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'Squeezed quantum cats'

slo1
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5/27/2015 10:41:51 AM
Posted: 1 year ago
http://www.sciencedaily.com...

Exerpt

.....

In their laboratory, Jonathan Home, professor of experimental quantum optics and photonics, and his colleagues catch a single electrically charged calcium ion in a tiny cage made of electric fields. Using laser beams they cool the ion down until it hardly moves inside the cage. Now the researchers reach into their bag of tricks: they "squeeze" the state of motion of the ion by shining laser light on it and by skilfully using the spontaneous decay of its energy states. Eventually the ion's wave function (which corresponds to the probability of finding it at a certain point in space) is literally squashed: now the physicists have a better idea of where the ion is located in space, but the uncertainty in its velocity has increased proportionately. "This state squeezing is an important tool for us," Jonathan Home explains. "Together with a second tool -- the so-called state-dependent forces -- we are now able to produce a "squeezed Schr"dinger cat."

To that end the ion is once more exposed to laser beams that move it to the left or to the right. The direction of the forces induced by the laser depends on the internal energy state of the ion. This energy state can be represented by an arrow pointing up or down, also called a spin. If the ion is in an energy superposition state composed of "spin up" and "spin down," the force acts both to the left and to the right. In this way, a peculiar situation is created that is similar to Schr"dinger's cat: the ion now finds itself in a hybrid state of being on the right (cat is alive) and on the left (cat is dead) at the same time. Only when one measures the spin does the ion decide whether to be on the right or on the left.

Stable cats for quantum computers

The Schr"dinger cat prepared by professor Home and his collaborators is special in that the initial squeezing makes the ion states "left" and "right" particularly easy to distinguish. At the same time, it is also pretty large as the two ion states are far apart. "Even without the squeezing our "cat" is the largest one produced to date," Home points out. "With the squeezing, the states "left" and "right" are even more distinguishable -- they are as much as sixty times narrower than the separation between them." All this isn't just about scientific records, however, but also about practical applications. Squeezed Schr"dinger cats are particularly stable against certain types of disturbances that would normally cause the cats to lose their quantum properties and become ordinary felines. That stability could, for instance, be exploited in order to realize quantum computers, which use quantum superposition states to do their calculations. Furthermore, ultra-precise measurements could be made less sensitive to unwanted external influences.
Saint_of_Me
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5/27/2015 12:36:34 PM
Posted: 1 year ago
Very interesting post. Thanks.

Quantum Computing could indeed change the world, as well as make current binary-based CPU's seem like an abacus! I also believe that through QC is our best bet to achieve that elusive Fuzzy Logic--which is needed so as to achieve true Artificial Intelligence.

Here is a nice little video on how QC works..........

https://www.youtube.com...
Science Flies Us to the Moon. Religion Flies us Into Skyscrapers.
slo1
Posts: 4,353
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5/27/2015 1:03:04 PM
Posted: 1 year ago
Cliff Note for Dummy Like Me

1. Current computers rely on transistors which have two states, which is represented as a 1 or 0 also known as a byte. (Amazing what just a collection of 1's and 0's when organized in logic gates can result in.)

2. Quantum computers will rely on another device which will allow more than two states. The third state is a superposition state. There would be a state of 1 or 0 or superposition 1 or superposition 0 also known as a qubit. It does not matter but having other states than 1 or 0 allows for more efficient logic and computing. Quantum computing if can be brought to fruition will make our current computers look like fisher price toys for 2 year old neanderthals.

3. The fundamental problem with quantum computers is maintaining the superposition state. It is a well known fact that if you measure something in a superposition state, it will not longer remain in that state and in the case of quantum computing it will result in a 1 or 0. So the quest is how do we get to a point where we can create a superposition state without it "collapsing" it into 1 or 0?

4. The above experiment first squeezes a calcium ion. Basically when you are trying to measure a position of a calcium ion, it will be in a particular spot. When you are not measuring a position the calcium ion, can be in in many or all possible locations within the constraint that the possible locations fit on a wave. When I measure the ion I could find it in the physical location of the crest of the wave, or I find it is in the trough, or anywhere in between. Until I measure it, it is in all locations along the wave.

Squeezing basically changes the shape of the wave so there are less physical locations where the ion can be when it is measured. The important part of this is that it is done in a way so the superposition state is not disturbed. I still don't know exactly where the ion is because it does not have a definite location, but I restricted the number of places it can be.

5. Now I take the ion and use a laser to interact with it. The laser pushes the ion left or right (or up or down if still visualizing a wave) depending upon the spin of the ion. Again since it is not being measured and when in a superposition state it does not have a defined spin (an intrinsic property of particles that can influence its magnetic field) it can be though of being both left or right. It will remain in that superposition state until it is measured at which time it will be just left or right or in computing terms 1 or 0.

