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Newly observed optical state could enable quantum computing with photons
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Re: Newly observed optical state could enable quantum computing with photons
#22[deleted]
Re: Newly observed optical state could enable quantum computing with photons
#23Is anyone else annoyed by the fact that while MIT news is good at creating interest in their stories, they are annoyingly watered down and never link back to the source paper they are paraphrasing? In this instance, they never mention the paper title even once.
And they tend to over-generalize - "While photons normally have no mass and travel at 300,000 kilometers per second (the speed of light)". The maximum speed of a photon is (currently?) around 300,000 kps but they often travel slower than this. Our fiber optics systems are coursing with photons that travel approximately 200,000 kps. The key results of this experiment is that the photons are interacting with each other…
Acquiring mass is interesting. It means that in the course of this process they must be interacting with the Higgs field.
Re: Newly observed optical state could enable quantum computing with photons
#24Earlier quoted context omitted.
And they tend to over-generalize - "While photons normally have no mass and travel at 300,000 kilometers per second (the speed of light)". The maximum speed of a photon is (currently?) around 300,000 kps but they often travel slower than this. Our fiber optics systems are coursing with photons that travel approximately 200,000 kps. The key results of this experiment is that the photons are interacting with each other…
Photons travelling through fiber are still traveling at 300,000 km/s. It's just that they bounce of walls making their path longer and much more importantly than that, the medium is denser. Speed of light through glass is ~2e5 km/s, but photons are still travelling at 3e5 km/s. It's just that they hit atoms, energy gets absorbed and re emitted and so on. But photons always move at 3e5 km/s. The speed of light, that i…
That's not correct, but a widely held view. The speed differs to the properties of the EM field in these materials, not due to absorption.
Re: Newly observed optical state could enable quantum computing with photons
#25Earlier quoted context omitted.
And they tend to over-generalize - "While photons normally have no mass and travel at 300,000 kilometers per second (the speed of light)". The maximum speed of a photon is (currently?) around 300,000 kps but they often travel slower than this. Our fiber optics systems are coursing with photons that travel approximately 200,000 kps. The key results of this experiment is that the photons are interacting with each other…
Photons travelling through fiber are still traveling at 300,000 km/s. It's just that they bounce of walls making their path longer and much more importantly than that, the medium is denser. Speed of light through glass is ~2e5 km/s, but photons are still travelling at 3e5 km/s. It's just that they hit atoms, energy gets absorbed and re emitted and so on. But photons always move at 3e5 km/s. The speed of light, that i…
Path length differs from velocity. The speed of light in a medium varies according to the refractive index of the medium. [1]
Free space (vacuum) has an RI of 1.0. Photons move fastest in free space, about 300,000km/sec.
Water has an RI of ~1.33, meaning photons move through water at about 1/1.33, or about 75% of the free space velocity of light.
RI of optical fiber is often ~1.4. So while there may be path length increase due to off-axis propagation and bouncing, the actual photon speed in the medium is 1/1.4, or about 71% of the 300,000km/sec speed of light in vacuum.
Re: Newly observed optical state could enable quantum computing with photons
#26Earlier quoted context omitted.
No, no changes to Maxell's equation, but I think it's easy to be mislead by the bad press coverage and title. They only made a weird material where photons interact in a strange way, the photons "like" to be bound in triplets in that material. There are other unusual materials, for example one special crystal can split a green photon into two infrared photons. Or the inverse, pick two photons and create a green photo…
I came here to say that. I'm no expert in optics, much less quantum optics, but they seem to have created some kind of fancy material with unusual optical properties. I'm very disappointed that MIT News themselves are so misleading. If I couldn't pirate the paper, I'd be left with the impression that they said they broke some kind of fundamental physics rule. They should leave heavy editorialization and sensationalis…
Agreed.
This seems like just another instance of "slow light", which has been a thing since 1998 [1].
Speed of light in tailored materials has been as low as zero. As in, stopped. And then restarted on command.
Re: Newly observed optical state could enable quantum computing with photons
#27"A photon’s phase indicates its frequency of oscillation."
That can't be right. Phase and frequency are orthogonal.
Re: Newly observed optical state could enable quantum computing with photons
#28Earlier quoted context omitted.
And they tend to over-generalize - "While photons normally have no mass and travel at 300,000 kilometers per second (the speed of light)". The maximum speed of a photon is (currently?) around 300,000 kps but they often travel slower than this. Our fiber optics systems are coursing with photons that travel approximately 200,000 kps. The key results of this experiment is that the photons are interacting with each other…
Photons travelling through fiber are still traveling at 300,000 km/s. It's just that they bounce of walls making their path longer and much more importantly than that, the medium is denser. Speed of light through glass is ~2e5 km/s, but photons are still travelling at 3e5 km/s. It's just that they hit atoms, energy gets absorbed and re emitted and so on. But photons always move at 3e5 km/s. The speed of light, that i…
Well ... no. The value of c is specific to the medium. In "empty" space, c is the constant we know and love, and is related to the permittivity and dielectric constant of the vacuum.
Specifically with a classical E-M model, when you are in a material different than vacuum, the differing dielectric and permittivity of the material are (in a macroscopic sense) what lead to the reduced c*. This is encapsulated in the form of the index of refraction, which is effectively the ratio of velocities between vacuum and in-bulk.
At a microscopic E-M quantum level, you can argue about vacuum state differences between physical vacuum and in-bulk. Indeed, in a physical vacuum, you have virtual pair creation/destruction, virtual photons, etc. In bulk, you may have that, but you also have the bulk electronic and physical structure to work with, as well as different fields and field structures.
Re: Newly observed optical state could enable quantum computing with photons
#29Earlier quoted context omitted.
Photons travelling through fiber are still traveling at 300,000 km/s. It's just that they bounce of walls making their path longer and much more importantly than that, the medium is denser. Speed of light through glass is ~2e5 km/s, but photons are still travelling at 3e5 km/s. It's just that they hit atoms, energy gets absorbed and re emitted and so on. But photons always move at 3e5 km/s. The speed of light, that i…
That's not correct, but a widely held view. The speed differs to the properties of the EM field in these materials, not due to absorption.
How do you explain the properties of the EM field in different materials in terms of photons, electrons, etc?
Re: Newly observed optical state could enable quantum computing with photons
#30TL;DR: entanglement of photons