Dear all colleagues:
I though this could be an interesting thread of discussion:
In branches of sciences and engineering like Nanotechnology, Electronics and/or Nanoelectronics, LASERs, the so called Phononics or Nanophononics, etc., consider mainly Nanosciences ...
When modeling or trying to interpret experimental results from a physical system,
There is something we can say with certitude ? about:
If we think about applied physics in function of the lenght scale, i.e. for example: Electric Circuits ... Electronic Circuits ... Microelectronics(MEMS, etc, ) ... Nanoelectronics ... Molecular Systems ...
Where is the threshold in lenght scale (order of magnitude) located ? Where Quantum Mechanical effects need to be considered, to obtain results that predicts and model accurately good enough the behaviour of these small systems.
e.g. when effects as:
Quantum Tunneling, Quantum Confinement, Quantum Size Effects, Energy Filtration of Carriers, etc, etc.. must be taken into account.
Hope anyone can say something interesting about it.
Best Regards ! :)
Franklin Uriel Parás Hernández
You continued the discussion on quantum mechanics, which I tried to ask. See
https://www.researchgate.net/post/There_may_be_quantum_entanglement_in_aqueous_micellar_solutions_of_ionic_surfactants
https://www.researchgate.net/post/There_may_be_quantum_entanglement_in_aqueous_micellar_solutions_of_ionic_surfactants
Questions relate to the quantum behavior of water in aqueous solutions. The problem is of tremendous importance for human health. The era of quantum technology is approaching, and while it is being worked on to create a quantum computer, transmit information and cryptography. It is believed that quantum behavior in a system at room temperature is impossible.
For your specific question. If the distance between two particles is much larger than the thermal de Broglie wavelength, then particles can be considered as classical, distinguishable objects. If less, then non-classical forms of correlation begin to develop and they become entangled.
Thank you for your contribution Yuri Mirgorod . These kind of questions are very relevant indeed.
"the thermal de Broglie wavelenght" ? I have seen that term mentioned once or twice in literature, but I don't know what exactly is,
It may be closely related with the "de Broglie Wavelenght" of particles ?, a particular case of it ?
Entanglement is not mandatory for groups/or regions of particles to show Quantum Mechanical effects, as far as I believe.
I know practically nothing about the chemistry (at the molecular level or otherwise) of nanoemulsions, surfactants and aqueous solutions at these lenght scales or at scenarios where reactivity becomes very important due to quantum size effects, since my field mainly is in the physics of material science (nanostructured materials, thin films, surface chemistry & surface physics, etc...)
Of course, the foundations of both questions are the same, so both scenarios aim to the same physics to be solved.
My question was pointed to the direction of quantum materials and its applications.
To all, for the sake of extending the discussion:
For example, you can deposit single layers of a given material, lets say ZnO, with a chemical technique called Atomic Layer Deposition. This technique allows you (if well controlled) to deposit the desired number of monolayers of a material, all conformed on a given substrate (this is an ideal scenario, I know). Lets allow us to imagine a conformal 2D (x-z) structure with no (or minimal number of) defects, one monolayer above another.
If I deposit a few monolayers of ZnO with this technique, lets say I get to measure its thickness by Ellipsometry or by AR-XPS, and I can calculate how many monolayers I have of this given material.
Next, if I want to measure, lets say, the electrical conductivity in the z-direction (but, it can be any another physical property of the material instead).
How to know if my measurements (could been done with different techniques; as van der Pauw, Two Probes, Four Probes, any classical model) still be valid ?, When the only consideration I'm taking in the measure is the description of transport phenomena just by Ohm's Law.
Or if I have to consider e.g. Quantum Tunnelling of electrons, because if I don't consider this description, the error on the measurements in the electrical conductivity (or resistivity) would turn the results unreliable.
What I mean, in practical terms, is:
Of course is not the same to try to measure a 7 nm thick film than a 5 nm, or a 3 nm thick film.
Of course if I have just 3 nm of material, Ohm's Law won't be the full description for the transport carriers in this scenario, and descriptions like models of Quantum Tunneling or the consideration of the Wave Function in a Quantum Well must be considered. And not to try to predict the electrical conductivity of this 3 nm material using Ohm's law ...
So, What would be the threshold in this scenario ? or What the threshold depends on ?
Best Regards !
Dear Franklin,
Quantum effects are not necessary restricted to very small (microscopic) scales (where device dimensions are comparable to de-Brouglie wavelength lamda = h/p) . In fact, there exist so many macroscopic quantum phenomena such as superconductivity (can happen in superconducting wires of kilometers long) and quantum Hall effect. Please refer to my Book Chapter, here in ReseachGate about the fundamentals of Quantum Physics.
This is very interesting question, and I want to know direct evidences and those reasons either.
