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From: jackson@ttidcb.UUCP (Dick Jackson)
Newsgroups: net.physics
Subject: Reality of Electric Field versus the Photon Heterodyne
Message-ID: <405@ttidcb.UUCP>
Date: Tue, 9-Jul-85 12:14:52 EDT
Article-I.D.: ttidcb.405
Posted: Tue Jul  9 12:14:52 1985
Date-Received: Fri, 12-Jul-85 04:18:49 EDT
Organization: TTI, Santa Monica, CA.
Lines: 21



Somebody beat me to it but I was going to protest that the electric field
seems awfully real when I hook up a sensitive, dynamic voltmeter (read
radio receiver) to a piece of wire.

After all, radio is the same as light, but slowed down. Consider the
superhet receiver. Using a local oscillator to beat the incoming carrier
down to a lower frequency for filtering and amplification, it is well
known to have a signal to noise ratio several times that of a power
detecting diode. Nobody thinks photons with radio (or even television).

Somewhere between microwaves and the visible spectrum it becomes useful to
think photon (for some kinds of problem). I believe (someone can contradict)
that quantum/photon noise is stronger than thermal noise for diode detection
of light (in fiber optic systems for example).

The optical version of the superhet is under development. I for one find it
dificult to imagine it working at low levels, when photons are coming in
(in phase!) in dribs and drabs.  Can anyone throw any light (hah!) onto
this curiosity?  How about a gamma ray superhet?  Neutron beams?