Question about SPDC (Making entangled photons)

In summary, the process of spontaneous parametric down conversion (SPDC) involves using a BBO crystal to create two entangled photons in the visible regime by shining a laser through it. The choice of wavelength for the photons depends on the specific wavelength of the laser and the crystal being used, but BBO crystals can function over a broad range of wavelengths.
  • #1
Xyius
508
4
Hello everyone,

I have a question about the process of spontaneous parametric down conversion (or SPDC). This process is used to create two entangled photons in the visible regime by shining a laser through a beta-barium borate (BBO) nonlinear crystal.

My question is, can this process be done at ANY wavelength in the visible regime? Or is the wavelength specific to the crystal?

So for example, say I wanted two photons at 800 nm. Does this mean I should choose a 400 nm laser to shine through the crystal so it splits into two 800 nm photons? Do I have the choice of wavelength (within the boundaries of the visible regime)?
 
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  • #2
Your setup will be for a specific laser line; the BBO crystal needs to be cut for your wavelength, and ditto for wave plates.

But the BBO crystals can function over a broad range.
 

Related to Question about SPDC (Making entangled photons)

1. What is SPDC and how does it work?

SPDC stands for spontaneous parametric down-conversion, which is a process that occurs in certain crystals where a single incoming photon can split into two new photons with lower energy. This process is based on the principle of conservation of energy and momentum, and it produces two entangled photons that are connected in a quantum state.

2. How are entangled photons created through SPDC?

In SPDC, a high-energy photon is sent through a nonlinear crystal, such as beta barium borate (BBO). The crystal causes the photon to split into two lower energy photons, known as signal and idler photons, which are correlated and entangled. This process creates a pair of entangled photons that have opposite polarization states.

3. What is the significance of entangled photons in quantum mechanics?

Entangled photons have been a crucial element in quantum mechanics experiments and quantum technologies. They allow for the observation of quantum phenomena, such as quantum superposition and quantum teleportation. Additionally, entangled photons have potential applications in quantum communication, quantum computing, and quantum cryptography.

4. Can entangled photons be used for faster-than-light communication?

No, entangled photons cannot be used for faster-than-light communication. While entanglement allows for instantaneous correlation between the two particles, it does not allow for the transfer of information or communication. This is due to the no-communication theorem, which states that it is not possible to use entanglement to transmit information faster than the speed of light.

5. How is SPDC and entangled photons being used in current research and technology?

SPDC and entangled photons are being used in various research fields, such as quantum computing, quantum communication, and quantum cryptography. They are also being explored for potential applications in secure communication networks, quantum sensors, and quantum encryption. Additionally, researchers are studying ways to improve the efficiency and reliability of SPDC for future technological advancements.

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