**Israeli physicists from the Weizmann Institute published in Science that they are the first to quantumly entangle photons in what are called NOON states - the superposition of N photons in an equal state in what appears to be one big fat photon with N equal to 5.**

Schrödinger's cat is known to be the most famous Hedken experiment in quantum theory. This thought experiment raises conceptual difficulties in interpretations of quantum mechanics. The cat is in a superposition of two extreme situations - alive or dead. The observer cannot say which of the states characterizes the fat cat until a measurement is made and puts the cat into one of these states. Many of these extreme "cat states" are manufactured in a laboratory. They underlie the emerging field of quantum information theory. Applications of this theory require quantum entanglement - a unique characteristic of quantum mechanics. They also require the use of cat-like modes, which consist of a superposition of many different modes. In this field, Prof. Yaron Zilberberg and his students, the doctoral student Itai Afek and the master's student Oron Ember from the physics department at the Weizmann Institute are involved. They recently made a sensational discovery that they have been working on for over a year.

**The fat photon is effective in microscopy, superfast computers and lithography**

And if we are talking about a cat, which in general consists of a collection of many particles or molecules, and all of them together are either alive or dead... Maybe it is even possible to create a situation, a kind of large particle, which is actually several particles found in a quantum entanglement? Theoretically, thoughts about the entanglement of some quantum particles could shed light on the vexing question, why don't we see quantum entanglement on macroscopic scales? And as for photons, these are slightly more practical applications, a significant contribution to the field of quantum optics.

Indeed, the attention of the group from the Weizmann Institute is focused on states called NOON states, many photons, meaning N photons in an equal state of superposition. The photons act as a collective entity, like a single fat photon, as they acquire phase at a much faster rate than a single photon of the same wavelength. It is possible using the NOON states to reach the fundamental quantum accuracy limit of the measurement.

NOON modes can be useful in microscopy. For example microscopes for biological uses which are very sensitive to light. NOON modes can provide the necessary resolution using single photons as opposed to conventional light. The diffraction limit for NOON modes is 1/N times that of conventional light. This means that NOON modes can improve optical microscopy and lithography. In such situations it is possible to use quantum lithography - photolithography, which makes use of the quantum properties of photons (quantum entanglement) to achieve a better effect than the usual lithography - to reach incredible resolution. Quantum lithography is a new field. The move will be etched with component photons instead of using a mask.

Another use of NOON modes is in quantum metrology, the study of performing measurements of physical parameters with high resolution and sensitivity with the help of quantum theory, utilizing quantum entanglement, to describe physical systems. NOON modes can be used to improve accuracy over a wide range of measurements. If an interferometer is used and the light is recombined in the instrument, measurement uncertainty is 1/N as a result compared to 1/N1/2 using conventional photon pulses. Therefore, the advantage of NOON modes is that compared to conventional light, the quantum measurement improves the accuracy. And this as the number of photons in the NOON states increases. Quantum metrology indeed aims to develop measurement techniques to provide better accuracy than the classical techniques.

Hence it is clear that in order to improve the resolution more photons are needed in NOON states, i.e. a large N.

**The group from the Weizmann Institute creates a fatter photon**

So far the creation of NOON states in the laboratory has been limited to N=3. Various researchers tried to cross this border, but it proved to be extremely difficult. One group managed to make N=4, but the move they used was very complicated and limited to four positions.

Silberberg's group from the Weizmann Institute managed to create NOON states up to N=5 with the help of a very general experiment. In contrast to the previous experiments, the experimental arrangement is based on a new wrestling course. The group used a Mach-Zehnder interferometer, a device used to determine the phase shift between nearly parallel rays from a coherent light source. The interferometer is used to measure small phase shifts caused by the change in the length of one of the tracks. The group additionally used a 50/50 polarized beam splitter when the NOON modes were created after it.

**Course of the experiment**

The group took a laser and produced short pulses of infrared light. Each pulse split in two. The group converted one half of the pulse into a conventional pulse, "classical light", and the other half into a quantum pulse containing entangled photons, "quantum light". The two half pulses were fired into the beam splitter.

