Part 2 of 2
Let’s get to the part where you make some money off lottery –
We noticed something weird while dealing with the Quantum nature of such particles, when we tried to measure them – there was no interference pattern. Scientists famously put it as “It is like the universe saying to the particles, the mankind has figured us out, try to act like normal particles now”. We have to agree that scientists have a sense of humor about them but they are also persistent.
The problem –
You see the problem was as soon as we measured one slit the particles lost their coherence or in other words they became decoherent.
What is Coherence?
Coherence is a way of predicting the peaks and troughs in the waves. If the waves are coherent we can measure one and predict the other.
The Solution –
The scientists found a way around this problem, they made a crystal that can replicate the Photon while preserving its coherence. We just made a clone of the photon actually we discovered Quantum Entanglement or as Einstein put it “Spooky action at a distance”.
The purpose of the crystal kept in front of slits is to produce an entangled pair for the photon. One of the photons goes to the screen and one goes to the measurement sensors. If A sensor lights up the photon came through slit A, similarly for sensor B.
The Spooky particles
These quantum Entangled Pairs are so deeply connected that they share the same wave function (DNA of quantum world) if you change a property of one particle its pair changes the property instantly (Faster than light speed) no matter how far they are kept, hence ‘spooky action at a distance’.
With the introduction of the entangled pairs, we can finally get the pattern again.
We create the entangled pair one goes to the screen and the other goes to the detector after the former reaches the screen yet the later somehow sends a message to the past to its pair to change its waveform and we don’t get an interference pattern.
This is so weird because we are not messing with the coherence it is simply that the universe is sending message to the past which is affecting the reality of the past.
So All we got was
Scientists get enraged now
I should explain, everyone converts anger to other feelings – it’s called channeling or transmutation. Scientists channel their anger to curiosity.
They introduced something called the Quantum eraser –
What a quantum eraser does is it erases the information of which slit the initial photon came out of, here is how it works.
The part of sensor C and D is called Quantum Eraser. The reflectors in front of sensor A and B are partial reflectors. They divert some of the entangled pairs to C & D when they reach C or D we don't know which slit the photon came from. So if we only measure the photons on the screen whose entangled pairs reached the sensor C or D we do get an
Interference pattern
The part where you win a lottery (Every time)
If we can somehow hold the entangled twin before the sensor, we can get a chance to either have an interference pattern on the other side or not after we release the photon. This is a binary system which means we can send a message to the past by either measuring the entangled pair or not.
How do we stop the photon
Scientists in 2013 were able to stop a photon for 13 seconds using cold atoms. Now, scientists are trying to hold the photons in place for longer by trapping them inside crystals and ultracold clouds of atoms. This field looks very promising and we see constant positive results.
The issue
The only issue with sending messages from the future is that we need to differentiate the photons on the screen as to which are in the interference pattern and which are not. We have come so far in this field that the future really looks promising which means the present really looks promising, pun intended.
Authors note - It couldn't be on Thursday but I tried to finish it off as fast as I could. Thanks for putting up with it and I hope this weeks update was worth the wait, tell me your views in the comments section.
I did get some pictures from PBS space time and credits are in order.
Next week on Thursday, we will have an episode on how the universe could be a balloon - spherical and inflatable.
