On Mon, 15 Jul 2024 22:41:06 +0200, Jeroen Belleman
<jeroen@nospam.please> wrote:

On 7/15/24 20:08, john larkin wrote:

On Mon, 15 Jul 2024 19:38:43 +0200, Jeroen Belleman
<jeroen@nospam.please> wrote:

On 7/15/24 18:20, Don wrote:

The Huntsville Hamfest, scheduled for Saturday & Sunday August 17 & 18, 2024,
will offer this interesting forum:

Understanding Quantum Entanglement - Hans G. Schantz, Ph.D., KC5VLD

Quantum entanglement occurs when two particles become
interconnected in such a way that the state of one particle
instantly influences the state of the other, regardless of
the distance separating them. This phenomenon was famously
described by Albert Einstein as "spooky action at a distance." >>>>> Applications include Quantum Key Distribution (QKD) [...]

I *do* wish that they'd stop that nonsense. More correct
would be to say that the *measurement* of the state of
one particle instantly changes the *description* of the
state of the other. There is no spooky action at a distance.

Jeroen Belleman

If one particle measures as having polarization UP, the other measures
DOWN. But if one is LEFT, the other is RIGHT.

That's spooky!

But that is not how it works! What you'd rather find is that
when you collect many measurements with aligned polarization
axes, the measurements are correlated, whereas when you do it
with orthogonal axes, they are not. The correlation varies
with the cos^2 of the angle between the axes.

Jeroen Belleman

Yes, but how do they know if you are going to measure up/down or
left/right?

Don wrote:

Jeroen Belleman wrote:

Don wrote:

The Huntsville Hamfest, scheduled for Saturday & Sunday August 17 & 18, 2024,
will offer this interesting forum:

Understanding Quantum Entanglement - Hans G. Schantz, Ph.D., KC5VLD >>>>
Quantum entanglement occurs when two particles become
interconnected in such a way that the state of one particle
instantly influences the state of the other, regardless of
the distance separating them. This phenomenon was famously
described by Albert Einstein as "spooky action at a distance."
Applications include Quantum Key Distribution (QKD) and ultra-
secure quantum communication. Challenges include maintaining
entanglement over long distances and dealing with decoherence
(loss of quantum coherence). Although the cost and complexity of
quantum communications currently limit the ability of amateur
radio operators to exploit this emerging technology, amateur
radio operators should keep informed and see if advanced
concepts can inspire new ideas and innovative approaches within
amateur radio practice.

<https://hamfest.org/wp-content/uploads/2024/07/Hamfest-Forum-List-2024-07-11a.pdf>

I *do* wish that they'd stop that nonsense. More correct
would be to say that the *measurement* of the state of
one particle instantly changes the *description* of the
state of the other. There is no spooky action at a distance.

"a few Pedants, who, most of them, being conscious of
their Ignorance, conceal'd it with hard Words"

<https://www.persee.fr/doc/rbph_0035-0818_2009_num_87_2_7676#rbph_0035-0818_2009_num_87_2_T7_0353_0000>

Schantz's nomeclature works best for me. Here's one of his papers published >> by the Royal Society of London:

<https://royalsocietypublishing.org/doi/10.1098/rsta.2017.0453>

If you think that pointing out the difference between a mathematical
model of a probabilistic process and the actual process is being
pedantic, then think about this: The average value of many dice
throws is 3.5, but how many individual throws will yield that value?

QM is a probabilistic theory. It gives you the mean and distribution
of a large number of measurements, not the result of any single
event.

Don wrote:

The Huntsville Hamfest, scheduled for Saturday & Sunday August 17 & 18, 2024,
will offer this interesting forum:

Understanding Quantum Entanglement - Hans G. Schantz, Ph.D., KC5VLD

Quantum entanglement occurs when two particles become
interconnected in such a way that the state of one particle
instantly influences the state of the other, regardless of
the distance separating them. This phenomenon was famously
described by Albert Einstein as "spooky action at a distance."
Applications include Quantum Key Distribution (QKD) [...]

I *do* wish that they'd stop that nonsense. More correct
would be to say that the *measurement* of the state of
one particle instantly changes the *description* of the
state of the other. There is no spooky action at a distance.