I Can identical particles be distinguishable?

Twigg
Science Advisor
Gold Member
Messages
893
Reaction score
483
Is it possible to have identical quantum particles that are distinguishable? By identical, I only mean that all particle properties like mass, spin, charge, etc., are identical. My guess would be no because the only thing that could tell the two apart is their trajectories, but their wavefunctions may overlap, which in my mind ought to make them indistinguishable. Is that anywhere in the ballpark of the right way to think about it?
On the other hand, is it theoretically possible to make gaseous atoms, as would normally obey the Maxwell-Boltzmann distribution, instead behave like a Fermi-Dirac or Bose-Einstein gas under the right conditions and on the right energy scales? Is there a well-known example of this? Would the superfluid phase transition of liquid helium be a valid instance?
 
Physics news on Phys.org
Twigg said:
Is it possible to have identical quantum particles that are distinguishable?
No, by definition of "identical" and quantum mechanics.
Twigg said:
but their wavefunctions may overlap
You cannot consider single-particle wave functions any more, you have to take a single wave function to describe both, and there is no "first particle here, second here" any more.
Twigg said:
On the other hand, is it theoretically possible to make gaseous atoms, as would normally obey the Maxwell-Boltzmann distribution, instead behave like a Fermi-Dirac or Bose-Einstein gas under the right conditions and on the right energy scales?
It is impossible to avoid this. FD and BE are the more fundamental distributions, for large temperatures they both can get approximated by Maxwell-Boltzmann.
 
  • Like
Likes Twigg
Makes sense. Thanks!
 
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
If we release an electron around a positively charged sphere, the initial state of electron is a linear combination of Hydrogen-like states. According to quantum mechanics, evolution of time would not change this initial state because the potential is time independent. However, classically we expect the electron to collide with the sphere. So, it seems that the quantum and classics predict different behaviours!
Back
Top