How do you create entangled photons? The entangled photons are created through spontaneous parametric down-conversion (SPDC) - a central procedure in experiments in quantum optics, especially for the creation of entangled photons. The photons enter a transparent β barium borate crystal and split into entangled pairs.

To measure how many entangled photons were created the team sent the photons through the beam splitter. All around were detectors that recorded the progress of the photons. As you remember, entangled photons in the NOON state behave as if they are part of a fat single photon block. The beam splitter has two inputs and two outputs. Therefore all N photons choose the same exit from the splitter as if they were a single photon. But the experimenters do not know which of the two exits all the photons will choose. The two tracks are then recombined in the Mach-Zehndr interferometer. By measuring the amplitude and phase of the resulting interference signal, the group determines the degree of entanglement and how many photons are entangled.

The group calculated that with their experimental arrangement they would be able to achieve an experimental accuracy of only 92%. This is good for an arbitrary number of photons. The experiment worked ninety percent of the time. However, taking this trade-off into account, the experiment is therefore general and can produce high NOON states, which the previous experiments failed to do.

For the five-photon NOON mode, the group measured a contrast in the interference signal of about 42%. For two, three and four NOON modes the contrasts were 95%, 86% and 74% respectively. If the photons are not entangled at all, the contrast is 17%.

## 42 תגובות

Thank you, father, and sorry for the spelling mistake.

Oron?

I would love to host an article by scientists writing about their own research.

To Abi Belikovsky (and Oron): I think there is a place to ask Oron (if he is ready), who I understand is one of the authors of the article (and explains wonderfully), to write another article about the experiment and its meanings, perhaps with a little background. The subject is fascinating, and I think there is room for a more comprehensive article.

And in general, in the case of an Israeli discovery - why not evacuate the scientists themselves, after all, they are here.

By the word modes or modes I mean states of the system that differ in their basic properties, some examples of different modes: different frequencies (photons with different energy), photons that move in trajectories that are spatially separated, perpendicular polarizations, etc.

It is not possible to know in which mode the photons chose to move because at any given time there are photons in the system they are in a superposition of being in both mode 1 and mode 2 with equal chances (what is called entanglement), similar to Schrödinger's cat. If we know which mode the photons have chosen with the help of a detector that detects photons only in one of the two modes, then the photons will no longer be in superposition between the 2 modes and will only be in one mode at a time (the cat will be alive or dead but no longer both together).

The collapse of the wave function describes the transition from a state of uncertainty between several possibilities to a deterministic state due to information we received about the system.

The addition of the phase in the system does not result in the collapse of the wave function (and the cancellation of the interlacing) because it does not add information to us about what is happening in the system, because we do not know whether or not the photons passed through the element that adds phase.

Oron

I have so many questions for you that I don't know what to ask... By the way, I also join the others - it's just a pleasure to read your explanations.

Again, just to know if I understood correctly what you are explaining, and forgive me for having almost no knowledge of physics, and for the phrasing of the questions:

What do you mean by 'mod'? Do you mean mode/route or are you referring to self-oscillating modes?

Why is there no way to know which mode the photons chose? Is it because they are in superposition after the grouping? Doesn't the collapse of the wave happen thanks to the staging of the show?

Thanks.

First of all, I am happy that there is such an interest in the subject and of course I am happy to answer as much as I can to your questions.

Regarding Ehud's question:

If we translate the diffraction effect into a quantum language of photons, then the experiment will be described as follows: there are N slits at a certain distance from each other and through them passes coherent light with Poisson statistics (in simple words - a normal laser). So in each pulse a random number (M) of photons will be released from the laser that will be divided between all the cracks and will go through a slightly different optical path until they meet again in the screen/camera/detector and the interference will stop due to the inability to distinguish from which crack the different photons came due to the fact that all the photons are identical.

In the case of NOON modes the number of photons is fixed (N) and not random and they will all pass through the same slit and will not be divided into several groups, and in each pulse they will all pass through one random slit.

