What is Double slit experiment: Definition and 481 Discussions
In modern physics, the double-slit experiment is a demonstration that light and matter can display characteristics of both classically defined waves and particles; moreover, it displays the fundamentally probabilistic nature of quantum mechanical phenomena. This type of experiment was first performed, using light, by Thomas Young in 1801, as a demonstration of the wave behavior of light. At that time it was thought that light consisted of either waves or particles. With the beginning of modern physics, about a hundred years later, it was realized that light could in fact show behavior characteristic of both waves and particles. In 1927, Davisson and Germer demonstrated that electrons show the same behavior, which was later extended to atoms and molecules. Thomas Young's experiment with light was part of classical physics long before the development of quantum mechanics and the concept of wave-particle duality. He believed it demonstrated that the wave theory of light was correct, and his experiment is sometimes referred to as Young's experiment or Young's slits.
The experiment belongs to a general class of "double path" experiments, in which a wave is split into two separate waves that later combine into a single wave. Changes in the path-lengths of both waves result in a phase shift, creating an interference pattern. Another version is the Mach–Zehnder interferometer, which splits the beam with a beam splitter.In the basic version of this experiment, a coherent light source, such as a laser beam, illuminates a plate pierced by two parallel slits, and the light passing through the slits is observed on a screen behind the plate. The wave nature of light causes the light waves passing through the two slits to interfere, producing bright and dark bands on the screen – a result that would not be expected if light consisted of classical particles. However, the light is always found to be absorbed at the screen at discrete points, as individual particles (not waves); the interference pattern appears via the varying density of these particle hits on the screen. Furthermore, versions of the experiment that include detectors at the slits find that each detected photon passes through one slit (as would a classical particle), and not through both slits (as would a wave). However, such experiments demonstrate that particles do not form the interference pattern if one detects which slit they pass through. These results demonstrate the principle of wave–particle duality.Other atomic-scale entities, such as electrons, are found to exhibit the same behavior when fired towards a double slit. Additionally, the detection of individual discrete impacts is observed to be inherently probabilistic, which is inexplicable using classical mechanics.The experiment can be done with entities much larger than electrons and photons, although it becomes more difficult as size increases. The largest entities for which the double-slit experiment has been performed were molecules that each comprised 2000 atoms (whose total mass was 25,000 atomic mass units).The double-slit experiment (and its variations) has become a classic for its clarity in expressing the central puzzles of quantum mechanics. Because it demonstrates the fundamental limitation of the ability of the observer to predict experimental results, Richard Feynman called it "a phenomenon which is impossible […] to explain in any classical way, and which has in it the heart of quantum mechanics. In reality, it contains the only mystery [of quantum mechanics]."
I read in a book the following assertion.
In a double slit experiment photons are passed through the slits and detected at the end plate.
Each of the two slits has a quarter wave plate which alters the polarization of the photons that pass through it in a way different than the other QWP.
Thus a...
Using the principle of least action can you figure out which path the photon took, or which slit it went thru given some initial condition. Or is this not possible and why.
Hi,
I was wondering what would happen with the interference pattern if I had a medium with higher refractive index than air in front of the slits. Would the interference fringes become narrower?
In https://www.sciencedirect.com/science/article/pii/S0378437109010401, the author claims that the interference pattern obtained in the double-slit experiment does not need a wave description of matter, and can be accounted for by the "quantized momentum transfer" from the slits to the electron...
General question to members, when you look at the results and the interference pattern of the double slit experiment for electrons. Does anyone have information on what the empty space is on the screen. The electrons fixed location on the screen shows gaps always. I watched one persons theory...
In most textbook/internet explanation of light coherence, it gives two conditions
1) monochromatic light, same frequency.
2) light in phase or constant phase difference.
Only with the two conditions can light interference pattern be observed in the double slit experiment.
But this cannot be...
Suppose a linear polarized light wave front is incident on a double slit. What happens if one places a quarter-wave polarizer in front of only one slit in the double slit experiment? Does one obtain the usual inteference fringes? Or the diffraction pattern only? Else?
