Let's say a memory qubit inside a quantum computer is in state(adsbygoogle = window.adsbygoogle || []).push({});

## α \left|1\right>+β\left|0\right> ##

This computer is equipped with a device that emits photons that carry the same qubit as the aforementioned memory location.

Alice and Bob, that are very far from each other, receive and measure those photons.

Let's say Bob measures this sequence of bits:

01010111011011111011111111111111111111

And Alice measures this sequence of bits:

010100100010000001000000000000000000000

I tried to make those sequences realistic looking in such case when probability of measuring either 1 or 0 is the same at the beginning.

Now Bob contains a classical bit 1, and Alice contains a classical bit 0.

Who has decohered here? The computer can still send out qubits to Joe and Jill, who can go to opposite classical states, so I guess the computer is not decohered. So it's more like Bob and Alice became decohered by their own measurements. Right?

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# B Decoherence thought experiment

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