The closest thing I can think of in the context of the analogy to diffraction is that in diffraction there is a connection of several identical (coherent) sources and in NOON modes there is a connection of N identical photons in the same mode. If instead of N identical photons in the same mode, we had N non-identical photons, then the quantum interference effects would not appear because the photons would not "talk" to each other (like a connection of N AM fields of different frequency). In addition to the fact that all the photons are in the same mode, only the interlacing between the two modes means that we can notice the fast phase accumulation when there is a superposition between the two different modes (N photons in mode 1 and zero in mode 2 and vice versa).

Therefore, NOON has 2 quantum properties that have no classical analogue: a fixed and non-random number of photons and entanglement.

Regarding the quantum algorithm: again I don't think there is a connection. In an ideal system when we tune the system to create a NOON state with N photons we do not filter the results, but only look at events of N photons. States with M photons (M different from N) will be similar to NOON states but with decreasing overlap as M is further away from N. It should be noted that as soon as we mix classical and quantum light the result will always be quantum (having some level of entanglement). The result of the mixing of classical and quantum light that creates the NOON states in our experiment is determined solely by the statistics of the states (Poisson statistics and squeezed vacuum statistics) and is very different and complicated than the input of Gruber's algorithm.

Answers to R.H. Rafa.im:

From the little I have read about spinoptics, I would say that this effect will not contribute in the near future to the improvement of photon detectors. The current trend in single photon detectors is cooled superconductors which will be able to distinguish photon numbers of about 10-20.

In the optical system in this experiment, there are 2 fixed modes, only for the sake of simplicity of explanation we chose them to be 2 separate optical paths. It is possible to imagine a T-junction where the photons that reach it can choose whether to turn left or right, where at each pulse the random choice is made anew, similar to tossing a coin (tree = left, Peli = right). And further down the road on the right there is an optical phase element that depends on an electric voltage (you can imagine a traffic light that with a variable voltage you can choose how long it will be red and delay the photons that reach it by X seconds). And finally the 2 paths meet again and a struggle is caused by the 2 options (left or right) that the photons have chosen.

The important point is that the modes are predetermined and the photons re-choose with each pulse which mode to turn to/choose and there is no way to know which mode they chose (because if we knew then the wave function would collapse and there would be no struggle between two options).

The reason that in this experiment we chose 2 different polarizations and not 2 different paths is an experimental reason, it is equally possible to perform the experiment with 2 modes which are XNUMX different optical paths.

Oron

Thanks again for the eye-opening explanations and investment!

Although diffraction is a classical phenomenon, I will try to explain the intuition behind my question

Regarding the relationship between uncertainties of the NOON state and diffraction.

In my opinion, mathematically, the questions about the quantum state of light are simply questions about connection

of complex numbers or vectors. If the directions of the vectors are random as in classical light

So we get an analogue of a drunk move (in N steps) where the mean is the origin and the distribution around it

It is Gaussian with a width that goes like the root of N. If we choose to connect the vectors in the same

Direction I expect that this will be similar to the connection of N coherent sources as is done in diffraction

in N cracks. In practice I assume that N entangled photons will give a state for the Bloch count which it also describes

pure states.

The link to the Grover algorithm is also completely unfounded and is an attempt to connect your experiment

with a quantum algorithm. The input in your experiment is described by all the states with up to M photons. Some of the states are entangled and some are not.

said N=5). That is, by neglecting the decoherence, you perform ontarian operations on photons and measure one entanglement state with high probability, in my opinion, a kind of analog for quantum computation. Again I think that the answer is here but the question is missing. That is, it is possible that in retrospect your experiments can be attributed to a search in a database using a quantum algorithm.

True, unfortunately I learned that writing English and writing strongly does not always transfer from computer to computer. If you insert an English word sometimes it messes up the whole sentence.

In any case, the article provoked many reactions and this means that the research of the researchers from the Weizmann Institute is of particular interest to scientists and also to people who do not come from the field of science. And that in itself is very happy and also important. Because in our country, science and education do not always receive the attention they deserve, nor do they always receive the appropriate budgets.

And one more question, so I know if I understood you correctly:

Is the mode of the entangled photons affected/depends on the medium (like the liquid crystal you mentioned) in which they cluster?

Thank you.

