Where do electrons go while making a quantum jump?

[todd]

I've always wondered this. Hopefully someone one knows. I always read the electrons jump, but they never say through what.

thanx

 

[mathman]

I am not sure what your question means. However when an electron goes from one state to another there is no inbetween.

 

[Phrak]

I thought it was quantum leak. As in leaking from one energy level to another.

 

[todd]

I am not sure what your question means. However when an electron goes from one state to another there is no inbetween.

Electrons don't orbit. They are said to jump from one energy state to another and that jump is shown as a later where electrons are further or closer to the nucleus. If they are closer or farther away then they most have jumped through something.

 

[f95toli]

If they are closer or farther away then they most have jumped through something.

No, because the were not "there" in the first place. Remember that we are not talking about classical objects here, electrons are not like tennis balls and usually they do not have well defined postions, their position is "smeared out" if you will (unless you somehow measure their position very acurately, but then their momentum becomes "smeared out" instead).

 

[todd]

Let's say we don't try to measure them. They then have a logical position. Where would they be and then do they jump? This metaphor seems very strong. People say they jump and that the different energy states map to position.

 

[ZapperZ]

Let's say we don't try to measure them. They then have a logical position. .

OK.. I don't measure the electron in the 1s orbital. Where is its logical position?

Zz.

 

[todd]

>Zz

Sorry to trouble you.

 

[f95toli]

They then have a logical position.

No, that is the point; they don't. Again, electrons are not "balls", you can't think of them as classical objects.
Also, I don't know where you read about "jumps" but it is a very sloppy description best.
We can -at most- talk about electrons making transitions from one state to another (e.g. a transition from the 1s state to 2s state); but that does not imply that an electron "jumped" from one position to another.

 

[Einstein Mcfly]

The electrons don't jump anywhere, the state changes from one state to another. They need a verb to describe this and they chose "jump". Don't read too much into it.

 

[newbee]

I am not sure what your question means. However when an electron goes from one state to another there is no inbetween.

But there is! And the Schrödinger equation governs the dynamics of the transition of "between" states.

 

[Phrak]

But there is! And the Schrödinger equation governs the dynamics of the transition of "between" states.

Oh. Then where are the electrons?

 

[malawi_glenn]

The reason why one calls it "jump" is that you draw an energy "ladder", and then on this ladder electrons goes up and down, in discrete steps = "jump". They never have an energy between those steps . http://cache.eb.com/eb/image?id=62996&rendTypeId=4

They do not jump in ordinary space, but in energy space (an abstract space)

(well the energy uncertainty relation holds, which relates to the lifetime of each energy state, but that is another issue than this one)

 

[ZapperZ]

But there is! And the Schrödinger equation governs the dynamics of the transition of "between" states.

So far we have had 2 unverified statements about the "logical position", and now this. Can you please show where the Schrödinger equation actually show such a thing?

Zz.

 

[Hyperreality]

Hi Todd. Quantum tunneling is indeed interesting conceptually. If we just look at the Schrödinger equation, it is obvious such a process is possible. But to understand it conceptually is another thing.

One way to think about quantum tunnelling is by perhaps looking at the Schrödinger equation in the momentum space so we are dealing with energy and momentum instead of position and time. This way one may be able to think of quantum tunneling in terms of probability of a system with momentum say p to end up in a state of momentum P where P>p.

This is conceptually appealing to me, but it cannot be done in general since one cannot take a Fourier transform of a general wave solution say psi(x)=exp(ikx) to obtain psi(p). However, one can show this is true if we have a simple harmonic oscillator. That is, the probability of quantum tunneling into the classical forbidden region is equal to the probability of measuring the state at E(forbidden) when say the energy of the state is at E0.

 

[ZapperZ]

I don't see how "tunneling" is relevant in this case.

