his Bachelor of Engineering (First Class Honours) in Electronics and Telecommunications from the University of Moratuwa, Sri Lanka in 2018. His current research interests include nanoplasma, low-dimensional electron transport and Floquet systems.
Sarath D. Gunapala is a solid-state physicist and senior research scientist at Caltech's Jet Propulsion Laboratory (JPL). He leads the Infrared Photonics Group at the Jet Propulsion Laboratory. He received his Ph.D. from the University of Pittsburgh in 1985. From 1985 to 1988, he was an associate researcher at Bell Communications Research. From 1988 to 1992, he was a technician at AT&T Bell Labs in Murray Hill, New Jersey. Currently, his research focuses on semiconductor nanodevices, including semiconductor devices based on quantum wells, lines, dots, and spin devices, especially infrared detectors and novel artificial bandgap materials for imaging focal planes. He has given more than 200 presentations and more than 100 invited presentations at technical conferences. In addition, he has authored more than 300 publications, including many book chapters on focal plane arrays for infrared imaging, and he holds 26 patents.
Malin Premaratne holds a number of degrees from the University of Melbourne, including a Bachelor of Mathematics, a Bachelor of Electrical and Electronic Engineering (First Class Honours), and a PhD in 1995, 1995 and 1998 respectively. Since 2004, he has been leading a high-performance computing applied research project for complex systems simulation at the Advanced Computing and Simulation Laboratory at Monash University in Clayton. Currently, he serves as Vice Chairman and Full Professor of the Academic Council of Monash University. In addition to his work at Monash University, Professor Premaratne is a visiting fellow at several prestigious institutions, including Caltech's Jet Propulsion Laboratory, the University of Melbourne, the Australian National University, UCLA, the University of Rochester in New York, and the University of Oxford. He has published more than 250 journal articles and two books, and serves as an associate editor for several major academic journals, including IEEE Photonics Technology Letters, IEEE Photonics journal, and Advances in Optics and Photonics. Professor Premaratne has received numerous fellowships for his contributions to the field of optics and photonics, including the Optical Society of America (FOSA), the Society of Optical Instrument Engineers (FSPIE), the British Physical Society (FInstP), the British Society of Engineering and Technology (FIET) and the Australian Institution of Engineers (FIEAust).
Journal Information: Scientific Reports, Physical Review B