Oron

Not long ago I heard about a new field of science called spinoptics

http://rbni.technion.ac.il/.upload/page23-feb09.pdf

A question out of curiosity - will this new branch, in the future, be able to contribute to the construction of a device with a higher sensitivity to light, than the existing one, which will help reach higher levels of N?

Or has it nothing to do with it?

thanks anyway.

jelly. Unfortunately, the safest thing is to write the powers in words (10 to the power of 50) so that nothing will be reversed or disappear. Although I know it's awkward.

my father

There is a typo in the article - a typographical error - because when transferring from computer to computer the possessions are often canceled. In the sentence that appears in the article:

"If an interferometer is used and the light is recombined in the device, the measurement uncertainty is 1/N as a result compared to 1/N1/2 when conventional photon pulses are used."

One sentence should have N fractions for measurement uncertainties.

and - one of N fractions to the power of 12 when using pulses of conventional photons.

If it helps someone understand Oron's explanations... 🙂 ...

In any case, it is very significant.

And Oron can explain this to you better than me 🙂 …

Answer to R.H. R.A.M.:

First of all, entangled photons behave macroscopically like any other photon, for example in the optical system mirrors, lenses, fibers are still used. And all the laws of geometric and Gaussian optics still apply. The difference is in their clustering in the same way (MOD) which causes the fast phase clustering and quantum entanglement phenomena that would not happen with normal (non-entangled) photons.

Answer to Ehud:

Discovering photons is a bit complicated business. When there is a large amount of photons ("large" can also mean a nanowatt which is 9-10 watts or 10 billion photons in visible light) then there is no problem turning the flow of photons into a flow of electrons that will create a measurable current. But when you try to measure a single photon, even if it excites one electron then the current that will be created will not be measurable. Therefore, APD type detectors are used:

http://en.wikipedia.org/wiki/Single-photon_avalanche_diode

Their principle of operation is based on the fact that a single photon can create a chain reaction (like an avalanche starting from a small snowball) that will eventually cause a measurable electric current at the output.

The advantages of detectors of this type is the simplicity of use that results from working without special cooling (no need for liquid nitrogen) and a low noise level (can even reach less than 100 events per second in relation to the signal which is usually at least a thousand or a million), the main disadvantage is the inability to distinguish If one or more photon detectors have been reached because the result at the detector output in all cases will be the same and therefore to detect N photons the beam must be split into N beams of equal intensity when each beam will reach a separate detector.

It should be noted that there are detectors that can also detect a number of photons, meaning that if N photons reached the detector, the output will have a signal proportional to N. But the technology is still immature and some of the current detectors need cooling with liquid nitrogen and work at a low rate and suffer from low detection efficiency in visible light. Given that these problems are solved then these detectors will replace the usual single photon detectors and allow the detection of a large number of photons at the same time.

When there are N photons in one light pulse, the beam must be split into N beams of equal intensity that will reach N separate detectors. Ideally, one photon will reach each detector in the time period characteristic of a pulse, therefore if in each pulse there will be an event of N "clicks" at the same time in the detectors, then we will know that we had N photons. The trick is of course to define the time window in which we will consider the arrival of the different photons "simultaneously" in such a way that only photons from the same pulse will count and minimize unwanted noise.

Even in a laser source, which is the light source closest to the classical one, you can see that each pulse has a random number (with Poisson probability) of photons, and if we make a histogram of all the pulses, we can accurately reproduce the entire statistics and the average will be directly proportional to the average light intensity of the laser.

NOON mode is a mode where there are N photons in one mode and zero in the other with equal probability of 50%. In this experiment the two modes were two perpendicular polarizations that moved in the same optical path when the phase added to one of the modes was based on an optical element (liquid crystal) which adds a phase as a function of electric voltage only to a certain polarization and does not affect the polarization perpendicular to it. The use of different polarizations and the same optical path stabilizes the system because noise dependent on spatial position (such as air movements) is not added between the two modes.

