Truth of Light and Matter Revealed by Superconducting Quantum Circuits?
What really are light and matter? Superconducting quantum circuits could reveal the answer
Excerpts and salient points ~
+ The definitions of entanglement and of photons are predicated on the idea that we can break-up overall quantum systems into constituent parts called quantum subsystems, such as “light” and “matter”. However, quantum theory’s inherently probabilistic nature imposes specific mathematical constraints on the ways in which we can do this. Combined with the gauge-freedom of electrodynamics, a most intriguing twist occurs in QED; different choices of gauge can provide us with different definitions of the subsystems.
These findings clearly sharpen a quite profound question: what really are light and matter at the quantum scale? If nothing else, perhaps it’s food for thought during your next late Sunday morning breakfast.
+ Artificial light-matter systems can be engineered using superconductors and afford a high-degree of experimental control. They can also realise ultra-strong light-matter interactions, which are distinguished by the property that even when the overall system occupies its lowest energy states there is a high population of virtual photons together with a high degree of light-matter entanglement. Virtual photons belonging to the cloud tied to the (artificial) atom are emitted and reabsorbed on very short timescales, but by switching-on and-off ultra-strong interactions fast enough (which requires energy), virtual photons could be released from the atom’s grip. If, after a virtual emission event, the interaction has ceased before the photon has a chance to be reabsorbed then the virtual photon must “detach” and should then be detectable as a real one. Of course, this assumes that virtual photons are there in the first place!
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