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touqra
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I know what polarization is in classical EM. But what is polarization in the language of photons and QM? I am thinking that it's something to do with spin.
touqra said:I know what polarization is in classical EM. But what is polarization in the language of photons and QM? I am thinking that it's something to do with spin.
Meir Achuz said:Photon polarization is usually described in terms of helicity, which can be
+1 or -1 for a photon. The helicity +1 state correspond to Left circular polarization and the -1 to Right circular polarization. A plane polarized photon is the same linear combination of circular polarizations as in Classical EM. The reason H=+1 corrsponds to LH circular polarization is that particle physicsts use a z=axis in the direction the photon is moving, while the classical circular polarization is how the E vector rotates as you look toward the oncoming photon.
zhangpujumbo said:I still want to know how helicity is related to polarization.
Can you recommend some readings?
Thank you!
Polarization refers to the orientation of the electric field of a photon. In quantum mechanics, polarization is described by the wave function of a photon and can be either linear, circular, or elliptical. This property of photons can be manipulated and measured in various experiments, making it an important aspect of quantum mechanics and photonics.
Polarization plays a crucial role in quantum entanglement, which is a phenomenon where two or more particles become intrinsically connected and share a state. When two entangled photons are measured for their polarization, the results are always correlated, regardless of the distance between them. This is one of the ways in which polarization demonstrates the non-locality of quantum mechanics.
Yes, polarization can be changed or controlled through various methods such as using polarizing filters, birefringent materials, or quantum gates. These techniques can alter the orientation of the photon's electric field, allowing for manipulation of its polarization state.
Polarization can be measured using various techniques, including polarimeters, interferometers, and quantum state tomography. These methods involve analyzing the intensity and orientation of light that passes through a polarizing filter or interacts with other materials. The results of these measurements can provide valuable information about the polarization state of the photons being studied.
Polarization has many practical applications in technology, including in optical communications, where it is used for efficient transmission of data through fiber optics. It is also crucial in various imaging techniques, such as polarized microscopy and magnetic resonance imaging. Additionally, polarization is used in the design of optical components, such as lenses and filters, for controlling and manipulating light in devices such as cameras, lasers, and displays.