Questions related to Quantum Optics and Quantum Information
In quantum Communication we encode information in polarisation state. But this can also be done performing phase modulation. And infact, we can go to more number of states using phase modulation. So, What is the difference between the two?
I am interested to know the opinion of experts in this field.
A rigid body with vertical proper length J rises along the Y direction in an inertial frame S(T,X,Y) with constant proper acceleration, therefore me may write the equation of hyperbolic motion of the body along the Y direction as:
1) J2 = Y2 - c2 T2
Using Born´s definition of rigidity, the proper length “J” must be invariant under Lorentz transformations between instant commoving inertial frames where the proper length (squared) J2 coincides with the line element (squared) along the Y direction: Y2 - c2 T2. It is straightforward to see that this is the case just for boosts along the Y direction. If the velocity of the body and its inertial commoving frames have an aditional constant component along the X direction, the line element is different, the vertical length J cannot be invariant in the inertial comoving frames and we get a violation of Born´s rigidity.
How do I should do to determine the energy band of superlattice? I want to determine the valence band offset of the superlattice .However, I am confused the methods to determine the valence band offset. What I know is that valence band offset can be derived by XPS, electronegativity, but I am still confused of determining the superlattice energy band ,including the valence band energy , condunciton band energy.
Consider two particles A and B in translation with uniformly accelerated vertical motion in a frame S (X,Y,T) such that the segment AB with length L remains always parallel to the horizontal axis X (XA = 0, XB = L). If we assume that the acceleration vector (0, E) is constant and we take the height of both particles to be defined by the expressions YA = YB = 0.5 ET2, we have that the vertical distance between A and B in S is always (see fig. in PR - 2.pdf):
1) YB - YA = 0
If S moves with constant velocity (v, 0) with respect to another reference s(x,y,t) whose origin coincides with the origin of S at t = T = 0, inserting the Lorentz transformation for A (Y = y, T = g(t - vxA/c2), xA = vt) into YA= 0.5 ET2 and the Lorentz transformation for B (Y = y, T = g(t - vxB/c2), xB = vt + L/g) into YB= 0.5 ET2 we get that the vertical distance between A and B in s(x,y,t) is:
2) yB - yA = 0.5 E (L2v2/c4- 2Lvt/c2g)
which shows us that, at each instant of time "t" the distance yB - yA is different despite being always constant in S (eq.1). As we know that the classical definition of translational motion of two particles is only possible if the distance between them remains constant, we conclude that in s the two particles cannot be in translational motion despite being in translational motion in S.
More information in:
1) Can the existence of an aether be compatible with local Lorentz invariance?
2) Can classical rigid bodies in translation be studied in this framework?
By changing the synchronization condition of the clocks of inertial frames, the answer to 1) and 2) seems to be affirmative. This synchronization clearly violates global Lorentz symmetry but it preserves Lorenzt symmetry in the vecinity of each point of the flat spacetime.
We may consider the time of a clock placed at an arbitrary coordinate x to be t and the time of a clock placed at an arbitrary coordinate xP to be tP. Let the offset (t – tP) between the two clocks be:
1) (t – tP) = v (x - xP)/c2
where (t-tP) is the so-called Sagnac correction. If we insert 1) into the time-like component of the Lorentz transformation T = g (t - vx/c2) we get:
2) T = g (tP - vxP/c2)
On the other hand, if we consider the space-like component of the Lorentz transformation X = g(x-vt) we know that the origin of both frames coincide x =X = 0 at t = 0. If we want x = X = 0 at tP = 0 we have to write:
3) X = g(x - vtP)
Assuming that both clocks are placed at the same point x = xP equations 2)3) become:
4) X = g (xP - vtP)
5) T = g (tP - vxP/c2)
which is the local Lorentz transformation for an event happening at point P. On the other hand , if the distance between x and xP is different from 0 and xP is placed at the origin of coordinates, we may insert xP = 0 into 2)3) to get:
6) X = g (x - vtP)
7) T = g tP
which is a change of coordinates that it:
- Is compatible with GPS simultaneity.
- Is compatible with the Sagnac effect. This effect can be explained in a very straightfordward manner without the need of using GR or the Langevin coordinates.
- Is compatible with the existence of relativistic extended rigid bodies in translation using the classical definition of rigidity instead of the Born´s definition.
- Can be applied to solve the 2 problems of the preprint below.
- Is compatible with all experimenat corroborations of SR: aberration of light, Ives -Stilwell experiment, Hafele-Keating experiment, ...
Thus, we may conclude that, considering the synchronization condition 1):
a) We get Lorentz invariance at each point of flat space-time (eqs. 4-5) when we use a unique single clock.
b) The Lorentz invariance is broken out when we use two clocks to measure time intervals for long displacements (eqs. 6-7).
c) We need to consider the frame with respect to which we must define the velocity v of the synchronization condition (eq 1). This frame has v = 0 and it plays the role of an absolute preferred frame.
a)b)c) suggest that the Thomas precession is a local effect that cannot manifest for long displacements.
