I Can I find a particle in two states simultaneously?

Ahmed1029
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If I want to get the spin angular momentum of a particle using the Stem-Gerlach experiment, I think I will find the spin 1/2 particle either spin up or spin down, but not both. I however want to ask this : Is there a non-zero probability that a particle which is spin-up in the z direction to be in both states of spin-up and spin-down simultaneously in an arbitrary direction that is not the z direction? Also, could measurement ever find the particle in the two states simultaneously?
 
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Ahmed1029 said:
If I want to get the spin angular momentum of a particle using the Stem-Gerlach experiment, I think I will find the spin 1/2 particle either spin up or spin down, but not both. I however want to ask this : Is there a non-zero probability that a particle which is spin-up in the z direction to be in both states of spin-up and spin-down simultaneously in an arbitrary direction that is not the z direction? Also, could measurement ever find the particle in the two states simultaneously?
Are you asking about states or measurement outcomes?

Do you understand the concept of superposition of states?

Ahmed1029 said:
Is there a non-zero probability that a particle which is spin-up in the z direction to be in both states of spin-up and spin-down simultaneously in an arbitrary direction that is not the z direction?
Spin up in the z-direction is a superposition of spin-up and spin down about any other direction.
Ahmed1029 said:
Also, could measurement ever find the particle in the two states simultaneously?
A measurement does not "find a particle in a state". A measuremement returns a measured value.
 
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Ahmed1029 said:
If I want to get the spin angular momentum of a particle using the Stem-Gerlach experiment, I think I will find the spin 1/2 particle either spin up or spin down, but not both. I however want to ask this : Is there a non-zero probability that a particle which is spin-up in the z direction to be in both states of spin-up and spin-down simultaneously in an arbitrary direction that is not the z direction? Also, could measurement ever find the particle in the two states simultaneously?
Just to emphasize what PeroK said, a particle is never in two states simultaneously, that makes no sense. It can be in one state that is a superposition of other states.
 
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Insights auto threads is broken atm, so I'm manually creating these for new Insight articles. Towards the end of the first lecture for the Qiskit Global Summer School 2025, Foundations of Quantum Mechanics, Olivia Lanes (Global Lead, Content and Education IBM) stated... Source: https://www.physicsforums.com/insights/quantum-entanglement-is-a-kinematic-fact-not-a-dynamical-effect/ by @RUTA
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