Search results
- An overview of quantum mechanics. L1.1. Quantum mechanics as a framework. Defining linearity (17:46) L1.2. Linearity and nonlinear theories. Schrödinger’s equation (10:01)
- Overview of quantum mechanics (cont.). Interaction-free measurements. L2.1. More on superposition. General state of a photon and spin states (17:10)
- Photoelectric effect, Compton scattering, and de Broglie wavelength. L3.1. The photoelectric effect (22:54) L3.2. Units of h and Compton wavelength of particles (12:39)
- de Broglie matter waves. Group velocity and stationary phase. Wave for a free particle. L4.1. de Broglie wavelength in different frames (14:53)
People also ask
What is quantum physics?
What is the first course in quantum physics?
What is a good book on quantum physics for beginners?
What do you learn in quantum mechanics?
Mar 14, 2021 · Have you always been curious about quantum physics and its mysteries but don’t know where to begin? You have found the right place, your journey to learn quantum physics starts now! Award-winner scientist, Carl J. Pratt, presents the most exhaustive and clear introduction to the topic.
- (1.6K)
- $14.95
- Carl J. Pratt
- Carl J. Pratt
- Classical Bullets vs. Electrons in A Two-Slit Experiment
- Advanced Remarks
- Summary of This Quantum Physics Introduction
- GeneratedCaptionsTabForHeroSec
a) Classical bullets
Consider first a machine gun that fires bullets to a wall. Between the wall and the machine gun, another wall has two parallel slits that are big enough to easily allow a bullet to pass through them. To make the experiment interesting, we take a “bad” machine gun that has a lot of spread. This means it sometimes shoots through the first slit and sometimes through the second, and sometimes it hits the intermediate wall. If we block the second slit, all bullets that reach the outer wall will ha...
b) Electrons – Quantum Mechanics
Now consider the same experiment on a much smaller scale. Instead of bullets from a machine gun we consider electrons that for example can stem from a heated wire parallel to the two slits in an intermediate wall. The electron direction will have a natural spread. The slits are also much smaller than before but much broader than a single electron.
c) Photons
What if you do not believe this? Well, the thought experiment with the electrons is rather difficult to perform with the proper scale of all elements of the experiment. But there is another very similar experiment that you can do at home. Instead of the electrons you use the photons (light particles) from a laser which you can buy for a few bucks. You let the laser shine through a double slit, darken the room, and look at the outer wall. And boom! What you see is not just two light lines on t...
Don’t watch!
The pattern with maxima and minima is called an interference pattern, since it comes about by the interference of the waves through slit 1 and slit 2. It has been found that you only get this interference pattern if you do not by other means (some additional measurement instrument) watch through which of the two slits the electrons or photons pass. If you do measure which of the two ways the particles pass by any other means, the interference pattern goes away. You will then find the sum dist...
Uncertainty principle
A measurement device for electrons would typically disturb the electrons. More precisely, their momentum p would typically change due to a measurement device, while the place x of its path would become known more precisely. In general, there will be some uncertainty left in the momentum and in the place of the electron. Heisenberg postulated that the product of these uncertainties can never be lower than a specific constant h: Delta x times Delta p >= h. No one ever managed to disproof this r...
Single Slit Experiments
We said that for proper distributions, you will find a similar result P1 and P2 as in the classical case. However, for other sizes one can achieve an interference pattern even for the single slits. This is the case when the slit is so broad that one can achieve an interference of the wave stemming from one side of the slit with the wave stemming from the other side of the slit.
In this quantum physics introduction, we told you that both photons and electrons behave as both particles and waves. This particle-wave duality is not understandable with classical mechanics. It results in us only being able to predict probabilities, while one classically can make deterministic predictions. You can easily test these results at hom...
Learn quantum physics in simple terms with a thought experiment involving bullets, electrons and photons. Discover how quantum mechanics differs from classical mechanics and why particles can behave like waves.
Learn the basics of quantum physics, the study of matter and energy at the most fundamental level. Explore the origins, concepts, mathematics, and phenomena of quantum science, and how it affects our understanding of the world.
Jan 10, 2021 · Learn the basics of quantum mechanics, the study of how small particles move and interact, through seven articles with no math and no philosophy. Explore the surprising effects of quantum mechanics and how they influence our everyday technology.
Learn the basics of quantum mechanics from Prof. Barton Zwiebach at MIT. This course covers the experimental basis of quantum physics, wave mechanics, Schrödinger's equation, and more.
Learn the fundamentals of quantum physics with 10 modules covering topics at the frontiers of research. Enroll for free and get access to videos, quizzes, homework, and a career certificate.
