How Can You Access Time Reversibility in Quantum Mechanics?

[ephen wilb]

In QM, time is reversible.. is there a setup where you can couple the system or interface it to classical apparatus such that you can access the time reversibility in qm and control it to reach the past and future (at least of the quantum system).. what would be this setup?

 

[bhobba]

In QM, time is reversible.. is there a setup where you can couple the system or interface it to classical apparatus such that you can access the time reversibility in qm and control it to reach the past and future (at least of the quantum system).. what would be this setup?

Laws are symmetrical - set-ups are not as implied by entropy.

Thanks
Bill

 

[Khashishi]

There's something called quantum revival. http://en.wikipedia.org/wiki/Quantum_revival
This is related to experiments with Rabi oscillation. http://en.wikipedia.org/wiki/Rabi_cycle
If you have a carefully controlled setup, you can manipulate the quantum state of two level systems -- i.e. qubits. You can set or reset the qubit state to some superposition state. The natural tendency of a system is to decay from the upper energy state to the ground state, so you can think of these manipulations as going forward and backward in time, if you take some large literary license with the term time.

 

[ephen wilb]

Laws are symmetrical - set-ups are not as implied by entropy.

Thanks
Bill

what if the setup can be made negative entropy.. can you access the symmetrical qm law with reversible past and future?

 

[bhobba]

what if the setup can be made negative entropy.

I think you are confused what negative entropy means - its what's required to keep a systems entropy low. Entropy always increases - there is no escaping it - and that is the origin of the arrow of time:
http://preposterousuniverse.com/eternitytohere/faq.html

Thanks
Bill

 

[ephen wilb]

I think you are confused what negative entropy means - its what's required to keep a systems entropy low. Entropy always increases - there is no escaping it - and that is the origin of the arrow of time:
http://preposterousuniverse.com/eternitytohere/faq.html

Thanks
Bill

In pure quantum, there is really no arrow of time such that it can be made to go 10 years ago back in time? Since atoms and molecules are pure quantum and time reversible, what does it mean to make it go backwards in time? how far can it go?

 

[bhobba]

In pure quantum, there is really no arrow of time such that it can be made to go 10 years ago back in time?

Why do you think such applies to a classical apparatus? Why do you think classical entropy doesn't emerge in that case?

Thanks
Bill

 

[ephen wilb]

Why do you think such applies to a classical apparatus? Why do you think classical entropy doesn't emerge in that case?

Thanks
Bill

But if the universe is close system. decoherence is reversible because superposition still occur.

Which of the interpretation where decoherence is reversible.. maybe bohmian mechanics where determinism is its middle name? Then in BM, time reversibility is possible?

 

[bhobba]

But if the universe is close system. decoherence is reversible because superposition still occur.

That is incorrect.

Thanks
Bill