- #1
Haorong Wu
- 413
- 89
- TL;DR Summary
- photons; Fock states; Coherent states;
Hi. I am reading quantum optics by Marlan Scully currently. Although the book has devoted a whole section to explain the photon concept, I am still confused about some nature of photons.
First, how do photons distribute in space? For example, there are ##n## photons for a Fock state ##\left | n \right >##, or ##\left | \alpha \right | ^2## photons for a coherent state ##\left | \alpha \right >##. Let a light beam be emited from point A and be detected in point B. Then how do these photons distribute between point A and point B?
Personally, I visualize that in a small interval in space, there are ##n## or ##\left | \alpha \right | ^2## photons for a Fock state or a coherent state, respectively. Each of these photons behaves like a wave packet which occupies the whole space of the interval. And these photons superpose together in the interval.
Is this image correct? If so, then what is the length of the interval? If not, what is the correct picture?
Second, how to create a Fock state or a coherent state. The fock states are easy to make by letting ##n## excited atoms to decay simoutaneously. But how to create a coherent state ##\left | \alpha \right > \propto \sum_0^ \inf \left | n \right >##? I can not figure it out, since it is a superposition of many different numbers of photons.
Thanks!
First, how do photons distribute in space? For example, there are ##n## photons for a Fock state ##\left | n \right >##, or ##\left | \alpha \right | ^2## photons for a coherent state ##\left | \alpha \right >##. Let a light beam be emited from point A and be detected in point B. Then how do these photons distribute between point A and point B?
Personally, I visualize that in a small interval in space, there are ##n## or ##\left | \alpha \right | ^2## photons for a Fock state or a coherent state, respectively. Each of these photons behaves like a wave packet which occupies the whole space of the interval. And these photons superpose together in the interval.
Is this image correct? If so, then what is the length of the interval? If not, what is the correct picture?
Second, how to create a Fock state or a coherent state. The fock states are easy to make by letting ##n## excited atoms to decay simoutaneously. But how to create a coherent state ##\left | \alpha \right > \propto \sum_0^ \inf \left | n \right >##? I can not figure it out, since it is a superposition of many different numbers of photons.
Thanks!