More information in:
We read and hear everywhere in conferences that QM is time reversible, but even for us laymen, the collapse of the wave function seems quite irreversible. It is also the case for interactions : if we take for example the e- + e+ -> ph + ph ; if you reverse the time the result will not be the initial state of the system since 1) the photons may not interact at all, 2) the result of the interaction may be a different type of particles, 3) the electron/positron pair will be ejected in a different direction.
It seems to me that the laws of QM that are time reversible are all statistical, but their realizations are in practice not time reversible, neither in fact deterministic.
As a beginning to my Masters thesis, I'm seeking to find resources about a single photon behavior in a a Mach-Zehnder interferometer cell.
more generally I'm trying to simulate the nanophotonic processor for quantum computing purposes in the paper bellow.
I would be very happy if anyone could help about the processes that need to be considered in this project.
It is worth mentioning that the preferred platform of simulation is MATLAB but any other simulating software would also be welcomed.
the paper that I mentioned above could be found here:
Hi, I am looking forward for collaborators (academic and research work) who are interested to work in the following area:
Quantum Artificial Intelligence
Internet of Drones
Blockchain and Quantum Computing
Is there a simple proof that the signal and idler photons created by spontaneous parametric down-conversion (SPDC) are entangled, whereas those that are created by optical parametric amplification (OPA) are not? SPDC has been used in the optical band to create entangled photons. A view of this is that the SPDC just amplifies the vacuum (zero-point energy) photon to create a signal photon, whilst an idler photon is created to preserve conservation of energy when the pump photon annihilates. In the OPA process a seed photon is parametrically amplified likewise to create a signal photon and idler photon, whilst the pump photon annihilates. What is the proof therefore that the signal and idler photon pair from OPA are not entangled?
The hydrogen spectral lines are organized in various series. Lyman series are the lines corresponding to transitions targeting the ground state.
Most pictures dealing with hydrogen spectra and available in the web are recordings dealing with extraterrestrial hydrogen sitting in celestial entities. Otherwise they are illustrations obtained not from experimental recordings, but from the well known Rydberg formula.
Of interest for the undersigned are pictures of Lyman series as recorded in laboratory observations of hydrogen atoms, with the atoms sitting in the laboratory itself. Not extraterrestrial hydrogen, nor molecules H2, even if the molecules are sitting nearby.
Presumably such recordings would have required ultraviolet sensitive CCDs, UV photographic plates, or similars. Particularly relevant would be careful raw recordings of Lyman series that INCLUDE THE ALPHA-LINE at 1216 Å.
Experimental remarks about the Lyman alpha-line, difficulties to observe it ---if any---, line width, line broadening, etc., and difficult-to-explain anomalies, are of particular concern. So far Web searching has not been successful.
I would appreciate any link or suggestions as to how to obtain the pictures and experimentally based information of the kind explained above.
Hi, i am sudying some quantum computer science and I am really struggling to find an explanation to the question done above.
Any kind of help would be wonderfull.
The fact that the measurement of vanishing distances is physically impossible, which preempts continuity, may lead us to not consider renormalization as a proper procedure in particle physics.
Also, it may lead us to disconsider it, as not needed to define derivatives using infinitesimals, and use Galois fields instead.
We may be pushing our equations too close, to limits where they probably do not apply, and renormalization just tries to solve the symptoms -- to avoid infinities. But the "problem" remains -- there are no infinitesimals in Nature, nor can be created.
Can we not use a concept that we cannot find nor encounter? Infinitesimals do not exist? Then, is renormalization necessary?
Since band gap energy is related to material size, somehow, the quantum phenomenon could be found in the range of Bohr atomic radius for semicondutor based materials. Did you know about that? How I can collect the data of atomic Bohr radii for photocatalysts?
I have tried to study quantum mechanics before but never understood it. After learning basics about quantum computing and quantum information including quantum hardware and qubit types, I wish to start studying quantum physics again. What are few of the areas of quantum mechanics that Quantum information systems relate or are based on?
The very common experiment in optics to demonstrate that light behaves same as the wave is single-slit diffraction.
If we assume that the thickness of the barriers is 0.1 mm, then the length of a slot along the optical axis will be a long route as a green photon will measure it nearly two hundred times larger than its own size.
Now the question is how the photon behaves along with that long route? Does it behave as a particle or wave? If the exit of the slot or a pinhole is causing photon behaves as a wave then why the entrance wouldn't do that? And if we accept that photon behaves like a wave as it enters the single slit or the pinhole, then formally we should apply the Fresnel diffraction equation from the entry of the slot that will lead us to nowhere.
