I believe photons are one of the most important elements in nature.

There wouldn't be any science without theme.
Only theories.
And awfully dark.
Which reminds me of the upcoming winter...

To be or not to be, is that superposition?

The Sun is shining over Italy at the moment. Much the better for photovoltaics plants.
Tullio

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The Sun is shining over Italy at the moment. Much the better for photovoltaics plants.
Tullio

Indeed.
Plants "eat" photons and we animals eat plants:)

|2b> or not |2b> is true

An attempt to explain superposition.
Photons can act like both a particle and a wave depending how you measure it.
Lets say you have CD disk with lots of bits of information.
Then use a laser, with a lens and let a beam of light, light it with one photon.
Now if you measure the reflection of that photon in all directions you will find out all bits on the CD.

The laser is reading zero's and one's.

Super-position is a mathematical construct formed by multiplying vectors and their conjugates by imaginary numbers. The amplitudes of these vectors when squared are said to be the probabilities of the vector states. We shall see if it can be properly related to physical structures and logic in the quest for understanding of Quantum computing. At the moment my knowledge is somewhat shallow: as I read and watch more and more it should become deeper.

The best book I know on quantum mechanics is "Quantum mechanics" by Albert Messiah. I have the original French edition. The book by Dirac does not cover the Schroedinger representation, which is the most used also by chemists and molecular biologists.All organic chemistry is based on the Schroedinger equation, integrated by numerical methods, such as the Hartree-Fok and the density functional theory.
Tullio

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Crucial hurdle overcome in quantum computing

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Next is the toughest part: how to go from a laboratory esperiment to mass production of microchips with quantum qubits. How do they produce transistors with only one electron I do not know. But the theory is already there. One must jump from science to engineering. Good luck to them!
Tullio

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A quantum simulator of impossible physics
it deals with operations prohibited in microscopic physical systems such as charge conjugation, which transforms a particle into an antiparticle, or time reversal, which reverses the direction of the time arrow.
http://phys.org/news/2015-10-quantum-simulator-impossible-physics.html

Next is the toughest part: how to go from a laboratory esperiment to mass production of microchips with quantum qubits. How do they produce transistors with only one electron I do not know. But the theory is already there. One must jump from science to engineering. Good luck to them!
Tullio

Seems like the University of New South Wales Australia is ahead with silicon quantum computers.

How To Make a Quantum Bit
https://www.youtube.com/watch?v=zNzzGgr2mhk

How Does a Transistor Work?
https://www.youtube.com/watch?v=IcrBqCFLHIY

Transistors & The End of Moore's Law
https://www.youtube.com/watch?v=rtI5wRyHpTg

How Does a Quantum Computer Work?
https://www.youtube.com/watch?v=g_IaVepNDT4

What is Quantum Mechanical Spin?
https://www.youtube.com/watch?v=v1_-LsQLwkA

Quantum Cooling to (Near) Absolute Zero
https://www.youtube.com/watch?v=7jT5rbE69ho

No, they just built a gate with 2 qubits. You need billions of them to make a computer.
Tullio

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No, they just built a gate with 2 qubits. You need billions of them to make a computer.
Tullio

My first computer had about 100 Kbits back in the 80's:)
A quantum computer needs a lot less of qubits than a classical one with bits to compute special algorithms.
A quantum computer with 100 Kqubits would be a quantum leap.

And The End of Moore's Law is soon here for classical computers...

they just built a gate with 2 qubits

What is the truth table for the input and output--what does it look like. What logical function does it perform (and, or etc).

How many inputs and how many outputs.

I was pondering over something yesterday evening.

We have the unattainability of zero in the law of thermodynamics. If there would be a theory of everything, wouldn't there have to be a general rule that speaks for quantum physics as well as for relativity. What I mean is, the scenario of the big crunch wouldn't exist in that case because there would be an infinite infiniteness. No beginning is possible as well as no end.

If the universe would end in a big rip or big freeze, what would happen with the dark energy? We all know dark energy as a hypothetical force that makes the universe expand at an accelerated rate. If all matter would have died, would the universe still expand because of that force? This also brings me back to the concept of time. Time never had a beginning, nor will it have an end, in my opinion.

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janneseti posted some things about this gate. I have no further information.
Tullio

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However, if the universe has a significant amount of dark energy then the expansion of the universe can continue forever—even if Ω > 1.

https://en.wikipedia.org/wiki/Ultimate_fate_of_the_universe

Are we sure or not sure yet about the existence of dark energy of which the universe would be comprised of for 68%? If we were to be sure, then we would know the fate of our universe.

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they just built a gate with 2 qubits

What is the truth table for the input and output--what does it look like. What logical function does it perform (and, or etc).

How many inputs and how many outputs.

AFAIK only a CNOT logic gate have been made.

However, if the universe has a significant amount of dark energy then the expansion of the universe can continue forever—even if Ω > 1.

=> even with a Closed Universe scenario

https://en.wikipedia.org/wiki/Ultimate_fate_of_the_universe

Are we sure or not sure yet about the existence of dark energy of which the universe would be comprised of for 68%? If we were to be sure, then we would know the fate of our universe.

NASA explains the following:

One explanation for dark energy is that it is a property of space. Albert Einstein was the first person to realize that empty space is not nothing. Space has amazing properties, many of which are just beginning to be understood. The first property that Einstein discovered is that it is possible for more space to come into existence. Then one version of Einstein's gravity theory, the version that contains a cosmological constant, makes a second prediction: "empty space" can possess its own energy. Because this energy is a property of space itself, it would not be diluted as space expands. As more space comes into existence, more of this energy-of-space would appear. As a result, this form of energy would cause the Universe to expand faster and faster. Unfortunately, no one understands why the cosmological constant should even be there, much less why it would have exactly the right value to cause the observed acceleration of the Universe.

[edit] Everyone is talking with such certainty about dark energy and yet it is still called a hypothetical force?

I think I read the NASA link before..

Another explanation for dark energy is that it is a new kind of dynamical energy fluid or field, something that fills all of space but something whose effect on the expansion of the Universe is the opposite of that of matter and normal energy. Some theorists have named this "quintessence," after the fifth element of the Greek philosophers. But, if quintessence is the answer, we still don't know what it is like, what it interacts with, or why it exists. So the mystery continues.

Ha! But we know it exists! So what does that tell us about the certainty on the fate of our universe?

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rOZZ
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I was pondering over something yesterday evening.

We have the unattainability of zero in the law of thermodynamics. If there would be a theory of everything, wouldn't there have to be a general rule that speaks for quantum physics as well as for relativity. What I mean is, the scenario of the big crunch wouldn't exist in that case because there would be an infinite infiniteness. No beginning is possible as well as no end.

If the universe would end in a big rip or big freeze, what would happen with the dark energy? We all know dark energy as a hypothetical force that makes the universe expand at an accelerated rate. If all matter would have died, would the universe still expand because of that force? This also brings me back to the concept of time. Time never had a beginning, nor will it have an end, in my opinion.

In our universe time did had a beginning.
The Big Bang theory says that both time and space was created in the "bang".
It's called the space-time fabric and you cannot separate them.
That universe will end seems impossible to me.
Only that all matter disappears, even blackholes, and all the energy is very dilluted.
I think that our universe will expand for ever and time will never stop.

NASA explains the following:

[quote]One explanation for dark energy is that it is a property of space.

It seems like "empty" space now have these properties, space, time, energy and dark energy.