7 ms·

I wonder what would happen if you sent the two entangled light beams through the double slit experiment, one through each slit. (I am not a physicist, this migh

I wonder what would happen if you sent the two entangled light beams through the double slit experiment, one through each slit. (I am not a physicist, this might be stupid) What are the practical uses for an entangled light beam vs existing entangled particles?

plank 4y ago
Not much. Yes, e.g. the phase of a photon from beam 1 may be highly correlated with the phase of the second (or, e.g. the polarisations may be highly correlated), but they will still behave as two particle beams. (Yes, I am a physicist, at least I was 30 years ago;-0).
- endofreach 4y ago
  May I ask why „30 years ago“?
  - adastra22 4y ago
    No OP, but another former physicist. There's not much career opportunity in that field, but physicists are eminently hireable in software engineering or investment banking.
    - was_a_dev 4y ago
      Current Physics PhD student here. Pretty much this is the case. Trying to not get spun out of academia is hard work, due to the limited opportunities. Especially is you're unable to move beyond your own country. Then the temptation of other jobs that easily pay three, four, fives times the salary creep in.
      - adastra22 4y ago
        And FAANG or investment banking pays even higher than then that.
        was_a_dev 4y ago
        Potentially, there's a lower glass ceiling in the UK
        adastra22 4y ago
        In engineering, probably not so much in banking. Unless you mean class barriers.
        was_a_dev 4y ago
        I mean SE salaries aren't what you'd get in the US for FAANG. Banking in the city is probably the higher paid job in the UK
  - plank 4y ago
    Did my PhD, when I started my studies there were 90 new students each year. Upon my promotion there were 30, and the faculty had merged(!). One of the groups (experimental, not my cup of tea) had been cancelled/stopped. I went into IT. A standard joke I used to say is that everyone who knows something about garden gnomes could go into IT. I knew nothing about garden gnomes (but learned myself C++ to [numerically] solve some nasty path integrals using object orientation) and easily adopted to the IT industry. (Started as a programmer, through DBA work (datawarehouse!), different software/data/business architecture, now a ‘portfolio manager’). I stopped being a physicist in 1997, so perhaps 30 year is overdoing it (26th year now, I guess).
- l33tman 4y ago
  Apparently there can be interference effects between two beams (4th order interference) so maybe such an effect could show up in this case. See Ghosh/Mandel 1987 "Observation of Nonclassical Effects in the Interference of Two Photons"
- Beltiras 4y ago
  How does one go about not being a physicist anymore?
- tomcam 4y ago
  Username almost checks out
  - plank 4y ago
    Yes, my name is another anekdote. (I had a summer school in Krete, Greece; there were people from the Max Planck institute. And yes, I probably made an impression as the organisers used the spelling of my last name to write down the emailadresses of those from the PlanCk institute;-0. But no, no known relation with Dr. Planck, would have been honored (did do my PhD in quantum optics, so in a related field I guess).
    - tomcam 4y ago
      Was hoping it was something close to that. DAMN quantum optics. That dissertation must have been a pile of work.
Laremere 4y ago
Not a physicist, but if you put one beam through each slit, it's no longer the double slit experiment. Instead it's just two single slits. So no interference pattern, just two spots of light.
DJPocari 4y ago
Kudos to you for accepting that it might be stupid. A lot of people say things with complete certainty these days when what they're talking about isn't in their area of expertise.
- blooalien 4y ago
  > "A lot of people say things with complete certainty these days when what they're talking about isn't in their area of expertise." Far more frustrating and annoying is when people like that say things that are blatantly and provably wrong with complete certainty to an expert in the field and then actively refuse to hear any explanation or proof of the reality of the situation.
  - deleted 4y ago
    [deleted]
  - detrites 4y ago
    Far more annoying, is when an expert is so mired in their professions dogma they lead those trusting them astray. The label "expert" is itself a counter to the skepticism and humility required to reliably maintain a grasp on reality.
    - empyrrhicist 4y ago
      Unless that's being assessed by a "skeptic" who literally can't do the math required to fully understand the topic they're being skeptical about.
      - mistermann 4y ago
        Tautologies are correct by definition, experts are not. Based on my observations they seem to be usually perceived as correct by definition, but that [culturally trained and regularly reinforced] perception, and the methodology that produces it, is technically incorrect.
lisper 4y ago
Not exactly what you asked, but you might find this interesting nonetheless: https://www.youtube.com/watch?v=dEaecUuEqfc https://www.youtube.com/watch?v=dEaecUuEqfc (Or https://flownet.com/ron/QM.pdf https://flownet.com/ron/QM.pdf if you don't want to sit through a video.)
ablatt89 4y ago
As others have mentioned, the double-split experiment is interesting in that when you leave a quantum system alone and let it travel through the double slit experiment, the interference pattern occurs. If you "force" an entangled system into a particular slit, then you don't have a quantum entangled system by definition; the entanglement comes from the quantum interaction of the system and how we can only describe it via an entangled wave function. I think in terms of practical use cases, generally for entanglement, it allows for high amounts of encoding since the particular basis used to describe each individual constituent becomes coupled with one another e.g. (|PsiA, PsiB> = (|A1> + |A2> + ... + |An>) * (|B1> + B2> + ... + |Bn>)) allow for a high number of configurations of a problem space to be encoded. I suppose there could be some interesting optical phenomena used for optical experiments/pulsed lasers but you'd probably need to discuss this with an optics expert :-)
blackpanda 4y ago
What would happen if you send one beam through double-slit and see how the other beam projects. Would it also form a pattern as the first one?