In my opinion, wave-particle duality is leading us solely to some useful approximation but it doesn't talk about reality, as it cannot explain a sort of experiments that unfortunately have been ignored or left behind such as the glory of the shadow, and also the stretching the shadows when they meet each other and so on.
For sure, wave-particle duality is not the end of science and for sure five hundred years later people will not consider the existence as do we do now the same as us that we don't see the things same as our ancestors, so we should be open-minded to be able to open the new horizons.
In recent research perspective this is very important field. Parity operation is reversal of co-ordinate (x->-x, p->-p)and time reversal operation is reversal of time (x->x,p->-p, i->-i).
But talking about this combined PT-symmetry in any field of science and engineering, what it implies?
The ideas which I have come across are:
- By creating an entangled state between two distant NV centers, by combining the control of multiple qubits in nodes with optical links and then measuring the outcome. This will also help in security as the origin of the state will be unknown to the detectors.
- Using semiconductor transmon qubits, which are to be interacted by quantum gates and using circuit QED, the readout is obtained from a quantum processor.
Taking into account the noise and distortion challenges along with controlling qubits and building the complex software and hardware systems, how will we be able to send and receive large quantum information from one quantum system to another, over very long distances like in millions, for example, for an error-free and undelayed satellite communication?
The superposition principle is moslety used in physical and natural phenomena modeling: The response caused by two or more stimulus is the SUM (integration, average) of the responses that would have been caused by each stimulus individually (Ex: quantum chemistry, chemistry interaction, visual perception, linear system, etc.). These effects happened naturally. I try to understand physical interpretation of Multiplication operation applied to two or more object with similar nature (Ex: waves, functions, forces, etc.). I wonder if there is, for example, linking between "Compression" "Attraction", or "Collision" and the multiplication result of their properties.
I have hands on with IBM quantum experience (QISKIT). I am in exploration phase now. I have studied all the basics related to quantum computing. I am also looking for fully funded Phd in quantum artificial intelligence. I would be happy to help in related research if anyone needs helping hand.
If we consider hypothetically and philosophically, i.e., why we always think light is spreading out. May be dark is fading away as an entity everytime faster than the light. Why faster? Because we haven't detected speed of darkness till now. And I want to connect this concept with Quantum Entanglement. Because according to this concept information is transfered faster than the speed of light between two entity separated by infinite distance. Who knows dark entity may be the answer to Quantum Entanglement??
At first, the answer seems obvious, as E/h = f, where E is the energy of the photon, h is the Planck constant, and f is the frequency of the photon. But then one realizes that the photon would need an infinite duration in order to have a single frequency (e.g., Fourier transform relation, and Heisenberg uncertainty principle).
The probability doctrine of quantum mechanics (QM) asserts that the indetermination, of which we have just given an example, is a property inherent in Nature, and not merely a profession of our temporary ignorance from which we expect to be relieved by a future better and more complete theory.
Such more complete theory appears to be Quantum Field Theory (QFT). The Heisenberg uncertainty principle in QM may then have to be reexamined.
Obviously, then, E/h = f is not the correct answer.
Nothing is infinite in Nature. We can't wait forever to measure a photon, and nothing can. The Universe would not exist.
The answer is to realize that something is wrong with the QM picture of a photon. The frequency of a photon is defined by its physical conditions in QFT, not by itself.
And it is not described by a Fourier transform either, which is a mathematically "continuous" procedure -- with the hypothesis of infinitely close frequencies -- and should never be used to represent a discrete phenomena, or artifacts of the interpolation will appear.
As Juan Weisz asks -- why is QFT better than QM? The answer may be relevant here, as QM is subjective but QFT is intersubjective. Like math, it is not enough to be subjective, as follows.
QM is based on two deep untruths, as revealed by Nature, in addition to the rather formalist easy-to-solve fact that QM is not combining the principles of Lorentz invariance (SR-MINKOWSKI-EINSTEIN). They are:
1. One needs to abandon the single-particle approach of QM (subjectivity). In any relativistic quantum theory, particle number need not be conserved, since the relativistic dispersion relation in SR, that E^2 = c^2p^2 + m^2c^4, implies that energy can be converted into particles and vice versa. This requires a multi-particle framework (intersubjectivity), a many-body interaction with SR included and uses QM. It is a many-body-relativistic-QM, not just QM.
2. Unitarity (basically, preserving the inner product) and causality cannot be combined in a single-particle approach, requires intersubjectivity.
QFT solves these two problems by using a different approach:
A. The fundamental entities are not the particles, but the field, an abstract object that penetrates spacetime.
B. Particles appear as the vibrations of the field.
The physical model of the photon, for example, is given as a vibration of the EM field, and follows QFT. Then, in QFT the frequency of the photon does NOT depend on the photon itself and only (that would be subjective), but on its physical conditions in a many-body-relativistic-QM (intersubjective). Then, that intersubjectivity can obtain objectivity to different observers, in different experiments, at differing spacetimes.
