Re:Chinese satellite is one giant step for the quantum internet
by Strilanc on Thursday July 28, 2016 @02:08PM
(#12181959)
It lets you bypass some classical limits. It's a well known idea. For example, John Preskill mentioned entangled telescopes in a non-technical talk back in February [1].
A specific case is "NOON" states [2]:
> NOON states are an important concept in quantum metrology and quantum sensing for their ability to make precision phase measurements when used in an optical interferometer.
---
Here's an example that doesn't exactly use entanglement, but does use quantum stuff to give you the general flavor. Suppose you have an optical setup like this:
B
|
v
A --> ◩ -----> D1
|
|
v
D2
When a photon is emitted from A, or B, it passes through a beam splitter then continues on to the two detectors and triggers one of them. If the detectors are classical, then there's no way for you to distinguish whether A or B emitted the photon. Both are a 50/50 split. But if the detectors can store their readings at various times as quantum information and keep that information coherent, then you can bring the stored qubits together, simulate un-applying the beam splitter, and voila! The same basic idea applies to telescopes: photons from different sources spread out in slightly different ways, and we can undo some of that spreading with quantum computation.
A specific case is "NOON" states [2]:
> NOON states are an important concept in quantum metrology and quantum sensing for their ability to make precision phase measurements when used in an optical interferometer.
---
Here's an example that doesn't exactly use entanglement, but does use quantum stuff to give you the general flavor. Suppose you have an optical setup like this:
When a photon is emitted from A, or B, it passes through a beam splitter then continues on to the two detectors and triggers one of them. If the detectors are classical, then there's no way for you to distinguish whether A or B emitted the photon. Both are a 50/50 split. But if the detectors can store their readings at various times as quantum information and keep that information coherent, then you can bring the stored qubits together, simulate un-applying the beam splitter, and voila! The same basic idea applies to telescopes: photons from different sources spread out in slightly different ways, and we can undo some of that spreading with quantum computation.1: https://youtu.be/lN8zT_Yk5sg?t=3m58s
2: https://en.wikipedia.org/wiki/NOON_state