I'm wondering if around 30nm is such a length of the boarder between QM and classical physics. When I did several experiments for concavo-convex coating on transparent substraets such as acrylate, polycarbonate, glass, the tribological property of the surface changes at the undulation around 30 nm. Less than 30 nm of the undulation the surface becomes quite sticky, than those of 50nm, 70nm, 100nm...
Franklin Uriel Parás Hernández Toru Yoshida
Yes de Broglie wave of particles.Nanoparticles are between quantum particles and classical ones. Therefore, quantum fluctuations along with thermal fluctuations can be observed in such systems. See
Preprint (1) PROPOSAL TITLE Quantum and thermal liquid -liquid phase ...
Dear Muhammad Hamza El-Saba thank you for bringin such a relevant point to the discussion. What you remark is true, these are called Macroscopic Quantum Phenomena, and as you mentioned there are several shown in non-conventional materials in emergent fields of material science, like High Temperature Semiconductors, Time Crystals, Topological Insulators, ...
Toru Yoshida : Interesting !, It could be in my opinion ! I would say that properties at the surface at very small scales (those scales) can show quantum size-dependent effects too. Properties like the Surface Energy and Chemical Reactivity at the very tiny scales (below 30 or 10 nm) defenetively will show these kind of effects.
Btw, another thing to consider is the nature of the material.
Quantum size effects would start to appear at different scale (different lenghts) for different materials. What I want to say is that this so called threshold depends as well on the type of atom involved.
Te Quantum Surface effects could be observed at a given leght for Al2O3 (for instance), but for another metal (lets say Cu, Au, etc.) this won't be observed before a more reduced lenght. This is because the Exciton's Bohr Radius of the atom involved.
Can anyone comment or correct me on this ?
Best Regards !
Uriel,
Dear Franklin Uriel Parás Hernández
I am afraid that I misunderstand what you say, but are you talking about examples that are difficult to show the quantum surface effects?
When I talk about the exciton Bohr radius, I think that the quantum dot may be one of the good examples.
The exciton Bohr radius is the distance in an electron-hole pair. QM dots having unique sizes and unique compositions can make the preferable electron-hole pairs, and causes the bands of energies to turn into discrete energy levels. When the size of the semiconductor crystalsc are small (what I mean getting close to the size of the exicitation Bohr size ), several QM dot materials have discrete energy levels to show 'observable' quantum size effects.
Commercially available quantum dot materials do not consist of single atoms except for carbon or graphene, for example ZnS, CdS, CdSe/ZnS, InP/ZrS-Graphene, CuInS2/ZnS...
Sorry for mistyping in the 3rd paragraph above:
crystalsc --> crystals
exicitation Bohr size --> exciton Bohr radius
Dear Toru Y. :
Thank you for replying, I appreciate it !
I tried to point out examples about scenarios where these Quantum size effects can be observed, and what could be some of the physical properties (surface- or bulk-nature) might be affected from these effects. So, since you were talking about a scenario related with a material's surface, I thought in mentioning two physical properties of surfaces that I believe can been modified due to these quantum size effects: Surface Tension and Chemical Reactivity.
I think I get you point though... I think. Do you think that material's surfaces are not good examples when talking about Quantum size effects? Well, the true is that I don't know much about Quantum size effects in material's surfaces. But I don't know, I think it was me the one who misunderstood the scenario you described in your first reply, since I'm not acquainted with plastics, tribological properties and/or surface topological properties of these materials.
Anyways.
Related to the Exciton's Bohr raidus:
I wanted to introduce to the discussion the importance of the Exciton's Bohr radius on studying properties which can be affected by Quantum Size Effects on Ultra thin films (1-5 nm).
These materials are particular cases of the so called Quantum Wells. and the Exciton's Bohr radius is relevant here too (mostly when we have semiconductor materials).
The relevance of this parameter it's found when you want to study/measure a property of the film on the z direction (i.e. the reduced-in lenght direction). The thickness of the thin film could be between 3-5 nm. So depending on the Exciton's Bohr radius value of the semiconductor, are the chances this material have of showing Quantum size effects on its properties measured in the z direction.
This means that the parameter: Exciton's Bohr radius is not just relevant to QDs, but to all the other Quantum Materials (i.e. Quantum Wells and Quantum Wires too, or nanoribbons,etc..). The Exciton's Bohr radius is closely related with the de Broglie Wavelengh of electrons... So yes, I was trying to introduce the example of Ultra-thin films, (which are examples of Quantum Wells) in a conversation of "observed Quantum effects due to the reduction in lenght of nanomaterials" (for this particular case, the reduction in just one direction).
Sorry for the missinterpretation
Hope you have a nice one sir !
Regards ! :)
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