Sean Carroll recently at https://www.youtube.com/watch?v=rBpR0LBsUfM and after the 45 minute mark specially.
The diffraction of light has been referred to as its wave quality since it seemed there was no other solution to describe that phenomenon as its particle quality and subsequently, it exhibited wave-particle duality.
Following well-known books in quantum mechanics (QM), such as "Quantum Mechanics" by Eugen Merzbacher, once influential and authoritative on QM, is today a slippery slope in many parts.
The simultaneous appearance of classical wave and particle aspects no longer can be defended in QM. The only thing that exists in Nature, as we know from quantum field theory (QFT), is quantum waves, NOT particles and NOT waves as in Fourier analysis (classical).
The Heisenberg uncertainty principle in QM seems, thus, to have to be modified -- as it is, in contradiction with itself, based on continuity by using the Fourier transform. Can we express it in QFT terms (not based on continuity)? Can that influence LIGO and other applications?
See also Sean Carroll recently at https://www.youtube.com/watch?v=rBpR0LBsUfM and after the 45 minute mark specially.
Thus, there is only one (not two or even three) case of photon interference in the two-slit experiment, and that is the case that is often neglected -- the quantum wave case. See the two-slit experiment at low-intensity, for example at: https://www.youtube.com/watch?v=GzbKb59my3U
Quantum entanglement experiments are normally carried out in the regime (hf>kT - where T is the temperature of the instrument) to minimise thermal noise, which means operating in the optical band, or in the lower frequency band (<6 THz) with cryogenically cooled detectors.
However, the omnipresent questions are whether in the millimetre wave band where hf<kT:
1) Could quantum entanglement be detected by novel systems in the at ambient temperature?
2) How easy might it be to generate entangled photons (there should be nothing intrinsically more difficult here than in the optical band - in fact it might be easier, as you get more photons for a given pump power)?
3) How common in nature might be the phenomenon of entanglement (this would be in the regimes where biological systems operate)?
Answers to 1) may lead to routes to answering 2) and 3).
For quantum applications we need more coherent wave distribution. To increase the coherency we need some strategies. What do you suggest for this application?
Let's assume that states |1> and |2> are degenerate states and the system is prepared in state |1>. Also, the matrix element of electric dipole moment is not zero between these two states (<1|mu|2>=!0). If we interact this system with vacuum field, does this system remain in its initial state? (I know from Wigner Weisskopf theory that if these two levels were not degenerate and level |1> was the excited state, the system would decay with Einstein rate.)
Assume that you are living in the time when the Gregorian calendar was introduced by Pope Gregory XIII in October 1582, when
Galileo Galilei was about eighteen years old. However, he was tried by the Inquisition, found "vehemently suspect of heresy", and forced to recant 1632, and then he spent the rest of his life under house arrest.
The most noticeable thing in this matter is that people of those years could realize the rotation and subsequently, they could calculate the rate and the duration of the rotation but what was not clear for them was what is rotating around what. At that time what would be your solution?
Now, if I can take this sad historical event as the fact, then I would ask myself if the integral theorem of Helmholtz and Kirchhoff plays a central role in the derivation of the scalar theory of diffraction along with the concept of the wave-particle duality, or it obtains the propagation of light in the diffracted space with an inhomogeneous refractive index?
In solid-state physics, a band gap/energy gap is an energy range in a solid where no electron states can exist. In graphs of the electronic band structure of solids, the band gap generally refers to the energy difference (in eV) between the top of the VB and the bottom of the CB in insulators and semiconductors. It is the energy required to promote a valence electron bound to an atom to become a conduction electron, which is free to move within the crystal lattice and serve as a charge carrier to conduct electric current.
A semiconductor will not absorb photons of energy less than the band gap and the energy of the electron-hole pair produced by a photon is equal to the band gap energy.
The band gap is a major factor determining the electrical conductivity of a solid. Band-gap engineering is the process of controlling/tuning the band gap of a material by controlling the composition of certain semiconductor alloys, such as GaAlAs, InGaAs, and InAlAs. Band gap depends on doping, size, temperature, pressure etc. It is also possible to construct layered materials with alternating compositions by techniques like molecular-beam epitaxy. These methods are exploited in the design of heterojunction bipolar transistors (HBTs), laser diodes and solar cells.
In a quantum dot crystal, the band gap is size dependent and can be altered to produce a range of energies between the valence band and conduction band. Band gap increases with decrease in size due to electron confinement at Nano-scale. It is also known as Quantum confinement effect.
However, I am working on inorganic semiconducting silicide materials for potential applications in solar cells. Beta phase Iron di-silicide (β-FeSi2) has a band gap of about 0.87 eV which can be tuned from 0.8 eV to less than 0.9 eV.
How can we increase its band gap further, beyond 0.9 eV? In particular, can we tune its band gap near to optimum band gap of 1.5 eV for solar energy harvesting?
