General · Media · Photo

Quantum dots – not just for TVs

John Healy

So, occasionally I run across articles which mention quantum dots; but more frequently I notice this technology promoted in higher quality flat screen displays and TVs. Photo-luminescent nanotechnology. This Phys.org article (below) reminds me that the technology is critical in quantum information processing, e.g., quantum computing.

And as Wiki notes, modeling quantum dots showcases the interplay of quantum mechanical, semiclassical, and classical physics: “A variety of theoretical frameworks exist to model optical, electronic, and structural properties of quantum dots. These may be broadly divided into quantum mechanical, semiclassical, and classical.”

Phys.org > “Direct visualization of quantum dots reveals shape of quantum wave function” by University of California – Santa Cruz (Nov 24, 2020)

Bilayer graphene visualization
Visualization of quantum dots in bilayer graphene using scanning tunneling microscopy and spectroscopy reveals a three-fold symmetry [vs. circularly symmetric rings in monolayer graphene]. In this three-dimensional image, the peaks represent sites of high amplitude in the waveform of the trapped electrons. Credit: Zhehao Ge, Frederic Joucken, and Jairo Velasco Jr.

Trapping and controlling electrons in bilayer graphene quantum dots yields a promising platform for quantum information technologies. Researchers at UC Santa Cruz have now achieved the first direct visualization of quantum dots in bilayer graphene, revealing the shape of the quantum wave function of the trapped electrons.

Understanding the nature of the quantum dot wave function in bilayer graphene is important because this basic property determines several relevant features for quantum information processing, such as the electron energy spectrum, the interactions between electrons, and the coupling of electrons to their environment.

“The peaks represent sites of high amplitude in the wave function. Electrons have a dual wave-particle nature, and we are visualizing the wave properties of the electron in the quantum dot.”

2 thoughts on “Quantum dots – not just for TVs”

  1. This article has a useful diagram showing the relationship between dot size and color emission [1]. Nanometers!

    • Gizmodo > “How Quantum Dot OLED Will Change the Way TVs Look” by David Nield (Jan 10, 2022) – At this year’s CES, a new type of display technology showcased an improved viewing experience.

    … the nano-sized particles in QD-OLED are slightly different sizes – between 2 nanometers and 10 nanometers – which affects the wavelengths they emit and therefore the colors they show when light goes through them.

    See also:

    • Cnet > “Samsung’s QD-OLED TV tech explained: Welcome to the quantum dot era” by Stephen Shankland (Jan 6, 2022) – The electronics giant says quantum dots offer more vivid colors than regular OLED TVs made by rival LG. But they’re gonna cost you.

    Notes

    [1] Here’s that diagram.

    • Samsung Display > “Quantum Dot”

    Relationship between dot size and color emission

    (image caption) Quantum dots that emit their own light can compose a wide range of detailed and precise colors at every contrast level and are receiving attention as they will be used in the next-generation large displays with their efficient use of light and simple structure.

  2. Entangled 'verse

    This article describes a research milestone in creating on-demand entangled photon pairs using semiconductor quantum (dot) emitters (vs. crystal-based spontaneous parametric down-conversion). The writer characterizes the pair as “linked.”

    • Phys.org > “New light source emits bright, entangled photons for quantum communication” by TranSpread (August 5, 2024)

    A pan-European, Asian, and South American research team has developed a new light source that emits exceptionally bright [as number of pairs of photons per second], entangled photons.

    The scientists created a unique device integrating a quantum dot with a special light-trapping cavity and a micromachined platform. This allows them to precisely control the properties of the light emitted by the quantum dot. By fine-tuning these properties, they achieved a breakthrough – a source that simultaneously generates bright, entangled photons [with the potential for even higher brightness and purity – perfect indistinguishability].

    Related articles

    • Nature > “Robust, high brightness, degenerate entangled photon source at room temperature” by M. V. Jabir & G. K. Samanta (October 3, 2017)

    • Lund University Publications > “A high brightness source of entangled photons” [pdf] (Spring 2010)

    1 Introduction
    1.1 History
    1.2 Photonic entanglement
    1.3 Different forms of entanglement
    1.3.1 Momentum
    1.3.2 Energy-Time
    1.3.3 Polarization
    1.4 Measuring entanglement
    1.4.1 Coincidence fringe visibility
    1.4.2 Bell’s inequality

    Related questions

    • How are entangled photons measured?

    • How do you know if two particles are entangled?

Comments are closed.