The phase sensitivity of the NOON states as a function of N causes the uncertainty (which is the standard deviation of the phase) in knowing the phase in the system to decrease as 1 part of N in contrast to a classical source where the uncertainty decreases as 1 part of the root of N (a classical source like the laser has Poisson statistics which has The property that the standard deviation is equal to the root of the mean, therefore uncertainties in the number of photons is equal to the root of the mean number of photons in pulse N).

As far as I know there is no connection between the phase sensitivity of NOON modes and Grover's algorithm, and diffraction phenomena are classical effects of interference of electromagnetic waves when entanglement effects are not

It can be described by the classical Torah, therefore there is no connection between diffraction and the quantum phenomena that happen to NOON states.

Happy Shavuot everyone

Here are articles on the subject:

http://www.reuters.com/article/idUSTRE64C4JT20100513

http://www.msnbc.msn.com/id/37138400/ns/technology_and_science-science/

http://www.sciencemag.org/cgi/content/abstract/328/5980/879

Oron, once again your explanations and patience are really commendable.

I have no idea what is written here. (;_;)

I would like to understand a little more about these issues. Maybe you will publish a reading list of popular science books in each category in science? this could be interesting.

Oron

Thanks again for the answers. Thank you if you find time to answer more questions:

You write that photons will always appear as distinct particles. I would be happy if you could tell:

1. How photons are discovered in the laboratory. What detectors are used to detect single photons?

2. What happens when I have a macroscopic number of photons in a certain state (analogous to condensate

of Bose Einstein) something that also happens with lasers. Are the photons detected in this case as well?

One by one or act collectively?

3. I assume that you discover the entanglement through correlations between the measurements of the photons

in specific detectors. What are the NOON modes in your experiment? Polarization modes? Or simply orbits

in space? I had difficulty understanding this from the article.

And a last question that may not be completely related, but it is said in the article that the noise is for N photons

entangled goes as 1 divided by N while the noise for N unentangled photons goes as root

N. This fact reminds me of Gruber's quantum algorithm (only in reverse) for searching a database when

The classical algorithm manages to find a data in order N searches and the quantum algorithm finds a data

In root order N. Is there a trivial connection between the things? Perhaps the phenomenon is basically related to diffraction

Through a single crack or N cracks?

Oron

I don't know if such an experiment has been carried out or not, and my level of knowledge in physics is low, so please don't be surprised by the question I'm asking and I'd be happy if you could clarify the matter for me:

What happens to the entangled photons when they pass through some medium?

Thanks

Answer to R. H. Rafa.im:

The wavelength of the photons in the system remains the same throughout the process, even if they intertwine and gain phase as one fat photon.

So 5 photons in near infrared will gain phase like one photon in ultraviolet (UV), but they will not get other properties of the ultraviolet light (such as absorption and ability to liquefy atoms).

Changing the wavelength of light can only be done by a non-linear process and that is another story.

Regarding the measuring devices - the creation of NOON states with many photons is limited only by the efficiency of the system, therefore using better detectors with a higher detection efficiency will only improve one (and not negligible) factor.

To create NOON states of hundreds or thousands of photons the system would have to be almost perfect (almost 100% efficiency) and I don't see that happening in the near future.

Answer to Ehud:

Loss is really a form of decoherence of the phase and it is caused when the photons do not survive the passage through the system (absorption, scattering, deviation outside the optical path, etc.).

The main problem with the loss is that when we try, for example, to create a NOON of 4 photons, the system also has 5 photon states that in an ideal system would not interfere with the measurement of the 4th.

But if there is a loss in the system, there is a chance that one of the 5 photons will disappear (leave the system) and be revealed as an event of 4 photons but with an incorrect phase, therefore the loss created noise which can completely mask the discovery of the desired events.

The only way to overcome this problem is to lower the light intensities in the system (then the chance of events of a higher order than desired will be negligible), but this will also cause the desired signal event rate to drop to an unmeasurable level.

Regarding the behavior of the 5 photons like a single photon: the entanglement of the photons is not related to the way we count or discover the photons (which are undifferentiated particles, i.e. completely identical).

N photons will remain and appear as N photons regardless of their quantum state.

I meant = you meant

sorry for the confusion

Oron

Thanks again for the explanation. Is it correct to assume that when you talk about loss you are referring to decoherence?

