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https://phys.org/news/2019-05-entangled-photon-gyroscope-classical-limit.html
On 2019-05-18 05:28, Tim Williams wrote:
https://phys.org/news/2019-05-entangled-photon-gyroscope-classical-limit.html
I think that 'entangled photons' in engineer speak translates
into 'synchronous detection'. We all know the advantages of that.
"Jeroen Belleman" <jeroen@nospam.please> wrote in message
news:qbp6mu$1ej6$1@gioia.aioe.org...
On 2019-05-18 05:28, Tim Williams wrote:
https://phys.org/news/2019-05-entangled-photon-gyroscope-classical-limit.html
I think that 'entangled photons' in engineer speak translates
into 'synchronous detection'. We all know the advantages of that.
After all, "entangled" just means interference in a system. It's in a
different direction (with respect to particles) than classical
interference (time or space). And articles reporting on it almost
always get it wrong, so there's that. :^)
On 18/05/2019 17:33, Tim Williams wrote:
"Jeroen Belleman" <jeroen@nospam.please> wrote in message
news:qbp6mu$1ej6$1@gioia.aioe.org...
On 2019-05-18 05:28, Tim Williams wrote:
https://phys.org/news/2019-05-entangled-photon-gyroscope-classical-limit.html
I think that 'entangled photons' in engineer speak translates
into 'synchronous detection'. We all know the advantages of that.
After all, "entangled" just means interference in a system. It's in a
different direction (with respect to particles) than classical
interference (time or space). And articles reporting on it almost
always get it wrong, so there's that. :^)
I think in this case it means making the system exactly symmetric with
an equal and opposite pair of entangled photons having better properties
in terms of their precise frequency when they are combined.
In simple terms classically if you have two photons frequency phi(v) and
phi(v+dv) going around the system opposite ways interfering at the end.
But if you can make an entangled mix of them then you get two entangled
photons both with frequencies phi(v+dv/2) to first order anyway.
On 5/19/19 6:42 AM, Martin Brown wrote:
On 18/05/2019 17:33, Tim Williams wrote:
"Jeroen Belleman" <jeroen@nospam.please> wrote in message
news:qbp6mu$1ej6$1@gioia.aioe.org...
On 2019-05-18 05:28, Tim Williams wrote:
https://phys.org/news/2019-05-entangled-photon-gyroscope-classical-limit.html
I think that 'entangled photons' in engineer speak translates
into 'synchronous detection'. We all know the advantages of that.
After all, "entangled" just means interference in a system. It's in a
different direction (with respect to particles) than classical
interference (time or space). And articles reporting on it almost
always get it wrong, so there's that. :^)
I think in this case it means making the system exactly symmetric with
an equal and opposite pair of entangled photons having better properties
in terms of their precise frequency when they are combined.
In simple terms classically if you have two photons frequency phi(v) and
phi(v+dv) going around the system opposite ways interfering at the end.
But if you can make an entangled mix of them then you get two entangled
photons both with frequencies phi(v+dv/2) to first order anyway.
I haven't read the paper yet, but FWIW almost all such schemes that I've
seen can in principle improve the SNR over the shot noise *with the same
laser power*.
Since the shot-noise-limited SNR increases linearly with laser power,
it's usually better (and always much easier) to just hit it harder.
There's a technique called 'quantum illumination' that I don't
understand very well, but which gets quantum SNR benefits without being
so very sensitive to path loss (as with squeezed states, which unsqueeze
again with only a few dB of path loss).
Cheers
Phil Hobbs
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510
http://electrooptical.net
https://hobbs-eo.com
https://phys.org/news/2019-05-entangled-photon-gyroscope-classical-limit.html
Thoughts?
Tim
--
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Design
Website: https://www.seventransistorlabs.com/
On Friday, May 17, 2019 at 5:28:11 PM UTC-10, Tim Williams wrote:
https://phys.org/news/2019-05-entangled-photon-gyroscope-classical-limit.html
Thoughts?
Tim
--
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Design
Website: https://www.seventransistorlabs.com/
I read most of the article
"Entanglement-enhanced optical gyroscope" by
Matthias Fink , Fabian Steinlechner ,
Johannes Handsteiner, Jonathan P. Dowling
Thomas Scheidl, & Rupert Ursin
The entanglement buzz-word here means that a
single photon emission from an atom is close
to the place where a second photon was already
emitted. They are created out of bonds that
touch each other in a crystal at -250 degrees C.
Detecting the single photon coming from one
glass fiber is done simultaneously with detecting
one photon from another glass fiber. That is
very difficult unless few photons are being used.
Effectively, only two photons are used in any
microsecond of measurements. The authors emphasize
that single photons are not measured, but thousands
of entangled photons together are measured. So
it is only a statistically significant entanglement
of large numbers of pairs that is used, and a pair is
not useable in this paper.
At room temperature, with a two photon limit,
the measurement should occur in a picosecond.
Then it is practical. The problem is that
standard science uses ancient algebra to describe
quantum physics, when that is a sterile,
oversimplified model. Experiments, not standard
theory, is their only hope for making a
product. Or a new theory using 8D geometry.
The authors write, "the resulting measurement advantage
is based on the collective behavior of N photons.
That is, all N photons are in an equal superposition
of being in either one of the two modes of an interferometer,
resulting in a shortened de-Broglie wavelength".