plank 4y ago

Not much. Yes, e.g. the phase of a photon from beam 1 may be highly correlated with the phase of the second (or, e.g. the polarisations may be highly correlated), but they will still behave as two particle beams. (Yes, I am a physicist, at least I was 30 years ago;-0).

endofreach 4y ago
May I ask why „30 years ago“?
- adastra22 4y ago
  No OP, but another former physicist. There's not much career opportunity in that field, but physicists are eminently hireable in software engineering or investment banking.
  - was_a_dev 4y ago
    Current Physics PhD student here. Pretty much this is the case. Trying to not get spun out of academia is hard work, due to the limited opportunities. Especially is you're unable to move beyond your own country. Then the temptation of other jobs that easily pay three, four, fives times the salary creep in.
    - adastra22 4y ago
      And FAANG or investment banking pays even higher than then that.
      - was_a_dev 4y ago
        Potentially, there's a lower glass ceiling in the UK
        adastra22 4y ago
        In engineering, probably not so much in banking. Unless you mean class barriers.
        was_a_dev 4y ago
        I mean SE salaries aren't what you'd get in the US for FAANG. Banking in the city is probably the higher paid job in the UK
- plank 4y ago
  Did my PhD, when I started my studies there were 90 new students each year. Upon my promotion there were 30, and the faculty had merged(!). One of the groups (experimental, not my cup of tea) had been cancelled/stopped. I went into IT. A standard joke I used to say is that everyone who knows something about garden gnomes could go into IT. I knew nothing about garden gnomes (but learned myself C++ to [numerically] solve some nasty path integrals using object orientation) and easily adopted to the IT industry. (Started as a programmer, through DBA work (datawarehouse!), different software/data/business architecture, now a ‘portfolio manager’). I stopped being a physicist in 1997, so perhaps 30 year is overdoing it (26th year now, I guess).
l33tman 4y ago
Apparently there can be interference effects between two beams (4th order interference) so maybe such an effect could show up in this case. See Ghosh/Mandel 1987 "Observation of Nonclassical Effects in the Interference of Two Photons"
Beltiras 4y ago
How does one go about not being a physicist anymore?
tomcam 4y ago
Username almost checks out
- plank 4y ago
  Yes, my name is another anekdote. (I had a summer school in Krete, Greece; there were people from the Max Planck institute. And yes, I probably made an impression as the organisers used the spelling of my last name to write down the emailadresses of those from the PlanCk institute;-0. But no, no known relation with Dr. Planck, would have been honored (did do my PhD in quantum optics, so in a related field I guess).
  - tomcam 4y ago
    Was hoping it was something close to that. DAMN quantum optics. That dissertation must have been a pile of work.

Laremere 4y ago

Not a physicist, but if you put one beam through each slit, it's no longer the double slit experiment. Instead it's just two single slits. So no interference pattern, just two spots of light.

DJPocari 4y ago

Kudos to you for accepting that it might be stupid. A lot of people say things with complete certainty these days when what they're talking about isn't in their area of expertise.

blooalien 4y ago
> "A lot of people say things with complete certainty these days when what they're talking about isn't in their area of expertise." Far more frustrating and annoying is when people like that say things that are blatantly and provably wrong with complete certainty to an expert in the field and then actively refuse to hear any explanation or proof of the reality of the situation.
- deleted 4y ago
  [deleted]
- detrites 4y ago
  Far more annoying, is when an expert is so mired in their professions dogma they lead those trusting them astray. The label "expert" is itself a counter to the skepticism and humility required to reliably maintain a grasp on reality.
  - empyrrhicist 4y ago
    Unless that's being assessed by a "skeptic" who literally can't do the math required to fully understand the topic they're being skeptical about.
    - mistermann 4y ago
      Tautologies are correct by definition, experts are not. Based on my observations they seem to be usually perceived as correct by definition, but that [culturally trained and regularly reinforced] perception, and the methodology that produces it, is technically incorrect.

lisper 4y ago

Not exactly what you asked, but you might find this interesting nonetheless: https://www.youtube.com/watch?v=dEaecUuEqfc https://www.youtube.com/watch?v=dEaecUuEqfc (Or https://flownet.com/ron/QM.pdf https://flownet.com/ron/QM.pdf if you don't want to sit through a video.)

ablatt89 4y ago

As others have mentioned, the double-split experiment is interesting in that when you leave a quantum system alone and let it travel through the double slit experiment, the interference pattern occurs. If you "force" an entangled system into a particular slit, then you don't have a quantum entangled system by definition; the entanglement comes from the quantum interaction of the system and how we can only describe it via an entangled wave function. I think in terms of practical use cases, generally for entanglement, it allows for high amounts of encoding since the particular basis used to describe each individual constituent becomes coupled with one another e.g. (|PsiA, PsiB> = (|A1> + |A2> + ... + |An>) * (|B1> + B2> + ... + |Bn>)) allow for a high number of configurations of a problem space to be encoded. I suppose there could be some interesting optical phenomena used for optical experiments/pulsed lasers but you'd probably need to discuss this with an optics expert :-)

blackpanda 4y ago

What would happen if you send one beam through double-slit and see how the other beam projects. Would it also form a pattern as the first one?