Is there a specific tune for decoherence in this case? According to your answer I assume that the decoherence is characteristic of the phase.

I may have just meant leakage out of the system of photons so I have

Another incomplete question: If I understood correctly, you calculate the probability of losing a photon or higher by the power of the number of photons, but isn't the state of 5 photons in one quantum state different and more similar to the state of a single photon?

This is because we have no real possibility to distinguish between the photons they are intertwined.

Thank you if you find time to answer and thanks again.

Oron

Thank you very much for the explanations, they are much better than the article itself.

I have a number of questions for you and I would appreciate it if you could answer them:

1- When the photons are interlaced their phase increases, this is what I understood, but what is the reason that the wavelength does not shorten? Is it because they appear as one photon with the same wavelength as the entangled photons? Why does the wave function of the photon not change?

2- With the help of a sophisticated measuring device - similar to what was used in the experiment, only much more sophisticated - is it possible to reach an N of at least a few hundred? That is, can the potential of N in the NOON state even reach hundreds or thousands?

Thanks.

To the respondent 3

You're getting into trouble anyway, too bad you'll keep getting into trouble.

Evolution apparently works not only in biology but also at the most basic level of nature: in the transition from the microscopic quantum standards to the macroscopic standards of relativity by the transition from superposition to the collapse of the wave of the strongest probability. That is, the survival of the fittest probabilities.

This is called Quantum Darwinism

http://en.wikipedia.org/wiki/Quantum_Darwinism

Answer to Ehud:

Until the article in question, the methods used to create NOON states were quite complicated and were intended for a specific N (N=2,3) and created the desired states with low theoretical (and even lower experimental) efficiency, but in the current system it is possible to create NOON states with any arbitrary N When you only change the intensity of the quantum light source (similar to turning a knob) relative to the intensity of the classical light source (the "normal" laser in the laboratory) to a specific number that can be easily calculated. And if the quantum light source is not strong enough (which usually happens), then there is no problem, because you simply increase the intensity of the classical light instead.

Theoretically, you can create NOON in this system as you can (which is limited to detection by the number of detectors, which are very expensive).

So why did the authors of the article stop at five (and it seems to me that they also know the following digits)? In my previous response, I talked about a phase that most people are used to thinking of as a real number, but sometimes a simulated number (a complex number) that is the mathematical representation of a loss (or alternatively the increase) sneaks in there. And so if we have losses in the system (and there always are) then the NOON modes will accumulate a loss N times faster (more accurate to the power of N faster).

Now in this specific system the efficiency only reaches 12% (which is due to all kinds of physical and technological constraints) so if we had M events of 5 photons per second in a perfect system without losses, then in a system with an efficiency of 12% we would only have 5^0.12*M events . The efficiency comes in the form of the chance to succeed in discovering a photon given one. That's why they stopped at 5 photons.

But if in an improved system (which is possible with a lot of hard work and very sophisticated means) the efficiency will reach 50%, then the authors state that even a NOON of 9 photons can be created and discovered at a reasonable rate. And that is the whole beauty of the system, only the efficiency is limiting and no other factor.

Michael

Thanks for the link to the article

Oron

Thanks for the enlightening explanation. By the way, what determines the limit for N NOON modes? That is

What limits the ability to see higher N states? I guess it's a relationship

Signal to noise meaning the number of states N is higher than the total of all states and gets smaller as N

increases and therefore the probability of receiving them is getting smaller but is there a simple function

which describes the dependence on N. Compared to the signal, what is the source of the noise in the experiment that limits the ability to measure?

An answer to some compliments… 🙂

Writing an informative article can be done on several levels. The article is popular, meaning without comparisons. But popular can be a Reuters report:

http://www.reuters.com/article/idUSTRE64C4JT20100513

And it can be a much more complicated report.

An article is usually between 800 and 900 words. 1000 words is already too long and people don't have the patience to read. To write an article of 800 words on average, you need to read the researchers' article and also read many other articles. Regarding quantum optics, I deal with the foundations of modern physics.

Thanks to Oron - the explanation is simply great.