Hi experts.. Can you explains why the excitation-“dependent” emission of aqueous N-CDs suddenly changed to ”independent” while binding with PVA (solid film). Is this related to PVA nature? Please help And thanks in advance.
In quantum key distribution (QKD) optical fiber networks, the quantum channel (QCh) is used for establishing and updating secure keys which are used to encrypt data . Public interaction channel (PICh) is used for exchanging other key related information . Traditional data channel is used for transmitting encrypted data .
My question is, what are the modulation schemes to be used for QCh and PICh?
I could not find information regarding the modulation scheme in any of the published articles I read. Please answer this question or suggest some articles that contain this information.
Please note that I am not looking for modulation schemes used for transmitting traditional data.
 Zhao, Y., Cao, Y., Wang, W., Wang, H., Yu, X., Zhang, J., Tornatore, M., Wu, Y. and Mukherjee, B., 2018. Resource allocation in optical networks secured by quantum key distribution. IEEE Communications Magazine, 56(8), pp.130-137.
If metamaterials could be designed to have non-linear susceptibilities (magnetic or electric) and phase matching properties for the refractive indices in the mm-wave band they might enable novel quantum processes. In naturally occurring dielectrics non-linear susceptibilities arise in non-centrosymmetric crystals. Perhaps something could be synthesized in synthetic materials. There might be magnetic counterparts to this. Scientists working on metamaterials must have considered this, so where is this at the moment? Comments welcome. N
As you know I had proposed
Achimowicz formulae stating that Information can be transformed to energy by the relation: (1) E = I x c2 in analogy to reasoning that E= m x c2 = h x omega as proposed by Planck
The next step is quantomize information so I shoud write:
E= I x c2 = h x omega
where h - Planck constant and omega is the information frequency.
Next question is : Does DNA have the own frequencies i.e. stable information frequencies at which it resonates?
. So what the quanta of information means ????
What is its interpretation ???
Any one wishing to answer this question ???
I am really confusing at this point, and i really need your help, my question is:
Assume that we have an atomic vapor cell, for example rubidium, and we send a strong linear polarized laser light (which is a coherent state) and at the end of the cell we observe that our polarization is rotated, and then we see that anything that is produced in orthogonal polarization is squeezed state, now i want to consider a full-quantum approach and write the equations and see the rotation of polarization and overall the evolution of the field in my formalism. please note that i want to consider the Zeeman sublevels, and my problem is, how should i consider this interaction between my light with multi-Zeeman-sublevel atoms and find out the rotation of polarization and etc?
Thank you in advance
For the double slit interference (Thomas Young 1901) the distance between the peaks b on the screen is derived by the well known formula b=H.l /D where H is the distance ftom the slits to the screen. D the distance between the slits and l is the wavelenght. So if D is not small (1-2 mm) the visibility of the peaks is unobservable.
Now the same must apply for the distance between the reference beam and points from the object. When this is D in holography and the same formula applies then there must not be intereference visibility - b should be very small. But holography interefernce is visible. How is that? Is there another formula and if yes why? I think holography is the closest to double slit Young experiment?
1. I have been wondering if the state of a quantum system (n) could be represented with a non-integer. I saw a lecture note recently where it was claimed that there is actually no reason why this case will not hold. I would really appreciate your expert opinions and text suggestions. I have attached a file for more information on this.
2. If this case is possible, what are the likely implications for the quantum oscillator.
I would like to put to the critic of the RG participants a hypothesis about the nature of the wave function (WF) - more specifically about WF collapse.
According to it: the particle is a real entity and creates a real wave, which has real nature and is described by the WF. This wave can interract with the particle by changing its trajectory as is evident from double slit and Mach Zehnder interferometer. So far it looks like de Broglie interpretation.
But the WF collapse is explained as impossibility of the wave to interact with the particle after the particle is affected in the process of measurement. After measurement the particle creates a new wave and can interact only with it. Maybe as a prove can be regarded the fact that when the measurement is weak there is partlial visibility of the interference.
Then there are two possibilities about the wave. First - It can not interact with other particles following Diracs sentence that “An electron interferes only with itself”.Then this wave is no more observable. Or can get observable after removing all consequences from the measurent (erasing the measurement). There can maybe offered an experiment (I didn’t thought about).
Second the wave can interfere with another particle provided it is in a state the original particle was in before the measurement. Indication of this are some papers of interference of two lasers and Hong-Mandel-Ou intereference. If this is the case I propose an experiment which may solve the case. The plot is the following file.
WF hipothesis plot.doc
There scheme is checked for D2 and D1 events and t2<t1 and vice versa. That would mean that the particle 1 is not in the right arm of the MZI and the wave had interacted with the second particle.
I would like to know is there an existing interpretation of QM like the presented. I myself never read a similar.
Does the idea show weak points and what?