In tunneling, there IS a probability for the particle to be in the forbidden region. In fact, I can manipulate the barrier by adding, say, magnetic impurities, without changing the barrier height/width, and that will affect the tunneling spectra. So this clearly shows that the particle did actually traverse through the barrier. This is NOT the case in atomic transition or any state transition where such a scenario of an "in between dynamics" is present. It doesn't.

Zz.

 

[Peter Morgan]

Alternatively, there are no quantum jumps between states, because the evolution of a quantum state satisfies a linear differential equation.

Uh, then there's von Neumann's projection postulate, that when we measure properties of a quantum system the quantum state of the quantum system changes instantaneously. However, it is not the state of the quantum system that changes more-or-less instantaneously, but the macroscopic state of a thermodynamic system that is carefully tuned to make a thermodynamic transition between a metastable thermodynamic state and a more stable "click happened" state (then there's a feedback circuit to return to the metastable ready state). In other words, we can think of the jumps we observe as macroscopic thermodynamic jumps of the experimental apparatus, not as jumps of a quantum system that we can't understand.

It's very clear that von Neumann's projection postulate is not an essential part of the interpretation or mathematics of quantum theory -- otherwise Everett-type and other no-collapse interpretations would not be possible -- and experimental verification of quantum mechanical models depends absolutely on statistics of ensembles of discrete events, not on individual discrete events, so it's best not to think there is such a thing as a quantum jump at all. If you can't think about QT without thinking in terms of discrete jumps, you need to re-tool. You can think in quantum jump terms if you want to, but be able to think in no-collapse ways as well.

On the other hand, despite the smooth evolution of quantum states there is discrete structure to be found in quantum theory. Thinking in terms of a simple classical wave analogy, the oscillations of a drum skin are continuous; however, the boundary constrains the oscillations so that we can have any amplitude of each of the discrete resonances. There is an effectively discrete constraint on what continuous oscillations are possible. As time goes by, the amplitude of each resonance decays smoothly (the decay rate of each resonance is different, so the sound changes over time, ...). Disanalogy: a better model of the drum skin would take nonlinearities into account.

Discrete structure is considerably harder to come by when we try to think in quantum field theory terms.

 

[DeShark]

Where do electrons go while making a quantum jump?

http://www.falstad.com/qm1drad/

 

[Phrak]

Either there's a tunnel somewhere, with a ladder in it, that electrons go to while leaping and jumping when they aren't being smeared around, or quantum mechanics deals with probability amplitudes.

After addition of energy to the system there is a nonvanishing probability of finding an atom in either energy state; a superposition of states. The popularized terminology of "leaping" is very misleading.

 

[Maaneli]

Either there's a tunnel somewhere, with a ladder in it, that electrons go to while leaping and jumping when they aren't being smeared around, or quantum mechanics deals with probability amplitudes.

After addition of energy to the system there is a nonvanishing probability of finding an atom in either energy state; a superposition of states. The popularized terminology of "leaping" is very misleading.

Phrak,

The answer to your question depends on your formulation of QM. In the de Broglie-Bohm or stochastic mechanics theories for example, the electron is a particle that moves in a definite, continuous trajectory during a "quantum jump"; and you can calculate that trajectory. Other formulations like GRW or MWI gives different answers.

 

[Phrak]

Phrak,

The answer to your question depends on your formulation of QM. In the de Broglie-Bohm or stochastic mechanics theories for example, the electron is a particle that moves in a definite, continuous trajectory during a "quantum jump"; and you can calculate that trajectory. Other formulations like GRW or MWI gives different answers.

What question? Did I have a question?

 

[newbee]

So far we have had 2 unverified statements about the "logical position", and now this. Can you please show where the Schrödinger equation actually show such a thing?

Zz.

My comment was with respect to Mathman's statement that "However when an electron goes from one state to another there is no inbetween.". The Schrödinger equation provides us with the evolution of the system under a Hamiltonian which presumably, in this case, contains an interaction term. The "inbetween" states are the superposition of eigenstates that evolve due to the interaction term which is assumed not to be diagonal in the representation of states that are "jumped between".