Again if I can keep it as both 1 & 0 and I have millions or billions of these qubits I can do powerful computing.

You will notice that they are using a laser to super cool the ion to start the experiment. We are very far from quantum computing, if just for the reason it takes tremendous energy to get these particles for one qubit in the proper state.

It is very interesting to see how science is approaching putting particles in a superposition state and using that state for something good. The irony is that we really don't even understand what that state exactly is.
Burzmali
Posts: 1,310
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5/27/2015 1:40:38 PM
Posted: 1 year ago
This is very cool, but the Schrodinger's cat analogy is so tortured that it makes the article hard to read. So many people know about the thought experiment without realizing that Schrodinger used it to show the absurdity of the "all states at once" misunderstanding. I can't help but cringe when I see it taken literally. It has to be up there with "god particle" as one of the most misused terms in modern science journalism.
UndeniableReality
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5/27/2015 2:26:31 PM
Posted: 1 year ago
At 5/27/2015 1:40:38 PM, Burzmali wrote:
This is very cool, but the Schrodinger's cat analogy is so tortured that it makes the article hard to read. So many people know about the thought experiment without realizing that Schrodinger used it to show the absurdity of the "all states at once" misunderstanding. I can't help but cringe when I see it taken literally. It has to be up there with "god particle" as one of the most misused terms in modern science journalism.

"Science" might be the most misused term in science journalism, especially when referring to "science" journalism and "science" journalists.
slo1
Posts: 4,353
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5/27/2015 3:14:47 PM
Posted: 1 year ago
At 5/27/2015 1:40:38 PM, Burzmali wrote:
This is very cool, but the Schrodinger's cat analogy is so tortured that it makes the article hard to read. So many people know about the thought experiment without realizing that Schrodinger used it to show the absurdity of the "all states at once" misunderstanding. I can't help but cringe when I see it taken literally. It has to be up there with "god particle" as one of the most misused terms in modern science journalism.

You don't know that it is a misunderstanding. It was intended to show the absurdity, but it has been proven time and time again that either one must accept the superposition state is a state where something is everything at once and not reality as we know it or they have to accept that a result in the present can effect the past.

I was just getting ready to post the latest experiment confirming the Delayed Choice experiment.
LostintheEcho1498
Posts: 234
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5/27/2015 4:28:02 PM
Posted: 1 year ago
At 5/27/2015 1:03:04 PM, slo1 wrote:
Cliff Note for Dummy Like Me

1. Current computers rely on transistors which have two states, which is represented as a 1 or 0 also known as a byte. (Amazing what just a collection of 1's and 0's when organized in logic gates can result in.)

2. Quantum computers will rely on another device which will allow more than two states. The third state is a superposition state. There would be a state of 1 or 0 or superposition 1 or superposition 0 also known as a qubit. It does not matter but having other states than 1 or 0 allows for more efficient logic and computing. Quantum computing if can be brought to fruition will make our current computers look like fisher price toys for 2 year old neanderthals.

3. The fundamental problem with quantum computers is maintaining the superposition state. It is a well known fact that if you measure something in a superposition state, it will not longer remain in that state and in the case of quantum computing it will result in a 1 or 0. So the quest is how do we get to a point where we can create a superposition state without it "collapsing" it into 1 or 0?

4. The above experiment first squeezes a calcium ion. Basically when you are trying to measure a position of a calcium ion, it will be in a particular spot. When you are not measuring a position the calcium ion, can be in in many or all possible locations within the constraint that the possible locations fit on a wave. When I measure the ion I could find it in the physical location of the crest of the wave, or I find it is in the trough, or anywhere in between. Until I measure it, it is in all locations along the wave.

Squeezing basically changes the shape of the wave so there are less physical locations where the ion can be when it is measured. The important part of this is that it is done in a way so the superposition state is not disturbed. I still don't know exactly where the ion is because it does not have a definite location, but I restricted the number of places it can be.

5. Now I take the ion and use a laser to interact with it. The laser pushes the ion left or right (or up or down if still visualizing a wave) depending upon the spin of the ion. Again since it is not being measured and when in a superposition state it does not have a defined spin (an intrinsic property of particles that can influence its magnetic field) it can be though of being both left or right. It will remain in that superposition state until it is measured at which time it will be just left or right or in computing terms 1 or 0.

Again if I can keep it as both 1 & 0 and I have millions or billions of these qubits I can do powerful computing.

You will notice that they are using a laser to super cool the ion to start the experiment. We are very far from quantum computing, if just for the reason it takes tremendous energy to get these particles for one qubit in the proper state.

It is very interesting to see how science is approaching putting particles in a superposition state and using that state for something good. The irony is that we really don't even understand what that state exactly is.

Thanks for the cliffnotes. I honestly had no idea what that meant.