In fact, I'm working on a thesis project on Quantum Information and precisely on quantum error correcting codes. I just started not long ago my research on the subject, and specifically how one can go from a classical signal to a quantum signal to describe the algorithms of error correction codes in physical channels.
"I thought about quantum mechanics a hundred times more than general relativity, but I still don't understand," Einstein said.
Perhaps the most difficult to understand is the wave-particle duality, which may be because the understanding of it is only in the form of mathematics.In fact, no one can actually verify the wave-particle duality, because the experiment can't verify a single photon.
Electrons orbiting the nucleus of the cycle and the volatility of the particles there are closely linked, we can think of chemical bonds between atoms and atomic are fluctuating, at a certain moment because electronic is only a position on the orbit, and from the time a constantly changing position, the this kind of change has the regularity.When two atoms of electrons near each other, two atoms repel each other, and when electrons in an atom near the nucleus of another atom when they will attract each other, so that can form regularity of volatility.
Inner surface cracks in the double-slit experiment of atom has been in a regular wave conditions, when the particle is trying to through the gap, when near the atom will be fluctuations in the perforated of atomic bomb, a reflection of photonic and electronic electromagnetic ejection in such a state of regular fluctuations, as the accumulation of time and the number of regular interference fringes are formed.The smaller the momentum of a particle is, the larger the Angle of the ejection is, the greater the spacing of the stripes, the longer the wavelength is.
Electronic counter near the double slit to observe, emitting a large number of photon hits the aperture inner surface of atoms, and makes the surface atomic wave interference, can be seen as inhibits such a state of regular wave, the particles will no longer through double slit by regular reflection and ejection, which in turn has emerged two bright stripe.
This is why increasing gap width will not cause interference and diffraction, because of the emitted particles and gap edge contact and collision probability becomes a matter of fact interference and diffraction and crack width, crack of fluctuations, particle momentum, launch position and the Angle of aperture.
I was wondering if graphene plasmonic waveguides could be synergic with some perhaps tunable non-reciprocal photonic devices?
For instance, coupled graphene SPPs with some non-reciprocal phase shift and interference / mode conversion scheme like Aharonov–Bohm effect?
Or could graphene or other 2D materials might possibly utilized in some somewhat tunable non-Hermitian photonics regarding perhaps PT-symmetric/ -broken schemes?
All the research papers I found so far, are just showing measurement of the squeezing parameter or quantum Fisher Information (QFI). Of course authors mention that, due to large QFI or strong squeezing this setup can be used for metrological purposes beyond standard quantum limit (SQL). I could not find any papers, which actually perform estimation of the unknown phase and show that the precision is beyond SQL. I am curious from the point of view of estimation in the presence of decoherence (which is always present). Theoretical papers indicate that entangled states are basically useless if frequency is estimated (e.q. Ramsey spectroscopy).
If one of the two photons of an entangled pair stimulates the generation of a third photon, by stimulated emission, does this destroy the entanglement of the original entangled pair? If it does destroy the entanglement, might there be anyway of using the third photon as a way of maintaining the entangled information. For example, if the stimulating and the simulated photon were both used together in the reception, perhaps the information would remain protected until detection was required.
many thanks, neil
I would like your opinions/solutions to a purportedly paradoxical scheme I propose below.
I wrote down only the bare-bones mathematical description of the scheme (attached file). It employs linear polarization and switching half-wave plates (HWPs).
Here is the summary to accompany the file:
An SPDC source, pumped by a CW/monochromatic laser, creates energy-degenerate product states |HH>. Now, because of the CW/monochromatic pump, the photon pairs are created at random times but the two photons in each pair are created simultaneously and they are strictly correlated in energy. So, if a photon on the left made it past its narrow-band filter (centered on the half-energy of the pump photons), its partner, on the right, will also make it past its (identical) filter.
There are two perfectly synchronized switching HWPs that implement "|H> to |V>" when in the ‘ON’ state and do nothing when in the ‘OFF’ state; one HWP in mode A and one HWP in mode B. The switching interval is significantly longer than the coherence time of the emitted (and still unfiltered) SPDC photons; however, after the HWPs, a subset of the SPDC photons does get filtered and, for this subset (which is the only subset to be detected), the coherence time of the photons is taken to be significantly longer than the switching interval—it is this hierarchy that enables us to superpose the two quantum states corresponding to the two macroscopic HWP states, respectively. Why? Since the coherence time of the filtered photons exceeds the switching interval of the HWPs, it is impossible, even in principle, to determine if the photons encountered the 'OFF' or 'ON' state, since the time-of-creation (and thus the time-of-flight) of these filtered photons is limited to their coherence time.
I consider two cases:
*Alice (left wing) and Bob (right wing) both have their HWPs synchronously switching, resulting in a maximally entangled state 1/sqrt2(|HH>+|VV>) and a mixed single-photon state ½(|H><H|+|V><V|) at either wing.
