# Relation between attosecond light pulses and photons?

As we know, the recent Nobel prize was awarded for the creation of attosecond light pulses. I read this excellent answer, describing both how the pulses are created and what applications they have.

I understand how the pulses are created by the addition of waves with harmonic frequencies in a classical sense.

However, from a quantum mechanical point of the view, light comes as photons with quantised energy, with the energy of each photon related to its frequency. As the attosecond pulses consist of many frequencies, I wonder how they relate to photons.

My guess would be that the attosecond wave describes the probability of detecting a photon at a particular location/time, but that the photon detected can have the energy corresponding to any of the constituent frequencies.

Is that a correct guess, or is that too simplistic? When we detect individual photons of the attosecond pulse, what frequencies can they have?

• Light, including pulses of light, consists of many photons. A very short pulse has a wide range of frequencies. See The more general uncertainty principle, regarding Fourier transformsA single photon can also have a long or short duration, and a narrow or wide range of frequencies. Commented Oct 20, 2023 at 14:48
• @mmesser314 I have never heard of single photons with a wide rage of frequencies. Each photon is always supposed to have a single quantified energy/frequency, otherwise the quantum effects would not occur. Can you refer to studies that show single photons with a range of frequencies? Commented Oct 21, 2023 at 10:15
• Here are a couple posts. Uncertainty Principle and the Momentum of Light talks about the uncertainty of momentum. Note that $p = h/\lambda$, Does the uncertainty principle apply to photons? talks about whether the uncertainty principle can be applied to photons. These posts talk about how localizing the photon matters. Note that a momentum eigenstate for a photon is a plane wave of infinite duration. Note that an attosecond pulse has a short duration. Commented Oct 21, 2023 at 22:34
• @mmesser314 I think I understand the Heisenberg uncertainty principle, it is used to create the attosecond pulses with precise location, but large uncertainty in the energies. But I don't understand what consequences it has for detecting the photons of attosecond pulses. When detecting a photon of an attosecond pulse, which energies can it have and why? Commented Oct 22, 2023 at 12:02