Can a photon be quantum entangled on more than one property/factor?

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Discussion Overview

The discussion revolves around the possibility of quantum entanglement involving multiple properties or factors of photons or particles. Participants explore various combinations of properties such as spin, momentum, position, and polarization, and consider the implications of entanglement across these dimensions.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions whether a photon can be entangled on more than one property simultaneously, providing examples such as spin and momentum, position and momentum, spin and position, and polarization and spin.
  • Another participant asserts that position and momentum can indeed be entangled, but does not elaborate further.
  • A different participant agrees that particles can be entangled with respect to multiple observables and notes that being entangled with one observable does not prevent entanglement with another, although there may be exceptions based on specific properties.
  • One participant expresses curiosity about the relationship between position and momentum, suggesting that position is akin to space and momentum to time, and questions whether space and time could be considered conjugates.
  • Another participant clarifies that position and momentum are conjugates, while time and energy are also conjugate pairs, and mentions that in relativistic quantum mechanics, the position 4-vector is conjugate to the energy-momentum 4-vector.
  • There is a question about whether quantum entanglement can occur between particles that travel slower than the speed of light, to which a participant responds that there are no restrictions on the speed of the particles involved in entanglement.
  • One participant mentions having read about the possibility of entangling frequencies between two forks, expressing uncertainty about the authenticity of that information.

Areas of Agreement / Disagreement

Participants express a range of views on the entanglement of multiple properties, with some agreeing on the possibility while others highlight specific conditions or exceptions. The discussion remains unresolved regarding the implications of entanglement across different properties and the nature of conjugate pairs.

Contextual Notes

Participants reference concepts such as canonical conjugates and the relationship between different observables, but the discussion does not resolve the complexities or dependencies involved in these relationships.

San K
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can a particle/photon be quantum entangled on more than one property/factor?
(at the same time-- redundant phrase(?))

for example can two photons be entangled along say -

a) spin AND momentum

b) position and momentum

c) spin and position

d) polarization and spin
 
Last edited:
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position and momentum: yes. That's all I know.
 
San K said:
can a particle/photon be quantum entangled on more than one property/factor?
(at the same time-- redundant phrase(?))

for example can two photons be entangled along say -

a) spin AND momentum

b) position and momentum

c) spin and position

d) polarization and spin

Good question!

Absolutely, and usually they are as a matter of fact. Their observables which are "canonical conjugates" will be entangled, for example, photons created by Type II PDC crystals. Keep in mind that there are all kinds of setups so this is just a statement regarding the general case.

However, spin and position are not conjugates. Spin and polarization are essentially the same thing for photons. Usually spin has several degrees of freedom which are conjugates.
 
Yes, particles can be entangled with respect to any two (or more) observables. Being entangled with respect to one observable does not prevent being entangled with respect to another. However, NOT being entangled with respect to one observable might prevent being entangled with respect to another observable, as in the case of position and momentum.
 
thanks DrChinese, Lugita, Stevie. great information.

lugita15 said:
However, NOT being entangled with respect to one observable might prevent being entangled with respect to another observable, as in the case of position and momentum.

interesting...how conjugates work

this is stretching it a bit far however --- position is more like space, momentum/velocity like time
wonder if space and time are conjugates?

another quick question:

can quantum entanglement happen, or be-created, between particles that travel much slower than the speed of light?

one keeps reading that entanglement has been demonstrated for in various scenarios beyond our basic particles like photon/electron...

for example ...read somewhere that you could make frequency between two forks entangled...not sure how authentic that information is
 
Last edited:
San K said:
this is stretching it a bit far however --- position is more like space, momentum/velocity like time
wonder if space and time are conjugates?
No, position and momentum are conjugates, while time and energy are conjugate. (It should be noted that in nonrelativistic QM we don't usually treat time as an observable, but in relativistic QM the position 4-vector which consists of time and spatial position is conjugate to the energy-momentum 4-vector).
can quantum entanglement happen, or be-created, between particles that travel much slower than the speed of light?
Yes, there's no restriction on how fast or slow they have to be. Quantum entanglement is perfectly well described by non-relativistic QM.
for example ...read somewhere that you could make frequency between two forks entangled...not sure how authentic that information is
That's resonance.
 

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