Help with quantum computing notation

  • Thread starter Joao
  • Start date
Hi everyone! Sorry for the bad English!
I'm trying to read the "entanglement between photons that never coexisted " from 2012. Avaliable at:

And there's this equation:
|φ± \rangle = \frac 1{√2}(|HaHb ± |VaVb\rangle)
|ψ± \rangle = \frac 1{√2}(|HaVb ± |VaHb\rangle)
where ha(vb) represents a horizontally (vertically) polarized photon in spatial mode a (b).

Soooo, I guess what it is saying is:
When photons are entangled, their polarization can be entangled in 4 different ways:
φ+ they have the same "polarization degree" (like vertical and vertical, or horizontal and horizontal) and the same phase (like when one wave is in "Crest" the other will also be in "crest")
φ- they have the same "polarization degree" but opposite phases.
ψ+ they have the opposite "polarization degree" (like horizontal and vertical) and the same phase.
ψ- they have the opposite "polarization degree" and the opposite phase.

And in our BBO cristal we create entangled photons, but we have no clue on what kind of entanglement they have until we measure it.

So far I understood correctly?
Thanks! =)


So far I understood correctly?
Yes, that is correct.

For reference, these four basis states are called Bell states and correspond to a two-particle basis in which each state corresponds to an entangled state.

Want to reply to this thread?

"Help with quantum computing notation" You must log in or register to reply here.

Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving

Hot Threads