Home » Posts tagged 'quantum'
Tag Archives: quantum
Quantum teleportation is a way of transferring a quantum state from one place to another without actually sending a particle in that state through space. (Source – Physicsworld.com)
Anton Zeilinger (right) of the University of Vienna has extended this distance to 143 km by teleporting quantum states across the stretch of sea separating two of the Canary Islands. The team claims that its triumph takes the prospect of quantum teleportation to and from satellites one step closer.
Zeilinger and co-workers teleported quantum states from La Palma to Tenerife, and to pull it off they had to develop several new technologies including a new source of entangled photon pairs and “ultra-low-noise” single-photon detectors. Timing also proved to be a challenge, because the 10 ns uncertainty in GPS timing signals was not good enough to achieve the teleportation. Instead, the team had to develop a new “entanglement-assisted clock synchronization” technique that relies on the detection of the entangled photons
What’s the use of Quantum Teleportation?
Read more at
I have read a lot about quantum mechanics but have a query.
using an entangled photon for this question.
If you can’t measure an entangled photon without affecting it’s entanglement then how do we know it was even entangled to start with and not just always a certain “spin”, either up or down. How can we say for sure that it is both at the same time (entangled) with never observing or measuring this?
[LM posted this]
As of now, We can only give you some links for further reference. Learnt visitors can respond with an anwer.
Can anyone answer this Quantum Physics Based question posted by Ian Mc Tavish?
“I would very much like someone who has access to the necessary equipment to perform the following suggested experiment or let me know if this has already been done and what the results were.
I should apologise in advance for my lack of proper scientific terminology as I have had no formal physics training other than the thought experiments I have posed to myself and reading a few books on physics and astronomy and articles online.
Firstly, I understand that when light is shone through two slits it causes a pattern of light and dark on the screen behind thus suggesting that light is a wave.
Secondly, when the rate at which the light is emitted is slowed down so it can only be a photon(?) at a time there is still an interference pattern. Suggesting the photon goes through both slits at the same time and somehow interferes with itself….giving birth to quantum physics and a whole lot of outlandish theories (I have an even more “outlandish” theory myself)
Finally, it gets even stranger, when any kind of device is put in place to measure or count which slit each light particle is going through, the pattern changes to diffuse. At last being what you would expect to see from individual particles.
The strange part is, of course is how can just the act of observing cause a diffuse pattern. If the measuring device is switched off it goes back to bands of light and dark.
I hope I have this reasonably correct so far ?
SO…..what would happen if the device that measured which slit photons went through was powered by some kind of voltaic cell that was placed where the light bands are.
That is to say only when the light was making the banded pattern would the power be sufficient to switch on the device measuring which slit the light particles went through….which will then make the pattern diffuse….which will switch off the machine…….which will then make the pattern banded……which will switch on the machine…..ad infinitum.
This seems to cause the same paradox as Schroedinger’s Cat but a lot easier to test and more animal friendly…..a bit of Hawkins style humour there…haha.
If this is the first time someone has suggested this and it does prove useful in any way I would very much like to make my parents proud and have this referred to as the “McTavish Twist”. The first part being my surname and “twist” because I love twists in both science and cocktails !!! Both are refreshing and alleviate the boredom..
One suggested result is that the measuring device switches on and off at the speed of its slowest component. If there was nothing slowing down its rate of switching then it would be very interesting to measure the number of times it changes state per second ? Although I imagine this may take some clever machinery indeed as the resulting figure should be the smallest possible measure of time. A “universal tick” ? (maybe we can call it a “McTavish Tick” or am I getting greedy !!). I imagine this should link mathematically to the maximum speed of light in some way.
Another possible outcome is that the machine will not switch on even though the light level appears sufficient to power it. This could happen because it is only really at half power…..being half in the diffuse pattern (that is to say half in another state/universe). It may be interesting to note where the “tipping point” is ? Does it really work out to be exactly one half or does it lean more towards one state ? Again this ratio may link mathematically to another well known number.
I imagine the actual results of the experiment will lead as usual to more questions. I would very much like confirmation of the results so my own thought experiments move on to new questions too.
Thank you sincerely for your attention.”
Experts in the field are requested to respond