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Re: Is photon a wave packet ?



Note that the creation operator for a single photon contains no spacetime
coordinate. This fact should answer your question.

Note also that a single photon cannot create an interference pattern.
Only a coherent assembly of photons can do that. It's like the legal
principle that a person, acting alone, can never be guilty of a
conspiracy.
Regards,
Jack



On Wed, 15 May 2002, Qiang Lu wrote:

Hello friends,

I have two questions.
One, if a single photon has the property of wave?
The single photon means an excited atom emits a single photon.
Two, if a single photon is a wave packet? i.e. if a single photon has
a width of frequency, but not monochromatic?
In quantum field theory

2
/ _
| \
A_{\mu}(x)= | d^3 k / (a_{k,i} A_{\mu}(k,i;x) + a*_{k,i} A*_{\mu}(k,i;x)
| -
/ i=1

Here creation operator a_{k,i} creats an single photon with
polarization i and frequency k. Thus for a single photon, it must be
absolutely monochromatic. While for wave packet, it is a fourier
expansion of variable frequency, may be k+-dk. For a wave packet the
frequency has a width dk, but not a define and single freqency.
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_______________________________________________________

k-dk k k+dk
From this point of wiew, one may say that a single photon is not a
packet. That is why I asked if a single photon is a wave packet?



--
Best regards,
Qiang


--
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