Duda Jarek

Being able to build gamma laser ( https://en.wikipedia.org/wiki/Gamma-ray_laser ), fusion could be trivial - e.g. 782 keV photons to reverse neutron decay: producing free neutrons from hydrogen. However, it is technically extremely difficult, for free electron lasers maybe 30keV might be reachable, here is 14.4keV for nuclear transition: https://journals.aps.org/prresearch/abstract/10.1103/PhysRevResearch.4.L032007

Talk about such potential more symmetric enhancement of quantum computers allowing to attack NP problems ( https://arxiv.org/pdf/2308.13522 , slides ) :

Separate paper about such 2WQC: https://www.researchgate.net/publication/372677599_Two-way_quantum_computers_adding_CPT_analog_of_state_preparation As stimulated emission-absorption are CPT analogs, creating negative-positive radiation pressure ( https://en.wikipedia.org/wiki/Radiation_pressure#Radiation_pressure_from_momentum_of_an_electromagnetic_wave ), we can imagine (unidirectional) ring laser as a pump. Below is such hydrodynamical analog - in pump with fluid running in circles, flow to split down is reduced by negative radiation pressure. The question to test is if it also true for ring laser: if intensity from beam splitter down is changed by opening/closing the shutter? If so, a bit more complex setting would lead to two-way quantum computers.

Optical pulling allows to pull in optical tweezers, negative radiation pressure to pull solitons - some hypothetical application: 2WQC (two-way quantum computers) maybe solving NP problems (standard 1WQC might be bounded with e.g. Shor, Grover). I would gladly discuss and generally am searching for collaboration in these topics, especially access to ring laser to test if it allows for negative photon pressure, what is required e.g. by CPT symmetry.

In CPT perspective the absorption equation would act on CPT(target on the left), what means emission equation acts on it in standard perspective (no CPT). This equation work only if there are excited atoms: N_2 > 0, hence we can use e.g. a lamp here continuously excited in corresponding spectrum - usually deexciting in isotropic way, opening the shutter additionally with the emission equation - increased probability of deexciting toward the laser, what would be seen as reduced intensity by detectors around.

Looking at the diagram, absorption equation applies to the central and right targets (shifted behind right mirror), the emission equation to the central - the question is if also to the left (shifted behind left mirror). From CPT perspective the equations would switch, the absorption equation would apply to CPT(central target) and to CPT(target on the left) - the latter means without CPT the emission equation would apply to the target on the left. While <E x H>/c radiation pressure can be negative (e.g. https://scholar.google.pl/scholar?q=negative+radiation+pressure ), turns out there are lots of optical pulling experiments, beside optical tweezers awarded with 2018 Nobel Prize, here is good summary: https://opg.optica.org/oe/fulltext.cfm?uri=oe-31-2-2665&id=525052 Seems all of them is pulling of objects with light, while ring laser should have related by different - pulling of photons, negative photon pressure, external stimulated emission.

Exactly, excited target usually deexcite in isotropic way, due to laser should additionally accordingly to the stimulated emission equation on the left - negative radiation pressure should increase probability of deexcitation in this direction, reducing monitored intensity seen by detectors around this target.

By "CPT(target on the left)" I have meant with applied all 3 symmetries. Or let us look from perspective of of radiation pressure : <E x H>/c, if ring laser creates positive radiation pressure, from perspective after CPT doesn't it mean negative?

From perspective after CPT symmetry the photons would travel toward CPT(target on the left) - if physics works the same after this symmetry, toward "minus time" this target would be excited accordingly to equation on the right, what toward "plus time" means it would be deexcited accordingly to the equation on the left ... if only it was excited in the first place like lamp: N_2 > 0. As ring laser causes "positive radiation pressure" in one direction, from perspective after CPT it means causing "negative radiation pressure".

Also, pulling with photons is done e.g. by https://en.wikipedia.org/wiki/Optical_tweezers EM radiation pressure is <E x H>/c ( https://en.wikipedia.org/wiki/Radiation_pressure#Radiation_pressure_from_momentum_of_an_electromagnetic_wave ) - doesn't have to be positive.

Turns out there is considered "negative radiation pressure" - predicted for solitons, searched e.g. for mechanical waves on graphene: https://scholar.google.pl/scholar?q=negative+radiation+pressure ... so the question is if it could be realized with EM waves, photons using lasers? Because believing in CPT symmetry, from its perspective photon trajectories would be reversed, the target on the left would be "standard target" to which we "push photons" (absorption equation), what from perspective without CPT would mean emission equation, "pulling photons", "negative radiation pressure".

The T transform here reverses photon direction, making the laser cause excitation of target on the left, what means causing deexcitation without T symmetry. Look at the two equations (from https://en.wikipedia.org/wiki/Stimulated_emission#Mathematical_model ) - to which of 3 targets they apply? The equation on the right applies to the central and right target. The equation on the left applies to the central target - my point is it also symmetrically applies to the target on the left - because in perspective after CPT symmetry the equations are switched.

The CPT theorem says that looking at setting from perspective after CPT symmetry, it should be governed by the same physics. For the discussed setting with asymmetric light source, in perspective after CPT symmetry the two target would be switched, laser would increase the number of excited atoms in the target on the left - toward negative time, what means decrease toward positive time. In other words, it should stimulate emission from this target - not only when it is the central pumped crystal, but also when it is shifted left.

To observe the dN_2/dt = -B rho N_2 evolution, we need N_2 > 0 initial excitation of the target - e.g. gas discharge lamp. Its continuously excited atoms normally deexcite in isotropic way, the laser should additionally increase probability of directional deexcitation - what would be seen by detectors around, watching isotropic radiation, by reduction of seen light intensity.