Don't confuse the measurement problem and its "indeterminism" with the fully deterministic nature of the Schrödinger equation.

 

[ZapperZ]

My comment was with respect to Mathman's statement that "However when an electron goes from one state to another there is no inbetween.". The Schrödinger equation provides us with the evolution of the system under a Hamiltonian which presumably, in this case, contains an interaction term. The "inbetween" states are the superposition of eigenstates that evolve due to the interaction term which is assumed not to be diagonal in the representation of states that are "jumped between".

Don't confuse the measurement problem and its "indeterminism" with the fully deterministic nature of the Schrödinger equation.

The superposition of states is not "in between". You don't measure any "in between" states. It also has nothing to do with electron traversing from one to the other as if this is a continuous evolution of the dynamics, as asked by the OP. Nothing in the Schrödinger equation describes that the way it describes the time evolution of the wave-function.

Zz.

 

[Bible Thumper]

Remember that we are not talking about classical objects here, electrons are not like tennis balls and usually they do not have well defined postions, their position is "smeared out" if you will

Shoot.
Well what about the Stern-Gerlich experiment?

 

[Maaneli]

What question? Did I have a question?

Woops, haha, I meant Peter Morgan.

 

[newbee]

ZapperZ
"The superposition of states is not "in between"."

At the level of sophistication of the OP I think that one can refer to a superposition of states as "inbetween" states.

"You don't measure any "in between" states."

If by that you mean that you don't measure simultaneous coefficients of a superposition of states then I would agree.

"It also has nothing to do with electron traversing from one to the other as if this is a continuous evolution of the dynamics, as asked by the OP."

The OP asked about "jumps" between states. The OP did not say what the corresponding observable those states are eigenstates is. That is, one need not read position operator into the OP.

"Nothing in the Schrödinger equation describes that the way it describes the time evolution of the wave-function."

Nothing in the Schrondinger equation describes what?

 

[gulsen]

Electron may be somewhere near the nucleus or in Hawaii. I'd also like to add that electron is, as far as we know, a structureless point particle. What is smeared out is the wave-function associated with it. When you go measure it, you'll find that it's a point particle.
The abrupt "quantum jump" you're talking about is a jump in energy state, not position.

 

[ZapperZ]

ZapperZ
"The superposition of states is not "in between"."

At the level of sophistication of the OP I think that one can refer to a superposition of states as "inbetween" states.

Let's see what the OP has written:

I've always wondered this. Hopefully someone one knows. I always read the electrons jump, but they never say through what.

thanx

Electrons don't orbit. They are said to jump from one energy state to another and that jump is shown as a later where electrons are further or closer to the nucleus. If they are closer or farther away then they most have jumped through something.

The fact that he's asking "through what" and the argument of electron's position with respect to the nucleus imply strongly that he's thinking of a position jump.

Furthermore, it is highly inaccurate to say to anyone who doesn't understand QM that a "superposition" of state is an "in between" state. What you mean by saying that isn't what is understood by the receiver. It gives the wrong impression that there is an in-between location, energy, and other observable that bridges the orthorgonal states.

I think this thread has gone off way beyond what is comprehensible to the OP,and I'm afraid that we are starting to delve into things that can easily give the wrong picture.

Zz.

 

[Naty1]

This thread seems to once again oscillate between the conventional continuous "logic" based on the kinds of large scale phenomena we are able to directly observe via our senses and the discontinuous discrete world of quantum "logic" where our intuition leads us astray.

The poster could have also asked with equal validity not where the electrons "go" but where did they come from? The question implies he thinks he knows, but in fact none of us really do know! Is the electron a particle or a wave: yes!

Interesting thread...good posts...

 

[pallidin]

Obsessing the particulars and implications of QM can drive a thoughtful person temporarily insane or to drink.

I've chosen the later, which is also insane.

Even still, out of chaos I believe there can be order.

Think on !