I Qubits: Can We Store Information Again After Read?

  • I
  • Thread starter Thread starter bzt
  • Start date Start date
  • Tags Tags
    Qubit Qubits
bzt
Messages
3
Reaction score
0
Hello everyone!

I'm having trouble understanding a specific aspect of qubits, maybe someone among you clever guys can help me.

I understand that a qubit is in superposition, we can store information (a quantum property equivalent of true or false) in it. I also understand that reading that information leads to the collapse of the wave function, so subsequent read is not possible.
1. set(true)
2. read() = true
3. read() = ?

But can we use that qubit again? I mean can we restore the superposition and store another information in it after a read?
1. set(true)
2. read() = true
3. set(true)
4. read() = true?

In other words is it possible to store information again on the same qubit, or that would be a totally independent qubit superposition with different wave function?

Sorry if my question does not make sense, I'm not a physicist, just a programmer.
bzt
 
Physics news on Phys.org
Yes, but you will have erased the information from the 1st superposition, so no. You could maybe freeze the superposition as a third qbit number, but that would be very tricky in practice. You only get one (true or false), every time. Once it has been 're-entangled', with a magnet, such as in a spin liquid experiment, as far as I know, only has one 'random' spin choice, with a true (don't read the information) or false ( read the information and collapse the wave function). What AI computing is doing in Qbit spin memory is two tasks, 'not reading the information/spin' (keeping useful information) or 'reading the information' (getting rid of un-useful and bad information by collapsing the wave function). Or vice versa, depending on your program modeling.
There is though, another snazzy technique that uses polarization logic gates and use 4 or 8 variations per q bit. put those pieces of information on a 'card' of let's say 144 qbits and by inter tangling those card numbers can create huge orders of processing, but the math is insanely difficult to program those number combinations into functions.

Here is a Perimeter Institue lecture on the 4 atom amplitude technique. From one of the most prestigious quantum computing experts.
 
Thank you very much for your answer!
So is it possible to keep (or re-establish) the entanglement after a read? I mean what if we have 2 qbits entangled at start? Would the 2nd superposition keep that spooky effect from the 1st superposition or it's erased along with the information?

1. set(q1, true) (this would also set the spin of q2)
2. read(q2) = true
3. set(q1, true)
4. read(q2) = true?

Or would q1 and q2 became independent after step 2? Hope my question makes sense :-)

bzt
 
The Born rule applies to measurement of Qbits, so in your first example in number three, where you have a question mark, that would read true as would any subsequent measurement.
 
Thank you!

I've followed your lead, read about the role. That yield to another (hopefully final) question :-) Is it possible to have q1 and q2 entangled when the wave function is normalized? Or does normalization rule that out and give only one qbit per wave function?

bzt
 
Insights auto threads is broken atm, so I'm manually creating these for new Insight articles. In her YouTube video Bell’s Theorem Experiments on Entangled Photons, Dr. Fugate shows how polarization-entangled photons violate Bell’s inequality. In this Insight, I will use quantum information theory to explain why such entangled photon-polarization qubits violate the version of Bell’s inequality due to John Clauser, Michael Horne, Abner Shimony, and Richard Holt known as the...
Not an expert in QM. AFAIK, Schrödinger's equation is quite different from the classical wave equation. The former is an equation for the dynamics of the state of a (quantum?) system, the latter is an equation for the dynamics of a (classical) degree of freedom. As a matter of fact, Schrödinger's equation is first order in time derivatives, while the classical wave equation is second order. But, AFAIK, Schrödinger's equation is a wave equation; only its interpretation makes it non-classical...
I asked a question related to a table levitating but I am going to try to be specific about my question after one of the forum mentors stated I should make my question more specific (although I'm still not sure why one couldn't have asked if a table levitating is possible according to physics). Specifically, I am interested in knowing how much justification we have for an extreme low probability thermal fluctuation that results in a "miraculous" event compared to, say, a dice roll. Does a...
Back
Top