The movie "At Noon Today" is much more enjoyable than the article.

I will try to answer some questions raised here before and clarify some basic issues in quantum optics.

Question: What is NOON mode?

Answer: Of course it has nothing to do with noon, but with the mathematical way of writing the situation which is that |0>+|0>|n . When n the photons are equally likely in one of the two different modes (modes) of the system (and zero photons in the other mode), when the modes can be spatial or different polarization, etc. High-NOON modes are simply NOON modes for high N (5 is high enough…).

Question: Why do the 5 photons gain phase five times faster?

Answer: According to the theory of quantum optics, N photons gain phase N times faster than a single photon. The reason we don't notice this for macroscopic light sources is the large and random number of photons for which the quantum phase is averaged (remember that for one watt of visible light there are about 10 to the 19th power!). Even for a laser source, which is the "most classical" quantum light source, the quantum phase averages to a phase that would have accumulated only a single photon due to the averaging over the Poisson statistics that determine the number of random photons in each pulse.

But in quantum states of light where there are exactly N photons (like the NOON states) we will see the fast phase build-up in the manner equivalent to using an N times smaller wavelength. It should be noted that the light at its base remains the same wavelength, therefore 5 photons in infrared do not really propagate UV radiation.

Another explanation for the special quantum nature of the NOON states is with the help of a slightly different (and approximate) version of Schrödinger's uncertainty principle which says that uncertainties in the number of photons multiplied by uncertainties in phase is greater than or equal to 1 (1=< dN * dPhi ) and for the states of - NOON uncertainty in the number of photons is maximal because dN=N and therefore phase uncertainty is the minimum according to quantum theory and is a lower barrier for any quantum state, which is one of the reasons the NOON states attract so much attention. Question: So what if the cat? Answer: Hello cat.

They performed a séance at noon and by remote ghosting managed to catch a fat cat named Gadanken.

During the séance it was impossible to tell if the cat was alive or if it was one of his 9 souls. There are many cat states, by examining the length of pulses of infrared light "a wave of the light received from it" it turned out to be his fifth soul.

Here is the article in a link that does not require an appointment

What is this article?! You pushed 3000 concepts into one big salad. The topic should be very interesting but it seems that the writing "knocked" everything off.

Despite everything - you are the number 1 science site in the world!!!!!!!!!!!!

The writing is really nothing. It seems that the writer translated what she read or heard word for word without exactly understanding what was said there. If you don't have the tools to explain contemporary quantum optics, maybe focus on other fields. The writing is a salad of facts that are difficult for the understanding reader (!) to follow. Some of the facts are not relevant at all to the lay reader.

See for example the following sentence that I fished out from the article:

"It is 1/N as a result compared to 1/N1/2 using conventional photon pulses."

Let's leave the relationship of "one divided by N" which appears incorrectly in the text...

Conventional photons? I want to say "not intertwined", or maybe "coherent state" and so on.

Mach-Zehnder interferometer - put some link to Wikipedia so that people will understand about it.

http://wapedia.mobi/he/%D7%90%D7%99%D7%A0%D7%98%D7%A8%D7%A4%D7%A8%D7%95%D7%9E%D7%98%D7%A8%D7%99%D7%94

Is there an update on the cat's health?

Orit, I rewrote the article in a more friendly way on my website. here:

http://www.notes.co.il/gali/67244.asp

Dr. Gali Weinstein

Maybe try to explain what you understand

It sounds confusing

Ronit:

http://www.sciencemag.org/cgi/content/abstract/328/5980/879

If you have access to science.

Dr. Gali Weinstein

Say you understand what you are writing.

It is not clear what is new in this experiment and how it differs from all the hundreds of similar experiments that are done.

Is it possible to link to the original article, maybe I will be able to decipher it myself

Explanation in simple words to R.H. R.F.Aim

A thin white moving wave sent three and Oriri

Hope the words are simple enough.

There is also an explanation with abstract words but I don't want to complicate things.

Why "they acquire phase at a much faster rate than a single photon of the same wavelength."? What is the cause of this?

(if possible explain in simple words)

interesting