Operating on spin angular momenta

[runninglow]

how am i supposed to carry out say, a lowering operation?for example:S_(upward spin & upward spin) or S_(downward spin & upward spin). and raising or lowering a combination of spin,what do they mean anyway?i want the physical feel of the situation.

 

[malawi_glenn]

raising and lowering of spin and angular momenta should be quite intuitive I guess, that it is an operation which increases or decreases the projection of a certain angular momentum about a fixed axis (the standard in almost all quantum mechanics is that one has the Z-axis as reference).

The length of the angular momentum vector is always fixed, and due to quantum mechanics, only certain projections on axes are possible (c.f with a "classical" vector which can have a continuous setup of projections)

A rasing, or lowering, operation just changes that projection, but of course by a disctrete amount.

If you want, provide a specific situation where you have trouble, and we'll try to help you.

 

[Entropia]

I can understand your confusion about operating on spin angular momenta. Spin is a fundamental property of particles that describes their intrinsic angular momentum. It is a quantum mechanical concept and can be a bit difficult to understand intuitively.

In the context of your question, carrying out a lowering operation means reducing the spin angular momentum of the system. This can be achieved by applying an external magnetic field, for example. The notation S_(upward spin & upward spin) or S_(downward spin & upward spin) refers to a system of two particles, where the first particle has an upward spin and the second particle has an upward or downward spin.

When we talk about raising or lowering a combination of spin, it means changing the spin state of the system as a whole. For example, if we have a system of two particles with opposite spin states (one upward and one downward), a lowering operation would result in both particles having a downward spin.

Now, it is important to note that these operations are not physically carried out in the traditional sense. They are mathematical operations that help us understand and describe the behavior of particles at the quantum level. The physical feel of the situation is not something that can be easily comprehended, as it is not within the realm of our everyday experiences.

I hope this explanation has helped clarify some of your questions about operating on spin angular momenta. It is a complex concept, and it takes time and effort to fully grasp its implications. Keep exploring and learning, and you will continue to gain a deeper understanding of this fascinating subject.