*Alice keeps her HWP always ‘OFF’ while Bob keeps his HWP switching, resulting in a joint state 1/sqrt2(|HH>+|HV>)=|H>1/sqrt2(|H+V>), which is a product state and Bob’s photon is in a pure state of linear polarization |+>=1/sqrt2(|H+V>) !!
Note: The initial two-photon state is in a polarization product-state, but there is initial entanglement in the time-energy domain; the time-energy entanglement is exploited to create polarization entanglement at Alice's and Bob's sites.
So-called "Light with a twist in its tail" was described by Allen in 1992, and a fair sized movement has developed with applications. For an overview see Padgett and Allen 2000 http://people.physics.illinois.edu/Selvin/PRS/498IBR/Twist.pdf . Recent investigation both theoretical and experimental by Giovaninni et. al. in a paper auspiciously titled "Photons that travel in free space slower than the speed of light" and also Bereza and Hermosa "Subluminal group velocity and dispersion of Laguerre Gauss beams in free space" respectably published in Nature https://www.nature.com/articles/srep26842 argue the group velocity is less than c. See first attached figure from the 2000 overview with caption "helical wavefronts have wavevectors which spiral around the beam axis and give rise to an orbital angular momentum". (Note that Bereza and Hermosa report that the greater the apparent helicity, the greater the excess dispersion of the beam, which seems a clue that something is amiss.)
General Relativity assumes light travels in straight lines in local space. Photons can have spin, but not orbital angular momentum. If the group velocity is really less than c, then the light could be made to appear stationary or move backward by appropriate reference frame choice. This seems a little over the top. Is it possible what is really going on is more like the second figure, which I drew, titled "apparent" OAM? If so, how did the interpretation of this effect get so out of hand? If not, how have the stunning implications been overlooked?
We have a linear chain of 3 trapped ions system (the interaction are taken XX interaction). We want to apply the external local magnetic field to each of this individual ions. Is it possible experimentally?
In the large cavity-laser detuning, the cavity modes can be eliminated adiabatically with the required condition that its decay rate should dominates the other interaction rates present in the system. However, the steady state can be obtained in the large detuning regimes by substituting the time derivative of cavity mode equals to zero( t approaches infinity). Can I correlates these two?
I think that CaSiO3 has direct and indirect band gap. I am trying to know the direct and indirect band gaps of wollastonite( location of BZ point). A band gab of 5.022 eV at gamma (G) point according to LDA (castep code) ( is that direct or indirect band ). There is another interesting minimum conduction band at B point ( is it related to indirect band gap) with valence band minimum at C point . I really need to interpret the results shown in the figure below accurately. any help will be appreciated.
Hi to all,
Consider the following scenario (shown in the attached file):
Two mutually coherent and collimated light beams intersect as shown, creating the depicted 'bright' and 'dark' stationary interference fringes (fig. 'A'). Suppose we insert a very thin (compared to the fringe width) and, ideally, perfectly conducting 'sheet' across, say, the central 'dark fringe'(fig. 'B').
It certainly appears as though we can "cut each of the light beams in two, across an impassable barrier", yet they will persist and continue to freely propagate! This appears to be the case both for 'classical' EM waves as well as quantum-optical wavefunctions. Of course, no infinitely thin and perfectly conducting sheet exists, but it does seem that this effect will remain sufficiently intact under realistic conditions.
Is this possible??
In quantum physics, the no-communication theorem states that it is not possible to transmit information from one observer to another observer, whether entangled or not, by making a measurement of a subsystem of a total state, common to both observers.
Most people think that the theorem is important because it limits quantum entanglement, that separated events cannot be correlated in any way to lead to the possibility of communication.
However, the double-slit experiment  says that what one observer does (e.g. turn on a detector) influences what is detected at the other observer (e.g. the electron did not pass here).
What is your reference or position on this question, could the double-slit experiment be used to negate the no-communication theorem?
Usually, the double slit experiment is viewed as two cases, with the quantum case as a proposed mixture of two classical cases: "The modern double-slit experiment is a demonstration that light and matter can display characteristics of both classically defined waves and particles." However, in a deeper view, there is only one case, the quantum case. The other cases, namely classically defined waves and particles, are NOT real, in the strict sense they do not actually exist!
The question is whether it would better for students to view the double slit experiment not as a Young's experiment but in all its aspects as three cases, particle, wave and quantum, where the quantum case is not somehow a mixture of particle and wave.
I need a feedback on review o myu paper on EMF effects in nonthermal doses on living creatures which is based on storage capacity of DNA. Can reincarnation be explained by physical mechanisms and can DNa MEMORIZE THE KNOWLEDGE OF OUR ANCESTORS ?
