How Many Photons in a Light Wave

peter.ell
Messages
42
Reaction score
0
I was just wondering how the concept of a single photon is compared to the concept of a light wave.

Is a single photon equivalent to a single light wave, or is a single photon just a tiny instantaneous part of a light wave? That is, if a single light wave of a given wavelength strikes a surface, would that surface respond as if only one photon hit it, or a stream of photons all hitting it with the same frequency as the light wave?

Or am I completely mis-understanding this and it's neither of these two? Please help me understand this conceptually.

Thank you so much!
 
Physics news on Phys.org
A single photon is what you would call a light wave, and vice versa.
 
Excuse me if I make a bunch of over-simplified statements.

Does a single photon have a beginning and an end? Whenever I think of light pulses I think of the localization in space (or time) as being due to the superposition of many modes closely spaced in frequency. If the light were truly monochromatic it would have to extend infinitely in time. I can send the pulse through an absorptive medium such that most of the light gets absorbed every time. If I repeat this enough times, for one of these pulses everything is absorbed except for a single photon (hv of energy). Then is it theoretically possible to send a pulse into a material and get a continuous wave out the other side?
 
Not an expert in QM. AFAIK, Schrödinger's equation is quite different from the classical wave equation. The former is an equation for the dynamics of the state of a (quantum?) system, the latter is an equation for the dynamics of a (classical) degree of freedom. As a matter of fact, Schrödinger's equation is first order in time derivatives, while the classical wave equation is second order. But, AFAIK, Schrödinger's equation is a wave equation; only its interpretation makes it non-classical...
Insights auto threads is broken atm, so I'm manually creating these for new Insight articles. Towards the end of the first lecture for the Qiskit Global Summer School 2025, Foundations of Quantum Mechanics, Olivia Lanes (Global Lead, Content and Education IBM) stated... Source: https://www.physicsforums.com/insights/quantum-entanglement-is-a-kinematic-fact-not-a-dynamical-effect/ by @RUTA
Is it possible, and fruitful, to use certain conceptual and technical tools from effective field theory (coarse-graining/integrating-out, power-counting, matching, RG) to think about the relationship between the fundamental (quantum) and the emergent (classical), both to account for the quasi-autonomy of the classical level and to quantify residual quantum corrections? By “emergent,” I mean the following: after integrating out fast/irrelevant quantum degrees of freedom (high-energy modes...
Back
Top