Particle-hole Symmetry: Definition & Resources

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In summary, Particle-hole symmetry is a concept in Dirac's theory of antimatter where electrons with negative energy can absorb energy and be in an excited state with positive energy, creating a hole in the negative energy sea. Similarly, an electron with positive energy can "fall" into a hole, releasing radiation. This symmetry is related to the matter-antimatter phenomenon and is known as CPT symmetry. It is considered in "effective theories" where the type of particle is not relevant.
  • #1
znbhckcs
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Hi
I've heard this term a few times and I couldn't find a definition in textbooks..
What is the definition of Particle-hole symmetry?
I gather it's something like taking c -> c+ , but is there a definition of an symmetry operator that commutes with the hamiltonian or something?
What does it mean, anyway?

Where can I read about this symmetry?

Thanks
 
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  • #2
You are probably referring to the Dirac theory of antimatter (which is a relativistic quantum theory for fermions). According to this theory, an electron with negative energy can absorb electromagnetic energy (photons) and be in an excited state with positive energy, in this case you will see an electron charge -e and energy E, together with a hole in the negative energy sea, that seen in the sea as the absence of a charge -e and energy -E, is interpreted as a charge +e with energy E, it is expected that the creation of electron-positron pairs. Similarly, in the presence of a hole an electron of positive energy can "fall" into it, releasing radiation, and this is the phenomenon of annihilation.

Then the symmetry to which you referring therefore, is on the matter - antimatter, the CPT symmetry.
 
  • #3
When you consider a "effective theory" you don't care what on hell the particle is, a hole or a real particle.
 

FAQ: Particle-hole Symmetry: Definition & Resources

What is particle-hole symmetry?

Particle-hole symmetry is a fundamental concept in physics that describes a symmetry between the properties of particles and holes in a system. A hole is an absence of a particle in a particular energy state, and particle-hole symmetry states that the properties of a system should be the same if all the particles are replaced by holes and vice versa.

How is particle-hole symmetry related to electronic band structure?

In electronic band structure, particle-hole symmetry refers to the symmetry between the conduction and valence bands. In a perfect crystal lattice, the energy bands of electrons and holes are symmetric around the Fermi level, which is the energy level at which a material is at its lowest energy state.

What are some examples of systems that exhibit particle-hole symmetry?

Particle-hole symmetry can be observed in a variety of systems, including superconductors, topological insulators, and quantum Hall systems. It is also an important concept in nuclear physics, where it describes the symmetry between protons and neutrons in a nucleus.

How is particle-hole symmetry broken?

Particle-hole symmetry can be broken in a system by the presence of external factors such as magnetic fields or impurities. These can cause an imbalance between the number of particles and holes, breaking the symmetry between them.

Are there any practical applications of particle-hole symmetry?

Particle-hole symmetry has important implications in the field of condensed matter physics, where it can help scientists understand the electronic properties of materials and develop new technologies such as quantum computers. It is also a key concept in particle physics, where it is used to study the behavior of fundamental particles.

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