Spin and position and mutually unbiased bases

In summary, recent papers by G. Svetlichny, J. Tolar, and G. Chadzitaskos have shown that the position of an elementary particle becomes unknown if it is measured exactly, due to the transition probabilities between bases being equal. This suggests that studying spin in a similar way may be useful, and for spin-1/2, there are three stable solutions. A paper by Carl Brannen explores this idea further and relates it to gravity, showing how the left and right handed particles interact with gravity in a uniform acceleration.
  • #1
CarlB
Science Advisor
Homework Helper
1,239
34
If you measure the position of an elementary particle exactly, then its position becomes unknown. So consecutive measurements of position do not give the same result. There's been some recent papers by G. Svetlichny, J. Tolar, and G. Chadzitaskos that show that position measurements move around because the Feynman path integrals can be written in terms of transitions between "mutually unbiased bases", that is, between bases where the transition probabilities from the states in one base to the states in the other are all equal. See:

Feynman's Integral is About Mutually Unbiased Bases
George Svetlichny
http://arxiv.org/abs/0708.3079 and

Feynman's Path Integral and Mutually Unbiased Bases
J Tolar, G Chadzitaskos
http://arxiv.org/abs/0904.0886

On the other hand, the behavior of spin is very stable. If you measure the spin of a free particle once, it stays like that and you get the same result the next time you measure it. But the above author's characterization of the Feynman path integral suggests that it might be useful to make the same analysis of spin. That is, we can assume that spin does move around from mutually unbiased base to mutually unbiased base.

For spin-1/2 there are three mutually unbiased bases at most. They could be any three orthogonal directions. If we think of spin on these bases we can perform Feynman path integrals to see what the long term evolution of spin is (under the assumption that it moves from mutually unbiased base to mutually unbiased base).

I've resummed these path integrals and showed that for spin-1/2 you get three stable solutions. Each can be thought of as a stable spin-1/2 that arises from an unstable spin-1/2 theory. And this seems to be related to the generations. The paper is here:
http://www.brannenworks.com/Gravity/EmergSpin.pdf

I'm planning on submitting it to Foundations of Physics and arXiv after I get some critiques of it. Thanks for any comments,

Carl Brannen
 
Physics news on Phys.org
  • #2
The paper was eventually accepted by Foundations of Physics and given the following DOI, where it can be read, if your institution has Found. of Phys:
http://dx.doi.org/10.1007/s10701-010-9465-8

From the backlog of "on line first" articles, I would guess that it is actually printed about a year from now, say March-April 2011.
 
  • #3
Congratulations Carl!

So, can we say that, in terms of Spin Foams, classical gravity is SM-like with N different spin configurations/charges -> infinity?
 
  • #4
MTd2 said:
So, can we say that, in terms of Spin Foams, classical gravity is SM-like with N different spin configurations/charges -> infinity?

Hey, that's wayyyy over my pay grade. I did send a paper into the annual gravitation essay contest but it is a little, uh, crackpotty, and it didn't win anything:
http://brannenworks.com/Gravity/Gravity2010Brannen.pdf

It gives some calculations that relate the "Spin Path Integrals and Generations" paper to gravity. The basic idea is to see how the left and right handed particles interact with gravity. In the first approximation this means a uniform acceleration, so the paper computes how the probability that a particle is left or right handed must change in order for the particle to undergo a uniform acceleration (relativistically).

Carl

P.S. Give me a second and I'll upload the (almost) current copy of the "Spin Path Integrals and Generations" paper. Okay, here it is:
http://brannenworks.com/Gravity/EmergSpin.pdf
 

What is spin and why is it important in quantum mechanics?

Spin is an intrinsic property of subatomic particles, such as electrons and protons, that determines their angular momentum. It is important in quantum mechanics because it affects the behavior of these particles and can be used to describe their states.

What is position and how is it related to spin in quantum mechanics?

Position is the location of a particle in space. In quantum mechanics, the position of a particle is described by a probability distribution, as particles can exist in multiple positions simultaneously. Spin and position are related through the Heisenberg uncertainty principle, which states that the more precisely we know a particle's position, the less we know about its spin and vice versa.

What are mutually unbiased bases and why are they important in quantum mechanics?

Mutually unbiased bases (MUBs) are sets of measurements that are unbiased, meaning they do not influence each other. In quantum mechanics, MUBs are important because they allow us to accurately measure the properties of a quantum system simultaneously, without affecting the system.

How are spin and position measured in quantum mechanics?

Spin and position are measured using different operators in quantum mechanics. Spin is measured using the Pauli spin matrices, while position is measured using the position operator. These measurements result in different outcomes, such as spin up or spin down for spin measurements, and a specific position for position measurements.

What are some applications of understanding spin and position in quantum mechanics?

Understanding spin and position in quantum mechanics has many practical applications, such as in quantum computing, cryptography, and quantum information processing. It also helps us understand the behavior of subatomic particles and how they interact with their environment, leading to advancements in fields such as materials science and nanotechnology.

Similar threads

  • Beyond the Standard Models
Replies
0
Views
506
  • Quantum Interpretations and Foundations
Replies
1
Views
522
  • Beyond the Standard Models
Replies
9
Views
9K
Replies
2
Views
1K
  • Beyond the Standard Models
Replies
9
Views
490
  • High Energy, Nuclear, Particle Physics
Replies
2
Views
2K
  • Quantum Interpretations and Foundations
Replies
22
Views
2K
Replies
3
Views
925
  • Beyond the Standard Models
5
Replies
163
Views
23K
  • Beyond the Standard Models
Replies
2
Views
2K
Back
Top