Is the following function F:[0,1] to [0,1]
F strictly monotonic increasing F(1)=1,(i presume this unnecessary as its specified by the first two
(1)ie x+y=1 if and only iof F(x)+F(y)=1 F(x)+F(1-x)=1; F-1(x)+F-1(1-x)=1
(2)F homomorphic(2) x+y+z=1 if and only F(x)+F(y)+F(m)= 1
(3) x+y+z+m=1; if and only ifF(x)+F(y)+F(z)+F(M)=1
Give F(x)=x and F continuous (it appears to entail cauchys equation with F(1)=1 over ethe unit triangle due tot he common term). F(x+y)+F(z)=1, F(x)+F(y)+F(z)=1, etc, F(x+y)=1-F(z)=F(x)+F(y)
In the Feymann QED strange theory of light he describes the partial reflection. There he mention that Newton made an experiment which poined for intereference of 34 000 wavelenghts thick transperant glass. Even more Feymann insists that if you use a laser 100 million wavelenghts interference is possible (50 meters thick glass).
1. I tried to find something on Internet about this experiment of Newton but I failed (Newtons experiments were very often not re-created by others). Can some point out where is this considered. Also about this experiments with laser - does somebody made them?
2. As far as I know the QM probabilistic wave is moving at speed of light for photons (by the way the question for a wave with photons is not clear in QM). So how is it possible that the photon would 'know' what happens 50 meters away (as it is reflected from the first surface). This looks suspiciously like breaking the Special Relativity postulate.
Dear all researchers, nowadays i devote myself to solving the optical constant of nanoparticles and recently investigate the K-K model. However, there is one confusing thing that is the calculation of the intrinsic frequency. My idea is that for any particle, since i know E=m*c^2 and E=h*v, is the v calculated here equal to the intrinsic frequency?
During the treatment of the gauge transformations for showing the A(r,t) in the context of Goeppert-Mayer gauge; it is expressed as the difference between the two transverse gauges vector potentials for the light-atom interaction picture, and when we go to derive the Hamiltonian for longer wavelength of the radiation field compared to the average size of the atom, we invoke the long-wavelength approximation which kills the GM gauge vector potential, i.e. the two potentials are equal. Why is that? and how can i derive explicitly this equality for long wavelengths?
In Quantum Computing, there is something known as the Holevo bound - which basically says that a q-bit cannot deliver more than a bit of information into our spacetime, although it can carry more.
The question is - where is the extra information kept?
The usual answer is that the extra info lies embedded in a superimposition of entangled states, and that any accessing of the information destroys the superimposition and with it, the extra information itself.
So far, so good.
But a number of experiments make it appear as far too simple an explanation. For starters, the extra information can be shown to be carried by a single photon, and only a later actualization decision determines which part of the information becomes actualized within our spacetime (so that the above explanation would necessitate a photon superimposed with itself, which then leads to a superimposition of spacetime). In other words, a form of time travel must be allowed (the photon being then 'told' by its future state which part of the information it should carry and which part it should not even take on board.)
But in other experiments (Michael Goggin et al.), the time travel possibility is not enough to explain what is going on, and the inescapable conclusion is that the photon not only carries more info than is accessible, but more information that could be stored in simple particle superimposition states.
Where is that information?
Is it carried in a parallel universe, as David Deutsch says, and therefore inaccessible to us in this space time?
Or, as Hamlet famously put it, is there more to it than we conceptualize, and the parallel universe idea is nothing but a reflection of our tendency to think in familiar boxes, and space time itself an illusion, woven by quantum correlations which are more fundamental than spacetime itself? (Spacetime being then, in effect, a byproduct of quantum correlations, which pops up when choices are made and the other latent possibilities become thus barred from becoming realized)? If the latter view is the case, then how many Spacetimes are precipitated that way, and does this explanation then, in effect, rejoin David Deutsch's?
The realism hypothesis in QM says that results of measurements on quantum systems, are completely determined by subquantal parameters (hidden or detectable, local or non-local). These parameters are supposed to get definite values before the measurement.
Is there an experiment that rules out the realism hypothesis? Please pay attention: realism does not necessarrily mean locality. Local realism was already disproved. My question is general, it refers to real factors, eventually non-local.
NOTE: at my question "Is the locality assumption necssary in Bell's inequality?", a polemic began about the particular issue whether Bohm's mechanics is correct or not. I invite all those who want to participate to that polemic, to post their comments here, not at that question.
When a spin possessing particle is in magnetic field B the spin 'rotates' around B. By example electron with spin on X will rotate perpendicular to B. But is this real? Can it be observed? Does this precession change the current in the coil creating B?
Secondly I tried to find out something about the classical situation. E.g. a compass must classically rotate then around B even when its blades are perpendicular to B. But than I could not find anything. Also it will look like perpetum mobile.
Thirdly I didn't see or can read about small magnets precessing around B? The spins must look like small magnets but there is nothing to confirm this?? And less about their effect on the B? Do really small magnet move precessingly around B and does this show up on the current of the coil?