Is anyone did experiment on wave function collapse in double slit experiment. Could you please share information about that, and also share research paper about that experiment.
What kind of observation done here, what kind of equipment used for that?
Hi,
Will there be interference if I point the laser thru one of the openings of the double slit aperture only while the other one is open?
And is the interference more pronounced or the same if I shine it thru both the apertures at the same time.
The spatial orientation of the double slit setup be so that the screen extends in a plane ##x = constant##, while the entire apparatus sits on a ray perpendicular to the screen (of course, the slits sit and extend a bit off this ray).
My questions are about the dynamics in x-direction if only a...
i would like to find the detailed calculation in the case of a two slits experiment with an excited atom.
i only found the formulas when it decays near the slits.
have you links?
thanks
Hi all!
I'm a physics enthusiast and I've been reading/watching a lot of stuff about the double slit experiments. I was watching a youtube video about the delayed quantum eraser experiment and it was really interesting and got me thinking. So here's my question.
What if the detector is placed...
I am still confused about the difference between measurement and interaction. I mean when electrons are traveling from source to the screen through the slits, there are air molecules in their way. And even if the electron double slit experiment is carried out in total vacuum in a completely...
It is said that if one shoots photons in a double slit experiment, and place a detectors around the slits to find which slit the photon went, one will not see the photon interfere. However, to detect a photon, one must absorb it. So how does the photon detectors work by detecting the photons and...
If you created the following double slit experiment would you still see interference?
1) Modify the slits so that the path from photon source through one of the slits to the detector is much shorter than the path through the other slit.
2) put a shutter in front of the photon source so that you...
hi
are the path lengths to the slits strictly equal?
If the difference of the path lengths is progressively increased, how evolve the fringes visibility?
I was wondering if it would be feasible to set up something like the following experiment to validate the pilot wave theory. The idea here is to set up a double slit experiment, but control the initial conditions of photons emitted from a source (i.e., their directions) such that one can...
Homework Statement
If a green laser is (wavelength = 532nm) sent through two slits with a separation of 127 um, how wide (in total) would the 11 green dots formed be if they were projected onto a screen 1.25m away from the slits?
Refer to this diagram sorry for bad quality...
Homework Statement
Suppose a double-slit experiment is immersed in water (with an index of refraction of 1.33). When in the water, what happens to the interference fringes?
Homework Equations
λ = λ0 / n
y = (λmL) / d
d = distance between slits
L = distance to viewing screen
n = index of...
Hi all
I was wondering what happens if one slit in youngs double slit is bigger than the other?
I recon that the of maxima will rise and in minima, there will be no dark spot, but dim light instead. Is that correct? If not can you please explain what happens?
Thanks
What would happen if a youngs double slit experiment is done with different slit sizes? I get the feeling that the intensity might never be zero as the waves might never cancel out completely. Am I right? How should I analyse the Intensity?
Would I have to do something like what is done while...
Homework Statement
a) Explain why a pattern of bright and dark fringes visible on a screen when a light is shone through a double slit.
b) Upon using Thomas Young's double-slit experiment to obtain measurements, the following data were obtained. use this data to determine the wavelength of...
1. The problem statement, all variables and given/known da
Homework Equations
Interference minima is asinΘ=nλ/2 where n=1,3,5,7...
[/B]The Attempt at a Solution
Putting ab/(2sqrt(b^2/4+d^2))=λ/2 for first order minima
And solving for d I get (b/2)*sqrt((2a/λ)^2-1) in which only the 2 factor...
Homework Statement
Hi
The experimental setup involved a helium neon laser of wavelength 670nm +- 1nm, pointed towards a lens with focal length 500mm +- 1mm. (so that the equations used corresponded to the far field diffraction pattern) and onto a photo diode so that for all intents and...
Hi, I have two questions concerning the double slit experiment in the scenario where we fire one photon at a time and it interacts with itself to create an interference pattern over time:
- Does the photon actually interact with itself or with the photons fired before/after it?
- What happens...