Mathematically, we have the two equations (from https://en.wikipedia.org/wiki/Stimulated_emission#Mathematical_model ), after CPT they would be switched: the right one (absorption equation) would apply to the target on the left, what without CPT means the emission equation should apply to the target on the left. In other words, while laser causes absorption by target on the rights ("push photons" there"), CPT symmetry says it has to also cause emission by target on the left ("pull photons" from there) - if only N_2 > 0: satisfied condition of being excited in the first place, e.g. lamp. To my knowledge, existence of such effect was not tested yet (?) - negative result would mean macroscopic violation of CPT symmetry, positive would lead to lots of new possibilities/applications.

From perspective after CPT symmetry, you would cause excitation of atoms of target on the left, what means causing deexcitation in perspective without CPT - sure polarized beam would mean pumping/unpumping one polarity, there should be also unpolarized settings, e.g. using free electron laser, wiggler/undulator, synchrotron radiation.

CPT violation would be not seeing this looking unknown effect required by CPT symmetry - that as we "push photons" to the target on the right, we should also symmetrically "pull photons" from the target on the left - because from perspective after CPT transform, we would "push photons" to this target. I also suspect this effect is true, but it needs experimental confirmation - if positive, it would open lots of new possibilities, applications. E.g. in case of low probability nuclear transition producing characteristic gammas, we could "pull them" this way e.g. with free electron laser - hopefully stimulating this nuclear transition. In case of negative result: preparing setting able to see effect on expected level but not seeing it, would mean violation of CPT symmetry on macroscopic level - that macroscopic setting does not work the same in perspective after CPT symmetry. Such credible negative result should also inspire further experiments - improving on potential limitations, searching for the scale where CPT starts being violated and its mechanisms.

Indeed stimulate the target to emit/deexcite, like pulling photons out of it - suggested by symmetry (T/CPT) ... if possible could lead to lots of new applications, e.g.: - new calculation possibilities e.g. for quantum computing, - low probability nuclear transitions - if they produce some characteristic gammas, then they could be stimulated by such caused deexcitation - these high energy photons are available e.g. in free electron lasers, wigglers/undulators in synchrotron ... also in standard laser setting using above Einstein's equation. Which nuclear transitions would be the most interesting, practical? - similarly for chemistry - probably useful for many technological processes ...

To test application of the emission formula for the target on the left, it needs to be initially excited - e.g. a lamp. In this case it would deexcite in isotropic way - the question to test is if there is additional deexcitation caused by the laser, what would be seen by detectors around: in this case getting a lower power of light.

The polarization might be interesting to try to use it to stimulate deexcitation of one polarization of atoms, what might allow e.g. for CPT analogue of state preparation for quantum computing. The basic test is for nonpolarized target: if the formula on the left applies also to the target on the left, as suggested by CPT symmetry switching the targets. The main difficulties of such test is requirement of high N_2/N excited population, and that the asymmetry is imperfect - some percentage of photons travel in the opposite direction, exciting our target. You are writing about the central target (pumped crystal) - to which both equations apply. The question is about the left/right targets - CPT symmetry suggests both should have corresponding formula.

Here is another perspective on the ring laser setting using formulas from https://en.wikipedia.org/wiki/Stimulated_emission There are two (Einstein's) formulas - for absorption it applies to the central target (pumped crystal), and the standard target on the right. The symmetric emission formula is considered only for the central target. However, in perspective after CPT symmetry the targets and equations would switch - hence emission formula should also symmetrically apply to the target on the left - stimulate its deexcitation (if satisfying condition of being excited). Some potential applications of such suggested by CPT symmetry stimulated deexcitation, intuitively "pulling of photons": - low probability nuclear transitions - if they produce some characteristic gammas, then they could be stimulated by such caused deexcitation - these high energy photons are available e.g. in free electron lasers, wigglers/undulators in synchrotron ... also in standard laser setting using above Einstein's equation. Which nuclear transitions would be the most interesting, practical? - similarly for chemistry - probably useful for many technological processes (which ones?). - maybe stimulated proton decay - ultimate energy source: complete matter -> energy transition, ~100x energy density than fusion from any matter. Violation of baryon number is required e.g. by baryogenesis, Hawking radiation. They cannot observe it in room temperature water, but maybe it is a matter of proper conditions, like pulling photons of characteristic energies by some powerful free electron laser? Could use normal laser setting. - ?

Deexcitation is time/CPT reversal, analogue of excitation - here caused by the action of laser.

Isn't it lots of microscale tests? The CPT symmetry seems nonintuitive especially due to time symmetry, e.g. applying it to macroscopic scenario with clear causality, naively it should reverse causality, e.g.: CPT(laser causes excitation of target) = CPT(laser) causes deexcitation of CPT(target) microscopically: CPT(stimulated emission) in laser = stimulated absorption Is it true? If so, it could bring lots of applications, but seems unknown ...

Thanks for the list, so I think we agree CPT should be true also in macroscale - but were there experiments really testing macroscopic CPT? If not, maybe it is worth to design and conduct such tests - like proposed, using time-asymmetric light sources e.g. ring laser or free electron laser. The only nonstandard in the discussed setting is being "behind" instead of "in front" of the source of coherent light ... but becoming proper "in front" when looking from perspective after applying CPT symmetry. This way we would ask physics if it works the same after applying CPT. Microscopically, while e.g. laser cooling is CPT analogue of laser heating, we are asking if there exists CPT analogue of stimulated emission - some stimulated absorption.

Because in CPT transform of this setting, photon directions would be reversed - laser would excite this target: increase probability of its atoms being excited. Hence returning from CPT, it translates into increased probability of these atoms being deexcited.