Question about superposition....

In summary: In other words, a photon can be in a state where it has been detected by one of the detectors, but not the other. This kind of superposition is called a quantum state.The experiment with two slits proves that two light waves can interference constructively and deconstructively just like any wave. The interesting part of the experiment comes when you only shoot single photons at a time. Either photon can only go through one slit, so we shouldn't see a constructive or deconstructive pattern. How can a photon interfere with itself? Well, surprise surprise, it can interfere with itself....because it is in a superposition of the two possible outcomes.
  • #1
Sundown444
179
7
Can anyone please describe to me how superposition in quantum mechanics works, preferably using real life places and objects as examples? I am having trouble understanding the concept.
 
Science news on Phys.org
  • #2
Sorry but no. Quantum mechanics is not like anything in everyday life. You can learn how QM works by study, but :

It is safe to say that nobody understands quantum mechanics. Richard Feynman.
 
  • #3
So it only applies to subatomic particles then, not objects?
 
  • #4
Sundown444 said:
Can anyone please describe to me how superposition in quantum mechanics works,
Do you know how superposition works, mathematically, with classical fields, e.g. the electric field?
 
  • #5
Sundown444 said:
Can anyone please describe to me how superposition in quantum mechanics works, preferably using real life places and objects as examples? I am having trouble understanding the concept.

What's your education, so far? What mathematics have you studied?
 
  • #6
jtbell said:
Do you know how superposition works, mathematically, with classical fields, e.g. the electric field?

Not by much. Please tell me if you can.

Stephen Tashi said:
What's your education, so far? What mathematics have you studied?

I have Algebra and some Calculus, and I know a good amount of physics, though I haven't gone much into Quantum Mechanics yet. What I recall is that superposition is the idea that a system is in all possible states at the same time until it is observed.
 
  • #7
Sundown444 said:
Not by much. Please tell me if you can.
I have Algebra and some Calculus, and I know a good amount of physics, though I haven't gone much into Quantum Mechanics yet. What I recall is that superposition is the idea that a system is in all possible states at the same time until it is observed.

If you know what a vector is, then you will be familiar with resolving a vector into the components in different directions.

For example, gravity near the surface of the Earth is a vertical vector. But, you can decompose that vector into, say, components tangential and normal to an inclined plane. And, in fact, you are free to decompose the vector into components in any pair of directions.

A quantum state is in fact an infinite dimensional vector. And superposition is the term used to describe its decomposition in a given basis of states.

Many people labour under the delusion that some states are in superposition and some are not. But, that is as absurd as saying some vectors can be decomposed and some cannot.

In short, given any state and any set of basis states, the state is in a superposition of those basis states. If you think, therefore, that superposition just means linear combination, then you'd be correct. Of course, if the basis you choose has the state in question as one of the basis states, then the superposition is trivial.

The role that linear algebra plays in QM goes much deeper than that. But, that's what a superposition is.
 
  • #8
PeroK said:
If you know what a vector is, then you will be familiar with resolving a vector into the components in different directions.

For example, gravity near the surface of the Earth is a vertical vector. But, you can decompose that vector into, say, components tangential and normal to an inclined plane. And, in fact, you are free to decompose the vector into components in any pair of directions.

A quantum state is in fact an infinite dimensional vector. And superposition is the term used to describe its decomposition in a given basis of states.

Many people labour under the delusion that some states are in superposition and some are not. But, that is as absurd as saying some vectors can be decomposed and some cannot.

In short, given any state and any set of basis states, the state is in a superposition of those basis states. If you think, therefore, that superposition just means linear combination, then you'd be correct. Of course, if the basis you choose has the state in question as one of the basis states, then the superposition is trivial.

The role that linear algebra plays in QM goes much deeper than that. But, that's what a superposition is.

I see. Does it have anything to do with that many worlds theory thing?
 
  • #9
Sundown444 said:
I see. Does it have anything to do with that many worlds theory thing?
I don't know much about the Many World's interpretation of QM. But, superposition is part of the core mathematical framework, so it's not specifically related to anyone interpretation.
 
  • #10
I think a good place to start is by looking at the double slit experiment. I hope you are familiar with this experiment.

The experiment with two slits proves that two light waves can interference constructively and deconstructively just like any wave. The interesting part of the experiment comes when you only shoot single photons at a time. Either photon can only go through one slit, so we shouldn't see a constructive or deconstructive pattern. How can a photon interfere with itself? Well, surprise surprise, it can interfere with itself. The photon is in a superposition of several states and these states can interact with each other.

If you are not aware of the experiment and what I am talking about, it would do you good to study the mathematical properties of waves and review a high school physics textbok.
 
Last edited:
  • #11
Sundown444 said:
Does it have anything to do with that many worlds theory thing?
The Many Worlds Interpretation in a nut shell gives each possible outcome its own "universe" to exist in, where the observed outcome relates to the universe we continue to exist in. Pilot wave theory simply gives a deterministic approach to the same probabilistic reality which is quantum superposition.
 
  • #12
Sundown444 said:
Can anyone please describe to me how superposition in quantum mechanics works
Schrödinger's cat is an example from way back, when QM was fairly new. Macroscopic objects don't behave this way but the thought experiment gives some clue as to why superposition is hard to conceptualize.
 

Question 1: What is superposition?

Superposition is a principle in quantum mechanics that states that a physical system can exist in multiple states or positions simultaneously. This means that an object can exist in two or more places or have two or more properties at the same time.

Question 2: How does superposition work?

In quantum mechanics, superposition occurs when a particle or system is in a state of uncertainty and can exist in multiple states or positions simultaneously. It is described by a mathematical equation called a wave function, which represents the probability of finding the particle in different states. The wave function collapses when the particle is observed, determining its actual state or position.

Question 3: What are some examples of superposition?

One example of superposition is the famous Schrödinger's cat thought experiment, where a cat in a closed box is in a superposition of being both alive and dead until the box is opened and the cat is observed. Another example is the double-slit experiment, where a particle can pass through two slits simultaneously, exhibiting wave-like behavior.

Question 4: Why is superposition important?

Superposition is important because it is a fundamental principle of quantum mechanics, which is a highly successful and accurate theory that describes the behavior of particles at the subatomic level. It also has practical applications in technologies such as quantum computing and cryptography.

Question 5: Is superposition a proven phenomenon?

Yes, superposition has been extensively tested and confirmed through various experiments and observations in quantum mechanics. It is a well-established phenomenon that is fundamental to our understanding of the behavior of particles at the subatomic level.

Similar threads

Replies
23
Views
9K
  • Quantum Physics
Replies
2
Views
839
Replies
1
Views
558
Replies
1
Views
749
  • Quantum Physics
Replies
27
Views
681
  • Quantum Physics
4
Replies
124
Views
3K
  • Quantum Physics
5
Replies
143
Views
5K
Replies
2
Views
1K
  • Quantum Physics
Replies
26
Views
2K
Back
Top