I have two questions about the following type of scenario:
We have a laser sending photons through the usual double slit apparatus giving us the usual interference pattern, except that now we introduce some physical matter (that are not photons) that the photons will interact with before going...
Special Relativity dictates that if there is relative motion between two objects; their relative experience of time will change and this is measurable at velocities approaching 'c'.
Within the context of the Double-slit Experiment (with detection): When a given quantum-duality is detected by a...
I'm delightfully reading the Grand Design by Hawking-Mlodinow. After many years, I became persuaded from it that Feynman's interpretation as multiple paths of interference patterns in the double slit experiment and, more generally, his path integral approach to quantum mechanics, are superior to...
Hello there,
I have a question about the double-slit experiment and conscioussnes.
Excuse me if I don't formulate things right and might come over as a total fool for asking this (English is not my native language and i don't study physics).
I just saw this video: <Moderator's note: link...
Homework Statement
From a procedure standpoint, our experiment consisted of a laser pointer on a retort stand with a holder, shining through a piece of sheet with slit measurements (I believe it's acetate) and measuring the height of the maxima on a whiteboard. What could be improved with this...
From a procedure standpoint, our experiment consisted of a laser pointer on a retort stand with a holder, shining through a piece of sheet with slit measurements (I believe it's acetate) and measuring the height of the maxima on a whiteboard. What could be improved with this experiment?
I understand Young's Double Slit Experiment, which basically consists of pointing a laser through two slits and seeing the maxima with different brightness, caused by constructive and destructive interference respectively. Through the experiment, I know that increasing the distance between the...
I have a few basic questions about the double slit experiment and was hoping someone might be able to answer them.
1) How far apart from each other would have I have to make the slits so effectively no detection took place? E.g. is there a limit to how far the wave function can spread and a...
Here is a setup that only uses fixed detectors.
Will the ratio between the number of detections at D0 and the sum of the numbers detected on D1 and D2
be close to 1?
For this question instead of the coincidence counter, 3 simple counters are needed.
Also the detectors D1 and D2 need some lenses...
Hi to all who might respond,
Consider the 'peculiar' double-slit setup below.
There is a double-slit configuration such that the two slits are never open at the same time. That is: whenever the top slit is open for a certain interval, Ts, the bottom slit is closed for the same interval and vice...
In a 'one photon at a time' double slit experiment, does the interference pattern still emerges if the time delay between individual photon emissions is increased to minutes or even hours?
Dear All,
I have a couple questions on the double slit experiment I hope you can help shed some light (or photons) on. =)
Arrival Timing of Photons
In a normal double-slit experiment like the above setup, do photons always arrive at the detector at a constant speed (basically, speed of light)...
Dear All,
I have a question on the double slit experiment. From the references I've read so far, they are focusing on the results of the detector AFTER the 2 slits.
Let's say when photons are fired, how many % actually pass through the slits and get detected at the end? Would some (and how...
Hi, my answer is about the double slit experiment: the interference is observable with the water waves, them are particle in movment, but when we observe it with the electrons, what is the medium for those waves? Are the particles made of matter between the gun and the slits? Or is it something...
In Delayed choice quantum eraser experiment (https://en.wikipedia.org/wiki/Delayed_choice_quantum_eraser) entangled photons are sent on different paths. They reach their detectors at different times. The one arriving early is called a signal photon. The photon that arrives at its destination at...
All these videos and articles about the Double Slit Experiment say that if we "look" where the single photons go, they act like particles and if we don't "look" they act like waves, creating the interference pattern...
BUT
What does it mean to "look"? We're not using our eyes or any camera...
Homework Statement
I am having troubles trying to figure out systematic and random errors when conducting Young's double slit experiment.
Homework Equations
NA
The Attempt at a Solution
I have found one error which could be correct, it is the fact that the laser was not at right angles with...
Homework Statement
A double-slit experiment uses a helium-neon laser with a wavelength of 633 nm and a slit separation of 12mm. When a thin sheet of glass is placed in front of one of the slits, the interference pattern shifts by 5 fringes. When the experiment is repeated under water, the shift...